19306 Federal Register / Vol. 61, No. 85 / Wednesday, May 1, 1996 / Notices

1The 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’’).

1The 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’’).

1The 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’’).

diethylphthalate in male or female

F344/N rats receiving 100 or 300 μL.

There was equivocal evidence of

carcinogenic activity of diethylphthalate

in male and female B6C3F1 mice based

on increased incidences of

hepatocellular neoplasms, primarily

adenomas.

In the initiation/promotion model,

there was no evidence of initiating or

promoting activity of diethylphthalate

or dimethylphthalate in male Swiss

(CD–1) 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

Diethylphthalate/Dimethylphthalate

(CAS Nos. 84–66–2 and 131–11–3) (TR–

429) 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: March 27, 1996

Kenneth Olden,

Director, National Toxicology Program.

[FR Doc. 96–10833 Filed 4–30–96; 8:45 am]

BILLING CODE 4140–01–M

National Toxicology Program;

Availability of Technical Report on

Toxicology and Carcinogenesis

Studies of Benzethonium Chloride

The HHS’ National Toxicology

Program announces the availability of

the NTP Technical Report on the

toxicology and carcinogenesis studies of

benzethonium chloride, which is used

primarily in cosmetics for its

antimicrobial and cationic surfactant

properties.

Toxicology and carcinogenicity

studies were conducted by dermal

administration of benzethonium

chloride to groups of 60 F344/N rats and

60 B6C3F1 mice of each sex at doses of

0, 0.15, 0.5, or 1.5 mg/kg body weight.

Benzethonium chloride was

administered to rats in ethanol 5 days

per week and doses were adjusted

weekly according to the average body

weights of the groups. As many as nine

rats per group were evaluated after 15

months. Mice received doses

administered in ethanol and dose

volumes were adjusted weekly

according to average body weights of the

groups. As many as ten mice per group

were evaluated after 15 months of

chemical administration.

Under the conditions of these 2-year

dermal studies, there was no evidence

of carcinogenic activity 1 of

benzethonium chloride in male or

female F344 rats or in male or female

B6C3F1 mice.

Exposure of rats and mice to

benzethonium chloride by dermal

application in ethanol for 2 years

resulted in epithelial hyperplasia in

male and female rats and mice and

sebaceous gland hyperplasia and ulcers

in female rats at the site of application.

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

Benzethonium Chloride (CAS No. 121–

54–0) (TR–438) 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: April 12, 1996.

Kenneth Olden,

Director, National Toxicology Program.

[FR Doc. 96–10834 Filed 4–30–96; 8:45 am]

BILLING CODE 4140–01–M

National Toxicology Program;

Availability of Technical Report on

Toxicology and Carcinogenesis

Studies of o-Benzyl-p-Chlorophenol

The HHS’ National Toxicology

Program announces the availability of

the NTP Technical Report on the

toxicology and carcinogenesis studies of

o-benzyl-p-chlorophenol. o-Benzyl-pchlorophenol, an aryl halide, is a broad

spectrum germicide used in disinfectant

solutions and soap formulations in

United States hospitals and households.

Human exposure to o-benzyl-pchlorophenol occurs by absorption

through the skin and mucous

membranes and by ingestion.

Toxicology and carcinogenicity

studies were conducted by dermal

administration of o-benzyl-pchlorophenol to groups of 50 Swiss

(CD–1) mice of each sex to study its

effect as an initiator, promoter, and

complete carcinogen.

Under the conditions of the 1-year

mouse skin initiation/promotion study

in Swiss (CD–1) mice, o-benzyl-pchlorophenol was a cutaneous irritant

and a weak skin tumor promoter relative

to strong promoters such as 12-Otetradecanoylphorbol-13-acetate. oBenzyl-p-chlorophenol had no activity

as an initiator or as a complete

carcinogen.1

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-pChlorophenol (CAS No. 120–32–1) TR–

444) 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 March 27, 1996.

Kenneth Olden,

Director, National Toxicology Program.

[FR Doc. 96–10835 Filed 4–30–96; 8:45 am]

BILLING CODE 4140–01–M

National Toxicology Program;

Availability of Technical Report on

Toxicology and Carcinogenesis

Studies of Methylphenidate

Hydrochloride

The HHS’ National Toxicology

Program announces the availability of

the NTP Technical Report on the

toxicology and carcinogenesis studies of

methylphenidate hydrochloride.

Methylphenidate hydrochloride is a

drug used in the treatment of narcolepsy

and attention deficit hyperactivity

disorders.

Toxicology and carcinogenicity

studies were conducted by

administration of methylphenidate

hydrochloride in feed to groups of 70

F344/N rats of each sex at doses of 0,

100, 500, or 1,000 ppm and to groups of

70 B6C3F1 mice of each sex at doses of

0, 50, 250, or 500 ppm.

Under the conditions of these 2-year

feed studies, there was no evidence of

carcinogenic activity 1 of