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Pesticides and Herbicides- Drinking Water
Massachusetts Water Resources Authority
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MWRA has tested for a wide variety of pesticides and herbicides in our source and treated water, including the controversial herbicide glyphosate. Due primarily to MWRA's well-protected watersheds, it is unlikely that they would be found, and both regular and special testing efforts have shown this to be true. Only one pesticide has ever been detected, and that result is considered uncertain.
| Substance | Measurement Units | Average | Range |
|---|---|---|---|
| PBO - Piperonyl Butoxide | parts per billion (ppb) | 0.0012 | 0 - 0.006 |
The State of Massachusetts sprayed for mosquito control in September 2019 in response to the elevated risk of Eastern Equine Encephalitis (EEE). The mosquitocide used was Anvil 10+10, composed of the pesticide Sumithrin (also known as d-Phenothrin) plus the synergist, piperonyl butoxide (also known as PBO). Water supplies identified by MassDEP as being in close proximity to the spraying were tested for the mosquitocide. EPA and MassDEP have a health guidance level of 992 ppb. Consumption of drinking water for many years above that level could result in effects on the liver and may possibly incdrese the risk of cancer. The state laboratory indicated that it had detected PBO in treated water from Wachusett Reservoir prior to spraying, but not in any samples of treated water after spraying. That result, if real, would have been more than 100,000 times lower that the health guidance level. |
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For more information, please contact:
Beverly Anderson, MWRA Public Health Project Manager
Updated June 17, 2020