The CDC released on August 10 a report on the pervasive environmental contaminant of lead. The CDC noted the EPA is reviewing and making changes to its Lead and Copper Rule (LCR) to further protect public health. Since 1970, considerable reductions in lead concentrations have occurred in air, tap water, food, dust, and soil, which significantly reduced the blood lead levels (BLLs) of children throughout the United States. However, children are still being exposed to lead, and no safe blood lead threshold for children has been identified. Many of these children live in housing built before the 1978 ban on lead-based residential paint. These homes might contain lead paint hazards, as well as drinking water service lines made from lead, lead solder, or plumbing materials that contain lead. Children can still be exposed to tap water with lead levels of ≥15 ppb if they live in older homes that are more likely to have lead water pipes or fixtures.
The health consequences of lead exposure depend on the cumulative dose of lead and vulnerability of the individual person rather than the environmental media (i.e., food, water, soil, dust, or air) in which the lead exists. Compelling evidence has established the cognitive effects of childhood lead exposure since they were first described in 1943. To date, no safe blood lead threshold for the adverse effects of lead on infant or child neurodevelopment has been identified. Recent evidence suggests that the dose-effect relationship might be supralinear, with a steeper dose response and potential risk for an adverse health effect such as IQ loss at BLLs <10 µg/dL compared with BLLs ≥10 µg/dL. The developing fetus and child are more sensitive to lead exposure than adults because of the immaturity of the blood-brain barrier, increased gastrointestinal absorption, and hand-to-mouth behaviors, all of which increase exposure. Evidence from several prospective studies suggests that the adverse effects of early childhood exposure on neurodevelopment persist into the second decade of life.
Adequate corrosion control reduces the leaching of lead plumbing components or solder into drinking water. The majority of public water utilities are in compliance with the Safe Drinking Water Act Lead and Copper Rule (LCR) of 1991. However, some children are still exposed to lead in drinking water. The EPA is reviewing the LCR, and additional changes to the rule are expected that will further protect public health. Childhood lead poisoning prevention programs should be made aware of the results of local public water system lead monitoring measurement under the LCR and consider drinking water as a potential cause of increased BLLs, especially when other sources of lead exposure are not identified.
Although the EPA has the primary responsibility for ensuring the safety of drinking water, state and local childhood lead poisoning prevention programs are important partners in ensuring that the public is protected from lead exposure. These programs promote blood lead screening, conduct blood lead surveillance, provide clinician and public education and outreach, and provide case management for children with elevated BLLs. Because children with elevated BLLs might be exposed to many sources of lead, all sources of lead should be considered when their homes are inspected. Childhood lead poisoning prevention programs can obtain data on lead in public drinking water systems from the water suppliers. Drinking water in older housing should be tested as a source of lead exposure when the local drinking water system is not in compliance with the LCR or when another source of lead exposure cannot be identified for children with high BLLs.
Partial lead service line replacement has been associated with short-term increases in lead levels in drinking water and has not been found to decrease risk for BLLs ≥5 µg/dL in children. These findings imply that the practice of partially replacing lead service lines as a method to comply with the LCR should be reconsidered. One alternative is full replacement of lead service lines, regardless of whether the lead service line is owned by the water authority or the property owner. Lower BLLs could be achieved if plumbing components contained the lowest possible levels of lead and monitoring and enforcement activities were effective. Finally, information about lead in plumbing components, often available in tax assessor data, could be incorporated into information routinely provided to homebuyers or renters before they make the decision to buy or rent a property.
See the CDC report