Risk to Consumers: Paraquat Residues found in Aquatic Life in Nan Province

The Department of Biology in the Faculty of Science at Chulalongkorn University has identified paraquat residues in the environment. Paraquat was found in several species [i.e. the grass frog (Fejervarya limnocharis), ricefield crabs (Somanniathelphusa), freshwater clams, and the fish Smith’s barb (Puntioplites proctozysron)]. The amounts of paraquat identified by the study exceeded the regulatory limit and reached levels that can cause harm to consumers.

This research is a study monitoring agricultural chemicals in farming areas of Wiang Sa District in Nan province. The chemicals monitored include glyphosate, paraquat, and atrazine. It was found that chemical residues had accumulated in the body of the grass frog; moreover, the grass frogs had enlarged livers, low body weight, and reduced immune response. In freshwater crabs found in the rice fields, all three chemicals had accumulated in the crabs’ bodies; these crabs also had low body weight and morphological changes. Chemicals were also found accumulated in the bodies of the freshwater clams collected from swampy areas nearby the rice fields; the clams had low body weight and were at risk of negative impacts on their development and on their reproductive systems. As for Smith’s barb fish, the fish collected from the Nan river likewise had accumulated chemicals in their bodies; the livers and kidneys of these fish were abnormally sized and the fish were at risk of impacts on their reproductive systems.

These findings were shared at the “Chula Expo 2017: CU@100 Toward Greater Innovation for Society” event marking Chulalongkorn University’s 100th anniversary. These findings coming from this long-established university further emphasize the pressing issue of environmental contamination from toxic chemicals such as paraquat that are used in agricultural areas. These chemicals can impact consumers’ health through bioaccumulation. These findings from Chulalongkorn University add to the already-significant body of evidence about accumulation of paraquat, including studies from Naresuan University and Mahidol University that have found paraquat residues in soil, water, and even in the bodies of newborn infants.