Study: City or Country; PCBs are Everywhere...

Photo: freedigitalphotos.net

Since polychlorinated biphenyls (PCBs) are produced through industrial processes or activities, it is assumed that people living in industrial cities will have higher concentrations of these toxic chemicals in their blood than people in rural communities.

Researchers at the University of Iowa say this isn’t the case. In a paper published in March in the journal Environmental Science & Technology, scientists report that mothers and children in East Chicago, Ind., and Columbus Junction, Iowa, had only subtle differences in their PCB blood levels. This analytical paper is the first to report such a comparison between two communities, between mothers and children, and including all 209 PCB compounds.

“This is not good news, and it certainly applies to all of us,” says Keri Hornbuckle, professor of civil and environmental engineering in the UI College of Engineering and senior author on the paper. “I thought it would be worse in a very industrial city than in a rural community. Our results really shook us up. We all have PCBs in our blood, and they are coming from somewhere. We don’t make them in our bodies.”

Study subjects from Indiana live in a highly industrialized community of 32,400 people that is bisected by the Indiana Harbor and Ship Canal on the southern shore of Lake Michigan. In contrast, Columbus Junction is a rural community of 1,899 with no known current or historical PCB sources.

Serum samples were collected from junior high school-aged students and their mothers who were enrolled in the Airborne Exposures to Semivolatile Organic Pollutants (AESOP) study between April 2008 and January 2009. The AESOP study is directed by Peter Thorne, professor of occupational and environmental health in the UI College of Public Health and a project leader in the Iowa Superfund Research Program.

The serum analyzed was gathered from 41 mothers and their 44 children in East Chicago, and from 44 mothers and their 48 children in Columbus Junction. Researchers found a greater variety of PCBs in the blood of mothers and children in East Chicago. Despite the expectation of a large environmental exposure difference, East Chicago and Columbus Junction participants had similar concentrations of PCBs in their blood.

“We’re looking for evidence of inhalation exposure. There are clearly big stores of PCBs in the environment,” says Rachel Marek, doctoral student in civil and environmental engineering and first author on the paper. “How can we reduce of the overall level of PCBs in the environment and therefore reduce exposure to PCBs? We need to be able to identify those sources and clean them up.”

PCBs can enter the human body by eating or drinking contaminated food, through the air we breathe, or by skin contact. Hornbuckle, however, doesn’t know why participants in East Chicago and Columbus Junction have similar PCB concentrations in their blood.

“What is probably going on is that these two communities eat similar things, because their demographics are similar, and they breathe similar air with respect to the total amount of PCBs in the air,” says Hornbuckle, a project leader in the Iowa Superfund Research Program who analyzes PCBs in blood and air.

Ninety-two individual PCB compounds were detected in the samples. Researchers report the detection of PCB 11 and PCB 83, which, to their knowledge, have not been found previously in human blood.

The researchers detected the neurotoxic PCB 11 in more than 60 percent of participants—more East Chicago mothers than Columbus Junction mothers. This finding helps verify that the environment is a significant source of PCB exposure. In particular, recent studies found that PCB 11 has been an inadvertent byproduct of paint production. The compound has been found in the air and in a wide variety of organic paint pigments from multiple manufacturers.

“PCBs are everywhere and they are really high in building materials, especially for homes that were built between 1950 and 1970. Both communities have similar housing materials,” Hornbuckle says. “We also found that PCBs are in modern household paint, so it doesn’t matter if you live in East Chicago or Columbus Junction.”

According to the Environmental Protection Agency, PCBs have been shown to cause cancer, along with a variety of other adverse effects on the body’s immune, reproductive, nervous, and endocrine systems. For more information, visit www.epa.gov/osw/hazard/tsd/pcbs/pubs/effects.htm.

“These chemicals are known to be toxic to humans, and they are known to be toxic for developing humans, so we want them out,” Hornbuckle says. “We don’t want them in our paint. We don’t want them in our indoor air. That’s why there are fish consumption advisories on all the Great Lakes, because we don’t want them in our food.”

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Women 16-49 at Risk from Multiple Pollutants, Which Could Harm Brain Development of Fetuses and Babies

Nearly 23 percent of American women of childbearing age met or exceeded the median blood levels for all three environmental chemical pollutants — lead, mercury, and PCBs — tracked in an analysis of data on thousands of women by Brown University researchers.

All but 17.3 percent of the women aged 16 to 49 were at or above the median blood level for one or more of these chemicals, which are passed to fetuses through the placenta and to babies through breast milk.

The study, published in the journal Environmental Research, identified several risk factors associated with a higher “body burden” for two or more of these chemicals.

The three pollutants are of greatest interest because they are pervasive and persistent in the environment and can harm fetal and infant brain development, albeit in different ways, said study lead author Dr. Marcella Thompson. But scientists don’t yet know much about whether co-exposure to these three chemicals is more harmful than exposure to each chemical alone. Most researchers study the health effects of exposure to an individual chemical, not two or three together.

“Our research documents the prevalence of women who are exposed to all three of these chemicals,” said Thompson, who began the analysis as a doctoral student at the University of Rhode Island College of Nursing and has continued the research as a postdoctoral research associate for Brown University’s Superfund Research Program with co-author Kim Boekelheide, professor of pathology and laboratory medicine. “It points out clearly the need to look at health outcomes for multiple environmental chemical co-exposures.”

Most of the childbearing-age women — 55.8 percent — exceeded the median for two or more of the three pollutants.

Risks of exposure

Data were collected between 1999 and 2004 from 3,173 women aged 16 to 49 who participated in the Centers for Disease Control and Prevention National Health and Nutrition Examination Survey (NHANES). The survey was designed to represent the national population of 134.5 million women of childbearing age. Because the original study also elicited a wide variety of information on health behaviors, socioeconomic and demographic characteristics, Thompson and Boekelheide were able to identify specific risk factors associated with increased odds of having higher blood levels of lead, mercury, and PCBs.


“We carry a history of our environmental exposures throughout our lives.” Credit: David Orenstein/Brown UniversityThey found several statistically significant risk factors. The most prominent among them was age. As women grew older, their risk of exceeding the median blood level in two or more of these pollutants grew exponentially to the point where women aged 30 to 39 had 12 times greater risk and women aged 40 to 49 had a risk 30 times greater than those women aged 16 to 19.

Thompson said women aged 40 to 49 would be at greatest risk not only because these chemicals accumulate in the body over time, but also because these women were born in the 1950s and 1960s before most environmental protection laws were enacted.

Fish and heavy alcohol consumption also raised the risk of having higher blood levels. Women who ate fish more than once a week during the prior 30 days had 4.5 times the risk of exceeding the median in two or more of these pollutants. Women who drank heavily had a milder but still substantially elevated risk.

Fish, especially top predators like swordfish and albacore tuna, are known to accumulate high levels of mercury and PCBs, Thompson said. However, there is no known reason why they found a statistically higher association between heavy drinking and a higher body burden of pollutants.

One risk factor significantly reduced a woman’s risk of having elevated blood levels of the pollutants, but it was not good news: breastfeeding. Women who had breastfed at least one child for at least a month sometime in their lives had about half the risk of exceeding the median blood level for two or more pollutants. In other words, Thompson said, women pass the pollutants that have accumulated in their bodies to their nursing infants.

Although the study did not measure whether women with higher levels of co-exposure or their children suffered ill health effects, Thompson said, the data still suggest that women should learn about their risks of co-exposure to these chemicals well before they become pregnant. A woman who plans to become pregnant in her 30s or 40s, for example, will have a high relative risk of having higher blood levels of lead, PCBs, and mercury.