Michigan school children's proximity to leaking underground storage tanks and hazardous waste treatment, storage and disposal sites

Michigan is updating its hazardous waste clean up criteria.  Current Michigan regulations use an age-adjusted receptor, averaging 6 years of childhood exposure and 24 years of adult exposure parameters.  These assumptions may underestimate actual exposures for children aged 7 to 18 years who spend more time outdoors with higher soil contact due to their play than adults.  Exposures from multiple sites are furthermore not considered, despite widespread legacy contamination. Based on U.S. Environmental Protection Agency School Siting Guidelines and public data from Michigan Department of Environmental Quality, we performed a proximity analysis in ArcGIS to identify schools in Michigan that were within 500 meters from documented releases from underground storage tanks (USTs) and 1,600 meters (1 mile) from hazardous waste treatment, storage and disposal (TSD) facilities. Of the 1,629,700 students attending 3,660 public and charter schools in Michigan in 2007, 547,400 students (33.6%) attended a school located within 500 meters from a leaking tank.  This reflects 36.2% of schools. Eight percent of Michigan public school children (131,900 students) attend 299 schools located closer than the EPA guideline to a TSD site.  For leaking tanks, the analysis did not show any disparities by race, gender or free/reduced lunch eligibility. For TSD facilities, a greater percentage of racial minority students and students eligible for free/reduced lunch attended schools near facilities (p-value<0.001) than would be predicted based on the overall population. No disparities were detected by student gender. Current regulatory exposure assumptions may not be adequately capturing the exposures of school-aged children.