Back in 1979, an insecticide that Suffolk potato farmers used to kill beetles and roundworms turned up in several private water wells.
Aldicarb is toxic in large doses, and it wasn't supposed to leach into groundwater. But it did. Today, decades after the chemical was banned here, traces still linger in the aquifers that supply local drinking water.
Concern over such persistent pollutants - and their potential effects on health when combined with other contaminants - has spurred new efforts to reduce the volume of pesticides applied to Long Island's lawns, nurseries and farms.
Some advocacy groups are pushing for laws to ban the use of weed killer and other chemicals for purely aesthetic reasons. Others want to outlaw all nonorganic products. At the same time, the state Department of Environmental Conservation is working on a new pesticide management plan, due out later this year, that may impose stricter limits for Long Island on some chemicals now allowed here.
"Is there a continued need for this material, knowing it's going to degrade Long Island groundwater?" asked the DEC's Vincent Palmer, the plan's project director.
The agency is working with landscapers, farmers and pesticide applicators to develop new guidelines. But businesses that rely on such chemicals to vanquish pests, or protect crops and ornamental plants have mixed views, particularly on proposals such as a zero-tolerance policy for pesticides proven to pollute groundwater.
Many professionals are already switching to less harmful products when available, said John Iurka of the Professional Certified Applicators of Long Island, which represents tree care specialists and exterminators.
"My problem with all this talk is that the homeowners use far more pesticides than the professional applicators, if you exclude farmers," Iurka said.
Whatever the source, over the past few decades more than 100 pesticide-related contaminants have been detected in Long Island groundwater, according to DEC data. Many are rare or found in concentrations far lower than the threshold set by drinking water standards to protect public health. But others, such as weed killers that haven't been sold here for years, have been detected in hundreds of wells.
Only a few at times exceed drinking water standards. But less is known about how multiple contaminants in drinking water interact with one other, or how those combinations could affect human health.
"If you can't answer those questions on those cocktails we're finding in the groundwater, why would you allow it . . . at any level?" Palmer said.
Others urge what they call a more pragmatic approach.
Joseph Gergela, executive director of the Long Island Farm Bureau, said products should not be taken off the local market unless equivalent, less harmful alternatives exist.
For instance, farmers unable to spray fungicides could lose entire tomato crops to late blight because the organic treatment, fixed copper, isn't as effective.
"It's not reasonable to ban every pesticide," Gergela said.
Glassberg and the dozen other activists from different organized groups out that day believe cancer and autism are linked to the chemicals applied to so many Long Island lawns.
He wants state lawmakers to pass a bill banning their sale or use, and says he's not satisfied with the evolving DEC pesticide plan.
"It doesn't go far enough," Glassberg said.