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Ecotoxicological information

Toxicity to soil macroorganisms except arthropods

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Description of key information

Two reliable guideline (OECD 207) studies on earthworms are available (Eisenia foetida), one performed with cloquintocet-mexyl (CGA185072 tech) (Rufli, 1989) and another with CGA153433 (metabolite of cloquintocet-mexyl). The endpoint selected for the chemical safety assessment is the LC50 of >1000 mg/kg reported by Rufli (1989).

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:
1 000 mg/kg soil dw

Additional information

Rufli (1989) investigated the toxicity of cloquintocet-mexyl (CGA185072 tech) to earthworms (Eisenia foetida) in a GLP compliant study performed according to OECD 207. The highest number of mortalities was observed at the highest test concentration of 1000 mg/kg, where 5 out of 40 earthworms (13%) perished. Based on this, the 14-day LC50is greater than 1000 mg/kg dry weight soil (nominal concentration). The study was GLP compliant and is considered to be reliable without restriction. 

An acute toxicity study of CGA153433 (metabolite of cloquintocet-mexyl) to the earthworm (Eisenia foetida) is also available (Kleiner 1999). The study was GLP compliant and performed according to OECD 207 with only minor deviation (Temperature deviation, not considered to have any impact on the test results). No effects were seen at the single nominal test concentration of 1000 mg test item/kg dry weight soil. Therefore the NOEC is determined to be 1000 mg test item/kg dry weight soil.

Both of the above studies are considered to be acute. The LC50 of >1000 mg/kg reported by Rufli (1989) for cloquintocet-mexyl has been selected for the chemical safety assessment.