Health Effects of Lead
Lead contamination poses a serious threat to the safety of our nation’s drinking water. This colorless, tasteless, and odorless heavy metal can go virtually undetected in drinking water. Excessive amounts of lead place adults at higher risk for cancer, stroke, and hypertension. It has even been hypothesized that Imperial Rome’s dependence on lead water pipes contributed to its decline…the suggestion being that the Roman aristocracy faltered and died off from nothing more complicated than simple chronic lead poisoning.
Lead, however, is even more harmful for the very young.
Fetuses, infants, and children up to the age of six have rapidly growing little bodies which, unfortunately, are quick and efficient absorbers of lead. Lead can cause brain damage, premature birth, reduced birth weight, seizures, behavioral disorders, and a lower IQ level in children. In most cases this damage is irreversible. Consequently, the U.S. Environmental Protection Agency (EPA) considers lead the most serious environmental health hazard for children in the United States. Many lead toxicologists agree and have even suggested that EPA’s lead standard for children’s drinking water be more stringent than that for adults.
Sources of Lead in Drinking Water
Rarely, lead gets into water from the erosion of natural underground deposits or industrial activity. It is much more likely to enter drinking water through corrosion as it passes through lead pipes, soldered connections, household plumbing, metal faucets and fixtures, and brass fittings on submersible well pumps. As other environmental controls have been placed on leaded gasoline, lead solder, leaded paint, and use of lead in housewares, drinking water as a source of lead over the past several decades has steadily increased in importance.
The EPA has estimated that about 40 million Americans are exposed to drinking water lead concentrations that it considers to be a health risk.
A survey of private water supplies (homes using wells and springs) across Pennsylvania, for example, found 20 percent contained unsafe lead levels — a corrosion problem that persisted in all regions of the state. Water corrodes lead from metal plumbing at increased rates as its acidity increases and its concentration of calcium carbonate decreases. A drinking water below a pH of 7 with a low calcium carbonate (CaCo3, limestone, chalk) content will generally corrode lead from a building’s plumbing system.
Water standing in contact with a building’s plumbing will be the first water out of the tap in the morning; therefore, lead concentrations in drinking water usually are the highest in the first water out of the system. These lead concentrations will decrease as the water is run. If lead pipes, leaded solder, or brass fixtures are present, even relatively noncorrosive water can dissolve dangerous amounts of lead if the water sits in contact with these materials for an hour or more. Similarly, heat will accelerate the lead corrosion process, so hot water will typically yield higher lead concentrations than cold water samples taken from the same tap. As noted below, parents are cautioned against using first flush tap water for preparing infant formula, and never to use hot water for that purpose.
A more recent contributor to the problem of lead corrosion in public water systems is the switch in disinfection agents from chlorine to chloramines. Chlorine reacts with dissolved organic matter in water to create by-products that are suspected of causing human health problems, including some forms of cancer. So, many public water treatment plants now are beginning to use chloramines, combinations of chlorine and ammonia. Unfortunately in some previously lead-stable public water supplies this switch has coincided with an increase in lead in the drinking water, perhaps because chloramines cause an increase in the water’s corrosivity.
It should be noted that some trade agreements with foreign nations still allow them to export plumbing components for sale in America that are not lead free and that, in fact, can contain significant amounts of lead.
Lead Abatement and Alternatives
As a general precaution, the Centers for Disease Control and Prevention (CDC) recommend using only cold tap water (that has been flushed long enough after a period of inactivity for the water to run noticeably colder) for drinking, cooking, and mixing infant formula. In homes with children or pregnant women with water lead levels exceeding EPA’s action level of 15 parts per billion of water (ppb), the CDC recommends using only bottled water for drinking, cooking, and infant formula.
If the drinking water still has elevated levels of lead after flushing, specific water filtration units or bottled water may be an effective long term solution. A National Sanitation Foundation (NSF) seal certifying lead reduction capability on a filtration system is one method of ensuring that the unit has been tested for adequate removal efficiency. All such filters must be maintained and replaced periodically in accordance with the manufacturer’s guidelines to be effective. All bottled waters produced by licensed bottlers in the United States are subject to a Federal Food and Drug Administration (FDA) maximum contaminant level for lead called a Standard of Quality (SOQ). This bottled water SOQ (5 ppb) is one third of the (15 ppb) amount allowed in tap water, and so bottled water can be assumed to safe from lead in water concentrations deemed to be a health risk by the EPA for tap water.
The most effective and most expensive lead removal method is to replace the leaded plumbing components with nonleaded components. This procedure often involves replacing copper pipes and lead solder with plastic PVC pipes (NSF-pw labeled). Replacing home plumbing components will be effective only if the source of the lead is within the home plumbing system. If the lead contamination originates from outside the home within a public water system’s lead service lines, this method may be of limited use.
Tap Water: Public Water Supplies with lead service lines or an adverse lead-testing experience (i.e., more than 10 percent of its household lead sampling results showing an exceedance of the EPA Action Level of 15 ppb) will be in violation of the National Primary Drinking Water Regulation for lead. The water utility must then notify the public and the local government of the violation and undertake corrective treatment measures. These measures may include replacement of lead service lines and/or the addition of corrosion-preventive chemicals to the drinking water. These chemical corrosion inhibitors added to the tap water may be sufficient to abate any dangerous lead concentrations in buildings with leaded plumbing components.
Bottled Water: Bottled water is regulated Federally as a pure food product. Instead of accepting EPA’s 15 ppb Action Level for lead in bottled water, a Congressional law mandated the FDA to issue a different, 5 ppb, SOQ for allowable levels of lead in bottled water. Furthermore, FDA Good Manufacturing Practices for Bottled Water (GMPs) prohibit water bottlers from using any food contact material (tanks, pipes, fittings, pumps, bottling equipment, containers, closures, etc.) which might adulterate or render the bottled water product unsafe — including, of course, contamination by lead. All bottled waters which use public water supplies as their source, at a minimum, remove chlorine and chloramines as the early part of their water treatment and product purification train.
Any finished bottled water product found to be in violation of the FDA’s 5 ppb lead SOQ for any reason and without exception is subject to removal from the market and must be destroyed.
Parity: Federal regulations governing the safety of drinking water under the Safe Drinking Water Act (SDWA) as amended in 1996 serve as the basis for various state regulations (which may not be set at any allowable contaminant levels less protective of public health than the Federal standards). Since the 1996 SDWA amendments, the FDA must also set bottled water SOQs that are at least as protective of public health for all contaminants subject to EPA MCLs and/or Allowable Levels for tap water. The same requirements for laboratory testing methods and relative sampling frequencies must also be applied to bottled water by the FDA…just as they are by the EPA for tap water.
Lead in drinking water is a serious public health matter — especially for children. Because of the end-of-the-pipeline origin of most lead in tap water, the nation’s laws and regulations dealing with lead contamination in tap water are very different from and less protective of children’s health than the laws and regulations which govern lead in bottled water. Parents who have children under the age of six should be aware of this profound difference and choose their family’s primary source of drinking water accordingly.
University of Pennsylvania, Environmental Resources Institute, Swistock, B.R. and Sharpe, W.E., “Lead in Drinking Water” issued as Extension Circular 416, Cooperative Extension Service of the College of Agricultural Sciences.
U. S. Food and Drug Administration, Center for Food Safety and Nutrition, FDA Consumer, January-February 1998, “Dangers of Lead Still Linger”.
Minnesota Dept of Health, “Lead In Well Water Systems”, http://www.health.state.mn.us/divs/eh/wells/waterquality/lead.html
New York State Department of Health, Information for a Healthy New York, “Get Ahead of Lead! Get the Lead Out of Drinking Water”, http://www.health.state.ny.us/environmental/lead/leadwtr.htm
EPA Lead Information – http://www.epa.gov/lead/leadinfo.htm
CDC Lead Information – http://www.cdc.gov/nceh/lead/lead.htm
Jack C. West is Chairman of Drinking Water Research Foundation’s Board of Trustees.