[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: 94-22811]


[[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 o-Benzyl-p-Chlorophenol

    Ths HHS' National Toxicology Program announces the availability of 
the NTP Technical Report on the toxicology and carcinogenesis studies 
of 0-benzyl-p-chlorophenol, an aryl halide biocide with use in 
hospitals and households as a broad-spectrum germicide in disinfectant 
solutions and soap formulations for general cleaning and disinfecting.
    Two year toxiocology and carcinogenicity studies were conducted by 
administering o-benzly-p-chlorophenol to groups of 80 male and 80 
female rats in corn oil by gavage 5 days a week for 103 weeks at doses 
of 0, 30, 60, or 120 mg/kg body weight for male rats and 0, 60, 120, or 
240 mg/kg body weight for female rats. Groups of 70 male and 70 female 
mice were administered o-benzly-p-chlorophenol in corn oil by gavage at 
doses of 0, 120, 240, or 480 mg/kg body weight 5 days a week for 103 
weeks.
    Under the conditions of these 2-year gavage studies, there was no 
evidence of carcinogenic activity\1\ of o-benzly-p-chlorophenol in make 
F344/N rats receiving 30, 60, or 120 mg/kg body weight. There was 
equivocal evidence of carcinogenic activity of o-benzyl-p-chlorophenol 
in female F344/N rats based on the occurrence of two rare renal 
transitional cell carcinomas. There was some evidence of carcinogenic 
activity of o-benzyl-p-chlorophenol in male B6C3F1 mice based on 
increased incidences of renal tubule adenoma and renal tubule adenoma 
or carcinoma (combined). There was no evidence of carcinogenic activity 
of o-benzyl-p-chlorophenol in female B6C3F1, mice receiving 120, 
240, or 480 mg/kg.
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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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    o-benzyl-p-chlorophenol was nephrotoxic for male and female F344/N 
rats and B6C3F1 mice. The severity of nephropathy was increased in 
male and female rats and the incidence and severity of nephropathy was 
increased in male and female mice. The incidence and severity of 
nephropathy increased with length of treatment. Other lesions 
considered to be associated with the nephropathy and the secondary 
hyperparathyroidism in male rats and in male and female mice included 
fibrous osteodystrophy and soft tissue mineralization. Increased 
incidences of squamous cell hyperplasia of the fore-stomach were 
observed in mice.
    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 o-Benzyl-p-
Chlorophenol (CAS No. 120-32-1) in F344/N Rats and B6C3F1 Mice 
(Gavage Studies) (TR-424) 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. 94-22811 Filed 9-14-94; 8:45 am]
BILLING CODE 4140-01-M