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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Deviations:
yes
Remarks:
see "any other information on methods and methods"
Qualifier:
according to
Guideline:
EPA OPPTS 870.3100 (90-Day Oral Toxicity in Rodents)
Deviations:
yes
Remarks:
see "any other information on methods and methods"
Qualifier:
according to
Guideline:
EU Method B.26 (Sub-Chronic Oral Toxicity Test: Repeated Dose 90-Day Oral Toxicity Study in Rodents)
Deviations:
yes
Remarks:
see "any other information on methods and methods"
Qualifier:
according to
Guideline:
other: MAFF Japan, 2-1-9 Notification 12 Nousan 8147, Agricultural Chemicals Regulation Laws (2000)
Deviations:
yes
Remarks:
see "any other information on methods and methods"
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid
Details on test material:
Purity: 98.5%
Impurities: Not reported

Test animals

Species:
rat
Strain:
other: Crl:CD(SD)
Details on species / strain selection:
The rat is the rodent model routinely used for evaluating the toxicity of various classes of chemicals and for which there is a large historical database.
Sex:
male/female

Administration / exposure

Route of administration:
oral: feed
Details on route of administration:
The oral route is one of the potential routes of human exposure to this test article.
Vehicle:
other: Meal Lab Diet
Analytical verification of doses or concentrations:
yes
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
The test article was available in the diet ad libitum.
Doses / concentrationsopen allclose all
Dose / conc.:
100 ppm
Remarks:
Males: 4.5 mg/kg bw/d; Female: 6 mg/kg bw/d
Dose / conc.:
400 ppm
Remarks:
Male: 18 mg/kg bw/d; Female: 23 mg/kg bw/d
Dose / conc.:
1 500 ppm
Remarks:
Male: 70 mg/kg bw/d; Female: 83 mg/kg bw/d
Dose / conc.:
6 000 ppm
Remarks:
Male: 274 mg/kg bw/d; Female: 316 mg/kg bw/d
No. of animals per sex per dose:
16
Control animals:
yes, plain diet

Results and discussion

Results of examinations

Clinical signs:
effects observed, non-treatment-related
Mortality:
mortality observed, non-treatment-related
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Adverse, test substance-related decreases (compared to control) in body weight parameters were observed in male and female rats at 6000 ppm. Overall (Weeks 1-13) mean body weight change at 6000 ppm for males and females was 21% (statistically significant) and 6% (not statistically significant), respectively, lower than control.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
-Adverse, test substancee-related decreases (compared to controls) in food intake parameters were observed in male and female rats at 6000 ppm, and correlated with the body weight effects. Statistically significant decreases in weekly mean food consumption were noted for all 13 weeks in males at 6000 ppm and for 11 of the 13 weeks in females at 6000 ppm (Week 6 and 12 values did not reach statistical significance). Statistically significant decreases in mean food consumption were noted for all 3 monthly intervals in males and females at 6000 ppm. Overall (Weeks 1-13) mean food consumption of males and females at 6000 ppm was statistically significantly lower (11% and 16%, respectively) compared to control.
Food efficiency:
effects observed, treatment-related
Description (incidence and severity):
- During the first week of the study, feed efficiency values were statistically significantly decreased at 6000 ppm for both sexes when compared to control. A statistically significant decrease (21%) in the mean food efficiency for Month 2 was noted in males at 6000 ppm.
- Overall (Weeks 1-13) food efficiency of males and females at 6000 ppm were lower than controls for males (11% which is not statistically significant) and higher than controls for females (12% which is not statistically significant).
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
no effects observed
Haematological findings:
effects observed, non-treatment-related
Description (incidence and severity):
.
Clinical biochemistry findings:
effects observed, non-treatment-related
Urinalysis findings:
effects observed, non-treatment-related
Behaviour (functional findings):
no effects observed
Immunological findings:
no effects observed
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
- Test substance related organ weight changes were limited to increased absolute and relative liver weights of males and females at 6000 ppm. Increased absolute liver, relative liver to body weight percentage and relative liver to brain weight ratios were observed in males by 5%, 19% (statistically significant) and 3%, and in females by 11%, 17% (statistically significant) and 9%, respectively. The increased liver weights correlated with minimal microscopic centrilobular hepatocellular hypertrophy in males at 6000 ppm and were considered most likely adaptive and non-adverse.
Gross pathological findings:
no effects observed
Neuropathological findings:
no effects observed
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Test substance related microscopic changes were limited to the livers of males at 6000 ppm. Minimal centrilobular hepatocellular hypertrophy was observed in 4 of 10 males at 6000 ppm. The centrilobular hypertrophy was characterized by minimal enlargement of the hepatocytes surrounding the central vein. The hepatocellular hypertrophy was considered non-adverse and consistent with an adaptive increase in liver enzyme content.
Histopathological findings: neoplastic:
not specified

Effect levels

Key result
Dose descriptor:
NOAEL
Effect level:
1 500 ppm
Sex:
male/female
Basis for effect level:
body weight and weight gain
food consumption and compound intake
food efficiency
Remarks on result:
other: 1500 ppm is equivalent to 70 and 83 mg/kg body weight/day for males and females, respectively

Target system / organ toxicity

Critical effects observed:
no

Applicant's summary and conclusion

Conclusions:
NOAEL(male/female): 1500 ppm (70 and 83 mg/kg body weight/day for males and females, respectively) (Based on adverse effects on body weight and nutritional parameters in male and female rats at 6000 ppm)
Executive summary:

The test was conducted according to guidelines, U.S. EPA OPPTS 870.3100, 870.6200 and OECD Guideline 408 to evaluate the subchronic toxicity of test substance when administered in the diet of rats for 13 weeks. Four treatment groups of 16 male and 16 female rats were administered the test article at respective dietary concentrations of 100, 400, 1500, and 6000 ppm. One additional group of 16 animals/sex served as the control and received untreated rodent diet. The untreated or treated rodent diet was available to all groups ad libitum for 13 weeks.

Observations for morbidity, mortality, injury, and the availability of food and water were conducted twice daily for all animals. Additional cageside observations were conducted once daily, except on the days of the weekly detailed clinical observation. Body weights were measured and recorded prior to randomization, predose on Day 1, and weekly thereafter. Food consumption was measured and recorded weekly. Food efficiency and compound consumption were calculated weekly. Ophthalmoscopic examinations were conducted on all animals pretest and on all surviving animals prior to the terminal necropsy. Functional Observational Battery (FOB) and Motor Activity (MA) tests were conducted on designated animals (10/sex/group) pretest and during Weeks 4, 8, and 13. Blood samples for clinical pathology evaluations were collected from designated animals at the terminal necropsy. Urine samples for clinical pathology evaluations were collected from designated animals prior to the terminal necropsy. Blood samples for possible determination of the plasma concentrations of the test article and/or metabolites were collected from designated animals on Day 60. During Week 14, the last six animals/sex/group were necropsied for neuropathology evaluations. At study termination for non-neuropathology animals, necropsy examinations were performed, organ weights were recorded, and tissues were microscopically examined. A full complement of tissues was microscopically examined for animals at 0 and 6000 ppm, with gross lesions and a potential target organ (liver) examined at 100, 400, and 1500 ppm.

The overall mean compound consumption of test substance in the 100, 400, 1500, and 6000 ppm groups was 4.5, 18, 70, and 274 mg/kg body weight (bw)/day, respectively, for male rats and 6.0, 23, 83, and 316 mg/kg bw/day, respectively, for female rats.

No test substance-related effects were noted on the following parameters: survival, clinical findings, functional observational battery, locomotor activity, ophthalmoscopic evaluations, hematology, coagulation, clinical chemistry, urine/urine chemistry, or macroscopic evaluations. There was one unscheduled death in the 100 ppm (female) group on test day 88; the cause of death was undetermined but was not attributed to the test article.

Adverse, test substance-related decreases (compared to control) in body weight parameters were observed in male and female rats at 6000 ppm. Weekly mean body weight changes were also generally lower compared to controls in males and females at 6000 ppm, but with only occasional statistical significance. Overall (Weeks 1-13) mean body weight change at 6000 ppm for males and females was 21 (statistically significant) and 6% (not statistically significant), respectively, lower than control.

Adverse, test substance-related decreases (compared to controls) in food intake parameters were observed in male and female rats at 6000 ppm, and correlated with the body weight effects. Overall (Weeks 1-13) mean food consumption of males and females at 6000 ppm was statistically significantly lower (11% and 16%, respectively) compared to control. Weekly food efficiency values were generally similar to control except for Week 1, when food efficiency was statistically significantly decreased in males and females at 6000 ppm compared to control.

Test substance related organ weight changes were limited to increased absolute and relative liver weights of males and females at 6000 ppm. The increased liver weights correlated with minimal centrilobular hepatocellular hypertrophy observed in 4 of 10 males at 6000 ppm. The hepatocellular hypertrophy was considered non-adverse and likely adaptive (enzymatic induction). There were no test substance related microscopic findings consistent with neurotoxicity.

Under the conditions of this study, the no-observed-adverse-effect level (NOAEL) of test substance was considered to be 1500 ppm (70 and 83 mg/kg body weight/day for males and females, respectively). The NOAEL was based on adverse effects on body weight and nutritional parameters in male and female rats at 6000 ppm.