Surveillance for Elevated Blood and Urine Arsenic Levels in Michigan, 2006–2024

Adverse health effects can result from human exposure to arsenic, which occurs in drinking water and chemical releases from industrial practices. Two types of arsenic compounds exist: inorganic (the toxic species) and organic (the nontoxic species). In 2005, Michigan began requiring clinical laboratories that conduct business in the state to report all blood and urine arsenic results. The source of exposure was investigated for levels that exceeded action thresholds and categorized as a work-related or nonwork-related exposure. Between 2006 and 2024, 554 individuals with elevated blood/urine arsenic tests were identified; 553 (99.8%) individuals had nonspeciated test results and 1 (0.2%) individual’s test was classified as inorganic. Blood arsenic levels ranged from 71 µg/L to 537 µg/L, and urine arsenic levels ranged from 53 µg/L to 2,981 µg/L. Of the 209 individuals with an identified exposure source, 29 (13.9%) had a work-related exposure and 180 (86.1%) had a nonwork-related exposure. Seafood consumption accounted for 157 (87.2%) of the nonwork exposures. Other nonwork exposures included drinking water, supplements, pesticides, rice, and wine. Laboratory tracking of elevated arsenic levels provides a way to identify uncommon exposure sources, monitor state trends, and educate the medical community how to order diagnostic tests for arsenic. Furthermore, tracking can result in ways to inform the public on how exposure occurs and how to prevent arsenic exposure.