ABSTRACT

In the repeat dose oral toxicity test, body weight gain decreased in both sexes of the 625 mg/kg group. Hematological examination revealed a slight anemia in males of the 625 mg/kg group. Blood chemical examination revealed changes in items related to kidney or liver function in both sexes of the 625 mg/kg group. Relative liver and kidney weights increased and relative spleen weight decreased in males of the 125 or 625 mg/kg groups. Absolute liver weight increased and ovary weights decreased in females of the 125 or 625 mg/kg group. Histopathological examination revealed peripheral fatty change of liver and hepatocellular swelling in females of the 125 and 625 mg/kg groups. The NOEL for repeat dose toxicity is considered to be 25 mg/kg/day for both sexes.

1-Naphthylacetic acid was not mutagenic in Salmonella typhimurium TA100, TA98, TA1535, TA1537 and Escherichia coli WP2 uvrA. Although continuous treatment (24 and 48 h) with this chemical substance did not induce chromosomal aberrations in CHL/IU cells, specimens sampled 24 h after the start of 6 h treatment showed marginal structural aberrations. This effect was confirmed by in vitro micronucleus assay. Lowering of the pH of the culture medium may have contributed to the response.

SUMMARIZED DATA FROM THE STUDIES

1. Repeat Dose Toxicity 1)

Purity	:	99.7%
Test species/strain	:	Rat/Crj:CD (SD)
Test method	:	Guidelines for 28-day Repeat Dose Toxicity Testing of Chemicals (Japan)
Route	:	Oral
Dosage	:	0(vehicle),25,125,625 mg/kg/day
Number of animals	:	Male, 5; female, 5 /group
Vehicle	:	0.5% CMC-sodium solution
Administration period	:	Male and female, 28 days
Terminal kill	:	Male and female, days 29 or 43
GLP	:	Yes

　Test results:

The test substance did not induce any toxic clinical signs. Body weight gain decreased in both sexes of the 625 mg/kg group and food consumption decreased in females of the 625 mg/kg group. Hematological examination revealed decreases in hematocrit, hemoglobin and fibrinogen in males of the 625 mg/kg group. Blood chemical examination revealed decreases in BUN, creatinine, total bilirubin and ALP, as well as an increase in triglyceride in males of the 625 mg/kg group, and an increase in triglyceride and a decrease in BUN in females of the 625 mg/kg group. On urinalysis, increases in urine volume, and the presence of leukocytes and epithelium cells were evident in both sexes of the 125 and/or 625 mg/kg groups. Absolute and relative spleen weights decreased and relative kidney weights increased in males of the 125 and 625 mg/kg groups, and relative liver weight increased in males given 625 mg/kg. In females receiving the 625 mg/kg dose, absolute or relative liver weights increased. On microscopic examination, peripheral fatty change of the liver and hepatocellular swelling were observed in females of the 125 and 625 mg/kg groups.

The NOEL is considered to be 25 mg/kg/day for males and females under the conditions of the present study.

2. Genetic Toxicity

2-1 Bacterial test 2)

Purity	:	96.4%
Test species/strains	:	S.typhimurium TA100, TA1535, TA98, TA1537 E. coli WP2 uvrA
Test method	:	Guidelines for Screening Mutagenicity Testing of Chemicals (Japan)
Procedures	:	Plate incorporation method
Solvent	:	DMSO
Positive controls	:	-S9, AF-2 (TA100, WP2, TA98), sodium azide (TA1535) and 9-aminoacridine (TA1537) +S9, 2-aminoanthracene (all strains)
Dosage	:	0, 312.5, 625, 1250, 2500, 5000 μg/plate
S-9	:	Rat liver, induced with phenobarbital and 5,6-benzoflavone
Plate/test	:	3
Number of replicates	:	2
GLP	:	Yes

　Test results:

Minimum concentration of test substance at which toxicity was observed:

No toxicity was observed up to a concentration of 5000 μg/plate with or without metabolic activation.

Genetic effects:
S. typhimurium TA100, TA1535, TA 98, TA1537

	+	?	-
with metabolic activation:	[ ]	[ ]	[*]
without metabolic activation:	[ ]	[ ]	[*]

E. coli WP2 uvrA

with metabolic activation:	[ ]	[ ]	[*]
without metabolic activation:	[ ]	[ ]	[*]

2-2. Non-bacterial in vitro test (chromosomal aberration test) 2)

Purity	:	96.4%
Type of cell used	:	Chinese hamster CHL/IU cells
Test method	:	Guidelines for Screening Mutagenicity Testing of Chemicals (Japan)
Solvent	:	Acetone
Positive controls	:	-S9, Mitomycin C +S9, Cyclophosphamide
Dosage	:	-S9 (continuous treatment): 0, 0.3, 0.6, 1.1 mg/ml -S9 (short-term treatment): 0, 0.4, 0.9, 1.7 mg/ml +S9 (short-term treatment): 0, 0.4, 0.9, 1.7 mg/ml
S-9	:	Rat liver, induced with phenobarbital and 5,6-benzoflavone
Plates/test	:	2
GLP	:	Yes

　Test results:

In the high concentration groups (1.7 mg /ml) short-term treatment with and without S9 mix caused 9% and 7% of the cells, respectively to demonstrate structural aberrations (including gaps). In in vitro micronucleus test conducted as a confirmation test, positive results were also obtained. However, it was suggested that acidic pH alteration may have been related to the induction of chromosomal aberrations.

Lowest concentration producing cytogenetic effects in vitro:

without metabolic activation (continuous treatment ): > 1.1 mg/ml

without metabolic activation (short-term treatment): 1.7 mg/ml (clastogenicity)

with metabolic activation (short-term treatment): 1.7 mg/ml (clastogenicity)

Genotoxic effects:

	clastogenicity			polyploidy
	+	?	-	+	?	-
without metabolic activation:	[*]	[ ]	[ ]	[ ]	[ ]	[*]
with metabolic activation:	[*]	[ ]	[ ]	[ ]	[ ]	[*]

1)	The test was performed by the Biosafety Research Center, Foods, Drugs and Pesticides (An-pyo Center), 582-2 Shioshinden Arahama, Fukude-cho,Iwata-gun, Shizuoka 437-12, Japan. Tel +81-538-58-1266 Fax +81-538-58-1393
2)	The tests were performed by the Hatano Research Institute, Food and Drug Safety Center, 729-5 Ochiai, Hadano-shi, Kanagawa 257, Japan. Tel +81-463-82-4751 Fax +81-463-82-9627