[Federal Register Volume 61, Number 242 (Monday, December 16, 1996)]
[Notices]
[Pages 66054-66055]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-31775]


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DEPARTMENT OF HEALTH AND HUMAN SERVICES

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

    The HHS' National Toxicology Program announces the availability of 
the NTP Technical Report on the toxicology and carcinogenesis studies 
of nickel oxide. Nickel oxide ``sinters'' are used in stainless steel 
and alloy steel production. Nickel oxide was nominated by the National 
Cancer Institute to the NTP for testing because exposure to this form 
of nickel may occur in the nickel industry. Increased incidences of 
lung and nasal sinus cancers have occurred among workers in certain 
nickel refining facilities, and nickel oxide was studied as part of a 
class study of nickel compounds.
    Toxicology and carcinogenicity studies were conducted by inhalation 
administration of nickel oxide (high temperature nickel oxide) to 
groups of 65 F344/N rats at exposures of 0, 0.62, 1.25, or 2.5 mg 
(equivalent to 0, 0.5, 1.0, or 2.0 mg) and to groups of 74 to 79 
B6C3F1 mice of each sex at exposures of 0, 1.25, 2.5, or 5 mg for 
6 hours per day, 5 days per week for 104 weeks.
    Under the conditions of these 2-year inhalation studies, there was 
some evidence of carcinogenic activity \1\ of nickel oxide in male 
F344/N rats based on increased incidences of alveolar/bronchiolar 
adenoma or carcinoma (combined) and increased incidences of benign of 
malignant pheochromocytoma (combined) of the adrenal medulla. There was 
some evidence of carcinogenic activity of nickel oxide in female F344/N 
rats based on increased incidences of alveolar/bronchiolar adenoma or 
carcinoma (combined) and increased incidences of benign 
pheochromocytoma of the adrenal medulla. There was no evidence of 
carcinogenic activity of nickel oxide in male B6C3F1 mice exposed 
to 1.25, 2.5, or 5 mg/m3. There was equivocal evidence of 
carcinogenic activity of nickel oxide in female B6C3F1 mice based 
on marginally increased incidences of alveolar/bronchiolar adenoma in 
2.5 mg/m3 females and of alveolar/bronchiolar adenoma or carcinoma 
(combined) in 1.25 mg/m3 females.
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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'' and ``some 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 rats to nickel oxide by inhalation for 2 years resulted 
in inflammation and pigmentation in the lung, lymphoid hyperplasia and 
pigmentation in the bronchial lymph nodes, and hyperplasia of the 
adrenal medulla (females). Exposure of mice to nickel oxide by 
inhalation for 2 years resulted in bronchialization, proteinosis, 
inflammation, and pigmentation in the lung and lymphoid hyperplasia and 
pigmentation in the bronchial lymph nodes.
    Questions or comments about the Technical Report should be directed 
to

[[Page 66055]]

Central Data Management at P.O. Box 12233, Research Triangle Park, NC 
27709 or telephone (91) 541-3419.
    Copies of Toxicology and Carcinogenesis Studies of Nickel Oxide 
(CAS No. 1313-99-1) (TR-451) 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. 96-31775 Filed 12-13-96; 8:45 am]
BILLING CODE 4140-01-M