[Federal Register Volume 62, Number 112 (Wednesday, June 11, 1997)]
[Notices]
[Page 31837]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-15298]
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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 Phenolphthalein
The HHS' National Toxicology Program announces the availability of
the NTP Technical Report on the toxicology and carcinogenesis studies
of phenolphthalein which is used as a laboratory reagent and acid-base
indicator and in over-the-counter laxative preparations. The results of
these studies were previously released in draft form prior to a public
peer review in December, 1995.
Toxicology and carcinogenicity studies were conducted by
administrating phenolphthalein to groups of 50 F344/N rats for 2 years
and to B6C3F1 mice at exposures of 0, 3000, 6000 or 12,000
ppm in the feed for 2 years (equivalent to average daily doses of
approximately 300, 600 or 1200 mg phenolphthalein/kg body weight to
males and 400, 800 or 1000 mg/kg to females).
Under the conditions of these 2-year feed studies, there was clear
evidence of carcinogenic activity \1\ of phenolphthalein in male F344/N
rats based on markedly increased incidences of benign pheochromocytomas
of the adrenal medulla and of renal tubule adenomas and adenomas or
carcinomas (combined). There was some evidence of carcinogenic activity
of phenolphthalein in female F344/N rats based on the increased
incidences of benign pheochromocytomas of the adrenal medulla in the
12,000 ppm group and of benign or malignant pheochromocytomas
(combined) in the 12,000 and 25,000 ppm groups. There was clear
evidence of carinogenic activity of phenolphthalein in male
B6C3F1 mice based on increased incidences of histiocytic
sarcomas and of malignant lymphomas of thymic origin. there was clear
evidence of carcinogenic activity of phenolphthalein in female
B6C3F1 mice based on increased incidences of histiocytic
sarcomas, malignant lymphomas of all types, lymphomas of thymic origin,
and benign sex-cord stromal tumors of the ovary.
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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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Exposure of rats to phenophthalein in feed for 2 years resulted in
increased incidences of focal hyperplasia of the adrenal medulla in
males and in increased incidences and/or severity of nephropathy of the
kidney in males and females. Exposure of mice to phenolphthalein in
feed for 2 years resulted in increased incidences of atypical
hyperplasia of the thymus in males and females, degeneration of the
germinal epithelium of the testis in males, and ovarian hyperplasia in
females.
Exposure of mice to phenolphthalein in feed for 2 years resulted in
decreased incidences of hepatocellular neoplasms and nonneoplastic
lesions in males and females.
Questions or comments about the Technical Report should be directed
to Central Data Management at P.O. Box 12233, Research Triangle Park,
NC 27709-2233.
Copies of Toxicology and Carcinogenesis Studies of Phenolphthalein
(CAS No. 77-09-8) (TR-465) are available from Central Data Management,
NIEHS, MD E1-02, P.O. Box 12233, Research Triangle Park, NC 27709-2233;
telephone (919) 541-3419.
Dated: May 28, 1997.
Kenneth Olden,
Director, National Toxicology Program.
[FR Doc. 97-15298 Filed 6-10-97; 8:45 am]
BILLING CODE 4140-01-M
