[Federal Register Volume 59, Number 178 (Thursday, September 15, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-22817]


[[Page Unknown]]

[Federal Register: September 15, 1994]


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DEPARTMENT OF HEALTH AND HUMAN SERVICES
 

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

    The HHS' National Toxicology Program announces the availability of 
the NTP Technical Report on the toxicology and carcinogenesis studies 
of Talc. Talc products are sold in a multitude of grades which have 
physical or functional characteristics especially suited for particular 
applications. Occupational and consumer exposures to talc are complex 
and can occur through pharmaceuticals and consumer products as well as 
in industrial settings by way of inhalation, ingestion or dermally.
    Toxicology and carcinogenicity studies of talc (non-asbestiform, 
cosmetic grade) were conducted by exposing groups of F344/N rats to 
aerosols containing 0, 6, or 18 mg/m3 talc for 113 weeks (males) 
or 122 weeks (females). Groups of B6C3F1 mice were exposed 
similarly.
    Under the conditions of these inhalation studies, there was some 
evidence of carcinogenic activity\1\ of talc in male F344/N rats based 
on an increased incidence of benign or malignant pheochromocytomas of 
the adrenal gland. There was clear evidence of carcinogenic activity of 
talc in female F344/N rats based on increased incidences of alveolar/
bronchiolar adenomas and carcinomas of the lung and benign or malignant 
pheochromocytomas of the adrenal gland. There was no evidence of 
carcinogenic activity of talc in male or female B6C3F1 mice 
exposed to 6 or 18 mg/m3.
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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 no 
observable effect (``no evidence''), and one category for studies 
that cannot be evaluated because of major flaws (``inadequate 
study'').
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    The principal toxic lesions associated with inhalation exposure to 
the same concentrations of talc in rats included chronic granulomatous 
inflammation, alveolar epithelial hyperplasia, squamous metaplasia and 
squamous cysts, and interstitial fibrosis of the lung. These lesions 
were accompanied by impaired pulmonary function characterized primarily 
by reducing lung volumes, reduced dynamic and/or quasistatic lung 
compliance, reduced gas exchange efficiency, and nonuniform 
intrapulmonary gas distribution. In mice, inhalation exposure to talc 
produced chronic inflammation of the lung with the accumulation of 
alveolar macrophages.
    Questions or comments about the Technical Report should be directed 
to Central Data Management at P.O. Box 12233, Research Triangle Park, 
NC 27709 or telephone (919) 541-3419.
    Copies of Toxicology and Carcinogenesis Studies of Talc (CAS No. 
14807-96-6) in F344/N Rats and B6C3F1 Mice (Inhalation Studies) 
(TR-421) are available without charge from Central Data Management, 
NIEHS, MD A0-01, P.O. Box 12233, Research Triangle Park, NC 27709; 
telephone (919) 541-3419.

    Dated: September 8, 1994.
Kenneth Olden,
Director, National Toxicology Program.
[FR Doc. 94-22817 Filed 9-14-94; 8:45 am]
BILLING CODE 4140-01-M