Aerial Spraying Leaves Pesticide Footprint in Local Waters

Detectable levels of a pesticide-borne chemical classified as a possible carcinogen have been found in Massachusetts water bodies, including drinking water sources, following aerial sprayings this summer, according to a state report posted today by Public Employees for Environmental Responsibility (PEER). While not spraying directly above water bodies, state officials allowed applicators to spray right up to water's edge, with no buffer zone or other attempt to limit pesticide drift into water bodies.

The pesticide applied aerially in Massachusetts to combat mosquito-borne diseases is Anvil 10 + 10, which contains 10% piperonyl butoxide (PBO). PBO is classified by the U.S. Environmental Protection Agency (EPA) as a possible human carcinogen. Its side effects in humans include respiratory problems and blisters with skin contact. Long term effects include disruption of the endocrine system by mimicking the female hormone estrogen, thus causing excessive estrogen levels in females and lowered sperm counts in men. Scientists believe it is more acutely toxic to children.

The purpose of the PBO is to inhibit the breakdown of the insecticide by the mosquitoes, so as to allow use of less pesticide. Tests conducted by the Commonwealth found the presence of PBO in waters after the aerial spraying. Of the 11 surface waters examined four were source water for Public Drinking Water Supplies (PWS). PBO was not detected in any samples prior to spraying. PBO was detected in some raw water samples, including some of drinking source water, the morning after and several days after spraying.

PEER is pursuing the following concerns with both state and federal officials:

• Flight crews were instructed to spray up to the edges of surface water bodies with no setbacks. However, under the terms of the federal water pollution permit, applicators must "minimize the discharge of pesticides to Waters of the United States." In order to avoid organic farms and other sensitive areas, applicators estimate how far the pesticide will drift and spray outside of a buffer zone. If there are buffer zones for farms, why are there none for waters?
• The Anvil label states: "This product is toxic to fish. Runoff from treated areas or deposition of spray droplets into a body of water may be hazardous to fish." Researchers consider PBO moderately toxic to fish, moderately to highly toxic to invertebrates (including crustaceans), and highly toxic to amphibians. Yet there has been no monitoring on aquatic life impacts; and
• While no PBO was found in treated drinking water, there was no testing for PBO daughter chemicals into which the compound could have broken down.

"While the levels of PBO found in waters are lower than what EPA deems a risk, we are not convinced that the chemicals are harmless to either the environment or to humans. With aerial spraying we are flying blind - combatting a known risk with a tool carrying unknown and perhaps even greater risk," stated New England PEER Director Kyla Bennett, a biologist and attorney formerly with EPA, noting that PBO has an average half-life of 79 days in aerobic soil, and 927 days in anaerobic (wetland) soils. "Allowing these pesticides to drift into our waters creates needless risks which buffer zones can help prevent."