Common pollutants include industrial wastes, gasoline, fuel oil, chlorinated solvents, pesticides, lead, mercury and other heavy metals. Many toxics resist natural degradation and contaminate air, soil, rivers, streams and groundwater. Solvents and a gasoline additive called MTBE (methyl tertiary butyl ether) produce soil gas vapors that can intrude into homes and buildings. Touching, breathing or consuming toxics can cause health hazards, including cancer, birth defects, nerve damage and chronic ailments, even at low-level exposures.