In May 2003, a Scottsdale, Arizona, resident asked the Agency for Toxic Substances and Disease Registry in Atlanta to investigate possible sewer gas exposures in a Scottsdale residential neighborhood. In June 2003, the Agency asked the Arizona Department of Health Services, to conduct an investigation to determine if sewer gas exposures were occurring. Because ambient and indoor air hydrogen sulfide data for the neighborhood were not available, the Arizona Department of Health Services and the resident collaborated in conducting an air monitoring investigation in the neighborhood from June 26, 2003, through July 15, 2003.

The Arizona Department of Environmental Quality and the California Department of Toxic Substance Control worked together to assess background levels of naturally occurring metals in groundwater wells at Topock and Golden Shores, Arizona. The communities expressed concerns regarding the findings, thus the ADEQ requested the Arizona Department of Health Services to evaluate whether these naturally occurring metals in groundwater wells are present at levels that may cause adverse health effects.