2-methylglutaric acid

Endpoint summary

Additional information

Terrestrial ecotoxicity results are available on two trophic levels: soil invertebrates (earthworms) and plants.

Due to the requirements of another regulation than REACH (Chinese notification), an experimental study, scored as Klimisch 1, is available on earthworm and was selected as a key study. It was performed in compliance with GLP according to OECD 207 test guideline. This study was designed to determine the acute toxicity of test substance 2-methylglutaric acid to earthworms (Eisenia foetida). The test worms were exposed for 14 days to the test substance or to a control treatment. The study comprised one range-finding test and a definitive limit test at 1000 mg/kg dw during which the mortality was recorded daily. As no mortality was observed in this study, the 14-day LC50 was determined to be higher than 1000 mg/kg dw. In these conditions, 2-methylglutaric is not harmful to earthworms.

Due to the requirements of another regulation than REACH (Chinese notification), an experimental study, scored as Klimisch 3, is available on terrestrial plants. It was performed in compliance with GLP according to a Chinese standard test guideline. This study was designed to determine the toxicity of test substance 2-methylglutaric acid to ten terrestrial plant species (Brassica chinensis L., Lactuca sativa, Oryza sativa L., Brassica oleracea, Cucumis sativus, Zea mays, Fructus Capsici Capsicum frutescens L., Lycopersicon esculentum, Glycine max, Raphanus sativus). Exposure was conducted in a quartz sand substrate mixed with test solutions at given concentrations of 2-methylglutaric acid. A control treatment was tested in parallel. The exposure duration lasted from 5 to 7 days depending on the species (the test period was ended when at least 65% of the control seeds have germinated and developed roots that are at least 20 mm long). The study comprised one range-finding test (tested concentrations: 0, 10, 100 and 1000 mg/L) and a definitive test (tested concentrations: 0, 53.3, 80.0, 120, 180, 270, 405, 607, 911 mg/L; knowing that different concentrations within this range were applied for the different species). The number of seeds that germinated was counted and root length was measured for each test species. Adverse effects on germination were observed for seven of the ten tested species. Root elongation was adversely affected in all the tested species. However, it has to be noticed that an important decrease of pH was observed when the concentration of 2-methylglutaric acid increased. Therefore, it cannot be ruled out that the observed effects could result from an indirect impact of pH rather than from ‘true’ toxicity of the test substance. Furthermore, the results of this study are expressed in mg/L and not in mg/kg of soil as classically required for a study dealing with terrestrial ecotoxicity. For all these reasons, this study was disregarded and scored as Klimisch 3.

Under REACH, the two above studies are not required because 2-methylglutaric acid (i) is not intentionally applied to soil, (ii) has a low volatility potential from water and because (iii) there is no indication for high adsorption (Log Kow < 5, Log Koc < 4), high persistence (rapidly degradable) or acute toxicity to aquatic organisms (L/EC50 > 100 mg/L in the three trophic levels). The studies were nevertheless provided here because they were performed for the purpose of another regulation, a Chinese notification, which required the performance of these tests in a Chinese laboratory.

Ecotoxicity tests on other soil species (terrestrial arthropods, soil micro-organisms) were waived based on points (i), (ii) and (iii) above explained.