2-(2H-benzotriazol-2-yl)-4,6-ditertpentylphenol

Endpoint summary

Description of key information

In the Inbifo study (No. A 0176/049, 1970) the oral repeated dose toxicity (90 days, subchronic) in the dog was determined similar to the OECD guideline 409 and a NOAEL was set at 30 mg/kg body weight in the dog. 
In the TNO study (No. R 2640, 1968) the oral repeated dose toxicity (90 days, subchronic) in the rat was determined similar to the OECD guideline 408 and a LOAEL was at 10 mg/kg body weight in the rat (lowest concentration tested). The NOAEL is assumed to be < 10 mg/kg bw. 

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

30 mg/kg bw/day

Study duration:

subchronic

Species:

dog

Additional information

Subchronic study (repeated dose 90 days, oral)

non-rodents

In the Inbifo study (No. A 0176/049, 1970) the subchronic oral toxicity of the test substance was determined in non-rodents (dogs). The study was conducted similar to the OECD-Guideline 409 (1998). 3 beagle dogs each dose level and sex were fed with food containing the test compound in dose levels of 15, 30, 60, 120, and 240 mg/kg body weight. The control animals (5 animals each sex) were fed plain diets. The dogs were observed and examined concerning food consumption and clinical signs, haematology, clinical chemistry, pathology, and histopathology. One male dog of the 240 mg/kg bw dose group died on day 55 after had had lost 33% of its initial body weight. No further mortalities occurred. The food consumption considerably decreased in the higher dose groups and hence a loss of body weight and a sleepy and weak behaviour was observed in those animals. Effects were observed in the haematological examinations, concerning primarily decreased numbers of erythrocytes, decreased haemoglobin concentrations in the blood, anisocytosis, and shrivelled formed erythrocytes. Distinct effects of the clinical chemistry were observed, like a test material related increase of the serum activity of glutamic oxaloacetic transaminase (GOT) (up to 4 fold compared to the control group), glutamate pyruvate transaminase (GPT) (up to 15 fold compared to the control group) and the alkaline phosphatase (up to 13 fold compared to the control group). Distinct effects already occurred in the lowest dose group of 15 mg/kg bw. The male dogs of all dose groups had increased bilirubin concentrations and one male dog of the highest dose level, which died during the study, showed extremely high bilirubin figures (> 180 mg/l, approximately 70 times higher than the mean of the control group). The main pathological finding was an icterus in three of the 120 and 240 mg/kg bw dose groups.2 and 1 male dogs of the 120 and 240 mg/kg bw dose groups showed low liver weights which were relative to body weight within normal limits, whereas the relative weights of a number of other organs of these dogs, e.g. brain lung, kidneys and adrenals, were larger than those of all other dogs. The forementioned three dogs were also remarkable because of their low testes and epididymes weights.The histopathological examination revealed test substance related changes in the liver. These changes concerned the KUPFFER’ cells (fatty change, hyperplasia) and hepatocytes (fatty change, protein globules in the cytoplasma, monocellular necrosis). Furthermore, signs of inflammation and fibrosis were detected. The effects occurred throughout all dose groups and even in the 15 mg/kg bw dose group distinct histopathological changes could be observed. Furthermore, in spleen, uterus, prostate, and testis test material related changes were detected. In higher dose groups (120 and 240 g/kg bw) compound related thymus atrophy was observed. The kidneys revealed histopathological changes in the glomeruli of the 30 mg/kg bw dose group and higher. Few of the treated animals showed changes in the adrenals, but the relation to the test material was reported to be questionable. The changes in the adrenals of the dog which died during the study were assumed to be compound related.

Based on these findings, a LOAEL was set at 60 mg/kg bw in the dog, and the NOAEL was established at 30 mg/kg/d. Liver and kidney determined to be the target organs due to test-material induced changes of organ weights, histopathology and enzyme activities.

 

rodents

In the TNO study (No. R 2640, 1968) the subchronic oral toxicity of the test substance was determined in rodents (rats). The study was conducted similar to the OECD-Guideline 408. 10 male and 10 female albino rats per dose group were fed with food containing the test compound in dose levels of 100, 200, 400, 800, and 1600 ppm (equal to 10, 19, 40, 81, and 173 mg/kg body weight, calculation based on body weight and food consumption). The control animals (10 each sex) were fed plain diets. During exposure, clinical signs, body weight development, food consumption and food efficiency were observed. At the end of the study haematology, enzymology, pathology, and histopathology were examined. No mortalities occurred during the study. At the highest feeding level, some male animals were of poor general state. No other clinical signs were described. Significant growth depression of 15-20% occurred only at the highest feeding level (173 mg/kg bw) in males. In females this effect was likewise observed at the highest level, although less pronounced and only during the first four weeks of the experimental period. Food efficiency figures were distinctly decreased only in males of the highest dose group. At lower dose levels no consistent differences in food efficiency occurred between groups, neither in males nor in females. Few effects were observed in the haematological examinations, concerning primarily haemoglobin content and packed cell volume in males (for both parameters up to -11%) at feeding levels of 19 mg/kg bw and above. In females this phenomenon occurred likewise, although the effect was significant only at higher dose levels (173 mg/kg bw). The activity of the enzyme glucose-6-phosphatase in the case of the livers, when expressed as G6P-ase activity or specific G6P-ase activity, increased with increasing levels of the test substance in the ration up to 19 mg/kg bw in both males and females. At higher feeding levels no further increase was observed. In contrast to the liver, the G6P-ase activity in the kidneys did not show a dose-effect relationship as a result of the ingestion of test substance. Average relative liver weights were distinctly increased at all feeding levels in both sexes after 90 days (up to 200%). Relative kidney weights were increased at the three highest dose levels (40, 81, and 173 mg/kg bw) in both males and females (up to 20%). Relative spleen weights of male rats were decreased at the 81, and 173 mg/kg bw level (up to 30%), and relative testicle weights were increased at the three highest dose levels (40, 81, and 173 mg/kg bw) (up to 30%). Relative thyroid weights of all test groups were higher than those of the controls in both sexes and increased with increasing dose levels of test substance. Gross pathologic examination after 13 weeks revealed distinct enlargement and greenish-drab discolouration of livers. In males, discolouration was observed at all dose levels, in females only at 81 and 173 mg/kg bw. Greenish discolouration of kidneys occurred in males and females at the two highest feeding levels (81 and 173 mg/kg bw). Microscopic examination of the livers revealed a dose-dependent hepatic damage in both males and females. Foci of necrosis were occasionally present in males, and in smaller number in females, at the 81 and 173 mg/kg bw feeding levels. Further results were primarily extremely enlarged and altered parenchymal cells, binucleated hepatocytes, necrotic cells, and proliferation of bile ducts. Microscopic examination of kidneys revealed tubular nephrosis at the two highest feeding levels (81 and 173 mg/kg bw) in males. In females yellowish-brown pigment granules in the cytoplasm of proximal tubular cells were noticed at 19 mg/kg bw and above; the amount of the pigment increased with increasing levels of test substance.

Based on these findings, a NOAEL was set at 10 mg/kg bw in the rat, which was the lowest administered dose in this study. Liver and kidney were determined to be the target organs due to test-material induced changes of organ weights and histopathology. 

Repeated dose toxicity: via oral route - systemic effects (target organ) digestive: liver; urogenital: kidneys

Justification for classification or non-classification

Dangerous Substance Directive (67/548/EEC)

The available experimental test data is reliable and suitable for the purpose of classification under Directive 67/548/EEC. 

Based on the data, the test substance has to be classified for oral repeated dose toxicity: Xn R48/22.

Classification, Labeling, and Packaging Regulation (EC) No. 1272/2008

The available experimental test data are reliable and suitable for the purpose of classification under Regulation (EC) No.1272/2008.

Based on the data, the test substance has to be classified for specific target organ toxicity - repeated exposure (STOT RE): Cat. 2.

.