Scientists in the Houston area are focusing research on the flare stacks at its hundreds of petrochemical plants -- which may be a major overlooked cause of smog.
Despite having been banned in most uses for years, carbon tetrachloride, a probable carcinogen, persists in the environment. USA TODAY found it outside 70 of 95 schools in 30 states.
"Railroad companies are pressing federal regulators to cut back on trains carrying hazardous materials through urban areas, saying they fear a catastrophic release of toxic chemicals in a large city."
Canadian scientists are taking a closer look at dioxin-like contaminants in the Great Lakes called polychlorinated naphthalenes. They accumulate in fish and are toxic to humans.
EPA has found suspect materials in a small sample of Chinese-made drywall that some believe may be causing corrosion in homes and possibly sickening people.
West Virginia's environmental agency says it's OK for fish there to contain more mercury than the federal EPA recommends -- because West Virginians consume less fish than the national average.