About 2.6 million rural Pennsylvanians use ground water for their drinking water supply, and about 37 percent of all Pennsylvanians get their drinking water from ground water. This water has not been regularly tested for contaminants. Previous works by the U.S. Geological Survey (USGS), the Pennsylvania Department of Environmental Protection (PADEP), and other agencies have identified arsenic as being present in some of the state’s ground water.
Long term ingestion of arsenic in drinking water is known to increase the risk of skin, lung, bladder, kidney, liver, and prostate cancer, as well as several non-cancerous ailments. The USGS has historical water quality data in regards to concentrations of arsenic in ground waters from various well sites across the state. However, information about elevated concentrations of arsenic and associated hydrogeologic and geochemical controls is limited and scattered among different government agencies, universities, and health centers. No comprehensive statewide assessment of arsenic in ground water is available.
The USGS proposes to assess existing ground water arsenic concentrations across the state of Pennsylvania. Individual wells having arsenic concentrations exceeding the United States Environmental Protection Agency (USEPA) Maximum Contaminant Level (MCL) of 10 micrograms per liter (mg/L) will be identified. Regions having inadequate data for analysis will be explored.
As a first step in assessing the impact of arsenic on human health, data must be gathered to (1) determine where current arsenic data are lacking, (2) sample ground water for arsenic in these areas, and (3) determine which species of arsenic most commonly occurs in the ground water of Pennsylvania.
Existing post-1979 ground water arsenic data will be compiled statewide and analyzed to identify locations containing elevated MCL concentrations, and regions where more arsenic data are needed. In selected regions of the state where arsenic data are lacking or concentrations of arsenic are commonly elevated, USGS, PADEP, and the Pennsylvania Topographic and Geologic Survey (PAGS) well data will be reviewed for information and completeness regarding (1) homeowner address (2) well construction (3) discharge, and (4) hydrogeologic attributes.
Based on this review, selected homeowners will be contacted to participate in the study. Each participating homeowner will be provided with a water sampling bottle, sampling instructions, a health and water use questionnaire, and a pre-paid return container. The samples will be sent to USGS for preservation and evaluation before submittal to the PADEP laboratory for total arsenic analysis.
Water from a maximum of thirty selected wells with arsenic concentrations greater than 10 mg/L will be sent to the USGS National Water Quality Laboratory (NWQL) in order to discern arsenic speciation. A final comprehensive data set will then be delivered to PADEP and the Pennsylvania Department of Health (PADOH).
With this data, PADOH would be able to match USGS results with statewide epidemiological data to explore connections between elevated arsenic concentrations and health effects. The cancer registry and other data sets (such as birth weight and gestational age) would be used to link health effects to arsenic “hot spots”.
By the end of the project, which is scheduled for July 31, 2006, it is expected that there will be a collection of new ground water arsenic concentration data (including speciation) for selected regions where data are currently lacking. From this new information, an electronic data report will be provided using Microsoft Excel and Geographic Information System (GIS) datasets and maps for ground water arsenic concentrations throughout Pennsylvania.
All chemical data will be site referenced by an accompanying latitude and longitude, allowing PADOH to link human epidemiological information with local exposure to arsenic in ground water. A synopsis of the project will also be available to the public on the Internet, posted on the USGS Pennsylvania Water Science Center homepage.
