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

Key value for chemical safety assessment

Effects on fertility

Description of key information

The fertility of the substance was experimentally determined in an extended dietary OECD TG 422 of circa 90 days. Repeated dose effects were seen and a NOAEL of circa 40 mg/kg bw is derived. No effects were seen on fertility for males and females and therefore the NOAEL is circa 120 mg/kg bw (the highest dose tested).

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

120 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

An dietary reproscreening study is carried out using an extended OECD TG 422 protocol, which is adequate for covering the fertility endpoint.

Additional information

OECD 422 study including 10 -week pre-mating period

The reproductive / developmental toxicity upon repeated oral exposure was examined in a study performed according to OECD TG 422 and in compliance with GLP. Groups of 12 male and 12 female Wistar rats received the substance via their diet, at concentrations of 0, 200, 750 and 2500 mg/kg 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. 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 (sperm analysis, weight and morphology of sex organs, mating index, pre-coital time, male and female fertility indices, female fecundity index, gestation index and length, pre- and post-implantation loss) and litter data (numbers of stillborn, live and dead pups, external abnormalities, pup weight on lactation days 1 and 4, necropsy of stillborn pups and pups that died during the study).

The results showed no treatment-related changes at 200 and 750 mg/kg diet. At 2500 mg/kg diet, 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. 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. Testicular sperm count and epididymal sperm motility, count and morphology were not affected by treatment. The weight of the testicular parenchyma in the high-dose group was statistically significantly lower than in the control group. Since no effects were observed on testis weight, this is considered an incidental finding. No female reproductive toxicity parameters were affected except for a slight statistically significant decrease in corpora lutea compared to the historical controls. The observed decrease in corpora lutea is of doubtful toxicological relevance and probably due to chance. Pre- and post-implantation loss were not affected by treatment. The viability of pups was not affected by treatment. The mean number of pups delivered in the high-dose group was statistically significantly lower than in the control group. This was due to the lower number of corpora lutea (probably due to chance) in the high-dose group. No treatment-related clinical findings or body weight changes were observed. Macroscopic examination of stillborn pups and pups that died during the study revealed no treatment-related abnormalities.

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. The NOAEL for fertility and reproductive performance of the male and female parental rats and the NOAEL for developmental toxicity were 2500 mg/kg diet based on the absence of reproductive effects up to the highest dose tested. This dietary level provided ca. 158 mg/kg bw/day in male parental rats and ca. 129 mg/kg bw/day in female parental rats.

Effects on developmental toxicity

Description of key information

The developmental toxicity of the substance was experimentally determined in an extended dietary OECD TG 422 of circa 90 days. Repeated dose effects were seen and a NOAEL of circa 40 mg/kg bw is derived. No effects were seen on developmental toxicity and therefore the NOAEL is circa 120 mg/kg bw (the highest dose tested).

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

129 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

The OECD TG 422 study has been carried out and literature information is included to cover the developmental toxicity endpoint for REACH.

Additional information

OECD 422 study including 10 -week pre-mating period

The developmental toxicity upon repeated oral exposure was examined in a study performed according to OECD TG 422 and in compliance with GLP. Twelve female Wistar rats per group 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 of the dams was up to 103 days. 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. 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 (weight and morphology of sex organs, mating index, pre-coital time, fertility indices, female fecundity index, gestation index and length, pre- and post-implantation loss) and litter data (numbers of stillborn, live and dead pups, external abnormalities, pup weight on lactation days 1 and 4, necropsy of stillborn pups and pups that died during the study).

The results showed no treatment-related changes at 200 and 750 mg/kg diet. At 2500 mg/kg diet, body weight (gain) and food consumption were statistically significantly decreased during the entire or substantial parts of the study. No female reproductive toxicity parameters were affected except for a slight statistically significant decrease in corpora lutea compared to the historical controls. The observed decrease in corpora lutea is of doubtful toxicological relevance and probably due to chance. Pre- and post-implantation loss were not affected by treatment. The viability of pups was not affected by treatment. The mean number of pups delivered in the high-dose group was statistically significantly lower than in the control group. This was due to the lower number of corpora lutea (probably due to chance) in the high-dose group. No treatment-related clinical findings or body weight changes were observed. Macroscopic examination of stillborn pups and pups that died during the study revealed no treatment-related abnormalities.

Based on these results the NOAEL for maternal toxicity was 750 mg/kg diet. This dietary level provided ca. 37 mg/kg bw/day in female rats (based on the overall mean substance intake during the gestation 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. The NOAEL for developmental toxicity was 2500 mg/kg diet based on the absence of effects up to the highest dose tested. This dietary level provided ca. 129 mg/kg bw/day in female parental rats.

 

Testing proposal:

A developmental toxicity study (OECD TG 414) in rats is proposed.

Justification for classification or non-classification

Based on the absence of adverse effects on fertility and of developmental toxicity in the oral (diet) Combined Repeated Dose Toxicity Study with Reproduction / Developmental Toxicity Screening Test in rats (10-week premating period), classification of the substance for effects on fertility or developmental toxicity is not warranted in accordance with EU Classification, Labeling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.