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Testing people for pollutants

A study looking for environmental toxins in breast-milk samples puts California at the forefront of the biomonitoring movement.

October 06, 2003|Shari Roan | Times Staff Writer

TORRANCE is home to a hazardous waste site; the Central Valley uses copious amounts of pesticides; and Marin County has an unusually high, and puzzling, rate of breast cancer. For scientists and environmental activists, these disparate locations are the ideal proving ground for a new theory. They believe that environmental pollutants may play a role in various diseases, such as breast cancer. To prove their hypothesis, they have begun collecting breast milk from new mothers in all three locations.

In doing so, they've placed California in the vanguard of a national biomonitoring movement.

Biomonitoring involves looking for "pollution in people" -- testing bodily substances, usually blood and urine, for the presence of harmful substances, such as dioxins, polychlorinated biphenyls, or PCBs, and DDT. Traditionally, estimates of human exposure to toxic substances have been based on measurements of chemicals found in food, soil, air and water.

Because many chemicals accumulate in the fat cells of the breasts, the milk of new mothers -- particularly during the first few weeks of nursing -- contains a high concentration of chemicals. Testing the milk could offer insight into any possible connection between pollution and disease.

"Biomonitoring is telling us what's in our bodies and are [the levels of those toxic substances] going up or down -- are there things we need to worry about?" says Kim Hooper, a state scientist who is co-directing the breast-milk biomonitoring study in Torrance, the Central Valley and Marin County. That study, of 120 women, is conducted by the Environmental Protection Agency and is already underway.

Activists in the field of breast cancer, frustrated that genetics and diet only partly explain the dramatic rise in rates of the disease in the past 50 years, are pushing to expand biomonitoring even further. They want a statewide program that will focus on possible causes of breast cancer as well as other diseases.

Legislation sponsored by the Breast Cancer Fund, a nonprofit health advocacy group, would -- among other things -- make California the first state in the nation to regularly test mothers' milk for dangerous chemicals.

"It became very clear to us that what is not being addressed is the unexplained risk factors in breast cancer," says Jeanne Rizzo, executive director of the group. "We saw more and more science connecting synthetic chemicals with breast cancer."

But efforts to use the relatively new science of biomonitoring is not without criticism. Some experts say that information from biological samples could be used by insurance companies or in hiring to discriminate against people or communities. Other experts worry that a detailed accounting of what's in breast milk could cause some women to stop nursing their babies. Focusing on chemicals in breast milk, they say, might inadvertently suggest that breast-feeding is not safe.

Regardless, biomonitoring's time seems to have come. Technological advances have made it possible to detect a wider array of chemicals in the body at much lower levels than before. The federal Centers for Disease Control and Prevention launched a study two years ago to examine blood samples from 5,000 Americans, citing evidence that chemicals may be influencing rates of cancer, asthma, autism, birth defects and Parkinson's disease.

Such advances coincide with mounting concern about environmental links to breast cancer, in particular. Studies suggest that fewer than half of breast-cancer cases can be explained by known risk factors, such as genetic traits and reproductive patterns. American women today have a one in eight chance of developing the disease, up from one in 22 in the 1940s.

Leading cancer researchers have endorsed breast-milk biomonitoring as an important new direction in breast cancer research.

More than 85,000 synthetic chemicals have been introduced in the last 50 years for industrial, farming and other uses, yet more than 90% of them have not been tested for their effects on human health. However, studies have linked 46 chemicals to mammary tumors in animals, according to the National Toxicology Program.

Previous breast-milk biomonitoring studies, performed mostly in Europe, have detected more than 200 toxic substances in breast milk, including dioxins (industrial byproducts), DDT (a pesticide) and PCBs (chemicals used to make an array of products).

Two recent breast-milk biomonitoring studies showed high amounts of flame-retardant chemicals -- called polybrominated diphenyl ethers -- in U.S. women. Those relatively small-scale studies were conducted by the Environmental Working Group, a nonprofit organization, and the University of Texas, Houston.

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