How does environment affect kids? U.S. plans major study

WASHINGTON -- Does a pregnant woman's exposure to certain chemicals put her child at risk of learning disabilities? Do genetics and pollution interact to cause asthma? What's the real impact of TV on toddlers?

The government is preparing the largest study of U.S. children ever performed -- it will track 100,000 from mothers' wombs to age 21 -- to increase understanding of how the environment affects youngsters' health.

It's called the National Children's Study, and pediatric specialists say it is coming at a crucial time. Rates of autism, asthma, certain birth defects and other disorders are on the rise, as is concern about which environmental factors play a role. And technology has finally advanced enough to allow study of multichemical and gene-environment interactions that might explain why some children seem at greater risk.

The study "really represents our generation's best hope of coming to learn the environmental causes of these conditions," says Dr. Philip Landrigan, an expert on children and the environment at New York's Mount Sinai School of Medicine.

It's a quest to prove both what's harmful, and what's not.

"There are things we probably should be worrying about that we're not worrying about enough, and there are things we're worrying about too much," adds Landrigan, who is advising the National Institutes of Health on the study's design.

The study, ordered by Congress in 2000, is in its late planning stages. Enrollment of pregnant women is set for 2006, although proponents hope three pilot sites could begin work late next year. Already, families alerted by interested patient-advocacy groups are asking how to participate.

The question is money. Scientists say they need $27 million to $50 million next year to ramp up, including hiring a laboratory big enough to store more than 2 billion anticipated biological and environmental samples -- from participants' blood and DNA to dust from their houses, soil from their yards and air from their neighborhoods.

Congress has provided roughly $12 million annually for three years of study preparation. President Bush requested the same amount for next year, and budget constraints have lawmakers indicating they're unlikely to provide more.

A partnership of strange bedfellows is lobbying for more. The industry's American Chemistry Council, which expects the study to vindicate some of its products, is pairing with environmentalists and patient and doctor groups, who argue that the study will help fight diseases that cost billions every year.

Its ultimate cost over two decades: $2.7 billion.

The National Children's Study is to be far more encompassing. Among its overall aims, says director Dr. Peter Scheidt of NIH's National Institute of Child Health and Human Development:

To measure environmental exposures of concern and hunt differences by degree of exposure. Chemicals and pollutants top the list. Scheidt cites a Minnesota study that found signs of pesticide exposure in the urine of 85 percent of children tested, but does exposure equal harm? Another example: chemicals such as phthalates, which soften plastic, may affect hormones to cause male birth defects or encourage early puberty.

Other environmental influences studied may include day care, diet, early-life infections and television.

To study health problems specifically suspected of environmental links, in hopes of pinpointing risk factors. For example, studies of genetically identical twins show when one twin gets Type 1, or juvenile, diabetes, the other has just a 50 percent chance of getting it. Genes put these children at risk, but something else, perhaps a virus, pushes them over the edge.

Brain development is another huge concern, and some substances can harm a developing brain in subtle ways and tiny amounts. Only recently have scientists learned to measure low-level contaminant exposure and to show not only that a person was around something toxic, but it actually absorbed into their DNA. And then there are windows of vulnerability: An exposure may harm during one month of pregnancy but not another.

Storing genetic and other health and exposure data long-term to test future questions without starting from scratch.

"The kinds of information we'll be collecting ... will provide an enormously valuable resource for doing this kind of research for decades to come," Scheidt says.