Contaminant Facts

A contaminant is a substance that is found where it shouldn’t be and can pollute, poison, and harm both environmental (soil, plants, air, water, and animals) and human health. Some contaminants have a long life and can spread over a wide area. Most contaminants are man-made substances (produced in factories), while some can be found naturally, like cadmium and certain metals. And whereas certain contaminants pose a harm at high levels, others can have harmful effects at low levels.

Some contaminants present unique issues and challenges to the environmental community. These substances had not been previously detected or were found in less concentrations but are recently detected in global water sources, soil, sediment, and/or air at levels that pose a risk to the public health. These substances are categorized as contaminants of emerging concern or emerging contaminants.

When a chemical is found in drinking water and no regulatory standards exist, the Department of Health develops Health Advisory Level (HAL)s. The HAL concentration of a chemical in drinking water is a value that, based on the available data, is virtually certain not to cause adverse human health effects if consumed over a lifetime.