Lead in Drinking Water

Initial Publication Date: December 13, 2012

Lead in Drinking Water

Author: Evan Link

This case study is part of a collection of pages developed by students in the 2012 introductory-level Geology and Human Health course in the Department of Earth Sciences, Montana State University. Learn more about this project.

Lead is rarely found in source water but can enter drinking water via corrosion in pipes. Homes built before 1986 are more likely to have lead pipes, fixtures, and solder. However, even newer homes are still at risk. Legally "lead free" pipes may contain up to 8 percent lead. More information on lead's health effects, sources, transport, and prevention tactics are contained within this page.

Introduction to Lead

Lead (Pb) in the environment is a major environmental health hazard. It has had wide use in a wide variety of commercial products ranging from leaded gas to household paint. However, Pb is a toxic substance that affects the development of the nervous system, and extended exposure can lead to neorological dysfunction and even death. Children six years old and under are most at risk because this is when the brain is developing. The primary source of lead exposure for most children is lead-based paint but lead in drinking water can add to that exposure. The purpose of this webpage is to introduce you to health hazards related to Pb exposure, and to provide some guidelines to protect your health.

Here is a great link to EPA's site on lead in drinking water

Sources of Lead in the Environment

Lead is a naturally occurring metal found in the earth's crust. There is a high occurrence of lead ore deposits around that are gathered, and distributed around the world. A person's environment is full of lead. People are exposed to lead in many different ways (such as paint, gasoline, solder, and consumer products) and through different pathways (such as air, food, water, dust, and soil). Although all there are several exposure sources, lead-based paint is the most widespread and dangerous high-dose source of lead exposure. Additionally, lead in drinking water accounts for 10 to 20 percent of human exposure. Infants who consume mainly mixed formula can receive 40-60 percent of lead through drinking water.

Transport of Lead into Water

Major sources of lead in drinking water are corrosion of household plumbing systems and erosion of natural deposits. Lead enters the water through contact with plumbing. Dissolving or wearing away of metal in plumbing allows this to occur. Also, lead can leach into water from pipes, solder, fixtures, faucets, and fittings. Amount of lead in your water depends on types and amounts of minerals in the the water, how long the water sits in the pipes, the wear in the pipes, the water's acidity, and its temperature.

Bioavailability

Lead is commonly found within plant tissues and in their roots. Most lead will accumulate in cell walls or vacuoles. This shows that big amounts of lead can now easily enter the food chain via plants. High tolerance to lead in plant roots is quite unfavorable for other members in the food chain, including man.

Impacts on Human Health

Infants and children who drink water containing lead in excess could experience delays in their physical or mental development. Young children could show slight deficits in attention span and learning abilities. Adults with exposure, over years, may develop kidney problems or high blood pressure. Even low levels of lead exposure can result in decreased performance on intelligence tests. Lead exposure in adults is also associated with fertility problems and cataracts. Additionally, lead is stored within bones/teeth, and can be released into the blood stream at times of stress. As new information has emerged about the neurological, reproductive, and possible hypertensive toxicity of lead, the CDC has progressively increased the level of concern for blood lead levels. CDC case management guidelines are designed to keep children's blood lead levels below 10 µg/dL, and adults below 30 µg/dL. The maximum contaminate level goal of lead in drinking water is zero, but the EPA's final rule is set at 15 µg/L.

Prevention or Mitigation

Lead in drinking water becomes a concern when lead levels exceed 15 ppb out of the tap. Either lead is getting into drinking water from the header pipe in the street, or lead is getting through the home's plumbing. For immediate correction of the problem, run a shower and all sinks with cold water for a minimum of 5 minutes to clear out all of the lead. If warm water is used, the lead levels will be greatly increased. It is recommended for older plumbing to be tested by contacting your state lead program. If the lead levels continue to be a problem, the only way to fully resolve the issue is a full replacement of household plumbing. For best results, copper should be used to minimize lead levels. If the pipes ever become repaired, lead solder should never be used. Local Health Departments are available for further questions and prevention tactics.