[Federal Register Volume 61, Number 63 (Monday, April 1, 1996)]
[Notices]
[Pages 14420-14427]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-7852]




[[Page 14419]]

_______________________________________________________________________

Part VII





Department of Health and Human Services





_______________________________________________________________________



Agency for Toxic Substances and Disease Registry



_______________________________________________________________________



Update on the Status of the Superfund Substance-Specific Applied 
Research Program; Notice

  Federal Register / Vol. 61, No. 63 / Monday, April 1, 1996 / 
Notices  

[[Page 14420]]


DEPARTMENT OF HEALTH AND HUMAN SERVICES

Agency For Toxic Substances and Disease Registry
[ATSDR-106]


Update on the Status of the Superfund Substance-Specific Applied 
Research Program

AGENCY: Agency for Toxic Substances and Disease Registry (ATSDR), 
Department of Health and Human Services (HHS).

ACTION: Notice.

-----------------------------------------------------------------------

SUMMARY: This Notice is an update on the status of ATSDR's continuing 
effort to implement the Substance-Specific Applied Research Program 
(SSARP). Authorized by the Comprehensive Environmental Response, 
Compensation, and Liability Act of 1980 (Superfund) or CERCLA, as 
amended by the Superfund Amendments and Reauthorization Act of 1986 
(SARA) (42 U.S.C. 9604 (i)), this research program was initiated on 
October 17, 1991. At that time, a list of priority data needs for 38 
priority hazardous substances was announced in the Federal Register (56 
FR 52178). The list was subsequently revised based on public comments 
and published in final form on November 16, 1992 (57 FR 54150).
    The 38 substances, each of which is found on ATSDR's List of 
Priority Hazardous Substances, are aldrin/dieldrin, arsenic, benzene, 
beryllium, cadmium, carbon tetrachloride, chloroethane, chloroform, 
chromium, cyanide, p,p'-DDT,DDE,DDD, di(2- ethylhexyl) phthalate, lead, 
mercury, methylene chloride, nickel, polychlorinated biphenyl compounds 
(PCBs), polycyclic aromatic hydrocarbons (PAHs--includes 15 
substances), selenium, tetrachloroethylene, toluene, trichloroethylene, 
vinyl chloride, and zinc (56 FR 52166, October 17, 1991).
    Priority data needs for 12 additional priority hazardous substances 
were recently identified and are also being announced in a Federal 
Register Notice. The 12 substances, each of which is included in 
ATSDR's List of Priority Hazardous Substances, are chlordane, 1,2-
dibromo- 3-chloropropane, di-n-butyl phthalate, disulfoton, endrin 
(includes endrin aldehyde), endosulfan (alpha-, beta-, and endosulfan 
sulfate), heptachlor (includes heptachlor epoxide), 
hexachlorobutadiene, hexachlorocyclohexane (alpha-, beta-, delta- and 
gamma-), manganese, methoxychlor, and toxaphene.
    This Notice also serves as a continuous call for voluntary research 
proposals. Private-sector organizations may volunteer to conduct 
research to address specific priority data needs by indicating their 
interest through submission of a research proposal to ATSDR (see 
ADDRESSES section of this Notice). A Tri-Agency Superfund Applied 
Research Committee (TASARC) comprised of scientists from ATSDR, the 
National Toxicology Program (NTP), and the Environmental Protection 
Agency (EPA) will review all proposed voluntary research efforts.

DATES: ATSDR considers the voluntary research effort to be important to 
the continuing development of the SSARP. Therefore, the agency strongly 
encourages private-sector organizations to volunteer at any time to 
conduct research to address identified data needs unless ATSDR 
announces that research has already been initiated for that specific 
data need.

ADDRESSES: Private-sector organizations interested in volunteering to 
conduct research may write to Dr. William Cibulas, Chief, Research 
Implementation Branch, Division of Toxicology, ATSDR, 1600 Clifton 
Road, N.E., Mailstop E-29, Atlanta, Georgia 30333.

FOR FURTHER INFORMATION CONTACT: Dr. William Cibulas, Chief, Research 
Implementation Branch, Division of Toxicology, ATSDR, 1600 Clifton 
Road, N.E., Mailstop E-29, Atlanta, Georgia 30333, telephone 404-639-
6306.

SUPPLEMENTARY INFORMATION:

Background

    CERCLA as amended by SARA (42 U.S.C. 9604(i)) requires that ATSDR 
(1) jointly with the EPA, develop and prioritize a list of hazardous 
substances found at National Priorities List (NPL) sites, (2) prepare 
toxicological profiles for these substances, and (3) assure the 
initiation of a research program to address identified data needs 
associated with the substances. Before starting such a program, ATSDR 
will consider recommendations of the Interagency Testing Committee on 
the type of research that should be done. This committee was 
established under section 4(e) of the Toxic Substances Control Act of 
1976 (TSCA).
    On October 17, 1991, ATSDR announced the identification of the 
priority data needs for 38 priority hazardous substances (56 FR 52178), 
requested public comments, and invited private- sector organizations to 
volunteer to conduct research to address specific priority data needs. 
On November 16, 1992, the agency published a revised list of 117 
priority data needs for these priority hazardous substances (57 FR 
54150).
    The major goals of the ATSDR SSARP are (1) to address the 
substance-specific information needs of the public and scientific 
community, and (2) to supply necessary information to improve the 
database to conduct comprehensive public health assessments of 
populations living near hazardous waste sites. This program will also 
provide data that can be generalized to other substances or areas of 
science, including risk assessment of chemicals, thus creating a 
scientific base for addressing a broader range of data needs.
    In section 104(i)(5)(D), CERCLA states that it is the sense of 
Congress that the costs for conducting this research program be borne 
by the manufacturers and processors of the hazardous substances under 
TSCA and by registrants under the Federal Insecticide, Fungicide, and 
Rodenticide Act of 1972 (FIFRA), or by cost recovery from responsible 
parties under CERCLA. To execute this statutory intent, ATSDR developed 
a plan whereby parts of the SSARP are being conducted via regulatory 
mechanisms (TSCA/FIFRA), private-sector voluntarism, and through the 
direct use of CERCLA funds.
    The TASARC, comprised of scientists from ATSDR, NTP, and the EPA 
has been set up:
    (1) To advise on the assignment of priorities on mechanisms for 
addressing data needs;
    (2) To coordinate knowledge of research activities to avoid 
duplication of research in other programs and under other authorities;
    (3) To advise on issues of science related to substance-specific 
data needs; and
    (4) To maintain a scheduled forum that provides an overall review 
of the ATSDR SSARP.
    The TASARC has met six times since the SSARP began. This Notice is 
an update on the status of ATSDR's efforts to implement the SSARP, 
focusing on ongoing activities relevant to test-rule development under 
TSCA/FIFRA, private-sector voluntarism, and the direct use of CERCLA 
funds.
    Additional data needs are being addressed through an interagency 
agreement with NTP, by ATSDR's Great Lakes Human Health Effects 
Research Program, and other agency programs. To date, a total of 63 
research needs associated with 38 ATSDR priority hazardous substances 
(including 15 polycyclic aromatic hydrocarbons) are being addressed via 
these mechanisms (Table 1).

[[Page 14421]]

    ATSDR believes that these priority data needs will remain on the 
agency's list until ongoing studies to address them have been 
completed, peer-reviewed, and accepted by ATSDR. However, priority data 
needs could be deleted from the list (Table 1) if upon re-evaluation of 
the existing database, the agency determines that additional studies 
are no longer needed. Three recent examples follow. ATSDR, in 
consultation with the TASARC, re-evaluated the database for acute 
inhalation toxicity for vinyl chloride and determined no additional 
data are needed at this time (Table 1). With regard to the priority 
data need for oral developmental toxicity studies for 
tetrachloroethylene (PERC), ATSDR recently re-evaluated the database 
during the update of the toxicological profile for this substance. 
ATSDR concluded that the database was sufficient to derive a minimal 
risk level (MRL) for acute oral exposure based on a developmental 
toxicity study. Although ATSDR believes that additional developmental 
data would be useful to more fully characterize the effects and 
increase the confidence level of the MRL, the agency now believes that 
this data is more appropriately classified as a data need rather than a 
priority data need. Therefore, this priority data need has also been 
deleted from the list (Table 1). Similarly, the priority data need for 
additional acute oral studies for trichloroethylene has been 
reclassified as a data need and thus deleted from the list (Table 1) 
because an MRL was derived during the updating of the toxicological 
profile. Conversely, additional priority data needs could be included 
in the ATSDR list based on assessment by agency programs (See Section 
F, ``Other ATSDR Programs,'' which discusses exposure subregistries).

A. TSCA/FIFRA

    In developing and implementing the Substance-Specific Applied 
Research Program, ATSDR, NTP, and EPA have established procedures to 
identify priority data needs of mutual interest to Federal programs. 
These data needs are being addressed through a program of toxicologic 
testing under TSCA. This research will be conducted according to 
established TSCA procedures and guidelines. Generally, this testing 
will address more than one Federal program's need. Following review and 
endorsement by the TASARC oversight committee during fiscal year (FY) 
1993, of the 117 priority data needs for 38 substances, approximately 
60 priority data needs were referred to the EPA under TSCA/FIFRA 
authorities.
    During 1994, EPA added 11 ATSDR substances (and associated 26 
priority data needs) to its master testing list, the first step in 
test-rule development under TSCA, Section 4 (59 FR 11434, March 10, 
1994). On September 30, 1994, EPA published a Federal Register Notice 
soliciting testing proposals from industry to address the priority data 
needs identified for ATSDR's priority hazardous substances (59 FR 
49934). Although no manufacturers or processors of these substances 
came forward with testing proposals, several industry groups responded 
by submitting proposals to address some of the data needs via ATSDR's 
voluntary research program described in detail in Section B, ``Private-
Sector Voluntarism.'' The priority data needs currently being addressed 
by TSCA/FIFRA are listed in Table 2.
    ATSDR shared its priority data needs for these substances with 
other Federal agencies and programs. On several occasions when ATSDR 
identified priority data needs for oral exposure, other agencies needed 
inhalation data. In response, ATSDR is considering proposals to conduct 
inhalation studies in conjunction with physiologically based 
pharmacokinetic (PBPK) studies in lieu of oral bioassays. ATSDR expects 
that inhalation data derived from these studies can be used with PBPK 
modeling to address its oral toxicity data needs.
    Table 2 includes the priority data needs for three metals, i.e., 
beryllium, chromium and mercury. However, the specific forms of the 
metals to be tested are yet to be determined. The TASARC has 
established a workgroup to address this issue. The workgroup will also 
consider the needs of other Federal agencies and EPA programs. The EPA 
will solicit testing proposals for these three metals at a later date.

B. Private-Sector Voluntarism

    As part of the SSARP, on February 7, 1992, ATSDR initially 
announced a set of proposed procedures for conducting voluntary 
research (56 FR 4758). Revisions based on public comments were 
published on November 16, 1992 (57 FR 54160). Private-sector 
organizations were encouraged to volunteer to conduct research to 
address these specific priority data needs.
    ATSDR has been pursuing voluntary research interests with three 
private-sector organizations: the General Electric Company (GE), the 
Halogenated Solvents Industry Alliance (HSIA), and the Chemical 
Manufacturers Association (CMA). Preliminary discussions are being held 
with a fourth organization, the Shell Oil Company. Through the 
voluntary research efforts of these organizations, data needs for two 
classes of substances (PCB compounds and volatile organic compounds) 
are being addressed (Table 2). To date, two memoranda of understanding 
(MOU) have been signed by ATSDR and the interested parties. A third MOU 
is under development.

General Electric Company (GE)

    On February 8, 1995, ATSDR entered into an MOU with GE. This was 
the first time a private-sector organization volunteered to conduct 
research to address ATSDR's data needs identified in its SSARP. The MOU 
with GE covers the following three studies on PCBs:
    * Project 1, ``An assessment of the chronic toxicity and 
oncogenicity of Aroclor-1016, Aroclor-1242, Aroclor-1254, and Aroclor-
1260 administered in diet to rats,'' was initiated on February 8, 1993.
    * Project 2, ``Metabolite detection as a tool for the determination 
of naturally occurring aerobic PCB biodegradation,'' was initiated on 
January 2, 1995.
    * Project 3, ``PCB congener analyses,'' was initiated on February 
8, 1993.
    While the above studies do not address ATSDR's priority data needs 
for PCBs, the three projects will address some of the agency's data 
needs for these substances. Specifically, although ATSDR has identified 
bioassays via the inhalation and dermal routes as data needs for PCBs, 
agency scientists believe information gained via GE's oral bioassay 
(Project 1) is pertinent to understanding the toxicity of PCBs. 
Furthermore, first-pass metabolism does not appear to play a key role 
for these substances. Therefore, toxicity information to be obtained 
from the GE oral bioassay is expected to be relevant to the inhalation 
and dermal routes.
    ATSDR has identified PCB degradation in sediment as a data need. 
Additional environmental fate information is needed to estimate 
exposure to PCBs under various conditions of environmental release in 
order to plan and conduct follow-up exposure and health studies. 
Therefore, Project 2 will address ATSDR's data need for the 
environmental fate of PCBs.
    Although ATSDR has not identified PCB congener analyses (Project 3) 
as a data need, agency scientists believe that the toxicokinetics data 
(using selected tissues from Project 1) may provide important knowledge 
about the correlation of health effects with relevant PCB congeners.

[[Page 14422]]


Halogenated Solvents Industry Alliance (HSIA)

    On April 4, 1995, ATSDR entered into an MOU with HSIA covering 
studies to address three ATSDR priority toxicity data needs for 
methylene chloride. The studies consist of acute- and subchronic-
duration, and developmental toxicity via oral exposure. The data will 
be obtained by using PBPK modeling. These studies were initiated on May 
23, 1995.
    HSIA has also proposed to conduct a 28-day immunopathology 
assessment for methylene chloride via oral exposure, a priority data 
need identified by ATSDR. The agency expects to receive a study 
protocol from HSIA for peer review in the near future.
    Currently, HSIA and ATSDR continue to discuss voluntary research 
efforts for trichloroethylene (TCE) and tetrachloroethylene (PERC).
    With regard to TCE, ATSDR has recently reclassified the priority 
data need for acute oral data to a data need, (see Background section 
of this Notice). The agency is continuing its discussion with HSIA to 
assess the possibility of conducting a study or utilizing benchmark 
dose modeling to address this data need. As for immunopathology data, 
HSIA proposed to first review the existing data for TCE. If the data 
are inadequate and the methylene chloride immunopathology study 
mentioned above has provided meaningful information, HSIA would then 
conduct a similar study for TCE.
    Regarding the priority data needs for PERC, HSIA plans to obtain 
the oral neurotoxicity data called for by the agency by PBPK modeling. 
The database to be used for modeling will include the HSIA-sponsored 
inhalation neurotoxicity study recently approved by EPA. EPA and ATSDR 
scientists recently reviewed and accepted the HSIA-sponsored 
reproductive toxicity study of PERC via inhalation. HSIA proposed to 
address ATSDR's priority data need for oral reproductive data using 
PBPK modeling. As for ATSDR's priority data need for immunopathology 
data, HSIA would follow the same procedures as for TCE (described 
above).
    Finally, with regard to ATSDR's data need for oral developmental 
toxicity studies for PERC (see Background section of this Notice), 
ATSDR is continuing its discussion with HSIA to obtain this data via 
PBPK modeling once the EPA-required inhalation developmental toxicity 
study has been completed.

Chemical Manufacturers Association (CMA)

    During FY 1995, the CMA submitted a study protocol addressing two 
ATSDR priority data needs for vinyl chloride, specifically, inhalation 
reproductive and developmental toxicity studies in rats.
    ATSDR accepted the study protocol as a candidate for voluntary 
research based on ATSDR peer reviews and CMA's satisfactory response to 
the peer reviewers' comments. ATSDR expects to finalize an MOU with CMA 
covering this study in the near future.
    EPA no longer requires inhalation neurological data for vinyl 
chloride as originally stated in its solicitation Notice (59 FR 49934, 
September 30, 1994). Its decision is based on a recent reevaluation of 
the database.

C. CERCLA-Funded Research (Minority Health Professions Foundation 
Research Program)

    During FY 1992, ATSDR announced a $4 million cooperative agreement 
program with the Minority Health Professions Foundation (MHPF) to 
support substance-specific investigations. This cooperative venture is 
supported by the direct use of CERCLA funds. About $4 million was 
allocated annually for FYs 1993 to 1995 to continue this research 
program that ends in September 1997.
    Currently, 9 priority data needs for 21 priority hazardous 
substances (including 15 PAHs) in the SSARP are being addressed by the 
MHPF institutions through this program. Also, the MHPF research program 
will address 13 other substance-specific data needs identified in the 
ATSDR toxicological profiles concerning exposures and related health 
effects. To date, more than 20 abstracts have been presented at 
scientific meetings, 4 manuscripts have been published in peer-reviewed 
journals, and 7 manuscripts are in preparation. The institutions 
receiving awards and their respective research projects are listed in 
Table 2.
    A not-for-profit 501(c)(3) organization, the MHPF comprises 11 
minority health professions schools. Its primary mission is to research 
the health problems that disproportionately affect poor and minority 
citizens. The purposes of the ATSDR-MHPF cooperative agreement are (1) 
to initiate research to address ATSDR-identified data needs for 
priority hazardous substances, and (2) to enhance existing disciplinary 
capacities to conduct research in environmental health at MHPF member 
institutions.
    The areas of research at MHPF institutions include those related to 
broad areas of toxicology and environmental health science. Some MHPF 
members are conducting health studies of minority groups exposed to 
ATSDR's priority hazardous substances.

D. National Toxicology Program (NTP)

    ATSDR maintains an interagency agreement (IAG) with NTP to conduct 
toxicologic testing of substances identified at NPL sites. The studies 
determine levels of exposure that present a significant risk to humans 
of acute, subchronic, and chronic health effects. Often these studies 
include an assessment of the substance's ability to cause cancer, 
reproductive toxicity, and birth defects. The results of these studies 
are used by regulatory agencies such as the Food and Drug 
Administration and EPA, various environmental and industrial groups, 
and ATSDR to improve the ability to conduct public health assessments 
at NPL sites.
    Under this agreement, one toxicity priority data need identified in 
the SSARP (immunotoxicology study of carbon tetrachloride) is being 
addressed.
    An area of ongoing research by the NTP is to study the 
bioavailability of PCBs in soil, a priority data need for ATSDR. 
Therefore, NTP research may also potentially address this ATSDR 
priority data need.
    During FY 1993, the existing IAG was modified to include toxicity 
studies of ATSDR's priority hazardous substances via application of 
structure-activity relationship (SAR) techniques and PBPK modeling. NTP 
indicated future plans for SAR modeling for reproductive and 
immunologic endpoints. ATSDR is continuing to work closely with NTP as 
the agency has identified many reproductive and immunologic data needs 
for the 38 priority hazardous substances. As discussed in Section A, 
``TSCA/FIFRA,'' ATSDR will consider using PBPK modeling to address data 
needs when models are well developed and validated. Therefore, ATSDR 
will continue to work closely with NTP in its efforts to refine the 
models.

E. Great Lakes Human Health Effects Research Program

    Some of the priority data needs identified in the SSARP have been 
independently identified as research needs through the ATSDR Great 
Lakes Human Health Effects Research Program, a separate research 
program. To date, 12 priority data needs for 19 priority hazardous 
substances (including 15 PAHs) identified in the SSARP are being 
addressed through this program. The institutions receiving

[[Page 14423]]
awards and their respective studies are listed in Table 2.
    The Great Lakes Critical Programs Act of 1990 mandated that EPA, in 
consultation with ATSDR, prepare a report that assesses the adverse 
effects of pollutants in the Great Lakes system on the health of 
individuals in the Great Lakes states. This report was recently 
transmitted to the Congress by the EPA Administrator.
    In support of this directive, ATSDR received funds to carry out 
research. The ATSDR-supported research projects focus on at-risk 
populations to further define the human health consequences of exposure 
to persistently toxic substances in the Great Lakes basin. The research 
activities include but are not limited to the following:
    (1) Characterizing exposure and determining the profiles and levels 
of Great Lakes contaminants in biologic tissues and fluids in at-risk 
populations;
    (2) Identifying sensitive and specific human reproductive/
developmental endpoints and correlating them to exposure to Great Lakes 
contaminants;
    (3) Determining the short- and long-term risk(s) of adverse health 
effects in progeny whose parents were exposed to Great Lakes 
contaminants;
    (4) Investigating the feasibility of establishing registries and 
surveillance cohorts in the Great Lakes region; and
    (5) Establishing a chemical mixtures database with emphasis on 
tissue and blood levels in order to identify new cohorts, conduct 
surveillance and health effects studies, and establish registries and 
surveillance cohorts.
    During FY 1992, ATSDR announced a $2 million grant program to 
conduct research on the impact on people's health from eating 
contaminated fish from the Great Lakes region. On September 30, 1992, 
ATSDR announced 9 awards under this program.
    In FY 1993, about $3 million was allocated to support the 
continuation of the research projects conducted at the 9 institutions 
originally funded during FY 1992. In addition, ATSDR awarded one new 
grant to the Michigan Department of Public Health to design, establish, 
and operate a professionally creditable, interlaboratory quality 
assurance/quality control program for the ATSDR Great Lakes Human 
Health Effects Research Program. Additional funding of $3 million and 
$4 million for FYs 1994 and 1995, respectively, was allocated to 
continue support of the 10 research projects.
    During FY 1994, ATSDR held a Great Lakes Research Symposium in 
Detroit, Michigan. The proceedings of the symposium will be published 
in the Journal of Toxicology and Industrial Health in the near future.

Other ATSDR Programs

    In its role as a public health agency addressing environmental 
health, when appropriate, ATSDR may collect human data to validate 
substance-specific exposure and toxicity findings. Information on 
levels of contaminants in humans has been identified and remains as a 
priority data need for 37 of the 38 priority substances (Table 1). 
ATSDR will obtain this information through exposure and health effects 
studies, and through establishing and using substance-specific 
subregistries of people within the agency's National Exposure Registry 
who have potentially been exposed to these substances.
    The list of 38 priority hazardous substances in the SSARP was 
forwarded to ATSDR's Exposure and Disease Registry Branch (EDRB), 
Division of Health Studies, for consideration as potential candidates 
for subregistries of exposed persons, based on criteria described in 
its 1988 document, ``Policies and Procedures for Establishing a 
National Registry of Persons Exposed to Hazardous Substances.''
    To date, ATSDR has selected benzene, chromium, and 
trichloroethylene as primary contaminants to establish subregistries in 
the National Exposure Registry. However, aldrin/dieldrin, carbon 
tetrachloride, chloroethane, chloroform, cyanide, p,p'- DDT, DDE, DDD, 
di(2-ethylhexyl)phthalate, mercury, methylene chloride, PAHs, selenium, 
tetrachloroethylene, and vinyl chloride remain in the candidate pool. 
They will be considered for selection as primary contaminants during 
each selection process (Table 1).
    Since the publication of the ATSDR March 10, 1994, Federal Register 
Notice (59 FR 11434), EDRB has re-evaluated the databases and included 
nickel, PCBs, toluene, and zinc in the candidate pool for consideration 
during each selection process (Table 1). However, arsenic, beryllium, 
cadmium, and lead are not considered to be in the pool of candidate 
substances for an exposure registry at this time. This decision will be 
re-evaluated as more information on the chemicals and exposure sites 
become available.
    Finally, the need to collect, evaluate, and interpret environmental 
data from contaminated media around hazardous waste sites remains a 
priority data need for all 38 priority hazardous substances by ATSDR. 
However, agency scientists realize that a substantial amount of this 
information has already been collected through individual State 
programs and the EPA's CERCLA activities; therefore, ATSDR will 
evaluate the extant information from these programs to characterize 
better the need for additional site-specific information.
    The results of the research conducted via the SSARP will be used 
for public health assessments and to reassess ATSDR's substance-
specific priority data needs. The agency expects to re-evaluate the 
priority data needs for priority hazardous substances every three 
years.

    Dated: March 26, 1996.
Claire V. Broome,
Deputy Administrator, Agency for Toxic Substances and Disease Registry 
.

 Table 1.--Substance-Specific Priority Data Needs (PDN) Currently Being 
            Addressed Under ATSDR's Applied Research Programs           
------------------------------------------------------------------------
      Substance           PDN ID        PDN description     Programs (1)
------------------------------------------------------------------------
Lead................  1A             Mechanistic studies   M            
                                      on the neurotoxic                 
                                      effects of lead.                  
                      1B             Analytical methods                 
                                      for tissue levels.                
                      1C             Exposure levels in    M, G         
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
Arsenic.............  2A             Comparative           .............
                                      toxicokinetic                     
                                      studies to                        
                                      determine if an                   
                                      appropriate animal                
                                      species can be                    
                                      identified.                       
                      2B             Half-lives in                      
                                      surface water,                    
                                      groundwater.                      
                      2C             Bioavailability from               
                                      soil.                             
                      2D             Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers                
Mercury.............  3A             Multigeneration       M, G         
                                      reproductive                      
                                      toxicity study via                
                                      oral exposure.                    
                      3B             Dose-response data    E            
                                      in animals for                    
                                      chronic-duration                  
                                      oral exposure.                    

[[Page 14424]]
                                                                        
                      3C             Immunotoxicology      E            
                                      battery of tests                  
                                      via oral exposure.                
                      3D             Exposure levels in    G            
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
                      3E             Potential candidate   A, G         
                                      for subregistry of                
                                      exposed persons.                  
Vinyl Chloride......  4A             Dose-response data    O (2)        
                                      in animals for                    
                                      acute-duration                    
                                      inhalation exposure.              
                      4B             Multigeneration       V (7)        
                                      reproductive                      
                                      toxicity study via                
                                      inhalation.                       
                      4C             Dose-response data                 
                                      in animals for                    
                                      chronic-duration                  
                                      inhalation                        
                                      exposure.                         
                      4D             Mitigation of vinyl                
                                      chloride-induced                  
                                      toxicity.                         
                      4E             2-species             V (7)        
                                      developmental                     
                                      toxicity study via                
                                      inhalation.                       
                      4F             Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers                
                      4G             Potential candidate   A            
                                      for subregistry of                
                                      exposed persons.                  
Benzene.............  5A             Dose-response data    E            
                                      in animals for                    
                                      acute- and                        
                                      intermediate-                     
                                      duration oral                     
                                      exposure. The                     
                                      subchronic study                  
                                      should include an                 
                                      extended                          
                                      reproductive organ                
                                      histopathology.                   
                      5B             2-species             M            
                                      developmental                     
                                      toxicity study via                
                                      oral exposure.                    
                      5C             Neurotoxicology       E            
                                      battery of tests                  
                                      via oral exposure.                
                      5D             Epidemiologic                      
                                      studies on the                    
                                      health effects of                 
                                      benzene (Special                  
                                      emphasis endpoints                
                                      include                           
                                      immunotoxicity).                  
                      5E             Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
Cadmium.............  6A             Analytical methods                 
                                      for biological                    
                                      tissues and fluids                
                                      and environmental                 
                                      media.                            
                      6B             Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
PCBs................  7A             Dose-response data    G            
                                      in animals for                    
                                      acute- and                        
                                      intermediate-                     
                                      duration oral                     
                                      exposures.                        
                      7B             Biodegradation of                  
                                      PCBs in water;                    
                                      bioavailability of                
                                      PCBs in air, water                
                                      and soil                          
                      7C             Dose-response data                 
                                      in animals for                    
                                      acute- and                        
                                      intermediate-                     
                                      duration inhalation               
                                      exposures. The                    
                                      subchronic study                  
                                      should include                    
                                      extended                          
                                      reproductive organ                
                                      histopathology                    
                      7D             Epidemiologic         G            
                                      studies on the                    
                                      health effects of                 
                                      PCBs (Special                     
                                      emphasis endpoints                
                                      include                           
                                      immunotoxicity,                   
                                      gastrointestinal                  
                                      toxicity, liver,                  
                                      kidney, thyroid                   
                                      toxicity,                         
                                      reproductive/                     
                                      developmental                     
                                      toxicity).                        
                      7E             Exposure levels in    G            
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
                      7F             Potential candidate   A (3)        
                                      for subregistry of                
                                      exposed persons.                  
                      7G (8)         Chronic toxicity and  V            
                                      oncogenicity via                  
                                      oral exposure.                    
                      7H (8)         Aerobic PCB           V            
                                      biodegradation in                 
                                      sediment.                         
                      7I (8)         PCB congener          V            
                                      analysis.                         
Chloroform..........  8A             Dose-response data                 
                                      in animals for                    
                                      intermediate-                     
                                      duration oral                     
                                      exposure.                         
                      8B             Epidemiologic                      
                                      studies on the                    
                                      health effects of                 
                                      chloroform (Special               
                                      emphasis endpoints                
                                      include cancer,                   
                                      neurotoxicity,                    
                                      reproductive and                  
                                      developmental                     
                                      toxicity,                         
                                      hepatotoxicity, and               
                                      renal toxicity)                   
                      8C             Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers                
                      8D             Potential candidate   A            
                                      for subregistry of                
                                      exposed persons.                  
  PAHs..............  9A             Dose-response data    M            
                                      in animals for                    
                                      intermediate                      
                                      duration oral                     
                                      exposures. The                    
                                      subchronic study                  
                                      should include                    
                                      extended                          
                                      reproductive organ                
                                      histopathology and                
                                      immunopathology.                  
                      9B             2-Species                          
                                      developmental                     
                                      toxicity study via                
                                      inhalation or oral                
                                      exposure                          
                      9C             Mechanistic studies                
                                      on PAHs, on how                   
                                      mixtures of PAHs                  
                                      can influence the                 
                                      ultimate activation               
                                      of PAHs, and on how               
                                      PAHs affect rapidly               
                                      proliferating                     
                                      tissues                           
                      9D             Dose-response data    M            
                                      in animals for                    
                                      acute- and                        
                                      intermediate-                     
                                      duration inhalation               
                                      exposures. The                    
                                      subchronic study                  
                                      should include                    
                                      extended                          
                                      reproductive organ                
                                      histopathology and                
                                      immunopathology.                  
                      9E             Epidemiologic         G            
                                      studies on the                    
                                      health effects of                 
                                      PAHs (Special                     
                                      emphasis endpoints                
                                      include cancer,                   
                                      dermal,                           
                                      hemolymphatic, and                
                                      hepatic).                         
                      9F             Exposure levels in    G            
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
                      9G             Potential candidate   A            
                                      for subregistry of                
                                      exposed persons.                  
Trichloro-ethylene..  10A            Dose-response data    O (2)        
                                      in animals for                    
                                      acute- duration                   
                                      oral exposure..                   
                      10B            Neurotoxicology       M            
                                      battery of tests                  
                                      via the oral route.               
                      10C            Immunotoxicology      V (4)        
                                      battery of tests                  
                                      via the oral route.               
                      10D            Epidemiologic                      
                                      studies on the                    
                                      health effects of                 
                                      trichloroethylene                 
                                      (Special emphasis                 
                                      endpoints include                 
                                      cancer,                           
                                      hepatotoxicity,                   
                                      renal toxicity,                   
                                      developmental                     
                                      toxicity, and                     
                                      neurotoxicity).                   
                      10E            Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
DDT.................  11A            Dose-response data                 
                                      in animals for                    
                                      chronic-duration                  
                                      oral exposure.                    
                      11B            Comparative                        
                                      toxicokinetic study               
                                      (across routes/                   
                                      species).                         
                      11C            Bioavailability and                
                                      bioaccumulation                   
                                      from soil.                        
                      11D            Epidemiologic         G            
                                      studies on the                    
                                      health effects of                 
                                      DDT, DDD and DDE                  
                                      (Special emphasis                 
                                      endpoints include                 
                                      immunotoxicity,                   
                                      reproductive and                  
                                      developmental                     
                                      toxicity).                        
                      11E            Exposure levels in    G            
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               

[[Page 14425]]
                                                                        
                      11F            Potential candidate   A, G         
                                      for subregistry of                
                                      exposed persons.                  
Chromium............  12A            Dose-response data    E            
                                      in animals for                    
                                      acute-duration                    
                                      exposure to                       
                                      chromium (VI) and                 
                                      (III) via oral                    
                                      exposure and for                  
                                      intermediate-                     
                                      duration exposure                 
                                      to chromium (VI)                  
                                      via oral exposure.                
                      12B            Multigeneration       E            
                                      reproductive                      
                                      toxicity study via                
                                      oral exposure to                  
                                      chromium (III) and                
                                      (VI).                             
                      12C            Immunotoxicology      E            
                                      battery of tests                  
                                      following oral                    
                                      exposure to                       
                                      chromium (III) and                
                                      (VI).                             
                      12D            2-Species                          
                                      developmental                     
                                      toxicity study via                
                                      oral exposure to                  
                                      chromium (III) and                
                                      (VI)                              
                      12E            Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
Tetrachloro-          13A            Dose-response data    V(4, 5)      
 ethylene.                            in animals for                    
                                      acute-duration oral               
                                      exposure, including               
                                      neuropathology and                
                                      demeanor, and                     
                                      immunopathology.                  
                      13B            Multigeneration       V(4, 5)      
                                      reproductive                      
                                      toxicity study via                
                                      oral exposure.                    
                      13C            Dose-response data                 
                                      in animals for                    
                                      chronic-duration                  
                                      oral exposure,                    
                                      including                         
                                      neuropathology and                
                                      demeanor, and                     
                                      immunopathology                   
                      13D            2-Species             O (2)        
                                      developmental                     
                                      toxicity study via                
                                      oral exposure.                    
                      13E            Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
                      13F            Potential candidate   A            
                                      for subregistry of                
                                      exposed persons                   
Aldrin/Dieldrin.....  14A            Dose-response data                 
                                      in animals for                    
                                      intermediate-                     
                                      duration oral                     
                                      exposure.                         
                      14B            Bioavailability from               
                                      soil.                             
                      14C            Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
                      14D            Potential candidate   A            
                                      for subregistry of                
                                      exposed persons.                  
Cyanide.............  15A            Dose-response data    E            
                                      in animals for                    
                                      acute- and                        
                                      intermediate-                     
                                      duration exposures                
                                      via inhalation. The               
                                      subchronic study                  
                                      should include                    
                                      extended                          
                                      reproductive organ                
                                      histopathology and                
                                      evaluation of                     
                                      neurobehavioral and               
                                      neuropathological                 
                                      endpoints.                        
                      15B            2-Species             E            
                                      developmental                     
                                      toxicity study via                
                                      oral exposure.                    
                      15C            Evaluation of the     E            
                                      environmental fate                
                                      of cyanide in soil.               
                      15D            Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
                      15E            Potential candidate   A            
                                      for subregistry of                
                                      exposed persons.                  
Carbon Tetrachloride  16A            Dose-response data                 
                                      in animals for                    
                                      chronic oral                      
                                      exposure. The study               
                                      should include                    
                                      extended                          
                                      reproductive organ                
                                      and nervous tissue                
                                      (and demeanor)                    
                                      histopathology.                   
                      16B            Immunotoxicology      NTP          
                                      battery of tests                  
                                      via oral exposure.                
                      16C            Half-life in soil.                 
                      16D            Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
                      16E            Potential candidate   A            
                                      for subregistry of                
                                      exposed persons.                  
Beryllium...........  17A            Dose-response data    E            
                                      in animals for                    
                                      acute- and                        
                                      intermediate-                     
                                      duration inhalation               
                                      exposures. The                    
                                      subchronic study                  
                                      should include                    
                                      extended                          
                                      reproductive organ                
                                      histopathology.                   
                      17B            2-Species             E            
                                      developmental                     
                                      toxicity study via                
                                      inhalation exposure.              
                      17C            Environmental fate    E            
                                      in air; factors                   
                                      affecting                         
                                      bioavialability in                
                                      air.                              
                      17D            Analytical methods                 
                                      to determine                      
                                      environmental                     
                                      speciation.                       
                      17E            Immunotoxicology      E            
                                      battery of tests                  
                                      following oral                    
                                      exposure.                         
                      17F            Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
Toluene.............  18A            Dose-response data    E            
                                      in animals for                    
                                      acute- and                        
                                      intermediate-                     
                                      duration oral                     
                                      exposures. The                    
                                      subchronic study                  
                                      should include an                 
                                      extended                          
                                      histopathologic                   
                                      evaluation of the                 
                                      immune system.                    
                      18B            Comparative           E            
                                      toxicokinetic                     
                                      studies                           
                                      (Characterization                 
                                      of absorption,                    
                                      distribution, and                 
                                      excretion via oral                
                                      exposure).                        
                      18C            Neurotoxicology       M            
                                      battery of tests                  
                                      via oral exposure..               
                      18D            Mechanism of toluene-              
                                      induced                           
                                      neurotoxicity.                    
                      18E            Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
                      18F            Potential candidate   A (3)        
                                      for subregistry of                
                                      exposed persons.                  
Nickel..............  19A            Epidemiologic                      
                                      studies on the                    
                                      health effects of                 
                                      nickel (Special                   
                                      emphasis endpoints                
                                      include                           
                                      reproductive                      
                                      toxicity).                        
                      19B            2-Species                          
                                      developmental                     
                                      toxicity study via                
                                      the oral route.                   
                      19C            Dose-response data                 
                                      in animals for                    
                                      acute- and                        
                                      intermediate-                     
                                      duration oral                     
                                      exposures.                        
                      19D            Neurotoxicology                    
                                      battery of tests                  
                                      via oral exposure.                
                      19E            Bioavailability of                 
                                      nickel from soil.                 
                      19F            Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
                      19G            Potential candidate   A (3)        
                                      for subregistry of                
                                      exposed persons.                  
Methylene Chloride..  20A            Dose-response data    V (5,6)      
                                      in animals for                    
                                      acute- and                        
                                      intermediate-                     
                                      duration oral                     
                                      exposure. The sub-                
                                      chronic study                     
                                      should include                    
                                      extended                          
                                      reproductive organ                
                                      histopathology,                   
                                      neuropathology and                
                                      demeanor, and                     
                                      immunopathology.                  
                      20B            2-Species             V (5)        
                                      developmental                     
                                      toxicity study via                
                                      the oral route.                   
                      20C            Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
                      20D            Potential candidate   A            
                                      for subregistry of                
                                      exposed persons.                  

[[Page 14426]]
                                                                        
Zinc................  21A            Dose-response data    M            
                                      in animals for                    
                                      acute- and                        
                                      intermediate-                     
                                      duration oral                     
                                      exposures. The sub-               
                                      chronic study                     
                                      should include an                 
                                      extended                          
                                      histopathologic                   
                                      evaluation of the                 
                                      immunologic and                   
                                      neurologic systems.               
                      21B            Multigeneration                    
                                      reproductive                      
                                      toxicity study via                
                                      oral exposure.                    
                      21C            Carcinogenicity                    
                                      testing (2-year                   
                                      bioassay) via oral                
                                      exposure.                         
                      21D            Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
                      21E            Potential candidate   A (3)        
                                      for subregistry of                
                                      exposed persons.                  
DEHP................  22A            Epidemiologic                      
                                      studies on the                    
                                      health effects of                 
                                      DEHP (Special                     
                                      emphasis endpoints                
                                      include cancer).                  
                      22B            Dose-response data                 
                                      in animals for                    
                                      acute- and                        
                                      intermediate-                     
                                      duration oral                     
                                      exposures. The                    
                                      subchronic study                  
                                      should include an                 
                                      extended                          
                                      histopathologic                   
                                      evaluation of the                 
                                      immunologic and                   
                                      neurologic systems.               
                      22C            Multigeneration                    
                                      reproductive                      
                                      toxicity study via                
                                      oral exposure.                    
                      22D            Comparative           E            
                                      toxicokinetic                     
                                      studies (Studies                  
                                      designed to examine               
                                      how primates                      
                                      metabolize and                    
                                      distribute DEHP as                
                                      compared to rodents               
                                      via oral exposure).               
                      22E            Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
                      22F            Potential candidate   A            
                                      for subregistry of                
                                      exposed persons.                  
Selenium............  23A            Dose-response data                 
                                      in animals for                    
                                      acute-duration oral               
                                      exposure.                         
                      23B            Immunotoxicology                   
                                      battery of tests                  
                                      via oral exposure.                
                      23C            Epidemiologic                      
                                      studies on the                    
                                      health effects of                 
                                      selenium (Special                 
                                      emphasis endpoints                
                                      include cancer,                   
                                      reproductive and                  
                                      developmental                     
                                      toxicity,                         
                                      hepatotoxicity and                
                                      adverse skin                      
                                      effects).                         
                      23D            Exposure levels in                 
                                      humans living near                
                                      hazardous waste                   
                                      sites and other                   
                                      populations, such                 
                                      as exposed workers.               
                      23E            Potential candidate   A            
                                      for subregistry of                
                                      exposed persons.                  
Chloroethane........  24A            Dose-response data    E            
                                      in animals for                    
                                      acute- and                        
                                      intermediate-                     
                                      duration oral                     
                                      exposures. The                    
                                      subchronic study                  
                                      should include an                 
                                      evaluation of                     
                                      immune and nervous                
                                      system tissues, and               
                                      extended                          
                                      reproductive organ                
                                      histopathology.                   
                      24B            Dose-response data                 
                                      in animals for                    
                                      chronic inhalation                
                                      exposures. The                    
                                      study should                      
                                      include an                        
                                      evaluation of                     
                                      nervous system                    
                                      tissues.                          
                      24C            Potential candidate   A            
                                      for subregistry of                
                                      exposed persons.                  
------------------------------------------------------------------------
\1\ ATSDR programs for addressing data needs. A=ATSDR Division of Health
  Studies; E=Environmental Protection Agency-TSCA/FIFRA testing; G=Great
  Lakes Human Health Research Program; M=Minority Health Professions    
  Foundation Schools; NTP=National Toxicology Program; V=Voluntary      
  research; O=Other.                                                    
\2\ No longer considered a priority data need based on recent evaluation
  of the database by ATSDR.                                             
\3\ These substances have been included in the pool of candidate        
  substances for subregistry development since the publication of the   
  Federal Register notice on March 10, 1994 (59 FR 11434).              
\4\ Potentially to be addressed by ATSDR's Voluntary Research Program.  
\5\ Data to be obtained by PBPK modeling.                               
\6\ Initiation of immunopathology study pending submission and peer     
  review of study protocol.                                             
\7\ Data to be obtained from a combined 2-generation reproduction and   
  developmental toxicity study in rats.                                 
\8\ Not a priority data need.                                           



                           Table 2.--Groups Addressing ATSDR Priority Data Needs (PDN)                          
----------------------------------------------------------------------------------------------------------------
                                    Firm, institution, agency,                                                  
           ATSDR Program                   or Consortium              Substance                 PDN ID          
----------------------------------------------------------------------------------------------------------------
Voluntarism.......................  Chemical Manufacturers      Vinyl Chloride......  4B, 4E                    
                                     Association.                                                               
                                    General Electric Company..  PCBs................  7G, 7H, 7I                
                                    Halogenated Solvents        Trichloroethylene...  10C                       
                                     Industry Alliance.                                                         
                                                                Tetrachloroethylene.  13A, 13B                  
                                                                Methylene chloride..  20A, 20B                  
Minority Health Professions         Florida A & M University..  Lead................  1A                        
 Foundation Schools.                                                                                            
                                    The King/Drew Medical       Lead................  1C                        
                                     Center of the Charles R.                                                   
                                     Drew University of                                                         
                                     Medicine and Science.                                                      
                                    Meharry Medical College...  PAHs................  9A, 9D                    
                                    Morehouse School of         Lead................  1C                        
                                     Medicine.                                                                  
                                    Texas Southern University.  Lead................  1A                        
                                                                Trichloroethylene...  10B                       
                                                                Toluene.............  18C                       
                                    Tuskegee University.......  Mercury.............  3A                        
                                                                Zinc................  21A                       
                                    Xavier University.........  Benzene.............  5B                        
                                                                Zinc................  21A                       
Great Lakes Human Health Research   Michigan State University.  Lead................  1C                        
 Program.                                                                                                       
                                                                Mercury.............  3D                        
                                                                PCBs................  7F                        

[[Page 14427]]
                                                                                                                
                                                                DDT.................  11D, 11E                  
                                    New York State Health       Lead................  1C                        
                                     Department.                                                                
                                                                Mercury.............  3D                        
                                                                PCBs................  7F                        
                                    State University of New     Lead................  1C                        
                                     York at Buffalo.                                                           
                                                                Mercury.............  3D                        
                                                                PCBs................  7E, 7F                    
                                                                DDT.................  11D, 11E                  
                                    State University of New     Lead................  1C                        
                                     York at Oswego.                                                            
                                                                Mercury.............  3A, 3D                    
                                                                PCBs................  7E, 7F                    
                                                                DDT.................  11D, 11E                  
                                    University of Illinois at   Lead................  1C                        
                                     Chicago.                                                                   
                                                                Mercury.............  3A, 3D                    
                                                                PCBs................  7E, 7F                    
                                                                DDT.................  11D, 11E                  
                                    University of Illinois at   Lead................  1C                        
                                     Urbana-Champaign.                                                          
                                                                Mercury.............  3D                        
                                                                PCBs................  7E, 7F                    
                                    University of Wisconsin--   Lead................  1C                        
                                     Superior.                                                                  
                                                                Mercury.............  3D                        
                                                                PCBs................  7A, 7E, 7F                
                                    Wisconsin Department of     Lead................  1C                        
                                     Health and Social                                                          
                                     Services.                                                                  
                                                                Mercury.............  3D, 3E                    
                                                                PCBs................  7F                        
                                                                PAHs................  9E, 9F                    
                                    ..........................  DDT.................  11D, 11E, 11F             
TSCA/FIFRA........................  Environmental Protection    Mercury.............  3B                        
                                     Agency.                                                                    
                                                                Mercury.............  3C                        
                                                                Benzene.............  5A                        
                                                                Benzene.............  5C                        
                                                                Chromium............  12A                       
                                                                Chromium............  12B                       
                                                                Chromium............  12C                       
                                                                Cyanide.............  15A                       
                                                                Cyanide.............  15B                       
                                                                Cyanide.............  15C                       
                                                                Beryllium...........  17A                       
                                                                Beryllium...........  17B                       
                                                                Beryllium...........  17C                       
                                                                Beryllium...........  17E                       
                                                                Toluene.............  18A                       
                                                                Toluene.............  18B                       
                                                                DEHP................  22D                       
                                                                Chloroethane........  24A                       
National Toxicology Program.......  National Institute of       Carbon Tetrachloride  16B                       
                                     Environmental Health                                                       
                                     Sciences.                                                                  
----------------------------------------------------------------------------------------------------------------


[FR Doc. 96-7852 Filed 3-29-96; 8:45 am]
BILLING CODE 4163-70-P