Diazinon—Chemistry and Environmental Fate: A California Perspective: Fid-Bau Portal

Diazinon—Chemistry and Environmental Fate: A California Perspective

Aggarwal, Vaneet / Deng, Xin / Tuli, Atac / Goh, Kean S.

Diazinon (O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate) was first registered in the USA in 1956 (US EPA 2006) by the Swiss company J.R. Geigy. Diazinon is a broad-spectrum contact organophosphorus pesticide that is used as an insecticide, acaricide, and nematicide. Diazinon has been widely used to control soil and foliage insects and pests on a wide range of crops such as rice, fruits, wine grapes, sugarcane, corn, and potatoes. Diazinon is also used to control mange mites, ticks, lice, biting flies on sheep, cows, pigs, goats, and horses. In California, diazinon has been applied primarily on fruits, vegetables, and for landscape maintenance and structural pest control. In 2010, a total of only 64,122 kg of diazinon was used in California (CDPR 2010a). Diazinon was formerly used in household and garden products for pest control. However, manufacturing of indoor use products was discontinued on June 30, 2001, and production of nonagricultural outdoor use products containing diazinon was discontinued on June 30, 2003. As of December 31, 2004, sales of diazinon-containing products for residential use ceased (US EPA 2000), resulting in diazinon falling to a rank of 94 among the most used pesticides in California by 2010 (CDPR 2010b). Diazinon is formulated as a wettable powder, granules, liquid concentrates, seed dressings, microencapsulations, and impregnated materials (US EPA 2006). Some typical formulations containing diazinon as an active ingredient (a.i.) include the following: Basudin® 10 (10 % a.i.), Knoxout® (Pennwalt, 23 % a.i.), Nucidol® 60 (60 % a.i.), Alfatox®, Gardentox®, and several other trade-named products. Although concentrations have decreased nationwide in urban waters, diazinon is still frequently detected as a residue in agricultural watersheds. In California’s agricultural regions with the highest diazinon use, the detection frequencies in 2005–2010 could reach 90 % of the monitoring samples; moreover, the exceedance rate vs. the water quality criterion of 0.1 μg/L was 66.7 % (Zhang and Starner 2011). This large proportion of detections and exceedance of water quality criteria have led to concerns about diazinon’s potential environmental impacts. In this chapter, we provide a review of the environmental fate of diazinon and describe its toxicity to aquatic organisms.