Drinking Water Contaminants- Lead
This is a factsheet about a chemical that may be found in some public or private drinking water supplies. It may cause health problems if found in amounts greater than the health standard set by the United States Environmental Protection Agency (EPA).
What is Lead and how is it used?
Lead is a metal found in natural deposits as ores containing other elements. It is sometimes used in household plumbing materials or in water service lines used to bring water from the main to the home.
Why is Lead being regulated?
In 1974, Congress passed the Safe Drinking Water Act. This law requires EPA to determine safe levels of chemicals in drinking water which do or may cause health problems. These non-enforceable levels, based solely on possible health risks and exposure, are called Maximum Contaminant Level Goals.
The MCLG for lead has been set at zero because EPA believes this level of protection would not cause any of the potential health problems described below.
Since lead contamination generally occurs from corrosion of household lead pipes, it cannot be directly detected or removed by the water system. Instead, EPA is requiring water systems to control the corrosiveness of their water if the level of lead at home taps exceeds an Action Level.
The Action Level for lead has been set at 15 parts per billion (ppb) because EPA believes, given present technology and resources, this is the lowest level to which water systems can reasonably be required to control this contaminant should it occur in drinking water at their customers home taps.
These drinking water standards and the regulations for ensuring these standards are met, are called National Primary Drinking Water Regulations. All public water supplies must abide by these regulations.
What are the health effects?
Short- and Long-term effects: Lead can cause a variety of adverse health effects when people are exposed to it at levels above the MCL for relatively short periods of time. These effects may include interference with red blood cell chemistry, delays in normal physical and mental development in babies and young children, slight deficits in the attention span, hearing, and learning abilities of children, and slight increases in the blood pressure of some adults.
Long-term effects: Lead has the potential to cause the following effects from a lifetime exposure at levels above the MCL: stroke and kidney disease; cancer.
How much Lead is produced and released to the environment?
Lead may occur in drinking water either by contamination of the source water used by the water system, or by corrosion of lead plumbing or fixtures. Corrosion of plumbing is by far the greatest cause for concern. All water is corrosive to metal plumbing materials to some degree. Grounding of household electrical systems to plumbing may also exacerbate corrosion. Over time, lead-containing plumbing materials will usually develop a scale that minimizes further corrosion of the pipe.
Lead is rarely found in source water, but lead mining and smelting operations may be sources of contamination. Eighty eight percent of the lead mined in the US comes from seven mines in the New Lead Belt in southeastern Missouri. From 1987 to 1993, according to the Toxics Release Inventory lead compound releases to land and water totaled nearly 144 million lbs. These releases were primarily from lead and copper smelting industries. The largest releases occurred in Missouri, Arizona and Montana. The largest direct releases to water occurred in Ohio.
What happens to Lead when it is released to the environment?
When released to land, lead binds to soils and does not migrate to ground water. In water, it binds to sediments. It does not accumulate in fish, but does in some shellfish, such as mussels.
How will Lead be detected in and removed from my drinking water?
The regulation for lead became effective in 1992. Between 1993 and 1995, EPA required your water supplier to collect water samples from household taps twice a year and analyze them to find out if lead is present above 15 ppb in more than 10 percent of all homes tested. If it is present above this level, the system must continue to monitor this contaminant twice a year.
If contaminant levels are found to be consistently above the Action level, your water supplier must take steps to reduce the amount of lead so that it is consistently below that level. The following treatment methods have been approved by EPA for controlling lead: Corrosion control.
How will I know if Lead is in my drinking water?
If the levels of lead exceed the Action Level, the system must notify the public via newspapers, radio, TV and other means. Customers will be informed of what they can do at home to lower their exposure to lead. Additional actions, such as providing alternative drinking water supplies, may be required to prevent serious risks to public health.
Drinking Water Standards:
Action level: 15 ppb
Lead Releases to Water and Land, 1987 to 1993 (in pounds):
part of the Drinking Water and Health pages, this fact sheet is part
of a larger U.S. EPA publication:
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