(Private Well Lead Sampling)
WEST CALN TOWNSHIP, CHESTER COUNTY, PENNSYLVANIA
The U. S. Environmental Protection Agency (EPA) asked the Pennsylvania Department of Health (PADOH) and the Agency for Toxic Substances and Disease Registry (ATSDR) to evaluate preliminary water well data from private wells near the Blosenski Landfill and determine if lead levels in the water pose a public health threat. Lead levels were unusually high (up to 1,430 parts per billion (ppb)) in some early samples collected from new homes before the water passed through in-home treatment systems.
Based upon the most recent and reliable data presented for review, the consumption of water from private wells poses no apparent public health threat to home owners. Water samples collected before home treatment systems (directly from the storage tank) contained higher lead levels than tap (finished) water, which is more representative of the actual exposure to residents. All of the tap samples from the latest sampling round contained less than 15 ppb lead, which is the action level commonly used for public water supplies. It is imperative, therefore, that residents maintain their water treatment systems in proper working order. At least one more sampling round is recommended to confirm the latest sampling results.
The Blosenski Lead Site (site) is on Acorn Way and Coffroath Road in West Caln Township, Chester County, Pennsylvania (Figures 1 and 2). A new residential subdivision of about 20 homes has been developed using private wells some 2000 feet north (Figure 2) of the Blosenski Landfill, a Superfund site for which closure and remedial work were completed in the late 1990s . Preliminary water samples collected by an EPA contractor in May 2001 from some of the new water supplies contained concentrations of lead as high as 1,430 ppb . However, all samples with elevated lead were taken at points in the plumbing system other than the final tap, and some samples were turbid (oral communication with ATSDR representative). Every home sampled on Acorn Way (six) is equipped with an in-home water treatment system to filter, soften, and improve taste. Two homes that were sampled on Coffroath Road have sediment filters. Therefore, PADOH and ATSDR do not believe the May 2001 data are representative of the exposure levels that residents experience on a daily basis.
Officials from the EPA and the Chester County Health Department (CCHD) decided to resample the affected homes before and after the in-home treatment systems. On December 4, 2001, six residential water supplies on Acorn Way and two supplies on Coffroath Road were sampled just after the storage tank (before treatment) and at the tap (finished water). The laboratory followed all EPA quality assurance protocols . From that sampling, pre-treatment lead levels ranged from 12 ppb to 142 ppb, and lead levels at the tap ranged from less than 2 ppb (six of eight samples) to 6.9 ppb . All tap samples were considerably below the EPA action level of 15 ppb, which is the maximum level allowed in public water supplies nationwide before corrective actions must be taken by the water server . ATSDR and the PADOH are unsure why some preliminary samples of water from those same homes indicated such high levels of lead.
Lead can enter drinking water from a number of natural and manmade sources. According to ATSDR's toxicological profile for lead , water samples taken from various districts of the American Water Works Service Company contained lead (4.5 ppb average) in one liter first-draw samples from homes that had only plastic piping in the plumbing system. Presumably, some of the lead came from brass or copper faucet fixtures. Therefore, lead is sometimes present at low concentrations even in newer homes that no longer use copper or brass pipes. Aside from the sampling point issue, health officials were skeptical of the high lead levels in preliminary samples, given some geological factors about the site.
- According to the U. S. Geological Survey representative familiar with the area, lead does not usually occur in natural groundwater at such a high level in the local bedrock (quartzite).
- Lead is not a major contaminant of concern in the groundwater beneath the Blosenski Landfill (oral communication with EPA representative). Volatile organic compounds are the major contaminants of concern.
- According to Fetter , lead, a cation, undergoes cation exchange with clays in weathered bedrock. Consequently, the mobility of lead in groundwater is limited to short distances, even if a source is nearby and groundwater flow direction is suitably oriented. Lead levels in tap water from homes on Acorn Way are well within the expected range for private water supplies.
Therefore, considering the reasons given above and in the background section of this document, PADOH and ATSDR believe that the December 4, 2001, sampling data more accurately represent exposures in the homes.
Although lead is a concern for adults, children are particularly susceptible to adverse effects from lead exposure. Scientific evidence indicates that a blood lead level of 10 to 25 micrograms per deciliter (µg/dL) may be related to delayed mental development, reduced intelligence quotient (IQ) scores, poor attention span, speech delays and impaired hearing . If young children drink lead contaminated water at the maximum (tap) concentration of 6.9 ppb, they will likely increase the blood lead level by only about 0.8 µg/dL. Therefore, exposure to lead through that water supply is not likely to cause any adverse health effects.
The in-home treatment systems are designed to adjust pH and remove undesirable elements such as calcium from raw water. That may explain why tap samples contained lead at much lower levels than water taken directly from the storage tank. If some of the lead was due to suspended particles (turbidity) in the pre-treated and unfiltered samples, those particles may have settled out or been filtered in the water treatment process before reaching the tap. Should further sampling confirm that the lead concentrations are due to the presence of suspended solids, residents without filters (softeners only) should consider upgrading their treatment systems to include an effective particle filter. It is important that residents continue to properly maintain their in-home treatment systems.
ATSDR and PADOH recognize that infants and children may be more sensitive to exposures than adults when encountering contaminated soil, air, or water. Children are smaller than adults, resulting in higher doses of chemical exposure per body weight. The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Lead, if ingested in high enough doses, is particularly detrimental to brain development in children. Therefore, ATSDR and PADOH are committed to evaluating their special interests as residents in homes where lead exposure through drinking water may occur.
The preliminary data from tap water samples taken on December 4, 2001, from homes along Acorn way and Coffroath Road suggest that consumption of water poses no apparent health hazard to home owners through their private wells. At the maximum concentration of 6.9 ppb in tap water, exposure to lead is not expected to cause adverse health effects, even in children. Though we believe the lead concentrations reported in recent sampling are not a public health threat, residents may want to consider performing an additional sampling round to confirm the results of December 4, 2001.
- Maintain all home treatment systems so that lead levels at the tap remain low, and consider resampling to confirm the effectiveness of treatment. Those activities are the responsibility of the individual home owner.
- Provide health education to residents at the site who may have health questions about the effects of leadin drinking water. This activity will be the responsibility of PADOH and ATSDR, in close coordination with the CCHD.
The CCHD has already provided health education to site residents through written material, phone calls, and personal visits. The PADOH, ATSDR, and CCHD will continue to provide health education to site residents after the next round of water samples are collected and all the data are analyzed.
- U. S. Environmental Protection Agency. 1998. October 14 Press Release on 11 Mid-Atlantic Cleanups.
- U. S. Environmental Protection Agency. 2001. December 11 Letter from James P. Harper to Willard Potter, Site Manager.
- Fetter, C. W., 1993. Contaminant Hydrogeology. Prentice-Hall, Inc., Upper Saddle River, New Jersey.
- U. S. Environmental Protection Agency. 2001. September 5 Updated Client Report of Analytical Data, Blosenski Landfill Site.
- Agency for Toxic Substances and Disease Registry. 1999. Toxicological Profile for Lead. ATSDR, Atlanta, Georgia.
J. E. Godfrey, M.S., P.G.
Licensed Professional Geologist
This Blosenski Lead Site Health Consultation has been prepared by the Pennsylvania Department of Health under cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the health consultation was initiated.
Technical Project Officer, SPS, SSAB, DHAC
The Division of Health Assessment and Consultation, ATSDR, has reviewed this health consultation and concurs with its findings.
Richard E. Gillig
Chief, SPS, SSAB, DHAC, ATSDR