1,2,3,5,6,7-hexahydro-1,1,2,3,3-pentamethyl-4H-inden-4-one

Endpoint summary

Description of key information

Under the conditions of the test (OECD 408, GLP), the NOAEL was determined to be 10 mg/kg bw/day, based on increased adverse clinical observations, decreased pH and increased ketones in the urine of female rats, increased kidney weights, increased liver weights for female rats only and increased incidence and/or severity of histological changes in the kidney at the three highest doses.

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

10 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

1

System:

urinary

Organ:

kidney

Additional information

90-day repeated dose toxicity

In a 90-d oral repeated dose toxicity study (OECD TG 408, GLP), with a 4 week recovery period, the test substance was administered via oral gavage to 60 male and 60 female Sprague-Dawley rats by at 0, 10, 50, 125, and 250 mg/kg bw. Control animals received the vehicle, canola oil, alone. The dosage volume was 10 mL/kg. All parameters measured from the OECD TG 408 have been recorded. Rats assigned to the main study were sacrificed on day 91 of study and rats assigned to the recovery study (included to study reversibility of effects) were sacrificed on day 118 of study.

Results:

Clinical signs: No mortality (males) was observed in any of the treatment groups. In the three highest dose levels of 50, 125 and 250 mg/kg/day increased adverse clinical observations were done (excess salivation, urine-stained abdominal fur, rales and ungroomed coat). In the 250 mg/kg/day treatment group, male and female rats displayed increased motor activity. Body weight gains were significantly reduced for both male and female rats in the 125 and 250 mg/kg/day treatment groups over the entire dosage period (DSs 1 to 90). Relative feed consumption values for male rats were significantly increased in these two groups over the entire dosage period (DSs 1 to 90).

Haematology: Haematology and coagulation parameters for male and female rats were generally comparable between the vehicle control and four treatment groups and no toxicologically important differences were observed on DS 43 and/or 91.

Urinalysis: Reduced pH and increased numbers of male rats with greater than 40 mg/dL ketones in the 125 and 250 mg/kg/day treatment groups.

Urine pH was significantly reduced for female rats in the 10, 50, 125 and 250 mg/kg/day treatment groups. The number of female rats with absent urinary ketones was significantly reduced in the 50 and 250 mg/kg/day treatment groups, and the number of female rats with greater than 40 mg/dL ketones in the urine was slightly increased in the 250 mg/kg/day treatment group.

Biochemical parameters: For male rats sacrificed on DS 91, values for total bilirubin (T-BIL) were significantly increased in the 125 and 250 mg/kg/day treatment groups. Blood urea nitrogen (BUN) was significantly increased in the 250 mg/kg/day treatment group. For female rats sacrificed on DS 91, the values for cholesterol (CHOL) and total bilirubin (T-BIL) were significantly increased in the 250 mg/kg/day treatment group.

Organ effects weight/macroscopy and histopathology: No test substance-related necropsy observations were noted in the male rats sacrificed on DS 91 and 118. The weight of the heart and the ratio of the heart weight to the brain weight were significantly reduced for male rats in the 125 and 250 mg/kg/day treatment groups. For male rats only, the weight of the right adrenal gland was significantly reduced in the 250 mg/kg/day treatment group, while the ratio of the left adrenal weight to the terminal body weight was significantly increased in the 125 and 250 mg/kg/day treatment groups. The weight of the liver and the ratio of the liver weight to the terminal body weight and brain weight were increased or significantly increased for female rats in the 50, 125 and 250 mg/kg/day treatment groups. After the recovery period, for female rats, the liver weight was significantly reduced and the ratio of the thymus weight to the terminal body weight was significantly increased in the 250 mg/kg/day treatment group on DS 118. Microscopic test substance-related findings were observed in the kidneys of both sexes. These findings included an increased incidence and/or severity of changes typically seen in chronic progressive nephropathy. A minimal hyaline droplet change was also observed in the cortical tubules of individual males in the 125 and 250 mg/kg/day treatment groups. The afore-mentioned test substance-related renal changes were not seen in the recovery animals and were therefore considered reversible.

Conclusion:

During the four-week recovery period, body weight gains and relative feed consumption values were increased for male and female rats in the 250 mg/kg/day treatment group. Test substance-related changes in clinical signs, urine pH and ketones, kidney weight/kidney histopathology and clinical pathology were not observed in the recovery animals and were therefore considered to be reversible. The NOAEL for test substance is considered to be 10 mg/kg bw/d, based on increased clinical observations, decreased pH and increased ketones in urine of female rats, increased kidney weights (absolute and relative) in male and female rats, increased liver weights in female rats and increased incidence and/or severity of histological changes (i.e., changes consistent with chronic progressive nephropathy and increased tubular dilatation in the renal outer medulla) in the kidney on the highest dose levels of 50, 125 and 250 mg/kg/day. In the 125 and 250 mg/kg/day treatment group male rats reduced body weight gain, increased relative feed consumption, decreased pH and increased urinary ketones, and reduced heart weights were observed.

System effects Reproduction/developmental toxicity screening test in rats

In a reproscreening study (OECD TG 421, GLP) test substance was given orally in the diet to Wistar rats at 0, 150, 600 or 1875 mg/kg food during a premating period of 2 weeks and during mating (1 week), gestation and lactation until postnatal day 4.

Organ effects: In males increased relative liver weight was seen: 9, 20 and 31% in the low, mid and high dose respectively of which the high dose may be considered adverse but not histopathology was performed and makes it difficult to assess its adversity. In females the increase was only 9% at the high dose and not considered adverse.

In males increased relative kidney weight were seen: 7, 14 and 22%, in the low, mid and high dose, respectively. In females this increase was 6%. In males, histopathology showed an increase in basophilic tubili: 3, 6, 6 and 12/12 animals, reaching statistical significance at the high dose. This high dose effects are considered adverse. Specific assessment of alpha-2u-microglobulins did not demonstrate treatment-related differences. In females of all dose groups no effects on liver or kidney weigh were observed.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
The 90-day oral repeated dose toxicity study available is adequate to cover the repeated dose toxicity

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

Justification for classification or non-classification

Based on the results of the 90-day repeated oral gavage study, Cashmeran does not have to be classified for repeated dose toxicity according to EU CLP (EC 1272/2008 and its amendments). An extensive review of the observed effects in the 90 day oral repeated dose toxicity study is available in the attached document. Please find below the summary and conclusion with regard to classification.

A NOAEL of 10 mg/kg bw and a LOAEL of 50 mg/kg bw is derived in the 90 day oral repeated dose toxicity study and the Reproscreen study. This LOAEL is within guidance values ranges mentioned in the CLP for which classification and labelling may be warranted. In both studies the target organ is the kidney. The effects seen in the kidney at 50 mg/kg bw (in a 90-day oral study) are not considered to be significant health effects that impair the function of the kidney and therefore STOT 2 classification is not warranted. The kidney effects of Cashmeran have been evaluated according to the CLP criteria in section 3.9.1.1 and in 3.9.2.7.3 for the presence of classification and 3.9.2.8.1 for its absence (CLP, 2008). The effects seen at this dose in urinalysis (decrease of pH and increase of ketones) are minor and of doubtful toxicological relevance and are therefore not considered to be significant adverse changes. At necropsy there are no macroscopically effects seen indicating the absence of severe organ dysfunction at any dose. The microscopically CPN seen (in male rats only) is minimal in nature at 50 mg/kg bw dose and is only increased to mild at the higher doses. The CPN associated regeneration processes are also minimal in nature (minimal tubular dilatation and basophilic tubili) at the 50 and 40 mg/kg bw in the 90-day and Reproscreen study, respectively. Though the NOAEL is 10 mg/kg bw, the effects seen at 50 mg/kg bw and higher doses are not indicating significant health effects impairing organ function. In evaluating the kidney effects following 3.9.2.7.3 it can be seen that the criteria set in 3.9.1.1 “All significant health effects that can impair function, both reversible and irreversible, should be included to conclude on classification” are not met.