Acetic acid, anhydride, reaction products with 1,5,10-trimethyl-1,5,9-cyclododecatriene

Endpoint summary

Description of key information

Under the conditions of the test (OECD TG 422, GLP), the NOAEL was determined to be 150 mg/kg bw/day for males and females, based on the increase of liver weights effect.

Under the conditions of the test (OECD TG 407, GLP), the NOAEL was determined to be 150 mg/kg bw/day for males and females, based on haematological, biochemical, organ weight and histopathological effects.

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

150 mg/kg bw/day

Study duration:

subacute

Species:

rat

Additional information

OECD TG 422

In a combined 28-days repeated dose toxicity study with reproduction/developmental screening performed in accordance with OECD TG 422 and GLP, the substance was administrated via oral gavage to Sprague-Dawley rats (10 per dose per sex) at dosages of 50, 150 and 500 mg test item/kg bw/day. Control animals received the vehicle, corn oil, alone. All parameters measured from the OECD TG 422 have been recorded.

Clinical signs: No treatment related effects were observed

Body weights: Lower body weight gain prior to pairing were evident in all groups of treated F0 males and females compared to Controls, with the greatest effect observed at 500 mg/kg/day. Since there was no effect of treatment on the clinical condition of the F0 males and females, and no effect on offspring survival or development, the extent of these body weight changes were not considered adverse.

Haematology: no effects observed.

Blood chemistry investigations at scheduled termination of males that received 500 or 150 mg/kg/day revealed 4.7 and 3.5% statistically significantly higher mean calcium levels, compared to Control. However, mean values for other blood electrolytes were similar to Control. Statistically significantly lower mean creatinine (23.8%) and glucose levels (15.6%), compared to Control, were also apparent for males that received 500 mg/kg/day. These males also showed higher mean albumin (5.6%) and albumin/globulin ratio (11.8%), although the level of mean total protein appeared unaffected. A statistically significantly 15.6% lower mean aspartate aminotransferase (AST) activity was apparent for males that received 500 mg/kg/day.

Thyroid hormones: Mean serum Thyroxine (T4) concentrations for all groups of treated F0 adult males at termination were higher than the Control group with a dose response apparent (21, 21, and 11% increase at 500, 150, and 50 mg/kg/day, respectively) and statistical significance attained at 500 and 150 mg/kg/day. Additionally, mean serum Thyroid Stimulating Hormone (TSH) concentration was 73% higher than Control for F0 adult males that received 500 mg/kg/day, but appeared unaffected in F0 males that received 150 or 50 mg/kg/day.

Organ weights: Absolute and body weight adjusted liver weights were increased in all groups of treated males with a dose response apparent and statistical significance attained at 500 and 150 mg/kg/day for the adjusted values. The adjusted weights were increased 43, 17, and 6% in the 500, 150, and 50 mg/kg/day dose groups, respectively. Compared to Control, absolute and adjusted kidney weights were also increased in all groups of treated males with statistical significance attained for the adjusted values at 500 mg/kg/day, but there was no dose response apparent (16, 8 and 11% higher adjusted weights in the 500, 150, and 50 mg/kg/day dose groups, respectively). On Day 13 of lactation, absolute and body weight adjusted liver weights for females that received 500 or 150 mg/kg/day were higher (25 and 6%, respectively for adjusted weights) with statistical significance attained at 500 mg/kg/day for adjusted weights. Absolute and body weight adjusted spleen weights were lower in all treated females (23, 23, and 21% lower in the 500, 150, and 50 mg/kg/day dose groups, respectively, for the adjusted weights) – statistical significance was attained for all treated groups for the adjusted weights.

Histopathology: Microscopic examination of the adult males and females revealed treatment-related findings in the liver and thyroid. Minimal to slight centrilobular hepatocyte hypertrophy was noted in four out of five males that received 500 mg/kg/day and in one out of five males that received 150 mg/kg/day. Minimal follicular hypertrophy was noted in the thyroid of four out of five males that received 500 mg/kg/day and in two out of five males that received 150 mg/kg/day.

Conclusion: Treatment related liver effects were considering biochemistry, organ weights and histopathology at 500 mg/kg bw. Related to the increased liver weights, increased metabolic capacity, increase in metabolization of T4, some increase in TSH, also thyroid weights and related hypertrophy was seen at 500 mg/kg bw. Therefore the NOAEL was set to 150 mg/kg bw.

OECD TG 407

In a 28-days repeated dose toxicity study (OECD TG 407, GLP) with a 2-week recovery period, the substance was administrated via oral gavage to Sprague-Dawley rats at dosages of 15, 150 and 1000 mg test item/kg bw/day. Control animals received the vehicle, corn oil, alone. All parameters measured from the OECD TG 407 have been recorded.

Clinical signs: No adverse effects considered to be associated with treatment were observed for mortality, clinical signs, neurobehavior, bodyweight and food consumption.

Haematology: Treatment resulted in lower group mean haematocrit and haemoglobin for females at 1000 mg/kg/day, increased group mean platelet counts for both sexes and activated partial thromboplastin times for males at 1000 mg/kg/day. At the end of the recovery period, general recovery from the previous changes in red blood cell parameters was evident, however higher than control platelet counts were still evident in females previously treated at 1000 mg/kg/day, though magnitude of difference was much less than during treatment.

Urinalysis: No adverse effects considered to be associated with treatment were observed.

Biochemical parameters: Higher group mean bilirubin and cholesterol and lower ALP, AST, glucose for both sexes and lower ALT in males, were recorded for animals receiving 1000 mg/kg/day. Males receiving 150 mg/kg/day also recorded lower AST and glucose compared with controls. In addition, higher than control group mean total protein, albumin, calcium and phosphorus and lower mean chloride and AG ratios were recorded for both sexes receiving 1000 mg/kg/day. No toxicologically important changes were recorded at the end of the recovery period, indicating general recovery from the previous effects of treatment.

Organ effects weight: Higher than control adjusted group mean liver weights were recorded for both sexes at 1000 mg/kg/day and for females at 150 mg/kg/day. Group mean adjusted kidney weights were higher for females receiving 150 or 1000 mg/kg/day. At the end of the recovery period, higher than control group mean adjust liver and kidney weights were still evident in females previously treated at 1000 mg/kg/day though recovery was evident. Enlargement of the liver was seen in one male rat and all female rats treated at 1000 mg/kg/day.

Macroscopy: No adverse effects considered to be associated with treatment were observed.

Histopathology: Treatment-related histopathological findings were seen in the liver and thyroids of both sexes given 1000 mg/kg/day and in the spleen of females of this dose group. They comprised centrilobular or generalised hepatocyte hypertrophy in the liver, follicular cell hypertrophy in the thyroids, and an increased severity of hemosiderosis and increased incidence of extramedullary haemopoiesis in the spleen. Centrilobular or generalised hepatocyte hypertrophy was also seen in several females given 150 mg/kg/day. Following a 2-week recovery period, there was evidence of partial or complete recovery from these changes.

Conclusions: Under the conditions of this study, the NOAEL for repeated dose toxicity was established to be 150 mg/kg bw/day for males and females, based on haematological, biochemical, organ weight and histopathological effects. Treatment-related findings were also evident at 150 mg/kg/day, but the degree of difference and number of changes seen at this level was less than at 1000 mg/kg/day. Thus as good evidence of recovery was seen at 1000 mg/kg/day, 150 mg/kg/day was concluded to be the highest NOAEL on this study. Because these changes, taken as a whole, were considered to represent minor but generally reversible toxicology, the substance does not need to be classified for specific target organ toxicity following repeated exposure in accordance with EU CLP (EC 1272/2008 and its amendments).

Justification for classification or non-classification

Based on the results of two repeated oral gavage toxicity studies, the substance does not have to be classified for repeated dose toxicity according to EU CLP (EC 1272/2008 and its amendments).