Inhalation toxicity of emerging, exposomic forms of lead: combining population-based study with validation data from an animal model

Lead (Pb) is a ubiquitous heavy metal that has been widely used since the ancient Romans. In modern time, it's unique physical and chemical properties have made it a commonly used heavy metal which was extensively mined, smelted, and found in food, water, medicines, cosmetics, paint, used for bullets, and also as fuel additive. East Chicago is the location of the former USS Lead Smelter which is currently one of the largest Superfund Sites contaminated with Pb. This dissertation stemmed from concerns among residents of the East Chicago community from unmonitored exposures to Pb and other toxic metals from a former smelter and several other persistent legacy sources.

Blood lead levels among mothers and children in East Chicago were found to be significantly elevated compared to national levels and comparable to those observed at the height of the Flint Water Crisis. Soil samples from 358 residential yards across all nine neighborhoods in East Chicago revealed widespread Pb contamination with 40% of samples tested falling above the EPA regulatory limit of 400 mg/kg. A subset of these samples was analyzed for Pb speciation which revealed that the initial legacy sources of Pb are not persistent and instead are extensively repartitioned into acid-soluble forms of Pb with greater bioavailability.

The inhalation toxicity was assessed by exposing mice to dusts generated from a real-world soil sample collected from a residential yard in East Chicago. Evaluation of toxicity endpoints revealed neurotoxic effects on memory and learning, immunological responses in the lung, and disruptions in essential metabolic processes. The findings from this animal study have significant human health implications as the blood lead levels of the mice were found to be similar to those observed in mothers and children in East Chicago.