The placenta was once viewed as an impenetrable wall, shielding a growing baby from toxins and pollutants in the environment, and from the mother’s blood. In the last 40 years, a combination of advancing technology and increased research has discredited this idea as nothing more than wishful thinking. Scientists now know that chemical exposures begin in utero and, in the last five to ten years, hundreds of industrial chemicals have been found in the umbilical cord blood of newborn babies of all ethnicities and among all economic levels across the nation. In fact, the more scientists look, the more they find. The question now is not whether children are being exposed in the womb to chemicals and pollutants, many of which are known toxicants, but whether these exposures result in harmful effects.
It’s not only unborn children who may be at risk, but their would-be parents as well. A rapidly expanding body of research indicates that chemical exposures may be linked to a host of reproductive health problems in women, including infertility, miscarriage, abnormal fetal development, endometriosis, and diseases and cancers of reproductive organs. Men are also affected by these exposures: Professor of Maternal and Child Health and Epidemiology Brenda Eskenazi and colleagues found in a recent study that male workers in China exposed to benzene show genetic abnormalities in their sperm, which can result in birth defects or miscarriage of their offspring. Other studies have linked chemical exposures to lowered sperm count and testicular cancer. Taken together, these reproductive and developmental health risks seem to indicate that our current methods of producing and distributing chemicals could be putting the procreation and prosperity of our species in serious jeopardy.
Protecting vulnerable populations from the some 83,000 industrial chemicals currently in use in the United States will take a Herculean effort. For most chemical compounds, including the new ones introduced every day, the health risks—if any—are mostly unknown, in large part because the 1976 Toxic Substances Control Act is outdated and has the government approving new chemicals at an average pace of seven per day with no mandated safety studies.
“We have a lot of chemicals that are currently registered and allowed to be used commercially without sufficient testing,” says Rachel Morello-Frosch, associate professor at the School of Public Health and the Department of Environmental Science Policy and Management. “So we are widely exposed to many substances, and we don’t know the health risks of that. The unspoken assumption is that those chemicals for which we have no information are safe. But we need to remember that ‘no data’ doesn’t mean ‘no problem.’”
Solving this very complex public health problem requires the combined efforts of scientists, chemists, policymakers, lawyers, and the business sector. At UC Berkeley, researchers are taking concurrent steps to effect change, including defining the problem’s scope, linking exposures to health outcomes with a body of rigorous scientific evidence, deciding the most helpful ways to disseminate findings and information to the public, and putting pressure on companies and policymakers to change chemicals policies and transform chemical design.
Blood always tells
An important first step is increasing the reach and efficacy of biomonitoring efforts, and in this arena there has been increased technology and interest, as well as some impressive progress. Biomonitoring—the assessment of exposure by measuring chemicals in biological samples such as human blood, urine, or breast milk—is considered a stronger assessment of exposure than indirect methods, such as measuring chemicals in air or water. It holds the promise of generating particularly useful information for shaping public policy and public health interventions.
Much of the advancement of this work is happening in California, primarily because in 2006 the state established and funded the nation’s first biomonitoring program, known as Biomonitoring California (BC). Morello-Frosch works on a study called Chemicals in our Bodies, in collaboration with BC and the UCSF Program on Reproductive Health and the Environment. The pilot program recruits pregnant women in their third trimester and tests their blood and urine, and the umbilical cord blood of the infants for the presence of chemicals, both in current use and “legacy chemicals” that have been banned and are no longer in use.
As exposure detection methods and technologies improve, biomonitoring could become more accessible and perhaps even commonplace. “The analytical chemistry has gotten better, more logistically feasible, and cheaper, so more people are able to do it,” says Morello-Frosch. “But our ability to detect these chemicals precedes our ability to totally understand what it means for health impacts. That’s going to take a while. But the evidence that’s emerging suggests that we need to start reducing exposures right now.”
Avoid information overload
Part of the challenge of presenting findings from biomonitoring to patients and the public is how to make the message clear without making people too scared, or conversely, too complacent about chemicals in their bodies and what they mean. “There’s a fine line between those two extremes,” says MPH student Julia Varshavsky. “It’s hard, not just for the media, but for researchers and everyone involved to come to a clear consensus. There are always going to be questions, particularly around cumulative impacts.”
Before coming to the School, Varshavsky worked with the Collaborative on Health and the Environment, a large organizational network designed to raise public and professional dialogue around the issue of environmental contaminants and human health. She is currently working with Morello-Frosch, the Silent Spring Institute, and researchers from Brown University on the most effective ways to report biomonitoring results back to people.
“There are major ethical questions regarding people finding out they have high levels of certain chemicals in their bodies when there’s no clear evidence of what the health implications of those levels will be,” says Varshavsky. “We continue to debate how much information is too much versus our right to know what is in our bodies. We believe there is a responsible way to report these results, but there are currently no clear best practices on how to do this.”
For guidance, Varshavsky has looked to the fields of medical imaging and genetic testing, which are experiencing similar dilemmas. These are areas where technology is also surpassing society’s ability to interpret results. She has found that while opinions differ on how much information should be shared, there is a consensus that more formal, standardized, and explicit methods need to be developed.
“Some people think more information is better and it will mobilize people to demand change,” she says. “Others say it will scare people too much or desensitize them to the situation. But everyone agrees that while no one has figured this out yet, we need to figure it out soon.”
Know thy enemy
Biomonitoring can tell us a lot about what chemicals are present and most pervasive in human bodies, but it takes more research to uncover the links between exposures and health risks. For that body of evidence, which is so crucial for policy reform, steadfast scientists like Eskenazi are indispensable. For more than 10 years, Eskenazi has been directing the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) cohort study, which follows a group of 536 children born to women in the agricultural community of the Salinas Valley. Bio-samples have been collected from the children at certain ages, and the children have been examined to assess their growth, neurodevelopment, respiratory disease rates, and general health.
“In this study, we’re primarily focused on environmental chemicals that occur in agriculture, but it’s not limited to those chemicals,” says Eskenazi. “For example, we also monitor flame retardants in addition to current use pesticides. Because of California’s unique flammability standards, the children in the CHAMACOS study—and likely California children in general—have some of the highest levels of exposure in the world to a class of chemicals that are well-known endocrine disruptors.”
Eskenazi’s group also monitors bisphenol A (BPA)—a high volume chemical found in baby bottles, sippy cups, the lining of food and beverage containers, and many other products—which has come under scrutiny because it leaches out of materials and is linked to certain cancers and a number of reproductive problems. They also track levels of dichloro diphenyl trichloroethane or DDT, even though this insecticide was banned in 1972 due to its toxic effects in ecosystems. The reason for this is twofold: Many Salinas Valley residents are immigrants from Mexico, where DDT was used to control malaria-bearing mosquitoes until 2000. Consequently there are fairly high levels of DDT in the mothers’ bodies that gets passed on to the children in utero and through breast feeding. As well, almost everyone in the United States has measurable levels of DDE, a breakdown product of DDT, in their bodies due to the long half-life of the compound in the environment and in biological tissues. “DDT is a chemical that has even been picked up in Antarctica,” says Eskenazi. “It’s everywhere, and the persistence is very long.”
The variety of health impacts that Eskenazi’s study has linked to chemical exposures is astounding. “We have shown that some exposures are associated with infertility, thyroid hormone in the mother, development of the children, and we are studying whether they may be related to childhood obesity,” she says. “Because of the fact that many of these chemicals disrupt the endocrine system, there might be an obesogen that’s raising the rates of childhood obesity.”
Several organophosphates were banned from home use in 2001, but they are still widespread in commercial agriculture. The CHAMACOS study has shown that exposure to these chemicals is associated with fetal and child development. Higher levels of a metabolite of organophosphates in the mothers’ urine were linked to shorter lengths of gestation, potentially impacting the health of infants born too early. Eskenazi says, “We’ve shown an association with the mother’s exposure during pregnancy and the child’s mental development at age two, and we’ve shown associations with ADHD at age five.”
And the latest findings are perhaps the most compelling. Now that the children in the study are age seven, neurodevelopment assessment is more reliable, and Eskenazi and her research team have found a consistent association between the mother’s exposure to organo-phosphates during pregnancy and the child’s IQ. Not only that, but in the same issue of Environmental Health Perspectives in which their findings were published in April 2011, there were two other studies—one from Columbia University and one from Mount Sinai Medical Center—showing a similar association.
“In epidemiology, when you see one paper that says something, you say ‘Hmm, that’s interesting,” says Eskenazi. “But when you see three that all come out and show associations with childhood IQ at age seven, you begin to feel that maybe this is real.”
Eskenazi believes there are decisions people can make and things they can do to protect themselves without compromising nutrition. “What I absolutely don’t want to happen as a result of our research is that women decide to stop eating fruits and vegetables because they’re concerned about pesticide residues on their food,” she says. “Always my last comment is, ‘Eat your fruits and vegetables—just wash them really well.’ From a public health standpoint, that’s really important.”
Agents of change
Varshavsky sees progress on the horizon, in terms of creating a less toxic environment for people to be born into. “There’s a huge push to do two things in the field—one is to reform our chemicals policies and the other is to push for green chemistry initiatives,” she says.
Michael P. Wilson PhD ’03, MPH ’98, associate director of integrated sciences at the UC Berkeley Center for Green Chemistry (BCGC) and the incoming director of the School’s Labor Occupational Health Program, is an instrumental player in both of these key movements. He is working to transform chemistry curriculum in the country—beginning at UC Berkeley— so that the next generations of chemists will be trained in toxicology, ecotoxicology, exposure, policy, law, and ethics, and will have the insight—and motivation—to create chemicals that are “benign by design.”
“It’s so clear that it’s no longer possible for us to clean up chemical pollution and exposures at the ‘end of the pipe,’ in workplaces and in products and in hundreds of thousands of hazardous waste sites,” says Wilson. “We have to design safer chemicals from the start.”
In Fall 2010, with funding from the State of California, green chemistry became an official part of UC Berkeley’s chemistry curriculum, with principles of sustainability, toxicity, and environmental impact being introduced to 1,350 students in Chemistry 1A labs. BCGC has received another grant from the California Department of Toxic Substances Control to design and add new labs for Chemistry 4A and 4B—introductory chemistry for science majors—and to develop several new graduate-level green chemistry courses.
“Green chemistry is already being taken up by some in the industry because it’s cheaper, you don’t have as much waste, you use less energy, and you’re making products that are safer,” said Marty Mulvihill, executive director of BCGC, who earned a doctoral degree in chemistry from UC Berkeley in 2009. “It just needs to be taken up by the entire industry in a transparent way that gives businesses and consumers the information they need to make choices.”
Wilson is also a driving force behind chemicals policy reform, especially in the state of California. He was the lead author of a 2006 chemicals policy report that inspired two new bills in California that were passed into law in 2008 by Governor Arnold Schwarzenegger: AB 1879 (Feuer, D-LA), the nation’s first effort by a state to craft a comprehensive approach to identifying, prioritizing, and taking action on hazardous products; and SB 509 (Simitian, D-Palo Alto), which created the Toxics Information Clearinghouse to give consumers, businesses, and workers better information about the health and environmental effects of chemicals. Senator Simitian said, “Well, all of this really got started with the report from UC Berkeley. What makes UC Berkeley’s role so critical is that this debate can quickly become all too political. What is the good science? What are the facts? Let’s start the conversation there.”
In February 2011, Wilson testified before two California legislative oversight hearings convened by the Assembly Committee on Environmental Safety and Toxic Materials and the Assembly Committee on Health. Calling attention to such problems as the proliferation of hazardous waste sites, the cost of cleanup, and the hazards children face from household cleaning products, Wilson concluded with an impassioned call for the Legislature to look towards the future.
“Mr. Chairman and members,” he said, “to be clear, these are not theoretical risks, and future generations will judge our actions accordingly. Much is at stake, and as the nation’s most populous and innovative state, and with global chemical production growing at a rate four times faster than global population, we have a responsibility, and now an opportunity, to do the very best we can.”