Thailand has placed paraquat, a herbicide and chlorpyrifos, an insecticide on a list of hazardous substances.  This has implications for the import of commodities that may contain residues of these compounds.

Thailand imports U.S. soybeans worth $500 million annually and is a major importer of U.S. wheat in addition to cooking oil and animal-feed ingredients.

The U.S. and Brazil have both lodged protest with Thailand over the ban on the two chemicals noting that detection of residues could seriously impact trade.

In terms of WTO agreement on Sanitary and Phytosanitary measures to justify bans, Thailand will have to provide scientific evidence supporting their action.

Chlorpyrifos is banned in California and the EU based on its deleterious effect on the development of the nervous system in children it should be phased out in favor of alternatives.  Thailand could make a case for chlorpyrifos and possibly for paraquat although evidence of detectable residues in imported commodities and feed ingredients would be necessary as a justification for action.