Environmental Fate and Toxicology of Methomyl

The insecticide methomyl (S-methyl N-(methylcarbamoyloxy)thioacetimidate; CAS 16752-77-5; Fig. 1) was first introduced by E.I. du Pont de Nemours in 1968 (US EPA, 1998b). In 1978, the US Environmental Protection Agency classified methomyl as a restricted-use pesticide (RUP; US EPA 1998a); currently 15 registered products are categorized as such (US EPA 1998b). Further restrictions were implemented in 1995, limiting use to certain agricultural production areas, requiring addition of an embittering agent during formulation and requiring the use of bait stations (US EPA 1998a). Within the USA, approx. 262,000 kg of methomyl (a.i.) was applied on agricultural crops annually from 1999 to 2004 (US EPA 2010). However, estimates for the period between 2001 and 2007 show annual average usage of approx. 363,000 kg (a.i.); major crop uses included sweet corn, lettuce, onions, and tomatoes (US EPA 2010). In 2007, some 227,711 kg of active ingredient was applied in California alone (CDPR 2007). © 2013 Springer Science+Business Media New York.