Lead can sometimes enter drinking water in water systems with pipes that contain lead. Usually the insides of those pipes are coated with a protective layer, but corrosive water (such as in the tragic case of Flint, Michigan) can expose the lead to the water. In cases where the municipal water system is safe, lead can still enter drinking water in homes with older pipes and fixtures.
According to the EPA, “Lead can enter drinking water when service pipes that contain lead corrode, especially where the water has high acidity or low mineral content that corrodes pipes and fixtures. The most common problem is with brass or chrome-plated brass faucets and fixtures with lead solder, from which significant amounts of lead can enter into the water, especially hot water.”
Plumbing since 1986 is generally lead-free, due the Safe Drinking Water Act (SDWA) of that year, which reduced the maximum allowable lead content “to be a weighted average of 0.25 percent calculated across the wetted surfaces of pipes, pipe fittings, plumbing fittings, and fixtures and 0.2 percent for solder and flux.”
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Mary Jean Brown, Stephen Margolis, “Lead in Drinking Water and Human Blood Lead Levels in the United States,” Supplements, Centers for Disease Control and Prevention, August 10, 2012, 61(04);1-9, http://www.cdc.gov/ mmWR/preview/mmwrhtml/su6104a1.htm.
Environmental lead exposure can cause detrimental health effects in both adults and children, with more significant impacts being observed in children. Because lead accumulates in the body after exposure, it is essential that environmental contamination be reduced or eliminated to reduce the risk of health effects and reduce overall blood lead levels (BLLs). There is no safe BLL for children. Lead has historically been used in plumbing materials that come into contact with drinking water. In children, lead in drinking water has been associated with BLLs ≥10ug/dL, the common threshold for intervention. In 1991, the EPA began enforcing the Safe Water Act lead and copper rule (LCR) which sets an action level of 15ppb of lead in 1L of water. Most water systems in the US are compliant, but still 40-45 million people drink water that is not subject to LCR regulations because it is serviced by private wells or supplied by private plumbing lines that have not been tested by the EPA. The EPA is currently reviewing the LCR along with the CDC to ensure safety and minimized exposure, particularly for children.
Aging pipe infrastructure is a growing problem in the United States. Most of the Eastern US has pipes with an average age of 50 years with some systems being more than 100 years old. This was one of the primary causes of the lad contamination problems in Flint earlier this year. When Flint switched from water sources from Detroit to sources from the Flint river, chlorine content in drinking water rose significantly. This caused corrosion of the lead in pipes, increasing is solubility and leading to highly contaminated water. Since the 1972 Clean Water Act, water has become significantly safer, especially with regards to lead levels. However, the act is not perfect, and EPA guidelines for lead testing need to be modified to ensure that situations like Flint do not continue to happen.
Seasonal variations in temperature may have an effect on lead solubility from pipes to drinking water. In this study of 8 testing sites in Washington DC and Providence, RI, temperature was shown to have an effect on solubility of lead minerals that were mixed with organic matter in water, but had little effect on solubility alone. Higher temperature did correlate with lead particulate release into water. Average lead particulate release was 6 times higher in summer months than in winter months in each of the sites tested. Additionally, particulate dissolution was 3 times higher in the summer compared to the winter. However, these trends are complicated by mineral and organic matter presence.
Triantafyllidou, Simoni; Parks, Jeffrey; Edwards, Marc, “Lead particles in potable water,” Journal – American Water Works Association (2007), 99 (6), 107-117 CODEN: JAWWA5; ISSN:0003-150X.
Lead in drinking water has been functionally determined not to be a problem by the USEPA since their introduction of the lead and copper rule (LCR) for water testing. However, the methods used to test water have been re-examined and shown to not be entirely effective or accurate. There are a few specific problems with the testing procedure identified by this article. The first is that because testing is often done in plastic bottles, there is a high likelihood that lead and other particulates will simply stick to the side of the bottle and thus not be available in the water for analysis. Another problem is that water is reduced to pH<2 using nitric acid, which may not be strong enough to actually dissolve lead particles enough for analysis. This means that there is a potential that large lead particles, which are not studied in water analysis, could still be getting into drinking water. Additionally, even particles that are observed in traditional testing but don’t dissolve enough to have an effect on results may have health effects because the human GI system is significantly more acidic, thus will dissolve lead at a higher rate than the testing conditions.
Washington DC has historically had problems with water lead levels (WLL). There have been a number of studies on their infrastructure that examine the effects on lead pipes and solder on blood lead levels (BLL), and while none of them have pointed out specific harms to lead levels in water, there were limitations in each of them. Primarily, no studies have focused on the effects on infants or specific neighborhood studies. However, even in this study of children younger than 30 months, no different levels were observed. While there were neighborhoods in DC that had different WLLs, none were above the EPA requirement.