TABLE 1.

Summary of Sources and Potential Mechanisms of Action for Pollutants

Pollutant	Source of Exposure	Potential Mechanisms of Toxicity
Lead	Paint from old buildings Soil near heavily used streets and roads or factories	Increased oxidative stress Stimulation of apoptosis Impairment of neurotransmitter release
Mercury	Consumption of fish and shellfish (particularly shark, swordfish, king mackerel, and tilefish)	Disruption of protein structure and function Increased oxidative stress, lipid peroxidation, and mitochondrial dysfunction
Air pollution	Factories, automobiles, and other machinery	Neuroinflammation Altered immune system response Aggregation of proteins Direct toxic effects
Polychlorinated biphenyls	Consumption of fish and animal fats	Impairment of neurotransmitter release Disruption of intracellular signaling Hormonal imbalance Altered neuronal connectivity
Dioxins	Consumption of animal fats	Interaction with aryl hydrocarbon hydroxylase receptor