Variation of United States environmental regulations on pesticide soil standard values

To specify the maximum allowable pesticide concentration in soil, pesticide residential soil regulatory guidance values (RGVs) have been promulgated by U.S. state regulatory jurisdictions to protect human health. A total of 12,451 RGVs for 456 identified pesticides adopted by 46 states were analyzed to evaluate whether there is the agreement among pesticide standard values regulated by the U.S.-related jurisdictions. Among them 62 pesticides with at least 50 RGVs were defined as the commonly regulated pesticides, and seven pesticides with at least 100 RGVs were defined as the most commonly regulated pesticides. A total of 12 states have provided over 500 pesticide soil RGVs and Texas alone has provided at least 1140 RGVs. Results indicate that these pesticide soil RGVs promulgated by the U.S. state jurisdictions for an individual pesticide could vary in a wide range of over six (DDT), seven (alpha-HCH), or even nine (Dieldrin) orders of magnitude. On the other hand, all of the seven most commonly regulated pesticides have a large RGV data cluster in which the state jurisdiction RGVs shared the U.S. Environmental Protection Agency (U.S. EPA) standards. To examine whether those pesticide soil RGVs could protect human health, cancer and non-cancer risk uncertainty bounds were calculated for the seven most commonly regulated pesticides. Results show that for the most commonly regulated pesticides, a total of 265 (41.8% of the total) soil RGVs exceeded the cancer risk uncertainty upper bounds and 30 (4.5% of the total) soil RGVs are above the non-cancer risk uncertainty bounds, which indicates that those RGVs cannot protect human health when exposing to the pesticides from soil.