Ted Schettler, Science & Environmental Health Network
We're busy. We've got a lot to buy, and we don't have time to analyze every purchase. But we'd better keep our brains turned on when we reach for ant and roach sprays, weed killers and flea and tick powders. These are all pesticides whose long-term effects are little understood at best and detrimental to human and environmental health at worst, despite being registered by the EPA.
By definition, pesticides inhibit the functioning of species or kill them outright. The problem is, of course, that our nervous, digestive and reproductive systems have more in common with rodents and insects and other pests than we've been in the habit of thinking. We also drink the same water, breathe the same air and eat many of the same foods that they do. So do songbirds, spring peepers, honey bees and other species we like.
A small battalion of Environmental Protection Agency scientists works to temper the lethality of pesticides before they enter the marketplace. Companies must register their pesticides with the EPA before putting them on the market in the United States, a process that requires companies to submit dozens of exposure studies and toxicity tests, costing about $4 million to $8 million to complete in the case of food-use pesticides.
From fatal doses to doses that cause deformities in nontarget species -- and in the rats, rabbits, hens and dogs that serve as proxies for humans -- the EPA calculates tolerance levels for pesticide residues and establishes guidelines for use. The EPA bears the responsibility for deciding how much we can kill without killing ourselves. As consumers, we have to decide whether to accept the EPA's judgment. Unfortunately, there are plenty of reasons not to.
Since its inception in 1970, the EPA has had to play catch-up to the marketplace. Many pesticide chemicals entered the marketplace in the 1950s (the ability to produce toxic chemicals advanced tremendously during World War II). In 1988, amendments to the Federal Insecticide Fungicide and Rodenticide Act required companies to reregister pesticides in use before 1984 with the EPA. The reregistration process evaluates old chemicals against current EPA test protocol. Of the 612 classes of pesticide chemicals to be reregistered, 132 have yet to be re-evaluated and continue to be sold.
The EPA is further disadvantaged because there's no scientific method to ferret out the effect of frequent sublethal doses of pesticides on complex bodily processes. How much of a learning problem, for example, should be attributed to neurological damage caused by low doses of pesticides ingested in breast milk, how much to an early fall from the bathroom stool and how much to a lack of appropriate intellectual stimulation?
"So many of the adverse health effects of chemicals in general are nonspecific, whether it's cancer or a learning disability," says Schettler, science director for the Science & Environmental Health Network. "Nonspecific meaning that they're not caused by a single thing. There are actually very few diseases where you see disease and you think of a single chemical or a single exposure. With breast cancer, non-Hodgkin's lymphoma, leukemia, brain tumors, learning disabilities, hyperactivity, epidemiological studies tell us that the risk of those outcomes increases with exposure to certain chemicals including pesticides, but they don't tell us that the chemicals caused this disease in John or Mary Smith."
Without the science to identify and evaluate direct interactions, we have only correlations between pesticide exposure and disease. A resource guide for health care professionals published in 2000 by Nobel Peace Prize-winning Physicians for Social Responsibility and Californians for Pesticide Reform referenced more than 150 independent studies linking pesticides with cancer, neurological damage, reproductive and developmental hazards, and immune-system and endocrine disruption.
But correlations don't prove a chemical guilty beyond a reasonable doubt, and correlations, unfortunately, emerge only over time and with use. "Another problem with the pesticide-registration process," says Susan Kegley, senior scientist for Pesticide Action Network North America, "is that we really don't learn what the effects are going to be until it gets out there in wide use, because there are just so many things and interactions that you don't think of. Pyrethroids (used for pest control in homes and on lawns) are now being found in stream sediments everywhere and killing off all the critters that live in the streams."
Even if a connection between a pesticide and a health or environmental problem becomes too compelling to ignore, the pesticides will remain on store shelves for several years. The EPA must conduct reviews and develop new test protocol. Companies will then be given a grace period to retest their products. The pesticide can be sold as before throughout this five- to 10-year process.
Poor test results may lead to a pesticide being restricted -- to use by professional applicators, for example, or to use in some states but not others -- rather than banned.
The case of dibromo chloro propane is illustrative. Used as a soil fumigant, DBCP was first produced in the 1950s by Shell and Dow Chemical. In the 1970s, DBCP was linked to male sterility among workers in factories where the chemical was produced. By 1977, the California Department of Food and Agriculture had banned the use of DBCP. In 1979, the EPA followed suit, banning DBCP except for use on pineapples. In 1985, nearly 15 years after the discovery of DBCP's testicular toxicity, the EPA banned use of DBCP entirely. However, even after the U.S. ban, the chemical was still sold into Central America. Today, there is a lawsuit against the companies that produced DBCP on behalf of thousands of sterile plantation workers.
There are more reasons to think for ourselves before purchasing a pesticide. One is that, with the exception of acute toxicity tests that determine the immediate effect of a single exposure to a pesticide, the EPA registration tests are conducted on only the active chemicals (the known toxins) in pesticides. But the pesticide formulations also include so-called "inert" chemicals. These chemicals might keep the toxin suspended in liquid or help it adhere to the leaves of plants it is designed to kill. Inert ingredients can have unforeseen impacts.
Schettler recalls a study of Canadian rivers conducted from 1975 to 1985: "Salmon were failing to return to some Canadian rivers. Investigations were done, and it was found that the failure coincided with aerial spraying for spruce budworm in New Brunswick. The insecticide had gotten into the rivers. But what was interesting was that it wasn't the active ingredient that caused the problem, it was the surfactant (a chemical that reduces surface tension), which was a weak estrogen, in the pesticide. The surfactant had interfered with the capacity of the young salmon to smolt, which means to be able to go from fresh to salt water. They have to be able to adjust to that new environment, and that adjustment turns out to be an estrogen-dependent mechanism. The surfactant disrupted the process so that when the young salmon went into the salt water they all died."
The reasons for testing only the active ingredients are largely economic: There are close to 900 registered active pesticide chemicals in the United States, but there are 20,000 formulations on the market. Companies continually reformulate their branded products, plus final formulations are considered trade secrets, companies' proprietary information.
Consider also that, unless the mechanisms of active ingredients are known to be additive -- meaning there could be an overdose even if the individual pesticides are used correctly -- the EPA doesn't evaluate the effect of exposure to more than one pesticide at a time. Yet we ingest multiple pesticides just eating an average meal, and we walk around with a cocktail of pesticides inside us. In 2003, the U.S. Centers for Disease Control and Prevention reported that the average person has 13 pesticides sloshing around inside his body at any given time.
So let's not get into too much of a hurry when buying pesticides. Let's take the time to remember that we're buying toxins and that we introduce poisons into our immediate surroundings when we use them. And let's remember that regulating a problem doesn't make it go away.
Deborah K. Rich is a Monterey writer and olive rancher. E-mail her at firstname.lastname@example.org.
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