Mosquito Spraying on Long Island

Suffolk County has had 139 positive West Nile mosquitoes so far this year—a number that jumped by 40 in less than five days—and three confirmed human cases of the virus.

“This could change today,” says McGovern. “This could change any time.”

The season doesn’t end until October.

But, according to Patti Wood, executive director of Grassroots Environmental Education, a Port Washington-based environmental health nonprofit, this spraying is dangerous—and unnecessary.

A fleet of trucks in Yaphank waiting to be deployed for spraying

“I understand the enormous pressure on the Department of Health to take action when we have human cases of [West Nile] Virus,” says Wood. “But the widespread use of pesticides is not without risks and has yet to be proven effective. I’m especially concerned that many people don’t even know about the spraying and they won’t take any precautions at all.”

Pesticide exposure is not risk free, the health department says the likelihood of experiencing adverse health effects from exposure to Scourge is extremely low since it breaks down quickly in the environment and the amounts sprayed are extremely small. Scourge contains resmethrin, which is found in other pesticide products used indoors and on pets to control ticks and insects, according to the health department. The resmethrin is dissolved in petroleum solvents, similar to paint thinner or kerosene, to increase its effectiveness.

Less than half a whiskey glass of the chemicals are used per acre sprayed, according to Kelly-McGovern.

“Certainly, weighing that against the possibility of getting West Nile, it’s the better choice,” she says.

But it’s the lack of specific scientific data on the long-term consequences of even small amounts of the chemical that have many alarmed.

“We really do not know what safe exposure levels are for these chemicals,” says Laura Weinberg, president of the Great Neck Breast Cancer Coalition. “The public must take precautionary measures to avoid exposure and reduce risk.”

The Material Safety Data Sheet (MSDS), a factsheet required by the U.S. government that explains the details of Scourge, is posted on both counties’ health department’s websites. Anyone can see it, but understanding it is another story.

“What person other than a scientist or an industrial hygienist would know what an MSDS sheet was?” says Wood. “How would you even know to click on it, and then how would you know to go to Section 11, which is the toxicological effects; what good would that do you?”

On the MSDS sheet, resmethrin is listed as a human carcinogen, and piperonyl butoxide is a carcinogen.

“Nobody, either on the county level or the state level, can tell you these chemicals are safe in any way,” says Wood. “The problem with carcinogens is that the effects of these exposures may not be seen for decades—and frankly, it’s ineffective.”

Does Spraying Work?

There are different types of spraying—ground spraying and aerial spraying, spraying for adult mosquitoes (adulticide), and spraying for mosquito eggs (larvacide).

“From my perspective, aerial spraying is never justified,” says Wood. “Targeted truck spraying is problematic but it’s a more reasonable and conservative approach, if they feel like they have to do this at all.”

While larvaciding is the preferred method—by the state, county and environmentalists—Dr. Scott Campbell of the Suffolk County Department of Health Services says this isn’t always feasible. Whether one method is used over the other depends on access and coverage.

“If the area that you’re trying to get has a nice road network, then you can use ground spray because that spray will go through the houses and get to the backyards,” he says. “But if you have these three-acre properties, it’s going to be hard to get into those, so that’s when you want to go to an aerial spray. You can cover a lot more by air than you can by ground.”

But some scientists feel this spraying should be stopped because it is completely ineffective.

“Truck spraying with pesticides is a waste of time and is done for political and cosmetic purposes,” Dr. David Pimentel, a Cornell University entomologist, said at a 2003 forum on West Nile Virus held in Cleveland, Ohio.

Pimentel said that only about .01 percent of the pesticide actually reaches the target organism. That leaves 99.9 percent of the spray going off into the environment where it can have detrimental effects on public health and ecosystems. At best, mosquito populations are reduced by 10 percent.

“To actually look at the efficacy of spraying is very, very difficult,” says Campbell. “To do it right is very, very involved. But we generally see a decrease in the numbers of mosquitoes after spraying versus before spraying.”