[Federal Register Volume 61, Number 242 (Monday, December 16, 1996)]
[Notices]
[Page 66054]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-31774]


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DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service


National Toxicology Program; Availability of Technical Report on 
Toxicology and Carcinogenesis Studies of Nickel Subsulfide

    The HHS' National Toxicology Program announces the availability of 
the NTP Technical Report on the toxicology and carcinogenesis studies 
of nickel subsulfide, this study was conducted because there is 
potential for exposure to this nickel compound during mining production 
and/or manufacturing processes in the nickel industry.
    Toxicology and carcinogenicity studies were conducted by inhalation 
administration of nickel subsulfide to a core group of 63 F344/N rats 
of each sex at 0, 0.15, or 1 mg (equivalent to 0, 0.11, or 0.73 nickel 
mg/m\3\) for 6 hours per day, 5 days per week, for up to 104 weeks and 
groups of 80 B6C3F1 mice of each sex at 0, 0.6, or 1.2 mg 
(equivalent to 0, 0.44, or 0.88 mg nickel/m\3\) for 6 hours per day, 5 
days per week for up to 105 weeks. Animals were removed at 7 or 15 
months for interim evaluation and/or determination of lung nickel 
levels.
    Under the conditions of these 2-year inhalation studies, there was 
clear evidence of carcinogenic activity \1\ of nickel subsulfide in 
male F344/N rats based on increased incidences of alveolar/bronchiolar 
adenoma, carcinoma, and adenoma or carcinoma (combined) and on 
increased incidences of benign, malignant, and benign or malignant 
(combined) pheochromocytoma of the adrenal medulla. There was clear 
evidence of carcinogenic activity of nickel subsulfide in female F344/N 
rats based on increased incidences of alveolar/bronchiolar carcinoma 
and alveolar/bronchiolar adenoma or carcinoma (combined) and an 
increased incidence of benign pheochromocytoma of the adrenal medulla. 
There was no evidence of carcinogenic activity of nickel subsulfide in 
male or female B6C3F1 mice exposed to 0.6 or 1.2 mg/m\3\.
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    \1\ The NTP uses five categories of evidence of carcinogenic 
activity observed in each animal study: Two categories for positive 
results (``clear evidence''), one category for uncertain findings 
(``equivocal evidence''), one category for studies that cannot be 
evaluated because of major flaws (``inadequate study'').
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    Exposure of male and female rats to nickel subsulfide by inhalation 
for 2 years resulted in inflammation, hyperplasia, and fibrosis in the 
lung; inflammation and atrophy of the olfactory opithelium in the nose; 
and hyperplasia in the adrenal medulla (females). Exposure of male and 
female mice to nickel subsulfide by inhalation for 2 years resulted in 
inflammation, bronchialization, hyperplasia, and fibrosis in the lung 
and inflammation and atrophy of the olfactory epithelium in the nose.
    Copies of Toxicology and Carcinogenesis Studies Nickel Subsulfide 
(CAS No. 12035-72-2) (TR-453) 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: November 13, 1996.
Samuel H. Wilson,
Deputy Director, NIEHS.
[FR Doc. 96-31774 Filed 12-13-96; 8:45 am]
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