[Federal Register Volume 59, Number 137 (Tuesday, July 19, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-17450]
[[Page Unknown]]
[Federal Register: July 19, 1994]
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DEPARTMENT OF HEALTH AND HUMAN SERVICES
National Toxicology Program; Availability of Technical Report on
Toxicology and Carcinogenesis Studies of Manganese (II) Sulfate
Monohydrate
The HHS' National Toxicology Program announces the availability of
the NTP Technical Report on the toxicology and carcinogenesis studies
of manganese sulfate monohydrate. Manganese is the 12th most abundant
element in the earth's crust. The base metal does not occur naturally,
but is a component of more than 100 minerals, including sulfides,
oxides, carbonates, silicates, phosphates, and borates. In addition to
occurring in foods and drinking water, manganese occurs in the
atmosphere from dust, volcanic activity, forest fires, and industrial
emissions. Manganese (II) sulfate monohydrate was chosen for study
because of its stability, solubility, and availability.
Toxicology and carcinogenicity studies were conducted by
administering manganese (II) sulfate monohydrate (97% pure) in feed to
groups of 70 male and 70 female F344/N rats and B6C31 mice at
doses of 1, 1,500, 5,000, or 15,000 ppm for up to 2 years.
Under the conditions of these 2-year feed studies, there was no
evidence of carcinogenic activity* of manganese (II) sulfate
monohydrate in male or female F344/N rats receiving 1,500, 5,000, or
15,000 ppm. There was equivocal evidence of carcinogenic activity of
manganese (II) sulfate monohydrate in male and female B6C3F1 mice,
based on the marginally increased incidences of thyroid gland
follicular cell adenoma and the significantly increased incidences of
follicular cell hyperplasia.
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*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 ingestion of diets containing manganese (II) sulfate
monohydrate was associated with an increased severity of nephropathy in
male rats, focal squamous hyperplasia of the forestomach in male and
female mice, and ulcers and inflammation of the forestomach in male
mice. These studies were not designed to assess any neurotoxicity that
might have been expected with chronic exposure to sufficiently high
doses of manganese.
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 Manganese (II)
Sulfate Monohydrate (CAS No. 10034-96-5) in F344/N Rats and B6C3F1
Mice (Feed Studies) (TR-428) 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: July 13, 1994.
Kenneth Olden,
Director, National Toxicology Program.
[FR Doc. 94-17450 Filed 7-18-94; 8:45 am]
BILLING CODE 4140-01-M
