Daily News Archive
From June 4, 2002

Americans Widely Exposed to Organophosphates and Carbamates

1997 findings of the Environmental Protection Agency (EPA) have found that, of the nearly 900 pesticides registered for use in the U.S., the 37 organophosphates and 22 carbamates pose the highest risks to human health. They are designed to kill insects by disrupting their brains and a key enzyme in the nervous system called cholinesterase.

The problem is that cholinesterase is not unique to insects; it is also a component of the human nervous system. Despite this fact, 17 organophosphate insecticides, plus additional carbamates, are registered for "residential" use, which includes use in and around homes and schools, on playgrounds, lawns, and gardens. Dursban, for example, the most heavily used insecticide in the country, just so happens to be an organophosphate.

Organophosphates are considered to be the most likely pesticide to cause an acute poisoning. 63,000 reports were made to U.S. poison control centers between 1993 and 1996 about unintentional residential exposures to organophosphates - almost 25,000 involving children under 6. Studies in animals show that even a single, low-level exposure to certain organophosphates during particular times of early brain development can cause permanent changes in bran chemistry, as well as changes in behavior, such as hyperactivity. This may mean that early childhood exposure to chemicals like chlorpyrifos, the active ingredient in Dursban, can lead to lasting effects on learning, attention, and behavior, just like the environmental neurotoxin lead.

Many organophosphates are used indoors, and are more persistent when out of the sunlight. Residues are also tracked into the home on clothes and shoes, and from drift from adjacent fields or lawns.

A study in Jacksonville, FL estimated that in spring, summer and fall there are detectable levels of the organophosphates malathion, diazinon, and chlorpyrifos in the indoor air of the home of at least 17, 83, and 8 percent of the population, respectively. Carpets, furniture, and house dust all collect pesticides. Some pesticide residues persist in carpets for up to a year. In this study, chlorpyrifos and diazinon were found in the carpet dust of at least 82 percent of sampled homes.

The majority of insecticides used in homes and schools are also used on food crops, which means that even intermittent residential exposure to organophosphate and carbamate insecticides are piled on top of a daily burden of residues on food.

For more information, see: http://www.nrdc.org/health/pesticides/forgano.asp