J Milton Clark’s research while affiliated with United States Environmental Protection Agency and other places

The Illinois Department of Public Health participated in the Chicago, Illinois, area methyl parathion (MP) response with several other federal, state, and local government agencies beginning in April 1997. This response was initiated on evidence that hundreds of homes in the Chicago area were illegally treated for cockroaches with MP over a period of several years. Through applicator receipt books and information reported by property owners and tenants, 968 homes were identified as having been treated with MP. Upon implementation of a response plan developed by the Methyl Parathion Health Sciences Steering Committee, environmental sampling and urine monitoring were provided for eligible households. Environmental sampling was conducted in 903 homes, with MP detected above levels of concern in 596 residences. Residents of these homes were offered urine sampling to determine the extent of exposure to MP. Urine samples were collected and analyzed for p-nitrophenol in 1,913 individuals. Implementation of the protocol resulted in 550 residents being relocated during the remediation of 100 households.

In November 1994 methyl parathion (MP), a restricted agricultural pesticide, was discovered to have been illegally sprayed within hundreds of residences in Lorain County, Ohio. Surface levels and air concentrations of MP revealed detectable levels of the pesticide 3 years after spraying. Because of the high toxicity of MP (lethal dose to 50% of rats tested [LD50] = 15 mg/kg) and long half-life indoors, risk-based relocation and decontamination criteria were created. Relocation criteria were derived based on levels of p-nitrophenol in urine, a metabolic byproduct of MP exposure. In Ohio, concentrations of MP on surfaces and in the air were also used to trigger relocations. The criteria applied in Ohio underwent refinement as cases of MP misuse were found in Mississippi and then in several other states. The MP investigation (1994-1997) was the largest pesticide misuse case in the nation, ultimately involving the sampling of 9,000 residences and the decontamination of 1,000 properties. This article describes the methodology used for relocation of residents and decontamination of properties having MP.