In 1985, the US Environmental Protection Agency (EPA) developed Integrated Risk Information System (IRIS) to establish "safe levels' for toxic chemicals. The levels set in IRIS are used as the scientific foundation for most EPA regulatory programmes, and for many state programmes, to establish health standards for air and water pollution, waste cleanup, and other programmes. IRIS is one of the most important sources of information on human exposure to potentially toxic chemicals in the world. The database contains risk assessment documents covering more than 540 contaminants. IRIS assessments can inform regulatory action (or inaction) intended to protect humans from the harmful effects of certain substances.