Malathion spraying
Malathion spraying involves the application of malathion, an organophosphate insecticide known for its neurotoxic properties. It is primarily used to control crop pests, including the Mediterranean fruit fly, aphids, and the cotton boll weevil, as well as pests in home gardens. Malathion is considered one of the least harmful organophosphates due to its relatively quick degradation in the environment and the ability of mammalian liver enzymes to neutralize it. Historically, it gained attention in the 1980s when a Medfly infestation in California led to significant public concern regarding potential health risks associated with aerial spraying.
Despite initial opposition from some local officials worried about health effects, evidence suggested that malathion posed minimal risk to humans, leading to its use in widespread aerial spraying efforts to protect California's agricultural economy. Residents were advised to take precautions during spraying events, such as staying indoors and covering outdoor items. The spraying campaigns were eventually deemed successful, with reports of Medfly eradication by the fall of 1982. While studies indicated no increase in birth defects among children of pregnant women exposed to the spraying, discussions about the necessity and effectiveness of aerial versus ground spraying continue to evolve. Malathion remains a key tool in pest control, sparking ongoing dialogues about public health, environmental impact, and agricultural practices.
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Malathion spraying
The Event An insecticide is widely used on crops and released over populated areas
Date July, 1981
Though used since the 1950’s and considered safe, malathion’s application by aerial spraying over a large populated area of California to kill Mediterranean fruit flies created public furor.
A neurotoxin, malathion is an organophosphate insecticide. Because mammalian liver enzymes neutralize malathion and because it degrades quickly in the environment, it is considered to be the least harmful organophosphate. Used in both ground and aerial spraying, it controls crop pests such as the Mediterranean fruit fly (Medfly), aphid, and cottonboll weevil, as well as home garden pests. Before the 1980’s, malathion was widely used, notably on citrus crops in Florida.
Medflies infest more that two hundred different crops and have the potential to cause great economic damage. In June, 1980, a male Medfly was found in a trap in California. By July, a commission had quarantined large areas in Los Angeles and Santa Clara counties. When the release of sterile male Medflies failed to curb the infestation, the U.S. Department of Agriculture proposed spraying with malathion. Fearing adverse effects on public health, some county officials voted to ban the spraying. This action spurred the California State Department of Health Services to survey literature on the effects of malathion on human health. When the department found little evidence of harm to humans, ground spraying commenced.
However, in June, 1981, Medfly larvae, which eat the fruit, were discovered. Sensitive to the demands of environmentalists, Governor Jerry Brown opposed the recommendation for aerial spraying of both agricultural and inhabited areas. When the federal government threatened to quarantine California produce, a threat to the $14 billion industry and to U.S. food prices in general, the governor changed his mind. Officials argued that the economic benefits far outweighed any possible risks to humans. They pointed out that because malathion was mixed with sugar and molasses in the aerial spray, it was difficult to inhale, and the director of the California Conservation Corps publicly drank a small quantity of very dilute malathion to demonstrate its safety. Aerial spraying of 1,400 square miles began in mid-July. During the spraying, residents followed simple rules, such as remaining indoors during the actual spraying, closing windows, removing toys and household articles from yards, and covering cars with sheeting. Few went to Red Cross shelters established as refuges. In the summer of 1982, the Medflies were discovered in the fruit-growing regions and malathion spraying commenced immediately.
Impact
In September, 1982, officials announced that the Medfly had been eradicated. Spraying with malathion continued off and on in California and Florida for the rest of the decade. Studies of children born to women pregnant during the spraying found no additional birth defects or premature deliveries. However, it was revealed that some of the male Medflies released were actually fertile. Another study suggested that aerial spraying might not have been necessary because the belief that ground spraying had failed resulted from miscalculations of the extent of infested areas, rather than actual failure.
Bibliography
Marco, Gino, Robert Hollingworth, and William Durham, eds. Silent Spring Revisited. Washington, D.C.: American Chemical Society, 1987.
Pimental, D., and H. Lehman, eds. The Pesticide Question: Environment, Economics, and Ethics. New York: Chapman & Hall, 1993.