New health studies from the government and environmental groups are shedding light on how chemical contamination pervades communities, and for activists, providing a platform for demanding policy changes.
As awareness of chemical risks slowly crystallizes, public health monitoring projects have sprung up to examine chemical exposures at both local and national levels. Activists say this wave of community-guided scientific inquiry is crucial both to advance research on the issue and to focus public scrutiny on failing regulatory practices.
Yesterday, the Centers for Disease Control and Prevention (CDC) published its third biannual National Report on Human Exposure to Environmental Chemicals, a compilation of data on exposures to 148 chemicals in adults and children.
The findings in the report included indicators that the number of children with elevated blood levels of lead had declined since the 1990s, and that in Mexican-Americans, many of whom work in the agricultural sector, the mean level of p, pâ€™-DDE, a metabolic product of pesticide contamination, was 2.5 times higher than the level in non-Hispanic whites, and twice the level in blacks.
The environmental coalition Pesticide Action Network North America (PANNA), an organization that works internationally to raise awareness about the health effects of pesticides, analyzed 2003 CDC data on pesticide levels and found that in the sample population tested for chemicals in blood and urine, the average adultâ€™s body carried 13 different pesticides. Children aged 6 to 11 were especially vulnerable to contamination, exhibiting higher levels of exposure than any other age group to ten distinct pesticides or their breakdown chemicals.
Environmental advocates have called on the CDC to expand its survey to test exposures in newborns and to release more detailed demographic data to help guide reforms in pesticide regulations.
Science has also provided some evidence linking legislative restrictions to improvements in public health. The Center for Childrenâ€™s Environmental Health at Columbia University released a study last March indicating that a ban on two household insecticides in 2000 had a substantial effect on newborn birth weights.
In a sample of more than 300 black and Hispanic babies in New York City, those with relatively high exposures to both chemicals, born prior to January 2001, weighed nearly half a pound less on average at birth than infants with no detectable contamination. After that date, chemical exposure levels dropped and the two groups no longer exhibited a difference in birth weight.
But activists warn that in some cases, a ban may come only after irreversible damage has been done. According to Ted Schettler, director of science at the Science and Environmental Health Network, a policy think tank, the Environmental Working Groupâ€™s discovery of long-banned pesticide chemicals in infant umbilical cord blood proves "that for certain chemicals that tend to persist in the environment, stopping their production and use doesnâ€™t guarantee that they will not continue to expose people."
In both state and federal advocacy campaigns, PANNA has found that community-oriented public health research is often the environmental movementâ€™s primary defense against the industry lobby. "The political will and the popular understanding of the problem," said Schafer, "needs to catch up with the financial incentives of â€¦ the chemical industry."
On a grassroots level, some communities have merged science and advocacy through monitoring programs that track chemical exposures in people over time, which serve as an awareness-raising tool as well as a public health resource. Residents in Churchill County, Nevada, for instance, worked with the CDC in 2002 to conduct "bio-sampling" of exposures to arsenic, tungsten and other substances, in order to research local trends in childhood leukemia.
Localized studies could provide a window into how some communities might be disproportionately impacted by chemical pollution. Dr. Bruce Lanphear, director of the Cincinnati Children's Environmental Health Center, noted, "For many chemicals, children of color and impoverished families will have higher degrees of exposure."
But Lanphear also pointed to his current research, which tracks chemical contamination in a group of 400 mothers from a wide range of demographic backgrounds, as evidence that "it affects everybody. It cuts across racial groups. It cuts across socioeconomic groups. It affects us all."