NRC Report Oil Copper in Drinking Water.

The federal government should not increase the maximum level of copper allowed in drinking water without studying the health effects in sensitive populations, according to a new NRC report. Higher levels of copper could lead to liver poisoning in infants and children with certain genetic disorders.

Under the Safe Drinking Water Act, U.S. EPA is required to establish the concentrations of contaminants permitted in public drinking-water supplies. The U.S. EPA goal for copper is a maximum level of 1.3 milligrams per liter (mg/L). This limit is designed to protect against short-term gastrointestinal problems. Some states, such as Nebraska and Delaware, have difficulty maintaining copper levels below this limit.

Because some recent population studies have reported no adverse health effects from copper ingested at higher concentrations, questions have been raised about the validity of the science on which U.S. EPA based its goal for drinking water. Some people believe that the goal might be unnecessarily low. Others believe that some individuals might get sick from copper levels at or below the current goal. In response to these concerns, Congress asked NRC for an independent review of U.S. EPA's goal for copper in drinking water.

Too much copper can cause several health problems, the NRC report concludes. Excessive doses can cause nausea, vomiting, and diarrhea. Long-term exposure can lead to copper poisoning, especially in people whose bodies have trouble regulating copper because of genetic disorders or illnesses like Wilson's disease. Severe cases of copper poisoning have led to anemia, liver poisoning, and kidney failure.

"We reviewed a wide range of data on exposure to copper from both food and water and concluded that EPA's current level protects sensitive individuals from the acute effects of excess copper, said committee chair Richard Bull, senior staff scientist with Battelle Pacific Northwest Division, of Richland, Washington. "We assume this level is protective of people with chronic disease, as well. But we need more information about the total copper doses received from drinking water, along with a better idea of how many people are sensitive to copper and what happens to them when they are exposed. Once this information has been gathered, the current level should be re-evaluated."

In the past, people with Wilson's disease were considered such a small and special portion of the population that it was thought best to protect them by limiting their copper intake individually. New evidence, however, suggests that brothers and sisters of people with Wilson's disease also may be at risk, even though they do not have the disease themselves. This in turn suggests that carriers--people with one copy of the defective gene--also could be at risk.

Children who carry the gene would be at particular risk because, in proportion to their size, their consumption of water is greater than that of adults. Although Wilson's disease is found in only one out of 40,000 people in the United States, the committee believes that as much as one percent of the population may carry the gene for the disease. No test is yet available to identify individuals at risk.

Copper is an essential mineral nutrient found in soil and plants. Most copper contamination in drinking water results from corrosion of copper pipes or fittings. Water that is high in acidity and high in temperature can cause corrosion, as can "soft" water (water free of the magnesium or calcium salts that create a protective coating inside pipes).

In 1989, the Institute of Medicine estimated that adults could safely ingest 1.5 mg to 3.0 mg of dietary copper per day and that infants could consume 0.4 to 0.6 mg per day to maintain good health. Generally, daily diet supplies copper within this range. Typically, only a small fraction of an individual's copper intake comes from drinking water. In some states and municipalities, however, water characteristics are conducive to greater leaching of the mineral into drinking water. The length of time that water sits in copper pipes also can greatly increase concentrations of copper--to several milligrams per liter of water. Copper concentration decreases in water that has been running from the tap for a few minutes.

Copies of Copper in Drinking Water are available from the National Academy Press at [phone] or [phone].