Lead is a metal found in natural deposits such 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. Lead and lead compounds are used in storage batteries, ammunition, metal products (solder and pipes), roofing, gasoline, and devices to shield people from x-rays, among many other products. Because of health concerns, lead has been banned from gasoline, ceramic products, paints for residential use, and solder used on food cans.
In 1974, Congress passed the Safe Drinking Water Act. This law requires the 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 (MCLG). The MCLG for lead has been set at zero because the 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, the 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 the 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.
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. Lead has the potential to cause stroke, kidney disease, and cancer from lifetime exposure at levels above the MCL.
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 pounds. These releases were primarily from lead and copper smelting industries. The largest releases occurred in Missouri, Arizona, and Montana.
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.
The regulation for lead became effective in 1992. Between 1993 and 1995, the 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 treatment method approved by the EPA for controlling lead is corrosion control.
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 & Land, 1987 to 1993|
|Total (in pounds)||970,827||143,058,771|
|Top Twelve States *|
|Lead smelting, refining||31,423||68,996,819|
|Steelworks, blast furn.||379,849||18,149,696|
|China plumbing fixtures||1,310||1,350,960|