While stereoisomers share the same molecular formula and bonding, they differ in the spatial arrangement of their atoms (e.g. cis- and trans- formations). This may lead to differences in their toxicological and/or environmental properties. In its finalised guidance on the assessment of plant protection product (PPP) active substances containing stereoisomers (as components, impurities, or transformation products), EFSA states that the isomers should, as a general principle, be handled as different chemical components in (eco)toxicological risk assessments.

European Food Safety Authority (2019). Draft guidance of EFSA on risk assessments for active substances of plant protection products that have stereoisomers as components or impurities and for transformation products of active substances that may have stereoisomers. http://www.efsa.europa.eu/sites/default/files/consultation/consultation/Draft_Guidance_of_EFSA_on_isomers.rev_.5.pdf


The above items were taken from the October 2019 issue of Toxicology and Regulatory News which is sent automatically to members of bibra.

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