[Federal Register Volume 64, Number 9 (Thursday, January 14, 1999)]
[Notices]
[Pages 2492-2493]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-890]



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ENVIRONMENTAL PROTECTION AGENCY

[FRL-6219-3]


Technical Workshop on Perchlorate Risk Issues

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of meeting.

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SUMMARY: EPA is announcing a workshop convened by the Research Triangle 
Institute (RTI), an EPA contractor, for external scientific peer review 
of the EPA draft document entitled ``Perchlorate Environmental 
Contamination: Toxicological Review and Risk Characterization Based on 
Emerging Information.'' The workshop will be held in San Bernardino, 
California, and will be open to members of the public as observers. The 
peer review, to be conducted by scientists from outside EPA, is being 
organized to assist in completing the toxicological review and risk 
characterization of perchlorate, and will include the protocols and 
reports of recent studies on perchlorate, as well as EPA's draft 
Toxicological Review document. Stakeholders in the perchlorate issue 
who have additional information which is relevant to the assessment of 
the potential health and ecological effects of perchlorate are invited 
to make a short presentation of this information at the peer review 
workshop.

DATES: The workshop will begin on Wednesday, February 10, 1999 at 8:30 
a.m. and end on Thursday, February 11, 1999 at 12:30 p.m. Members of 
the public may attend as observers.

ADDRESSES: The meeting will be held at the San Bernardino City Council 
Chambers, 300 North D Street, San Bernardino, California 92418. Since 
seating capacity is limited, please contact Ella Darden of RTI, by 
telephone, at 919-541-7026; by facsimile, at 919-541-7155; or by E-
mail, at [email protected], by January 31, 1999 to attend the workshop as an 
observer. Observers who wish to make a short presentation of 
information which may be relevant to the assessment of potential health 
and ecological effects of perchlorate should register to do so with RTI 
by January 31, 1999.

FOR FURTHER INFORMATION CONTACT: For technical and logistical inquires, 
contact Ella Darden, Research Triangle Institute, by telephone, at 919-
541-7026; by facsimile, at 919-541-7155; or by E-mail, at [email protected]. 
Copies of the draft Toxicological Review document will be available for 
inspection on EPA's National Center for Environmental Assessment web 
site (http://www.epa.gov/ncea/), at EPA's Regional Superfund Records 
Centers, and at the EPA Headquarters Information Resources Center, 
Washington DC. Inquiries concerning additional opportunities for 
document review should be directed to Ella Darden at Research Triangle 
Institute.

SUPPLEMENTARY INFORMATION:

Background

    EPA is in the process of conducting a toxicological review for 
perchlorate, including the development of a revised provisional 
reference dose (RfD), a cancer assessment, and an ecological 
assessment. An RfD is an estimate of a daily oral human exposure that 
will result in no deleterious noncancer effects over a lifetime. 
Ideally, an RfD is based on an array of endpoints that address 
potential toxicity during various critical life stages, from developing 
fetus through adult and reproductive stages. The noncancer, cancer and 
ecological assessments may be used to support development of a health 
advisory and/or drinking water regulations and cleanup decisions at 
hazardous waste sites. In accordance with EPA's 1998 Peer Review 
Handbook, a key step in the development of the Toxicological Review 
document for perchlorate is the upcoming external peer review, in the 
form of a workshop, which will cover protocols for and reports of the 
recently completed toxicity studies, the Toxicological Review document, 
and the proposed revised provisional RfD, cancer assessment and 
ecological assessment in that document.
    EPA's Superfund Technical Support Center issued a provisional RfD 
for perchlorate in 1992 and a revised provisional RfD in 1995. The 
provisional RfD values (1992 and 1995) were based on an acute study in 
which single doses of potassium perchlorate caused the release of 
iodide from the thyroids of patients with Graves' Disease. The 
provisional RfD values did not undergo internal Agency, or external, 
peer review. In March of 1997 a peer review panel convened by an 
independent organization, Toxicology Excellence for Risk Assessment 
(TERA), determined that the health effects and toxicity data for 
perchlorate were insufficient to generate a credible RfD for risk 
assessment purposes. The reviewers were concerned that developmental 
toxicity, notably neurological development due to hypothyroidism during 
pregnancy, could be a critical health effect of perchlorate that has 
not been adequately examined in studies to date. They also concluded 
that insufficient data were available on potential effects of 
perchlorate on organs and tissues other than the thyroid.

New Health Effects/Toxicology Studies Underway

    As a result of that peer review, a set of toxicological and 
ecological studies was undertaken is underway to address key data gaps 
and provide a comprehensive database related to the toxicity of 
perchlorate. The studies are being funded and overseen by a variety of 
organizations with potential responsibility for perchlorate 
contamination in the environment including the United States Air Force, 
the National Aeronautics and Space Administration and the Perchlorate 
Study Group (PSG).1
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    \1\ The PSG is a consortium of defense contractors and 
manufacturers including: Aerojet, Alliant Techsystems, American 
Pacific/Western Electrochemical Company, Atlantic Research 
Corporation, Kerr-McGee Chemical Corp. Lockheed Martin, Thiokol 
Propulsion Group, and United Technologies Chemical Systems.
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    To date, a 90-day subchronic oral study, a neurobehavioral 
developmental toxicity study, genotoxicity studies, a segment II 
developmental toxicity study, and ecotoxicity studies in Daphnia, 
earthworms, lettuce and fathead minnow have been completed. Currently 
ongoing studies include a two-generation reproductive toxicity study, 
absorption, distribution, metabolism, and elimination (ADME) studies, 
perchlorate mechanistic studies, and immunotoxicity studies. The 
results of most of these studies will be discussed in the Toxicological 
Review document and utilized for development of the proposed revised 
RfD, and cancer and ecological assessment for perchlorate.
    Ten independent scientists from the fields of general toxicology, 
thyroid function and toxicology, developmental toxicology, 
neurotoxicology, immunotoxicology, pharmacology, genetic toxicology, 
medical endocrinology with an emphasis on thyroid function, 
biostatistics, assessment of risks due to non-cancer and cancer health 
effects, and assessment of risks due to ecological effects will review 
the scientific data, methods, and analyses, along with the assumptions 
and uncertainties that are associated with the revised provisional RfD, 
cancer assessment, and ecological assessment for perchlorate. These 
scientists were selected by RTI from among the experts nominated by 
stakeholders for possible service as external peer reviewers. Following 
the peer review workshop, RTI will issue a

[[Page 2493]]

report summarizing the workshop. EPA will address the comments of the 
peer reviewers in finalizing the Toxicological Review document for 
perchlorate and adopting the revised perchlorate RfD. The RfD will be 
utilized in performing risk assessments of perchlorate contamination in 
the environment. Although such risk assessments will be one of the 
factors considered in making future decisions regarding perchlorate 
contamination, these decisions and other risk management issues will 
not be a part of the peer review process.

    Dated: January 7, 1999.
Timothy Fields, Jr.,
Acting Assistant Administrator, Office of Solid Waste and Emergency 
Response.
[FR Doc. 99-890 Filed 1-13-99; 8:45 am]
BILLING CODE 6560-50-P