Measuring Human Exposures to Environmental Pesticides and Metals in Washington State

BACKGROUND: Biomonitoring is used to improve the understanding of environmental exposures by the direct measurement of environmental chemicals in human tissues. The Washington State Department of Health developed the Washington Environmental Biomonitoring Survey (WEBS) to increase biomonitoring capacity at the Public Health Laboratories (PHL) and to provide state and local information to compare with the National Health and Nutrition Examination Survey (NHANES). Washington residents may have higher exposures to arsenic and certain pesticides than the U.S. population in general due to local sources, including naturally occurring arsenic in groundwater and arsenic soil contamination from historical industrial and agricultural practices. Organophosphate pesticides continue to be used widely in agriculture orchards and other cropland in Washington. Pyrethroid pesticides have replaced organophosphates as the most common residential pesticide.

METHODS: We conducted a state-wide survey of 666 households to obtain estimates representative of the Washington State population for urinary levels of arsenic and selected pesticides. Within a household, all residents ages 6 and older were invited to participate. We also surveyed one locality with elevated levels of groundwater arsenic. We gathered questionnaire information and sent water and frozen urine samples to the PHL for analysis.

RESULTS: We collected a total of 1422 urine samples from participants. Creatinine-corrected median levels of total urinary arsenic were: NHANES: 7.9 ug/g (95% confidence interval [CI]: 7.0, 9.0), Washington: 11.9 ug/g (CI: 10.8, 13.3), and high-risk sample: 28.4 ug/g (CI: 20.2, 38.2). Thirty percent of high-risk participants had total urinary arsenic ≥50 ug/L, compared to 10% of the general population. Results for speciated arsenic, pyrethroid pesticide and organophosphate pesticide metabolites will be presented.

CONCLUSIONS: The WEBS survey allows us to understand environmental contaminant exposure to guide prevention efforts in Washington State.