2/18/2009
Mass DEP Issues Pesticide Guidance for Wareham Water
The Massachusetts Department of Environmental Protection, Office of Research and Standards (Mass DEP ORS) has recently released health guidance values for pesticides detected at low levels in drinking water of the Wareham Fire District Water Department (the District). The Mass DEP ORS has determined that all of the pesticide results are below health protective guidance values and pose no unacceptable health risk to water customers.
This notice has been prepared to inform local water customers and residents of the Mass DEP drinking water guidance values and the testing results to date.
Since 2001, the District has been voluntarily conducting extensive groundwater testing for pesticides at thirteen well locations in the vicinity of its public water supply wells. The District began this testing program as part of an ongoing commitment to maintaining the safety of its drinking water, and to evaluate the potential impact of pesticides used in cranberry agriculture near its supply wellfields. The testing was originally funded through state grants, and is now part of the District’s Water Department annual operating budget.
Every fall, the Water Department and S~E~A Consultants, Inc. release an annual report presenting the results of the testing program. The results are also presented at a publicly noticed Board of Water Commissioners meeting. To date, the testing program has found trace levels of six pesticides (2,6-dichlorobenzamide, carbaryl, norflurazon, chlorothalonil, methoxyfenozide, and napropamide). Currently no federal or state standards exist to specify permissible drinking water levels of these detected pesticides. Although the detected levels are extremely low, the District periodically requests the health risk scientists at Mass DEP ORS to review testing data and provide health guidance values. Mass DEP ORS has recently released the results of their latest review.
The Mass DEP ORS has determined that the pesticide levels measured in monitoring and drinking water wells to date do not pose an unacceptable public health risk.
Of over 200 samples collected to date under this program, only one single sample (chlorothalonil, 1.7 ppb) slightly exceeded the health guidance value of 1.5 ppb. All other detections have been far below the other drinking water health guidance values. Given this situation with chlorothalonil, chronic (long term) exposures at these levels are not taking place, indicating no unacceptable health risk. DEP uses an approach for deriving drinking water guidelines that evaluates cancer and non-cancer health effects and uses the lowest value to be protective of all health effects. 1.5 ppb of chlorothalonil in drinking water is associated with a one-in-one-million lifetime cancer risk, assuming 2 liters of water are ingested per day, every day. In addition to agricultural use, chlorothalonil is used to treat
lawns and golf courses. ORS also estimated the potential health risks from exposure to a combination of pesticides, using the highest concentrations detected in all locations. These chemicals collectively posed no unacceptable health risk either.
The Water Department will continue to take extraordinary measures to monitor the safety of its water supplies by funding the testing program. The District will coordinate with Mass DEP, the cranberry growing community, and the UMass Extension station to help safeguard the Town’s water resources. The District is working towards implementing a well management program to reduce reliance on its wells that are located downstream from cranberry bogs. The Water Department will continue to publish testing results annually. Complete copies of the DEP’s Health Risk Assessment report and the Water Department’s Wellhead Protection report are available for public review at the Water Department at 2550 Cranberry Highway in Wareham. Persons with additional questions can contact the Wareham
Fire District Water Superintendent, Michael Martin, at (508)295-0450.
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