The Clean Air Act classifies 188 chemicals as Hazardous Air Pollutants or toxins. These chemicals can damage human and animal genetics, cause reproductive effects such as birth defects or damage to liver and kidneys. Many of these chemicals can cause cancers. Some toxic chemicals can remain in the environment for decades, even centuries before breaking down.
Many states have concerns about the levels of mercury in fish and other animals.
Over 32 states issue advisories for children and nursing and pregnant women to limit fish consumption. Much of this mercury first enters the environment as air emissions. EPA predicts some health concerns in Iowa are attributed to breathing these chemicals for many years. Despite toxic chemical reductions being a major goal in the 1990 Clean Air Act, Iowa is one of 14 states without an air toxics control program. Without rules and resources to address toxic emissions fully, permits often do not specifically restrict toxic exposures, although this occurs for sulfur and nitrogen oxides, particulates, and carbon monoxide.