Nearly a year after 1,300 Eight Mile residents sent a list of medical complaints purportedly linked to a 2008 mercaptan spill to the Alabama Department of Public Health (ADPH), the agency is saying the residents might be onto something.

The complaints were compiled from a survey conducted of Eight Mile residents who reported a range of adverse health effects related to a persistent, noxious odor since a lightning strike caused an unknown amount of tertiary butyl mercaptan to spill at a processing facility owned by Mobile Gas.

The chemical — added to odorless natural gas to detect leaks — has since migrated into the groundwater and topsoil in the area, though detectable levels of mercaptan have dropped since 2013 when Mobile Gas began treating groundwater with ozone to neutralize the chemical.

“Based on the current scientific evidence and available information, we believe that the community is affected by the odors. These odors may impact residents’ sense of well-being and quality of life,” ADPH Chief Medical Officer Dr. Mary McIntyre said Wednesday. “Mercaptan causes irritation to mucous membranes and has been associated with some of the symptoms reported by the residents of Eight Mile.”

ADPH also said the breakdown of organic materials in marshes close to the Eight Mile community could be “another factor” in complaints residents have made about a noxious odor many have compared to the “rotten egg” smell often attributed to mercaptan.

“Unfortunately, health assessments alone do not address the question of association or causation,” McIntyre added. “Even though unpleasant odors can impact [residents’] quality of life, not all odors are toxic. We continue to work with the Eight Mile community.”