Reaction mass of 3,5,6,6-tetramethyl-4-methyleneheptan-2-one and (E)-3,4,5,6,6-pentamethylhept-3-en-2-one

Endpoint summary

Description of key information

In an oral (diet) Combined Repeated Dose Toxicity Study with Reproduction / Developmental Toxicity Screening Test in rats (10-week premating period), performed according to OECD guideline 422, the mid-dose level of 750 mg/kg diet was a NOAEL for systemic toxicity. This dietary concentration provided ca. 42 mg/kg bw/day in male rats and ca. 41 mg/kg bw/day in female rats (based on nominal dietary test material concentration corrected for 27% loss on storage in animal room for one day). At the high-dose level (2500 mg/kg diet and circa 120 mg/kg bw/day) body weight and food consumption were decreased in both sexes and total and differential white blood cell counts were decreased in male rats.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

41 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

The repeated dose toxicity study using an extended OECD TG 422 protocol is adequate for covering this endpoint and can be used as a replacement for the 90-day study.

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

OECD 422 study including 10 -week pre-mating period

The toxicity upon repeated oral exposure was examined in a study performed according to OECD guideline 422 and in compliance with GLP. Groups of 12 male and 12 female Wistar rats received the test material via their diet, at concentrations of 0, 200, 750 and 2500 mg/diet during a 10-week premating period and during mating (one week), gestation and lactation until postnatal day 4. The total exposure duration was up to 83 days in male rats and up to 103 days in female rats. Homogeneity and correct concentration of the test material in the diet were confirmed by analysis. The test substance was not stable in the diet upon storage in the animal room. The decrease in concentration during a 1-day storage period was 18%, 27% and 22% at the low-, mid- and high-dose, respectively. To minimize loss of test material under experimental conditions as much as possible, the feed in the feed hoppers was replaced daily by a fresh portion from the freezer (stability in the freezer was confirmed by analysis). Moreover, the fresh feed was provided in the afternoon instead of in the morning because rats eat most of their feed during the dark period. These doses resulted in final mg/kg bw of circa 10, 40 and 120 mg/kg bw. The following endpoints were evaluated to assess general toxicity: daily clinical observations, neurobehavioural examination (grip strength; functional observational battery including sensory reactivity to different stimuli; spontaneous motor activity), body weight, food consumption, routine haematology and clinical chemistry (in week 10 of the premating period), organ weights, macroscopic examination and histopathological examination of a wide range of tissues and organs (except for the kidneys which were examined in all groups, only high-dose animals and controls were subjected to histopathology). Endpoints to assess reproductive / developmental toxicity included parental fertility and reproductive performance (including sperm analysis) and litter data are discussed in Section on Toxicity to reproduction.

The results showed no treatment-related changes at circa 10 and 40 mg/kgbw. At circa 120 mg/kg bw, body weight (gain) and food consumption were statistically significantly decreased during the entire or substantial parts of the study in rats of both sexes, and total and differential white blood cell counts were decreased in male rats (40%). In addition, male rats showed renal changes consisting of an increased relative kidney weight (at the high-dose level) and a dose-dependent increase of alpha 2-microglobulin nephropathy. This type of nephropathy in male rats is generally regarded as of no relevance for humans. The changes in clinical chemistry values in male rats (higher chloride at all dose levels and lower potassium at the high-dose) might be related to the nephropathy.

Based on these results the NOAEL for general toxicity was 750 mg/kg diet. This dietary level provided ca. 42 mg/kg bw/day in male rats and ca. 41 mg/kg bw/day in female rats (based on the overall mean substance intake during the premating period). The intake of the test material per kg body weight was calculated from the nominal dietary concentration corrected for the loss measured after storage in the animal room for one day.

Justification for classification or non-classification

The NOAEL is set at 41 mg/kg bw. This, however, does not warrant a STOT 2 classification, because the effects seen at 100 mg/kg bw do not indicate effects as mentioned at 3.9.2.7.3 of the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008, such as morbidity, functional changes in the nervous system, significant changes in haematology parameters and/or significant organ damage.