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Ecotoxicological information

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Terrestrial toxicity studies are available concerning the effects of cloquintocet-mexyl on earthworms, soil microorganisms, plants and birds.

The substance is of low toxicity to earthworms, with a 14 day LC50 of >1000 mg/kg (dry weight) soil being reported in an OECD 207 study (Rufli, 1989).

In a GLP and guideline compliant study a Nitrogen Transformation Test (OECD 216) and a Carbon Transformation Test (OECD 217) have been conducted (Schulze, 2013, Klimisch 1). The results are considered reliable and adequate for risk assessment. The NOEC in both tests was 1000 mg/kg soil dw. A NOEC from such a 28 day test can be considered as a long-term result for microbial populations.

In addition the influence of cloquintocet-mexyl on soil microorganisms was investigated in a 28-day study performed according to the BBA Part VI, 1-1 guideline (Morgenroth, 1992). The study was GLP compliant and is considered to be reliable. However the maximum soil concentration tested was 0.27 mg/kg soil dw.

A GLP and guideline compliant short-term terrestrial plant toxicity study (OECD 208) is available (Bramby-Gunary, 2013, Klimisch 1). Ten plant species have been tested. The most sensitive species was tomato (Lycopersicon esculentum) with an EC50 of 275 mg/kg soil dw.

Cloquintocet-mexyl is of low toxicity to birds, as indicated by the results of six acute toxicity studies.