Testing people for pollutants
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.
Health activists in communities with known environmental hazards have long sought to draw attention to the potential risks of living in such areas, says Cynthia Babich, a longtime environmental activist. She once lived near the federally designated Del Amo Toxic Waste Site in Torrance, a Superfund site contaminated with DDT, a cancer-causing chemical that is now banned in the U.S. Her house and others were razed several years ago in order to clean up the contamination.
While biomonitoring may turn up bad news, the information is important to safeguard the community, says Babich, who is helping to coordinate the EPA study in Torrance. The idea that even the very youngest members of the neighborhood -- newborns -- could be affected by environmental contamination might make people sit up and take notice.
“I think it’s important for science to understand what our body burdens are,” she says. “People act like it doesn’t matter that we have DDT in our blood. Maybe breast-milk biomonitoring will be something that will make people pay attention.”
Scientists caution that biomonitoring can only contribute preliminary information about cancer and toxic exposure. While biomonitoring almost always yields evidence of some chemical exposure, what that exposure means to human health may require years of study.
“If a chemical accumulates in breast fat and it is a carcinogen, I would want to look at it very closely. But we have to be careful. We can’t assume everything in breast milk is related to breast cancer,” says Dr. Gina Solomon, a senior scientist at the Natural Resources Defense Council, an environmental group that sponsors a Web site to promote both breast-feeding and biomonitoring.
And, says Patricia Buffler, an epidemiologist at the UC Berkeley School of Public Health, the principal investigator of last year’s conference: “The theory is that breast milk is better than other bodily fluids in telling the story of environmental exposure because chemicals are stored in fatty tissue. But we don’t know if that is true.”
The purpose of the proposed state biomonitoring legislation is not to uncover a smoking gun, backers say. Instead, the program, which would include collecting blood and urine samples, would attempt to point out trends in chemical exposures, identify disproportionately affected communities, link exposures to disease, assess the effectiveness of current regulations and set priorities for research and legislation.
The bill, SB 689, proposing this two-year program, was introduced by Sen. Deborah Ortiz (D-Sacramento) and passed a Senate committee before stalling. The bill will be reviewed in January.
The bill has garnered widespread -- although not unanimous -- support.
Like any research involving donated biological samples, unethical or sloppy research could result in the misuse of that information. For example, detection of a particular pollutant that causes cancer, at least theoretically, could be used by health insurers to deny coverage or for other forms of discrimination, says James Hodge, deputy director of the Center for Law and the Public’s Health at Johns Hopkins Bloomberg School of Public Health in Baltimore. If individuals in a community were found to be carrying high levels of a harmful substance, entire communities could be branded with that information.
“This is a new type of health surveillance involving sensitive health data,” Hodge says. “Any time we’re testing any individual through any bodily sample, there are privacy concerns at the core.”
However, much like the EPA-funded study already underway, a state program would be voluntary. Individual results would be confidential and study subjects would be counseled about the findings -- a way to address fears over privacy invasion and misuse of the data, proponents say.
The $150,000 EPA study was funded in part to demonstrate how researchers can conduct biomonitoring in a particular community without alienating its residents, Hooper says. The major scientific goal of that study is to look for evidence of flame-retardant chemicals in breast milk.
But information gleaned from breast-milk biomonitoring may undermine a different health objective. Several health groups say they fear biomonitoring will frighten women from nursing their infants.
Leaders of La Leche League, an international breast-feeding education organization, view breast-milk biomonitoring with trepidation.
“Yes, we have to clean up the environment, but don’t use breast milk as the call to arms. It will get attention but it will have a very negative effect,” says Marian Tompson, one of the organization’s founders. “I know well-educated women who have been scared away from breast-feeding because they have read about contaminants in breast milk.”
Traditionally, American women have been far less likely to breast-feed compared with other cultures, despite the many health and economic advantages associated with nursing. However, researchers reported in December that 69.5% of mothers now breast-feed in the early postpartum period -- the highest levels in at least half a century in this country -- and rates are rising by 2% per year.
Barbara Brenner, executive director of Breast Cancer Action, a San Francisco-based breast-cancer advocacy organization, says her group withdrew its support for the biomonitoring legislation after becoming concerned about the potential impact of the studies on breast-feeding.
“We were hearing increasingly from people working with new mothers about the challenges, particularly in the United States, with getting people to breast-feed at all,” Brenner says. “We are concerned that an emphasis on breast-milk biomonitoring is going to make that problem worse, not better.”
Dozens of studies point to the benefits of breast-feeding. For babies, breast-feeding has been linked to enhanced immunity; resistance to infection and allergies; a lowered risk of obesity, diabetes and several childhood diseases, and higher intelligence.
Breast-feeding appears to be good for mothers too. Studies show that breast-feeding for one year or longer can reduce the risk of breast cancer.
Biomonitoring proponents say the studies can be accomplished without affecting breast-feeding rates. For example, the state Senate bill would include funding for public education to explain that breast-feeding -- even with contaminated milk -- is still the best choice for infant nutrition.
It’s even possible that the nutritious components in human breast milk help protect a baby from exposure to pollutants. Any substances in a mother’s body is likely be transferred to a fetus via the bloodstream, experts say. Breast-feeding, though it can transfer toxic substances, is considered such an ideal food for babies that it may help fight cell damage caused by in utero chemical exposure.
“The little we do know is it looks like any damage [from pollutants] happens to the fetus in utero and breast-feeding tends to reverse that damage,” Hooper says.
Rizzo, of the Breast Cancer Fund, notes that biomonitoring has not caused a decline in breast-feeding in Sweden. Yet the discovery of toxic flame-retardant chemicals in breast milk led to a swift ban on the chemicals in that nation.
“They said: You know what? Flame retardants shouldn’t be in breast milk -- whether there is a link to breast cancer or not,” Rizzo says. “When breast milk talks, people listen.”
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Monitoring breast milk
Testing breast milk can detect chemicals that accumulate in the body. These substances are released when a new mother nurses, providing a snapshot of chemical exposures over time. Some of these chemicals include:
* Dioxins: These industrial byproducts have been linked to cancer as well as reproductive problems and the disruption of hormones.
* Organochlorine pesticides: These chemicals, used on crops, are sometimes called endocrine-disruptors because they mimic the female hormone estradiol, causing breast cells to proliferate.
* Polybrominated diphenyl ethers: This class of widely used flame retardants has only recently been recognized as potentially harmful to infant brain development.
* Polychlorinated biphenyls: PCBs are banned but remain in the environment. They were used to make adhesives, paints, lubricants, coolants and many other products. High levels of exposure have been linked to problems in infants, such as low birth weight.