2-methylglutaric acid

Endpoint summary

Additional information

Acute toxicity:

Acute toxicity results are available on four trophic levels: fish, aquatic invertebrates, algae and aquatic micro-organisms.

An experimental study, scored as Klimisch 1, is available on fish and was selected as a key study. It was performed in compliance with GLP according to OECD 203 test guideline. Using a static design, fish (rare minnow, Gobiocypris rarus) were exposed for 96 hours to a control treatment or to 2-methylglutaric acid at 100 mg/L (limit test). Mortality was recorded daily. No dead fish was observed in any of the treatment. Analytical monitoring revealed that measured concentrations were at the level of nominal at the start of the test and remained stable during the exposure. Consequently, the effects parameters were reported in terms of analytically confirmed nominal concentrations. On this basis, the 96h-LC50 was set > 100 mg/L; implying that 2-Methylglutaric acid is not harmful to fish.

An experimental study, scored as Klimisch 1, is available on daphnids and was selected as a key study. It was performed in compliance with GLP according to OECD 202 test guideline. Using a static design, daphnids (Daphnia magna) were exposed for 48 hours to a control treatment or to 2-methylglutaric acid at 0.1, 1, 10 and 100 mg/L (combined range-finding/limit test). Immobility was recorded daily. No immobile daphnid was observed in any of the treatment. Analytical monitoring revealed that measured concentrations were at the level of nominal at the start of the test and remained stable during the exposure. Consequently, the effects parameters were reported in terms of analytically confirmed nominal concentrations. On this basis, the 48h-EC50 was set > 100 mg/L; implying that 2-Methylglutaric acid is not harmful to aquatic invertebrates.

An experimental study, scored as Klimisch 1, is available on algae and was selected as a key study. It was performed in compliance with GLP according to OECD 201 test guideline. Using a static design, algae (Pseudokirchneriella subcapitata) were exposed for 72 hours to a control treatment or to 2-methylglutaric acid at 0.1, 1, 10 and 100 mg/L (combined range-finding/limit test). Cell densities were measured daily and allowed to calculate average specific growth rate and yield. Compared to control treatment, there is no inhibition of average growth rate and yield in any of the treatment. Analytical monitoring revealed that measured concentrations were at the level of nominal at the start of the test and remained stable during the exposure. Consequently, the effects parameters were reported in terms of analytically confirmed nominal concentrations. On this basis, the 72h-ErC50 was set > 100 mg/L; implying that 2-Methylglutaric acid is not harmful to algae.

An experimental study, scored as Klimisch 1, is available on aquatic micro-organisms and was selected as a key study. It was performed in compliance with GLP according to OECD 209 test guideline. Using a static design, activated sludge from a sewage treatment plant receiving predominantly domestic sewage were exposed for 3 hours to a control treatment or to 2-Methylglutaric acid at 10, 100 and 1000 mg/L (combined range-finding/limit test). While the concentrations of 10 and 100 mg/L were tested only under neutralized conditions, the concentration of 1000 mg/L was tested with and without pH adjustment. Respiration rate was investigated through measurements of oxygen consumption after a contact time of 3 hours. Under neutralized conditions, 2-Methylglutaric acid was not toxic to waste water (activated sludge) bacteria at a concentration of 1000 mg/L: the NOEC is thus superior or equal to 1000 mg/L. The EC50 was > 1000 mg/L. However, exposure to a 2-methylglutaric acid concentration of 1000 mg/L under non neutralized conditions showed a severe toxic effect to waste water (activated sludge) bacteria (98% inhibition). The EC50 was < 1000 mg/L, meaning that in the absence of neutralization, the acidity of the test item induced adverse effects to waste water bacteria.

Chronic toxicity:

Chronic toxicity results are available on three trophic levels: fish, aquatic invertebrates and algae.

Due to the requirements of another regulation than REACH (Chinese notification), an experimental study, scored as Klimisch 1, is available on fish (Rare minnow, Gobiocypris rarus) and was selected as a key study. It was performed in compliance with GLP according to OECD 210 test guideline. Exposure, conducted under semi-static conditions (72h renewal) lasted from the fertilised egg stage to 28-day post-hatching and organisms were exposed to 2-methylglutaric acid concentrations of 1, 2, 4, 8 and 10 mg/L and to a control treatment. The recorded effect parameters were hatching, survival, weight, length, behaviour and malformations. The hatching rates recorded in control treatment and treatments exposed to 2-methylglutaric acid (at 1, 2, 4, 8 and 10 mg/L) ranged between 95 and 98.3% and the survival rates between 91.7 and 96.7 %. The inhibition of weight compared to the control fish ranged between 4.37 and 5.45% for the different concentrations of 2-methylglutaric acid; which is not statistically significant. For length, the inhibition ranged between 0.67 and 2.54%; which is not statistically significant neither. Neither abnormal behaviour, nor abnormal appearance was observed in any of the control fish or fish exposed to the different concentrations of 2-methylglutaric acid. For all the considered endpoints (i.e. hatching, survival, weight, length, behaviour, malformations), the NOEC is thus superior or equal to 10.0 mg/L (corresponding to a measured concentration of 10.1 mg/L). In these conditions, 2-Methylglutaric is not harmful to fish in the long term.

Due to the requirements of another regulation than REACH (Chinese notification), an experimental study, scored as Klimisch 1, is available on daphnids (Daphnia magna) and was selected as a key study. It was performed in compliance with GLP according to OECD 211 test guideline. Exposure was conducted under semi-static conditions (72h renewal) and lasted 21 days. Parental daphnids were exposed to 2-methylglutaric acid concentrations of 0.1, 0.2, 0.4, 0.8 and 1.60 mg/L and to a control treatment. The number of living adults and offsprings were counted daily. At the end of the test period, no adults died in control, 0.10, 0.20, 0.40 and 0.80 mg/L treatments, and 5 adults died in the 1.60 mg/L treatment. The mean number of living offspring produced per control parent animal surviving at the end of the test was 60~88. The reproduction rates of treatments more than 0.20 mg/L are significantly different from that of the blank control. Indeed, at 0.2 mg/L, the reproduction rate was inhibited by 28.5%, by 35.5% at 0.4 mg/L, by 34.9% at 0.8 mg/L and by 47.8 or 65% at 1.6 mg/L (depending whether the reproduction rate is considered per adult or per surviving adult). The 21-day NOECs on Daphnia magna were equal to 0.8 mg/L based on survival and to 0.11 mg/L based on reproduction; showing that 2-Methylglutaric acid is harmful to aquatic invertebrates with long-lasting effects.

A chronic toxicity result is available on algae and was obtained during the study above described and performed in compliance with GLP according to OECD 201 test guideline. In top of the 72h-ECr50 > 100 mg/L, this study also reported 72h-ErC10 and 72 h-NOErC values which are considered as indicative of chronic toxicity. These values were set > 100 mg/L and >= 100 mg/L respectively; meaning that 2 -Methylglutaric acid is not harmful to algae also with respect to long-lasting effects.