April 11, 2019
The EU is planning to ban the fungicide chlorothalonil in April or May, according to The Guardian ("EU bans UK's most-used pesticide over health and environment fears" 3.29.19). The fungicide is being banned after the European Food Safety Authority found that the compound poses high risks to amphibians and fish, as well as bumblebees. The main breakdown product of chlorothalonil, hydroxy-2,5,6-trichloro-1,3-dicyanobenzene (SDS-3701), is 30 times more toxic than chlorothalonil, is highly persistent in the environment, and may have the ability to cause damage to DNA (genotoxic).
California agriculture currently uses about 1 million pounds of chlorothalonil annually, which is applied as a fumigant to various crops, including nuts and stone fruit. One can see the distribution of chlorothalonil in California using Tracking California?s Agricultural Pesticide Mapping Tool showing that chlorothalonil applications are highest in the Central Valley.
There has been major losses in several bumble bee species and declines in their geographic range; bumblebees are important as they pollinate many plants and crops such as tomatoes, pumpkins, and blueberries. Chlorothalonil has been linked to stunted colony growth in bumblebees and an increased vulnerability to a fatal gut infection in both bumblebees and honeybees.