Changes in Blood Lead Levels Associated with Use of Chloramines in Water Treatment Systems
Changes in Blood Lead Levels Associated with Use of Chloramines in Water Treatment Systems
Environmental Health Perspectives Study
Marie Lynn Miranda, Dohyeong Kim, Andrew P. Hull, Christopher J. Paul, and M. Alicia Overstreet Galeano
Environmental Health Perspectives Online - November 7, 2006 (Available at http://www.nicholas.duke.edu/cehi/about/publications.htm)
An increasing number of municipal water treatment systems are switching from chlorine to chloramines for disinfection to reduce the formation of disinfection byproducts. However, the introduction of chloramines to water systems with lead service lines or homes with lead- containing fixtures or solder may increase the amount of dissolved lead in the water.
This study examined the relationship between blood lead levels, age of housing and water disinfection method in Wayne County, North Carolina.Wayne County has two water treatment systems - one that switched to chloramines for disinfection and one that did not. More than 7,200 records of blood lead levels from children drinking water from the two different systems were examined.Statistical and graphical analyses were designed to look at differences in blood levels across both water treatment systems and age of housing (as determined from tax parcel data).
In Wayne County, blood lead levels were significantly higher in children living in households served by the water system that switched to chloramines. The increase was greatest in children living in houses built before 1926, followed by houses built between 1926 and 1950. For houses built after 1950, the blood lead levels did not differ between the two different water treatment systems. This is consistent with observations that older homes are more likely to contain lead pipes or lead-containing fixtures or solder.
These findings highlight the need for water treatment administrators and public health officials to closely monitor water lead levels at the tap following the introduction of chloramines as a disinfection agent and to provide more intensive outreach and education to residents in older housing. In prioritizing children to screen for elevated blood levels, the Wayne County results suggest that health departments should target children living in housing prior to 1950 when chloramines are NOT being used. When chloramines are being used, health departments should direct their screening efforts towards children living in housing built prior to 1975.
The results of this study are directly relevant to Wayne County, North Carolina, and may not be directly applicable to other systems using chloramines. Much uncertainty still surrounds the underlying environmental chemistry of how different disinfectants and other water treatment agents combine with water qualities like pH, alkalinity, temperature, oxidation potential and other chemical species to affect lead in drinking water. This study provides guidance to water systems and health departments on what houses should be targeted for monitoring of lead in both water and children’s blood. The study did not directly measure lead in water and thus can only indirectly conclude that the increase in blood lead levels was due to an increase in lead in drinking water.