Summary for Lead

A Public Health Goal (PHG) of 2 ppb is developed for lead in drinking water based on the neurobehavioral effects of lead in children and the hypertensive effects of lead in adults. Lead has been known as a toxic metal since ancient times, and has been studied for its toxic effects since the middle ages. It is a widespread contaminant in the human environment and occurs in drinking water as a consequence of leaching from plumbing containing lead. Lead may also enter drinking water from other sources, for example, directly from soil contaminated with lead or deposited from air emissions. Lead has multiple toxic effects on the human body. Among its most serious noncarcinogenic effects are decreased intelligence in children and increased blood pressure in adults. Lead is a carcinogen in laboratory animals and a probable human carcinogen. The U.S. Environmental Protection Agency (U.S. EPA) has adopted a Maximum Contaminant Level Goal (MCLG) of zero for lead in drinking water based on "occurrence of low level effects" and because U.S. EPA classifies lead as a Class B₂ carcinogen. Based on the toxicological data for noncarcinogenic endpoints, and potential human exposures, a PHG of 0.002 mg/L (2 ppb) is calculated for lead in drinking water.