Changes in Blood Lead Levels Associated with Use of Chloramines in Water Treatment Systems
Miranda, Marie Lynn, Kim, Dohyeong, Hull, Andrew P., Paul, Christopher J., Overstreet Galeano, M. Alicia, Environmental Health Perspectives
BACKGROUND: More municipal water treatment plants are using chloramines as a disinfectant in order to reduce carcinogenic by-products. In some instances, this has coincided with an increase in lead levels in drinking water in those systems. Lead in drinking water can be a significant health risk.
OBJECTIVES: We sought to test the potential effect of switching to chloramines for disinfection in water treatment systems on childhood blood lead levels using data from Wayne County, located in the central Coastal Plain of North Carolina.
METHODS: We constructed a unified geographic information system (GIS) that links blood lead screening data with age of housing, drinking water source, and census data for 7,270 records. The data were analyzed using both exploratory methods and more formal multivariate techniques.
RESULTS: The analysis indicates that the change to chloramine disinfection may lead to an increase in blood lead levels, the impact of which is progressively mitigated in newer housing.
CONCLUSIONS: Introducing chloramines to reduce carcinogenic by-products may increase exposure to lead in drinking water. Our research provides guidance on adjustments in the local childhood lead poisoning prevention program that should accompany changes in water treatment. As similar research is conducted in other areas, and the underlying environmental chemistry is clarified, water treatment strategies can be optimized across the multiple objectives that municipalities face in providing high quality drinking water to local residents.
KEY WORDS: blood lead levels, chloramines, GIS, lead risk, water quality. Environ Health Perspect 115:221-225 (2007). doi:10.1289/ehp.9432 available via http://dx.doi.org/ [Online 7 November 2006]
Exposure to lead has long been recognized as hazardous to human health (Pueschel et al. 1996). Until the 1970s, concerns about lead poisoning primarily focused on acute exposures resulting in convulsions, paralysis, anemia, and gastrointestinal problems (International Program on Chemical Safety 1995). There is now recognition of significant asymptomatic health effects at levels much lower than those previously considered safe, particularly for children (Bellinger 1995; Canfield et al. 2003a, 2003b; Gardella 2001; Huseman et al. 1992; Lanphear et al. 2000; Needleman and Gatsonis 1990; Needleman et al. 1990, 1996; Schwartz 1994; Schwartz et al. 1986).
Environmental lead exposure occurs through ingestion or inhalation of lead particles (Davidson and Rabinowitz 1991). Most childhood lead uptake in the United States results from exposure to deteriorating lead paint in household dust and soil and to lead in soil from historic deposition from mobile sources (Davidson and Rabinowitz 1991; Mielke and Reagan 1998), although drinking water can be a source of chronic exposure (Maas et al. 2005a; Raab et al. 1987; Sherlock et al. 1984; Thomas et al. 1979). Although drinking water is not the primary route of exposure for most children, the U.S. Environmental Protection Agency (EPA 1994) has estimated that 14-20% of total childhood lead exposure in the United States is from drinking water (U.S. EPA 1994).
In 1991, the U.S. EPA (1991) set a maximum contaminant level goal for lead in drinking water of zero and an action level of 15 ppb. Although water supplies themselves can be contaminated with lead, most lead in drinking water comes from residential plumbing (Davidson and Rabinowitz 1991). Lead piping was uncommon after the 1930s, but lead soldering was common and legal until 1986, and some plumbing fixtures today still contain lead (Maas and Patch 2004; Safe Drinking Water Act Amendments of 1986; Troesken and Beeson 2003). Lead is soluble in water, and this solubility is markedly increased by high water softness and acidity (Davidson and Rabinowitz 1991; Gaines 1913; Raab et al. 1993).
Drinking water preparation can differ significantly across water systems, depending on the type and quality of source water, and is intended to protect the public from microbial pathogens, prevent dental caries, reduce harmful disinfection by-products, and reduce metal contamination from pipes (U. …