Reaction mass of 3-(4-hydroxy-4-methylpentyl)cyclohex-3-ene-1-carbaldehyde and 4-(4-hydroxy-4-methylpentyl)cyclohex-3-ene-1-carbaldehyde

Endpoint summary

Description of key information

 In the one-generation study with rats, the NOAEL for parental toxicity was set at 25 mg/kg bw/day, based on gestation length increase in 100 and 500 mg/kg bw. 

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

25 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

The selected study is in compliance with GLP and a guideline study and has klimisch score of 1

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

One-generation study, rat

Oral repeated dose toxicity of the test substance was studied in an OECD TG 415 study in compliance GLP using Sprague-Dawley rats. The substance was administered at dose levels of 0, 25, 100 and 500 mg/kg bw/day as a solution in arachis oil to groups of 24 rats/sex/dose for 76 days pre-mating and during maximum 21 days mating, after which males were killed, while females were killed and examined on day 21 post-partum. Females were killed and examined after day 25 post-coitum.

Results: Mortality: One male treated with 500 mg/kg bw/day was killed in extremis on day 93. One female from this treatment group was found dead on day 97 and a further two females were killed in extremis on days 99 and 100 following difficulties during parturition. Clinical signs: Episodes of hunched posture, pilo-erection and tiptoe gait were evident in 500 mg/kg bw/day females during the final week of gestation. Body weight: Body weight gain for males of the 500 mg/kg bw/day group was generally lower (average -22 %, range -9% to -43 %) than control animals throughout much of the treatment period, with statistical differences observed in weeks 4, 5, 6 and 10. Females treated with 500 mg/kg bw/day showed a notable reduction in food consumption (average -21 %, range -17 % to -28 %) throughout lactation, with statistically significant differences throughout 3 weeks. Sperm effects: There were no toxicologically significant effects on the concentration, motility or morphology of samples of epididymal sperm. There were no treatment-related effects on the concentration of homogenisation resistant epididymal or testicular spermatid counts. Gestation: An increased gestation length was observed in the 100 and 500 mg/kg bw dose groups. Macroscopy: At necropsy, the adult male treated with 500 mg/kg bw/day that was killed in extremis showed gaseous distension in the gastrointestinal tract. The female treated with 500 mg/kg bw/day that was found dead around parturition had 21 foetuses in-utero. The two females from this treatment group that were killed in extremis both had dead/inactive foetuses in-utero and red/brown staining around the ano-genital region and dark contents in the stomach or enlarged adrenals and an absent rougae on the non-glandular region of the stomach. Microscopy: No treatment-related microscopic changes were observed in the parental animals.

Conclusion: Based on the observed increased gestation length, the NOAEL for parental toxicity was set at 25 mg/kg bw/day.

OECD 407, rat

In the OECD TG 407, in compliance with GLP, study test substance was administered at dose levels of 0 (vehicle control), 15, 150 and 1000 mg/kg bw/day to groups of 5 male and female Crl:CD (SD) IGS BR rats by gavage in arachis oil for 28 consecutive days. Animals were observed for mortality and clinical signs, changes in body weight, food and water consumption. On the 28th day, blood was collected from all rats for haematological and clinical chemistry examinations. Prior to the start of treatment and on days 3, 10, 17 and 24 animals were observed for signs of functional/behavioural toxicity. Functional performance tests were also performed on all animals during week 4, together with an assessment of sensory reactivity to different stimuli. Observations were carried out from ca. 2 hours post-dosing on each occasion. At the study termination, all animals were necropsied and subjected to gross pathological and histopathological examinations.

Results: Clinical signs: Animals of both sexes treated with 1000 mg/kg bw/day showed transient increased salivation around the time of dosing from day 3 onwards. Isolated incidents of red/brown staining around the mouth and scab formation (males only) were also evident between days 13 and 25. Episodes of respiratory pattern changes and hunched posture were evident in animals of either sex treated with 1000 mg/kg bw/day during the final two weeks of study. Body weight: Males treated with 1000 mg/kg bw/day showed a reduction in body weight gain during week 1. Females treated with 1000 mg/kg bw/day showed a slight reduction in body weight gain during week 1 and 4 only, whilst males from this treatment group and 150 mg/kg bw/day showed a reduction in body weight gain throughout the remaining treatment period. Males treated with 1000 mg/kg bw/day showed a reduction in food consumption and food efficiency during week 1 only. Behaviour: No toxicologically significant changes in neurobehavior were noted. Clinical chemistry: Animals of both sexes from the 1000 mg/kg bw/day group showed an increase in plasma aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, albumin and albumin/globulin ratio when compared with the controls. In 1000 mg/kg bw/day males statistically significant reductions in plasma cholesterol, total protein and glucose were observed. An increase in alkaline phosphatase and alanine aminotransferase, and an increase in albumin were observed in 150 mg/kg bw/day females and males, respectively. Organ weight: At necropsy, animals of both sexes of 1000 mg/kg bw/day and males of 150 mg/kg bw/day groups showed an increase in absolute and relative liver weight. Males treated with 1000 mg/kg bw/day also showed an increase in absolute and relative kidney weight. Macro/microscopy: Centrilobular or generalised hepatocyte enlargement, frequently with associated focal centrilobular inflammatory cell infiltrates, were observed in animals of both sexes of the 1000 mg/kg bw/day group. In addition, centrilobular hepatocyte necrosis was seen in males treated with 1000 mg/kg bw/day. Three males treated with 150 mg/kg bw/day also showed hepatocyte enlargement. The proximal tubular epithelium of males treated with 1000 mg/kg bw/day was observed to be generally denser than in controls. Changes in cytoplasmic density are occasionally observed as a consequence of test material administration and are frequently adaptive in nature in the absence of associated degenerative changes. Animals from the remaining treatment groups were not similarly affected.

Conclusion: Based on the results of the study, the NOAEL was set at 25 mg/kg bw/day, based on an increased relative liver weight and centrilobular or generalised hepatocyte enlargement associated with focal centrolobular inflammatory cell infiltrates in both sexes, and centrilobular hepatocyte necrosis in males at 1000 mg/kg bw/day. The histopathological changes detected at 150 mg/kg bw/day were confined to adaptive liver changes in three males.

Oral (gavage) repeated dose toxicity study, rat

Method: An exploratory oral (gavage) repeated dose toxicity study with postnatal observations was conducted in Crl:CD (SD) rats. This study, in compliance with GLP, was designed to determine the potential for adverse effects on the offspring observed in the one-generation reproductive study. It was designed to evaluate: 1) whether the pup dermal effects observed in the one-generation reproductive toxicity study were due to pre- or post-natal exposure to test substance; 2) whether the test substance produced a functional zinc deficiency in the dams, thereby producing the skin sloughing, peeling and/or flaking in pups. Fifty female rats were randomly assigned to 6 dosage groups: groups I - III for the main part of the study and Groups IV - V for the satellite part of the study, intended to evaluate the role, if any, of zinc in observed effects. Group Ia was administered the vehicle and group II was administered the test substance once daily from gestation day 0 through gestation day 21 or 24. Group Ib was administered the vehicle and group III the test substance once daily from lactation day 1 through 21. Group IV was administered the vehicle and Group V was administered the test substance once daily from gestation day 0 to 14. Dams were asphyxiated on gestation day 15 (groups IV and V) or lactation day 21 (Groups Ia, Ib, II and III). The following parameters were evaluated: viability, clinical observations, body weights, feed consumption and necropsy observations. Rats assigned to groups Ia through III were evaluated for fertility parameters, adverse clinical signs during parturition, duration of gestation, litter sizes, pup viability at birth and maternal behaviour. Whole blood samples were collected on gestation day 15 from each rat assigned to groups IV and V for evaluation of Zn levels. Portions of livers from rats from groups IV and V were evaluated for metallothionein concentrations. Whole blood samples were collected from each rat assigned to groups Ia through III on lactation day 2 for evaluation of Zn levels and for clinical biochemical evaluations. Each litter was evaluated for viability, and clinical observations throughout preweaning, body weights and external gross lesions were recorded.

Results: Administration of test substance at 500 mg/kg bw/day caused mortality as a result of dystocia and adverse clinical signs in the dams treated during the gestation period (Group II). Reductions in body weight gain occurred during the gestation treatment period; although not statistically significant, the reductions were substantial enough (90.3% of the concurrent vehicle control group value) to be toxicologically important. No apparent effects of the test substance on body weight gain were noted during the lactation period, following the cessation of test article administration. At sacrifice, the average terminal body weight was significantly increased, reflecting significant increases in maternal body weight gains after treatment was stopped. Serum chemistry parameters during early lactation, specifically glucose levels, blood urea nitrogen levels and alkaline phosphatase levels and the albumin to globulin ratio were significantly increased by 500 mg/kg bw/day test substance (Group II).

Treatment of the dams during the lactation period (Group III) resulted in increased liver weights, body weights (with fluctuating periods of body weight gain and body weight loss) and terminal weights. Cholesterol levels were lower in dams treated during the lactation period (Group III), while creatinine, aspartate aminotransferase, inorganic phosphate levels and albumin to globulin ratios were significantly increased in these dams.

Treatment of dams with the test substance during gestation or lactation had no biologically important effect on zinc or metallothionein levels.

Pups growth and viability was affected by the test substance treatment during the gestation period (Group II), in that increased incidences of stillbirths occurred as well as pup deaths near parturition and up to lactation day 3. As a result, the viability index was significantly reduced, the lactation index was reduced, and live litter sizes were significantly lower than control group values (Group Ia). Transient reductions in pup weights were noted in the F1 generation as a result of maternal treatment with the test substance during the gestation period (Group II). Clinical signs of cold to touch, often associated with pup mortality, and transient observations of flaking occurred in F1 generation pups. These effects were observed at a dose that caused reduced maternal body weight gains and maternal mortality.

Observations in the F1 generation from dams treated during lactation (Group III) included significantly reduced viability and lactation indices, reductions in pup weights that were sustained until sacrifice, compared to the vehicle control (Group Ib), and persistent observations of skin peeling in all litters.

Conclusion: In conclusion, when pregnant rats were treated with test substance during the gestation period, transient clinical signs of flaking were noted in the F1 generation pups with relatively few observations of skin peeling. This effect occurred at maternally toxic levels. Conversely, treatment of the dams with test substance during the lactation period resulted in skin peeling in all F1 generation pups, without resolution, and with minimal observations of flaking prior to sacrifice.

Justification for classification or non-classification

The NOAEL is set at 25 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.