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Although no specific data is available for cloquintocet-mexyl for toxicity to terrestrial plants cloquintocet-mexyl is used on a wide range of plants as a safener (component of a herbicide plant protection product). Therefore, at application rates of up to 15 g/ha, cloquintocet-mexyl is considered to have no adverse effects on plants.

In order to fulfill the data requirement of Regulation (EC) no. 1907/2006, Annex IX, 9.4.3, OECD Guideline 208 (Terrestrial Plants Test: Seedling Emergence and Seedling Growth Test) testing is proposed by Syngenta Ltd (lead registrant). This additional test is only needed in order to fulfill the data requirement but is not needed as a consequence of the chemical safety assessment.

According to Regulation (EC) no. 1907/2006, Annex IX, 9.4, column 2, long-term studies should be considered for substances that have a high potential to adsorb to soil. Background from Guidance on information requirements and chemical safety assessment, Chapter R.7c, May 2008): "Some substances present a particular concern for soil, such as those substances that show a high potential to partition to soil, and hence may reach high concentrations, or those that are persistent". Koc is considered as the relevant parameter to describe the adsorption potential to soils. For cloquintocet-mexyl log Koc is 4.1 (based on mean Koc of 12850 mL/g), thus log Koc is below 5. Therefore the substance does not qualify for "highly adsorptive". In addition the substance degrades very rapidly in soil, thus its accumulation potential is very small. As a consequence no long-term plant study is proposed.