Chemicals and the Developing Brain

 

By Judy Mann

Wednesday, June 14, 2000; Page C17

 

If yours is a typical household, you've probably got several pesticides,

and chances are at least one of them contains chlorpyrifos. The

compound, known generically as an organophosphate, has been linked to damage in

the developing brain and was restricted by the Environmental Protection

Agency last week. Chlorpyrifos, commonly marketed under the trade names Dursban and

Lorsban, is found in more than 800 products ranging from flea collars to lawn

care products and in bug sprays used everywhere. More than 20 million pounds

of the pesticide is sold annually, making it one of the most widely used in

existence. Under an agreement between the EPA and the manufacturers,

products containing chlorpyrifos can remain on store shelves until the

end of next year. New production for nonagricultural uses is to stop by the

end of this year. The EPA is imposing tighter restrictions on its use in

some agricultural products but is still allowing it on many crops.

"We've got actual studies that show it injures the developing brain,

even at low-dose exposure in gestation or early life," says David Wallinga, a

physician and senior scientist at the Natural Resources Defense Council,

a Washington-based environmental group. "You see lasting changes in brain

chemistry in animal studies. Drops in the cells in the brain, drops in

the synthesis of DNA in the brain. . . .

 

"It is one of 35 organophosphates which act in the same ways. We simply

haven't tested the others. We are often quite ignorant when we put

things on the market. To really make sure kids are protected, the chemical

should have been banned," he says, adding that continued use of the chemical

will expose many pregnant women and children.

"There are plenty of alternatives for just about all these uses, both in

agriculture and in the home."  Wallinga and other public health advocates such as the Greater Boston

Physicians for Social Responsibility make the point that it has taken

thousands of studies and 30 years to get this one pesticide restricted.

It's like having one brand of cigarettes removed from the market every

30 years. "You've got a huge pesticide industry that's been having closed-door

meetings with EPA staff for years and plows millions into lobbying and

in turn generates enormous profits," Wallinga says. "You can't turn that

around overnight." The Boston physicians' group issued a report in May warning that

developmental, learning and behavioral disabilities have reached

epidemic proportions among American children. Nearly 12 million youngsters under

the age of 18 suffer from one of more of these problems. The number of

children on California's autism registry increased by 210 percent between 1987

and 1998.

 

The report, "In Harm's Way," cited numerous peer-reviewed studies of

animals and humans that demonstrate that many neurotoxins commonly found

in the environment can contribute to these problems. They include lead,

mercury, cadmium, manganese, nicotine, pesticides, dioxin and other

chemicals that accumulate in the food chain, and solvents. They operate

by being directly toxic to cells or interfering with hormones,

neurotransmitters and other systems involved with growth. Small exposure

to mercury, such as frequent maternal consumption of fish, has been

implicated in language, attention and memory impairment that appears to be

permanent.  The EPA has estimated that 1.16 million pregnant women eat enough

mercury-contaminated fish to risk developmental brain damage in their

children.  Most chemicals that go into consumer products are not tested for their

toxicity on humans. Moreover, the report points out, even when

regulated, the risks of chemical exposure are often estimated for one chemical at a

time. In reality, children are exposed to a varied combination of

chemicals, ranging from lead and mercury to pesticides--chemicals that

can interact to magnify damage. Wallinga says the regulatory system should

be looking at the developing child and all the things that can affect

behavior.

 

"Children shouldn't be the guinea pigs for these chemicals," says

Wallinga, who worked on the report. "But unfortunately we have a deeply flawed

regulatory system that seems to put them in that role." A child's

developing organs are extremely vulnerable to chemical exposure, he

says. "At the right time, it can throw development completely off course. The

brain and nervous system are especially susceptible to that kind of

injury."  He recommends reducing exposure to things we know or suspect to be

toxic. He notes that potential exposure to these contaminants for inner-city

residents could "well be higher" than for others. Dursban, he says, has

been one of the two most heavily used insecticides by the New York City

Housing Authority in each of the past two years. He urges consumers not

to use organophosphates in their homes.

The problem with that, of course, is that I am looking at eight

different containers of insecticides, and although I found chlorpyrifos listed on

one, I can't tell from the chemicals listed on the others whether they

are organophosphates or not. Short of banning them altogether, the

government ought to require manufacturers to label these substances so that

consumers will know what the pesticide contains and what the effects might be.

Wallinga says a fairly limited number of chemicals are posing the

greatest risks, and if we got rid of about 100 of them, "you could reduce much of

the risk to children." In other words, this is not some Herculean task

beyond the ability of the mere mortals charged with protecting the

environment. We've got plenty of evidence now that chemical contaminants

can cause damage to children's brains and nervous systems. We should not

wait for this to be proven with "scientific certainty" to establish much

stronger safeguards for children's public health than we have now.