Malathion: A Common Poison
Pam Poulson was up early, as usual. The July sun had yet to clear the Wasatch, and already she was padding across damp lawns, ducking under trees, and brushing past bushes as she tossed bundled newspapers onto doorsteps in Rose Park. She felt good, energetic. The heat of the day was just setting in as she tossed the last paper, climbed into her morning glory blue Miata, and headed to her second job, at Red Butte Garden and Arboretum. After a day of guiding tour groups and answering questions at the Visitor's Center, she cruised home, changed, ate, lugged her bulky string bass into the tiny car and drove to band practice. Once there, she became violently ill. Her chest tightened abruptly, and she began to shake. The sweat suddenly pouring off her body was rank with an intense chemical smell. Poulson, a long-time landscaper and habitu* of garden centers, recognized the odor. Alarmed, she stumbled to a telephone and called Poison Control."I think I have malathion poisoning," she told the person on call. "What do I do?"The woman who answered had obviously had many such calls before -- she didn't even have to look up Poulson's symptoms. "Go to a steamroom," she said. "Breathe a lot of steam. Take a lot of showers. The only way to get rid of it is to sweat it out." Her breathing increasingly labored, she drove home and followed orders. By morning, she felt even worse, so she went to see her doctor. He, too, recognized the symptoms immediately, and diagnosed her condition as chemical bronchitis, induced by inhaling the fumes of the common insecticide. There was nothing that could be done for the condition, she was told, and she'd get worse before she got better. The typical time-line for a mild case of chemical poisoning like hers, he said, was 10 days, though it may be years before she stops sweating it."What frightens me," she says, "is that my doctor told me malathion is essentially a nerve gas. All we could figure is I walked under a tree that had recently been sprayed, and I breathed in the fumes. I didn't even get any on my skin, or I would have been a lot sicker. And this is an ingredient in any one of a dozen products that can be bought off the shelf of any garden center! I've heard plenty of horror stories about people getting sick from using it, or, like in my case, from even their neighbors applying it to their trees or grass. I know how bad it is -- I haven't used malathion in my garden in over 25 years -- but I think there's a lot of people out there who still don't have the slightest clue how dangerous it is."It's a (Nerve) GasMalathion. Carbophos. Maldison. Mercaptothion. Cythion. Karbofos. Celthion. Dielathhion. Maltox. El 4049. Emmaton. Fyfanon. Exathion. All are names for the same yellow liquid compound (O,O-dimethyl S-1,2-di(ethoxycarbamy)ethyl phophorodithioate), widely used to kill many of the insects that threaten, aggravate, or merely irritate the human race. Introduced by American Cyanamid Co. in 1950, malathion is a organophosphate insecticide, closely related to GB (sarin), mustard gas and VX, the nerve agents currently being destroyed at the Chem. Demil incinerator in Tooele County. Like all nerve agents, if kills by inactivating the enzyme (acetylcholinesterase, or AChE) that controls nerve impulse transmission. It has been seized upon as a safe replacement for DDT (banned in the United States in 1972), as it has a fairly short half-life (it breaks down in the environment in one to three weeks) and purportedly does not bioaccumulate.Malathion is used heavily in commercial agriculture, forestry, mosquito abatement, and in millions of households -- in the yard (for garden pests), on the body (for head and body lice) and in pet care products. It is sold in myriad forms: shampoo, medicated soaps, pet collars, animal dips, ground and aerial sprays, aerosols, foggers, baits, paints and cattle feed blocks, frequently in harmless-sounding products like "Harvest Insurance" and "Fruit Tree Spray."Like other organophosphates, malathion is far from benign. In humans, low exposure can cause severe anxiety, headaches, diarrhea, nausea, sweating, muscle spasms and weakness, elevated blood pressure, irregular heartbeat, cramps and respiratory distress. "Prolonged worsening illness," immune system deficiency, unconsciousness, convulsions, respiratory failure, liver damage and, occasionally, death, are symptoms of high level poisoning. Malathion has been shown to be more toxic to males than females. Those on low-protein diets, such as vegetarians, are more severely affected.Several studies have found that malathion is able to literally knock genes off DNA molecules. A California investigation, which followed 933 pregnancies in relation to Malathion exposure during aerial spraying for the Mediterranean fruit fly, found that children who had been exposed to the insecticide during the second trimester of pregnancy showed more than two and one-half times more gastrointestinal disorders (affecting the stomach and small intestines) than those not exposed to the chemical. There are possible links between malathion exposure and childhood leukemia, kidney damage and brain damage, particularly in older people.Despite all these findings, Malathion is still considered to be relatively benign by many government agencies, and by the general public. Only recently have its dangers, to both humans and the environment, begun to make headline news.Med Fly MadnessSince the middle of June, the Florida Department of Agriculture has been aerially blanketing three counties, Hillsborough, Polk and Manatee, with malathion. The intended target is the Mediterranean fruit fly, a pest capable of devastating the area's citrus crops. Many residents, suffering from symptoms of malathion poisoning, are concerned about the impact of the insecticide, not only on themselves, but on the environment, too.Unfortunately, it's not just the Med flies that are dropping like flies, it's all of them, including the pollinators necessary for the survival of the citrus groves, and the parasitic wasps that normally prey on the Med flies. Residents say bees, ladybugs and other beneficial insects have all but vanished from the three counties since the spraying began. Only the mosquitoes are thriving, having developed an immunity to the pesticide after decades of heavy use by the states' Mosquito Abatement program.According to Florida news reports, the fish, too, are dying by the millions, their pale, poisoned bodies bobbing on the surface of ponds, lakes and rivers. Malathion affects them in much the same way that dioxin does, mutating genes, disrupting growth, maturation and mating. It is highly toxic to all aquatic invertebrates (clams, crabs, lobsters, etc.) and the aquatic stages of amphibians (tadpoles), as well as to lizards, water snakes and frogs. While the chemical is not usually fatal to birds, it still inflicts significant damage, including reduced hatch rates, low birth weight, increased beak and leg defects, impaired growth and nerve damage. Neither the long-term nor short-term affects on mammals (except rats) have been studied.Armed with ample scientific data, a grassroots action group called Citizens for Responsible Application of Malathion, or CRAM ("The politicians just crammed this spraying campaign down our throats," explains member Eugenia Clark), is demanding a stop to the spraying. They say the state has gone far beyond the EPA guidelines which specify how much, how often, and where the chemical can be sprayed. They want Florida to adopt the safer Integrated Pest Management (IPM) program used by the California Department of Agriculture, in which malathion is used only to supplement organic measures. The group, over 9,000 strong a mere three months after its inception, is moving towards legal action against the state.Florida agricultural officials counter the groups' claims, citing their own studies showing that malathion has no adverse health effects. Florida Deputy Secretary of Agriculture Martha Roberts claims malathion is so safe she is willing to drink a glass of it, though she hasn't, yet. The state has, however, recommended that residents take some precautions to avoid exposure, especially those with respiratory ailments, depressed immune systems and chemical sensitivities. But, say residents, the spraying is so frequent, they'd have to stay inside 24 hours a day to avoid it. Eugenia Clark describes attempting to go for a walk in her Tampa neighborhood:"I knew they had sprayed earlier in the week, so I waited until the third day after, and figured it was okay to take a walk. But I didn't know they had sprayed again just the night before. Once I got outside, I could taste it. Soon, I couldn't breathe, and everything felt very heavy. Then the peripheral nerves in my extremities began to fire without control, and I began twitching."BiocideUtah State Extension Service Agent Larry Sagers empathizes with the Florida citrus farmers, and feels they have no choice but to spray the marauding Med flies with whatever works. He remembers a similar infestation, here in Utah, by the western cherry fruit fly, a cousin of the Med fly."If you've never dealt with a pest that has come in and invaded an area, you just can't imagine the devastation that can occur," he says. "It used to be that you could grow cherries anywhere in northern Utah. But now, if you don't do considerable spraying, going to a lot of trouble and expense, the fruit flies just eat them up. If we had been able to control the fruit fly by aerial spraying, we could have kept them from getting a hold. Anything you can do to destroy a pest like that is justifiable."However, many biologists, ecologists and organic agriculturists disagree that the end (a healthy crop) always justifies such drastic means. Biologist Ty Harrison points out that not only are insecticides like malathion dangerous, but they eventually become impotent."All of the ecology tells us that the use of insecticides is a losing proposition for many reasons," he says. "First, the insects always eventually become immune to the chemical, just like some bacteria have become immune to antibiotics. Second, it kills the predacious insects that control the plant-eating insects. Third, it disrupts the whole ecosystem to engage in the mass killing of any species. Regardless of the life form, there is another living creature out there that depends on it for a food source."A May 1997 press release sent out by the Utah Department of Natural Resources Division of Forestry, Fire and State Lands, inadvertently illustrated the dangers of uneducated insecticide use. The letter, sent to local media for reprinting, discussed a common Utah insect, the fall cankerworm caterpillar, commonly known as the inchworm. This caterpillar feeds on the leaves of several trees, including oak, maple, elm and box elder. In years when the inchworm population is high, trees can suffer serious defoliation -- though, as the letter pointed out, they usually refoliate once the caterpillar hatch is over. The letter recommended that as a safeguard, and for reasons of "aesthetic impact and general nuisance," landowners should "control" the inchworm by spraying trees with an insecticide, such as Bt or malathion.What the letter didn't mention is that the fall cankerwom caterpillar is the primary diet of a score of neo-tropical migratory songbirds (western tanagers, northern orioles, blackheaded grosbeaks and others) and that these birds' flights, from Costa Rica and Panama to Utah, are timed precisely to coincide with the caterpillar's hatch. Without the cankerworm, many of these songbirds would perish.That the press release promoted the use of insecticides, totally disregarding the complex global relationship among trees, caterpillars and birds, infuriates Harrison. "We must gain a better understanding of biodiversity," he says. "And we need to develop a new aesthetic, one that appreciates insects and their place in the food chain. When I take my students [at Westminster College] on field trips I teach them to celebrate holes in tree leaves, because it means that the area is healthy. When you see tree leaves that don't have some holes in them, you know there's something wrong."Spreading the WordFortunately, the word on malathion does seem to be spreading, albeit rather slowly. Most public agencies contacted for this article said they have phased out, or are in the process of phasing out, malathion use. Ironically, in light of the May press release, a spokesperson for the Division of Forestry says that in his division, "Malathion is rarely used, except for large projects, like the Mormon cricket outbreak a number of years ago, and then only in conjunction with the Department of Agriculture or the Bureau of Land Management."One of the few agencies still using the chemical regularly is Salt Lake City Mosquito Abatement. "We use it in an ultra low-volume spray arielly over the marshes near the airport," says spokesperson Sammy Dixon. "And in such small quantities that it doesn't even kill grasshoppers, just mosquitoes. Most people wouldn't even know the application had occurred. "Dixon doesn't know if anyone has done water testing in the marshes, or checked for damage to the fish and wildlife, despite the warning on the label of products containing malathion stating "This product is toxic to fish, aquatic invertebrates and the aquatic larvae of amphibians." But, he says, the city has stopped using malathion in neighborhoods, parks and golf courses."We quit spraying residential areas at least 10 years ago," he says. "The reason being some people want the spraying, but others don't, either because they don't like chemicals, or they have real or perceived reactions to them. And it's impossible to spray some houses and not others, because the wind blows it from one to another."[Salt Lake County Mosquito Abatement uses Dursban, another -- and even more toxic -- organophosphate, though a spokesperson says the department does not spray the chemical, and will be discontinuing its use when current supplies run out.]Salt Lake City Forester Bill Rutherford says his department has switched to using insecticidal soaps and dormant oils to manage pests on City trees."We looked hard and long at our pest control practices," he says, "and we made the decision not to use insecticides. Not just because of the side effects, but also because the insects build up resistance. They also kill the beneficials, the good guys, and then the bad ones rebound really fast. So the products we now use provide greater control, plus safeguard the well-being of the community."The public outcry in Florida has also prompted renewed efforts to find a replacement for the insecticide that is affordable, lethal only to fruit flies, and has no environmental consequences. While such a product sounds too good to be true, there are some "biorational" pesticides, like Bt (Bacillus thuringiensis) a naturally occurring bacterium found in soil, that can be used to kill specific insects.Just as importantly, the United States Department of Agriculture (USDA) and other agencies are beginning to devote more time, money and energy into promoting organic agriculture. In 1988, a program to fund research and demonstrations on low-input sustainable agriculture (LISA) was created. The goal of the program is to lower the costs of crop production, maintain optimum yields, increase profits and protect human health and the environment.The next and most important step, says Ty Harrison, is to educate the public. "We've become a nation of nozzleheads," he says, "who think the solution to every pest problem is a bottle of pesticide and a spray nozzle. Much of the abuse of insecticides and herbicides lies squarely with the average person, who needs to learn that not all insects are bad and not all chemicals are good."A month-and-a-half after her Malathion exposure, Pam Poulson feels okay again. The iron hold on her lungs has loosened, and she's pretty much back to normal, except that her pores still exude Malathion, especially from her feet. She says she considered giving up her paper route because of the experience, but decided to stick with it. But she has clarified her feelings about a couple of things."I'm totally convinced that malathion should not be on the shelf at every garden store in town -- I don't think any nerve gas should be. Even if a person follows the directions on the bottle -- which a lot of people don't -- you're still endangering other people and the environment."And I have to confess, I haven't been an entirely organic gardener. I've been using snail bait and some non-contact pesticides. But after this episode, I'm seriously considering going organic all the way."SidebarLow Tech Anti-Bugging Methods* plant resistant varieties * keep garden clean (clear away crop debris) * till soil frequently * handpick insects * use water to blast off pests * ring seedlings with cardboard or aluminum foil * plant trap crops (a similar crop to the main crop) * mix up beds; interplant crops, like flowers in middle of vegetable rows * mulch * invite beneficials by planting flowers and allowing herbs to flower in around garden * rotate crops -- change what you plant in particular spot year to yearOrganic Pest Controls:* Floating row covers: a translucent, white porous polyester fabric that acts as a barrier to keep out insects while letting in water and up to 80% of the available light. Very useful against cabbage moths, Colorado potato beetles, aphids, Mexican bean beetles and squash bugs.* Diatomaceous Earth: Mined, fossilized remains of tiny prehistoric algae-like creatures called diatoms. Kills pests by absorbing their oily or waxy outer cuticle, causing them to lose body fluids. Works against slugs, earwigs, aphids and other soft-bodies pests, but may also kill beneficials.* Pheromone traps: scented lure traps that reproduce the powerful scent emitted by some insects during mating season. Mostly attract male insects, so not completely effective.* Sticky traps: rigid material of specific color that is coated with a sticky substance that physically catches insects attracted to that color. Yellow traps white flies, fruit flies, male winged scale, leafhoppers, fungus gnats, midges, male winged mealybugs, leafminers, thrips, psyllids and winged aphids. White lures whiteflies, tarnished plant bugs, cucumber beetles and flea beetles. Light blue attracts flower thrips. Red traps apple maggot flies.* Insecticidal soap contains unsaturated long-chain fatty acids that dissolve the cuticle (skin) of insects. Highly effective against mites, aphids, white flies, and other soft-bodied insects. Must come into contact with insect while it's wet. Don't use during heat of the day, and rinse leaves off plants after a few hours.* Oils sprays: dormant oils used to smother insect pest eggs, disease spores on trees and shrubs, and aphids, mites, beetles, leaf miners, caterpillars, thrips, leafhoppers and white flies.* Bacillus thuringiensis (Bt): naturally occurring bacterium found in soil, some of which can be used to kill specific insects. Most common strain can be used against caterpillars such as cabbage loopers, tomato hornworms, cabbageworms, corn earworms, European corn borers, squash vine borers and Colorado potato beetles.* Parasitic nematodes: beneficial nematodes that attack armyworms, cornworms, squash vine borers, white grubs, weevils, root maggots, cutworms.* Nosema locustae: naturally occurring protozoa that infect and kill many species of grasshoppers. For best results, use around the garden before the young grasshoppers get their wings, when they are about half an inch long.