[Federal Register Volume 61, Number 188 (Thursday, September 26, 1996)]
[Notices]
[Page 50500]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-24626]


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DEPARTMENT OF HEALTH AND HUMAN SERVICES

National Toxicology Program; Availability of Technical Report of 
Comparative Initiation/Promotion Skin Paint Studies of B6C3F1 
Mice, Swiss (CD-1) Mice, and SENCAR Mice

    The HHS' National Toxicology Program announces the availability of 
the NTP Technical Report on the Comparative Initiation/Promotion Skin 
Paint Studies of B6C3F1 Mice, Swiss (CD-1) Mice, and 
SENCAR Mice.
    All three strains of mice demonstrated sensitivity by developing 
skin tumors after topical application of the chemicals under study 
(7,12-dimethylbenz(a)anthracene (DMBA), N-methyl-N'-nitro-N-
nitrosoguanidine (MNNG), 12-O-tetradecanoylphorbol-13-acetate (TPA), 
and benzoyl peroxide (BPO). The most sensitive of the three strains 
appeared to be SENCAR mice, in the sense that lower doses of the test 
chemical were generally required to produce effects equivalent to those 
in the other two strains. Skin tumors also tended to develop earlier 
and with greater multiplicity in SENCAR mice than in the other two 
strains. By these criteria, the overall sensitivity of Swiss (CD-
1) mice was intermediate, and B6C3F1 mice showed the 
least overall sensitivity to dermal carcinogenicity.
    The 1-year complete carcinogen studies used repeated applications 
of low concentrations of the carcinogens DMBA and MNNG. There was a 
high incidence of skin tumors in all three strains with both 
carcinogens. More B6C3F1 and SENCAR mice developed skin tumors and 
averaged more tumors per mouse than did Swiss (CD-1) mice. 
Skin tumors developed earlier in SENCAR mice than in B6C3F1 and 
Swiss (CD-1) mice. Although B6C3F1 mice exhibited the 
lowest overall sensitivity to the initiation/promotion protocol when 
compared to Swiss (CD-1) and SENCAR mice, the response of 
B6C3F1 mice was similar to Swiss (CD-1) and SENCAR mice 
for complete carcinogen studies.
    Questions or comments about the Technical Report should be directed 
to Central Data Management at NIEHS, MD E1-02, P.O. Box 12233, Research 
Triangle Park, NC 27709 or telephone (919) 541-3419.
    Copies of the Comparative Initiation/Promotion Skin Paint Studies 
of B6C3F1 Mice, Swiss (CD-1) Mice, and SENCAR Mice (TR-
441) are available without charge from Central Data Management, NIEHS, 
MD E1-02, P.O. Box 12233, Research Triangle Park, NC 27709; telephone 
(919) 541-3419.

    Dated: August 21, 1996.
Kenneth Olden,
Director, National Toxicology Program.
[FR Doc. 96-24626 Filed 9-25-96; 8:45 am]
BILLING CODE 4140-01-M