In the 1960s and '70s, researchers and policymakers began to sort out the effects that air pollution and chemical waste have on human health. Although laws and industry regulations have improved much of our surroundings since then, significant environmental threats to health still exist. The definition of environment has expanded to include how people behave in certain settings and at certain ages. Long-term studies have also increased our understanding of how environmental risks affect individual and public health over time.

• A recent study reports that changes in lead levels in men's semen can account for up to a fifth of the variation in the men's fertility rates. [1]
• In 1995, the EPA estimated that each year, passive smoking causes between 150,000 and 300,000 lower respiratory tract infections in infants and children younger than 18 months old, resulting in between 7,500 and 15,000 hospitalizations each year. [2]
• Nearly 1 million children in the United States have lead levels in their blood high enough to cause irreversible damage to their health. Most of these children live in inner cities, where auto exhaust and lead paint from older buildings are the most common sources of contamination. [3]


• Population-based studies of children in the United States show that more than 90 percent of children have detectable residues of at least one neurotoxic pesticide in their urine. [4]
• A telephone survey five weeks after the September 11 attacks on the World Trade Center in lower Manhattan found that among the 13 percent of respondents with asthma, 27 percent reported experiencing more severe asthma symptoms after September 11. Stress, smoke and airborne debris are thought to be the main culprits. [5]
• A study of 500,000 adults in U.S. cities found that the number of deaths from lung cancer increases by 8 percent for every 10 micrograms of fine particulate matter, like soot, per cubic meter of air. [6]
• A 1997 study reported that 1 percent to 3 percent of women between ages 15 to 44 - classified as "childbearing age" - eat sufficient amounts of fish to be at risk for fetal methylmercury exposure. High-risk fish include swordfish, shark, fresh tuna and tilefish. [7]
• In December 2002, the National Toxicology Program added 15 new substances to a list of known human carcinogens, bringing the total to 228. Among the new cancer-causing agents are estrogen, wood dust and several types of ultraviolet radiation. [8]
• Extreme weather can cause acute health problems, particularly among vulnerable groups such as children and older people. In July 1995, a prolonged heat wave caused more than 500 deaths in Chicago. [9]
• In 1993, approximately 22 percent of children lived in an area served by a public water system that had at least one major drinking water contaminant violation. That percentage dropped to approximately 10 percent in 1999. [10]

The ABCs of PCBs: Toxic Chemical Compounds Appear Everywhere with David O. Carpenter, M.D.

David O. Carpenter, M.D., is director of the Institute for Health and the Environment at the University of Albany, where he is also professor of environmental health and toxicology and former dean of the School of Public Health. His research has focused on basic problems in neurobiology and neurotoxicology, and he has long been involved in studies of human populations exposed to polychlorinated biphenyls, better known as PCBs.

Q. Describe some of the major human health effects associated with PCB exposure.

A. PCBs do so many things. It's getting to be a long list these days. They cause developmental problems. A lot of my work focuses on some of the detrimental effects PCBs have on IQ. PCBs cause many of the same kinds of problems that exposure to lead does. We see children with ADHD, shorter attention spans and more disruptive school behavior. PCBs are carcinogenic, and the resulting cancers are seen primarily in adults. They interfere with the normal operations of the hormonal system. This has been best documented in the thyroid gland. They can alter the sex hormones in a complex fashion. PCBs are really a mixture of different chemicals, and some mimic the female hormone estrogen, while others actually antagonize estrogen.

Then there is a building body of evidence, not as strong as the things we've talked about already, that heart disease and diabetes are linked to PCB exposure. Most of what we know about that comes from studies of dioxins, which have some of the same chemicals as PCBs and may have the same effects. But PCBs tend to be present in the environment in greater amounts.

There is also evidence that PCBs may suppress the immune system, so that you might get colds more easily, for instance. People may not even think about the link between exposure and these kinds of complaints.

Q. Is there a "toxic" level of exposure to PCBs, or a threshold amount at which health is affected?

A. I interpret the evidence to suggest that there is not a threshold effect. If it's not normally present in the body, it's not doing anything that's good for you. There may be different levels at which different people get blatant disease, but PCBs do not do anything but harm.

Q. What kinds of environments or behaviors bring people in contact with PCBs?

A. They are everywhere. We are all exposed and can't help being exposed. You can't eat a Big Mac without getting some. They're found in all animal fat in the food chain, in butter and fish and chicken and meats. Probably the biggest individual source of PCBs is fish from contaminated waters.

There are also people who live near waste sites that are highly contaminated. They get exposed through breathing, by having contaminated dust that gets into their food and their body. It's more difficult to do anything about this exposure.

Q. What other factors contribute to the health effects of PCBs?

A. A big part of PCB studies right now is genetic susceptibility. Clearly, people are not all genetically alike. Some smokers will get lung cancer, and some won't, and this probably reflects some genetic trait that makes them more vulnerable. It isn't the genetics that cause the disease, but the genetics in conjunction with exposure is the problem. We are all exposed to PCBs and probably have different health effects on the basis of genetic factors.

Q. Children seem to be especially vulnerable to chemical toxins, but is there evidence that lifetime accumulation of PCBs and other chemicals also affects health?

A. The studies that I mentioned about heart disease and diabetes may be one indication that adults are vulnerable to lifetime exposure. There is clear evidence in adults that chemical toxins can affect learning and memory. In one study, it was possible for investigators to show that after eating contaminated fish, adults' learning and memory functions didn't work the way they used to. The effects on children are probably the same.

Q. Are diseases caused by PCBs and other toxic chemicals reversible or treatable in any way?

A. It's a real problem. There is a fair bit of evidence that their effects on the brain and behavior are not reversible. It's a tragedy that some people who are exposed during development are going to have a reduced ability to be productive in the way that you want them to be throughout their lives.

Q.Are chemical health hazards in the United States increasing, decreasing or holding steady?

A. The period of greatest contamination in our environment was the 1960s, and the levels of contamination have gone down much since then. But in some cases these levels are at a plateau. This is particularly true of PCBs. For instance, PCB levels in fish in the Great Lakes have been pretty much stable since we stopped dumping chemicals in the water. Industries are not putting in more, but they are not disappearing either. If PCBs are buried deeply, like in lake sediment, they're probably never going to go away. When they are nearer to the surface, bacteria can change them in certain ways to make them more water soluble and volatile. They can go into the air where sunlight can destroy them. But they can also migrate to other areas once they are in the air.

Q. How does the United States rank in terms of environmental chemical health threats compared to other countries?

A. We do better than other countries in general, but we've got a long way to go. The problem is that we have so many contaminated bodies of water and hazardous waste sites, but we don't really know how to get rid of them. In the Hudson River, for instance, there is an ongoing dredging project [to remove PCB contaminated sediments]. Dredging is a good thing, but no one knows what to do with these sediments when we get them out. There is no cost-effective way of getting rid of them now that won't hurt someone later when they dig up a foundation for their house and find the reburied sediments.

Q. What is the state of the science regarding environmental chemical health threats?

A. The science of understanding the hazards of these compounds is very, very good. The science of understanding how to clean them up has a long way to go. While the levels of these chemicals in our environment have been going down since the 1960s and 1970s, our knowledge of how dangerous these chemicals are has been going up faster than the levels have been going down. We appreciate today that the problem is much larger than we thought. No one had any idea how many diseases were caused by exposure to these compounds.

Q. Can individuals change their behaviors to protect themselves from these types of environmental hazards?

A. There are many things that individuals can do. Almost every state issues advisories on contaminated fish, such as, "Don't eat fish from the Hudson River," and many times people are totally unaware of these advisories. We have problems because people don't read the information that comes with their fishing licenses. But also our government doesn't always do a very good job of letting people know that diseases can result from exposure.

There is a background level of these chemicals that people can't do much about at all, besides reduce their intake of fatty animal products. And I'm not an advocate of becoming a vegetarian to avoid PCBs because then there are the pesticides in your broccoli.

Q. What kinds of larger policy changes could help protect individuals?

A. I am working on a National Academy of Sciences panel on this question, and we do have some idea of what steps might be taken. The United States produces 10 billion pounds of waste animal fats each year, and almost all of it is fed back to other animals. We don't feed cow fat back to other cows now because of mad cow disease, but we feed it to pigs, to chickens, to fish. We sort of just recycle this stuff into our food supply, and we hope that we can break this cycle to some degree to reduce the amount of contaminants we eat.

Q. You host an environmental health segment on public radio. What are some of your audience's responses to stories about environmental health threats?

A. We get a lot of mixed feedback. There is a segment of society that is very concerned about this, that is anxious to reduce their exposure. There is a lot of hostile response from people in industry, people who argue that we're negatively affecting the economy by trying to protect human health. And there is a large section of the population that doesn't want to know or doesn't care.

Americans can be confused by the messages [on environmental health] and end up thinking that everything can hurt them. We need to get good information into women's magazines and kids' magazines, into the sources of information that reach the mainstream of society.

Close to the Ground: Unique Environmental Risks for Children with Marie Lynn Miranda, Ph.D.

Marie Lynn Miranda, Ph.D., holds the Gable Chair in Environmental Ethics and Sustainable Environmental Management at the Nicholas School of the Environment at Duke University. She also directs the Children's Environmental Health Initiative at Duke. Her research focuses on using state of the art understanding of the natural sciences to build better social science models and analysis.

Q/ What factors put children at greater risk of toxic environmental exposures?

A/ People talk all the time about the fact that children are not little adults, and that we have to think about them differently. There are three things that I think put children at greater risk. The first is behavior. Children are short, they spend a lot more time closer to the ground, and if you think about where you spray pesticides, for example, it's down by the baseboards. Children spend a lot of time outdoors, and they don't always wash their hands as carefully as adults. Young children also are more likely to put their hands in their mouths. These types of behaviors are more likely to lead to exposure.

Children also breathe more air, eat more food and drink more water per unit of body weight than adults. Their respiratory systems and gastrointestinal tracts are kicked into higher gear, so their uptake of contaminants tends to be greater. If I fed a pellet of lead to you and to a 19-month old, the 19-month old would take up five times as much lead into her system.

Because of their developmental status, children are also more likely to express the toxic effects of exposure. Their respiratory systems are not fully mature until they are 7 to 9 years old. Their reproductive systems, neurological systems and immune systems are not fully mature, and that means that they are more likely to show effects than adults.

Q/ Some of your research involves a technique called geographic information systems, or GIS. What is GIS?

A/ The basic idea behind GIS is that for every piece of data you collect, you attach a spatial location to it. The location can be as specific as an individual house or as general as a state or county. You then use these attached geographic locations to form the backbone of the analysis. So you can see a spatial relationship between who is getting lead poisoning and who is living in certain old houses, who is getting asthma and where they live relative to bus routes and heavy traffic corridors. You can imagine all sorts of questions where the sources of exposure and the effects of exposure could be related.

Q/ What sort of power does this bring to research on environmental health risks?

A/ It helps you to make a better case for relationships that people might have thought were plausible to start off with, and it also helps you see relationships that may not have been as obvious. One of the other things that is very powerful about this approach is that you can do very sophisticated analyses and present them in ways that are immediately accessible to the public. You can present results that are meaningful to people even if they don't know anything about statistics or GIS. It's like that old adage that a picture is worth a thousand words.

Q/ At what scale - the household level, the community, the state - do researchers tend to use GIS?

A/ Many of the GIS applications in public health are done at the census tract or block group level, but there are groups of us trying to push the analysis toward finer geographic resolution. I think that is where the field is going. There is the caveat that for some problems, going down to the household level doesn't get you any new information. But if you want to know about lead exposure, pesticide exposure, then going down to the household level would help.

Q/ Where are there gaps in the kind of data that you would need to do GIS analysis?

A/ The data are a little bit weaker on exposures associated with small manufacturing facilities. We have lots of federal rules and regulations that track large manufacturing facilities, but for smaller facilities, like dry cleaners for instance, they're not required to report to the federal government. I was at a conference in New York City where a speaker mentioned that in one square mile of Manhattan, there were more than 500 dry cleaners! From an exposures perspective, that would be something you would want to know. We're trying to develop methods where we can attribute emissions from smaller facilities using data that already exists. If we're successful, I think that will help a lot.

Q/ Do you see GIS studies as a tool that can "prove" why certain children are sick, or as a preventive tool that can assess where the risks are and what action is necessary?

A/ For me, that's the whole point of doing this analysis. We need to switch from approaches that mitigate the problems to approaches that prevent them.

Right now, we wait for kids to get sick and then we go to their homes, their schools, their day care centers and try to figure out what's going on there. We wait for them to get elevated blood levels or get asthmatic.

What we're trying to do at Children's Environmental Health Initiative is determine where children are likely to have adverse exposures and then help community and local groups clean up these problems where they are likely to occur, before they make children sick.

For instance, one of our studies calculated the risk of lead exposure associated with each house in a particular community, which the local health department and community groups could then use as a basis for targeted intervention programs. Prior to this, Durham County had determined that the prevalence rate for harmful lead exposure [10 micrograms per deciliter of blood] was 1.1 percent.

Now, when they screened homes based on our model where we indicated a high risk of lead exposure, the prevalence rate was 6 percent.

At the same time, the Department of Housing used our model to determine priorities for rehabilitating certain homes with funds that they have from a HUD grant. This is leading to different outcomes for kids, which we think is just great.

Q/ Part of CEHI's mission involves environmental justice. Explain what you mean by environmental justice in this case.

A/ It means that we focus our efforts on environmental problems that are more pressing for low-income and minority communities, subpopulations that bear a disproportionate risk to contaminant exposure.

Typically people think of environmental health just in terms of where hazardous waste facilities are located or where there's pollution, which are very important and we pay a lot of attention to these issues.

But we also look at whether there is good infrastructure in the neighborhood, sidewalks for children to walk on, green spaces, community spaces like pools and parks and soccer fields.

These aren't risky exposures like lead, but they are environmental assets in the community that may influence outcomes for children. Low-income and minority groups are likely not to have these things.

Q/ Have your studies been used in legal briefs or other legal action?

A/ I personally have not been involved in legal cases or testimony, but I know there is some interest among groups in using our studies for legal proceedings.

Q/ What kind of response has your research received in the communities that you study?

A/ We do a lot of outreach, but we do it in partnership with community groups, which I think is very important. It's not just Duke coming into a community; it's tapping into the network and expertise that's already active in the community. And as a consequence, I think that it gets people motivated to change things in the community.

If I just went out and did outreach myself directly in the community, there's some possibility that the information wouldn't improve people's lives, because the information could be upsetting. I think it's only empowering if there is access to the right resources to change things. By choosing to partner with community groups, that outreach and education makes it possible to tap into a resource base. Instead of feeling helpless and overwhelmed, people feel energized and motivated.

We need help from people who have expertise in community organizing, and we need to be smart enough to know what we don't know. We have had the benefit of working with some amazing people.

Q/ What steps would you suggest individuals take to avoid environmental health risks?

A/ You can certainly change cleaning techniques around the house to adjust for lead and asthma risks. You can make sure kids do careful hand washing.

To the extent that you can afford it, you can make sure that your children are getting good nutrition, since if they are deficient in certain nutrients like calcium or in overall calories, they will be more likely to take in contaminants at toxic effects.

There are some things we can do at an individual level, but beyond that, we have to have a society-level commitment to making better environments for children. That's one of the reasons we're so committed to working with community and public health groups. We have to decide that it's not OK for children to grow up exposed to these risks.

Environmental health isn't all clean air and chemicals: Loud and repetitive noises can take a toll on health too. In fact, the World Health Organization has upgraded noise pollution from a nuisance to a serious hazard.

According to the WHO, prolonged or excessive noise exposure has been linked to high blood pressure, heart disease, concentration problems and, of course, hearing loss. Industrial workers face the most serious noise pollution, but frequent concertgoers and people who live in neighborhoods near highways and airports also experience noise risks.

The average environmental noise is 70 decibels, about as loud as the conversational hum of a noisy restaurant.

In 1990, about 30 million Americans worked in environments where the average noise level was 85 decibels, or as loud as a busy city street. [13]

Howard Frumkin asked the 200 people at a recent NIH conference to raise a hand if they had walked to school as a child. Most people's hands went up. He then asked how many had children who walked to school. The crowd of waving arms dwindled down to a tentative few.

Those lost walks represent more than just a passing way of life. The same factors that keep children from walking to school are creating dangerous roads, polluted skies, overweight citizens and maybe even unfriendly neighborhoods, the Emory researcher cautioned his audience.

Frumkin studies the health effects of the "built" environment, which includes everything from the chemicals in carpet fibers to the layout of suburban streets and urban crosswalks and the view from an office park window. All of these elements may be contributing to poor health, especially chronic conditions like asthma and obesity, he says.

For instance, many suburban communities are designed to encourage driving at the expense of walking, leading to increased pollution and safety problems. Homes in these neighborhoods are walled off from one another and accessible only from a major highway. Schools, stores and workplaces are located away from the homes, beyond walking distance and connected only by that same highway.

"Physical activity, and really the human dimension, seems to be an afterthought. And not only that, these places are ugly, they lack a sense of place," Frumkin says.

Such "unspeakable acts of civil engineering" create traffic jams and rush hour peaks in ozone levels, and discourage people from exercising and socializing with neighbors as part of their daily routine, he notes.

Things are not much better in cities, according to Frumkin. Although residential, office and recreational spaces tend to mingle in urban areas, "many of these ideal areas are abandoned as investment moves from the central city. It's all part of the sprawl story," he says.

On the bright side, newly built communities that encourage physical activity and civic beauty are in high demand on the real estate market, proving that healthy neighborhoods are desirable, Frumkin says.

They're small, they're still growing and they have a tendency to put all kinds of things in their mouths. That's why children are more vulnerable to environmental toxins than adults, researchers say.

But there is some good news for children's health, according to a February report released by the Environmental Protection Agency. Since 1990, children have been breathing easier and drinking and eating safer, thanks to decreases in air pollution, secondhand smoke, drinking water contaminants and pesticide residues.

Levels of lead in the blood of children have also improved dramatically, dropping 85 percent since 1980. [10]

Rising asthma rates - still something of a mystery given recent air quality improvements - and the growing potential for mercury exposure are the next causes for concern, according to the report.

Asthma rates among children have more than doubled between 1985 and 2001, and nearly 8 percent of women ages 16 to 49 have levels of mercury in their blood that could potentially harm a fetus. [10]

The EPA has also updated its guidelines on the carcinogenic potential of pesticides and other chemicals, suggesting for the first time that regulators should consider children to be 10 to 20 times more vulnerable to cancer-causing agents. [11]

Older people are also particularly vulnerable to environmental health risks, since their bodies may be less able to fight incoming toxins and have already been exposed to a lifetime's worth of contaminants. The elderly are also sensitive to environmental conditions like heat waves that may not affect the health of younger adults.

In April, the EPA launched a series of public hearings to discuss a National Agenda on the Environment and the Aging. The agenda will focus on the main environmental threats to older Americans and look at how the rapidly expanding elderly population might affect the environment in return. [12]

For more information on physician-patient communication and health literacy, try:

1. Benoff, S. et al. (2003) Increased seminal plasma lead levels adversely affect the fertility potential of sperm in IVF. Human Reproduction, 18, 374-383.

2. United States Environmental Protection Agency (1995) The Inside Story: A Guide to Indoor Air Quality. EPA Document # 402-K-93-007.

3. Wargo, J. and Wargo, L.E. (2002) The State of Children's Health and Environment: Common Sense Solutions for Parents and Policymakers. Children's Health Environmental Coalition, Princeton, N.J.

4. Needham L., Hill R., Ashley D., Pirkle J., Sampson E. (1995) The priority toxicant reference range study: interim report. Environmental Health Perspectives, 103 (suppl 3), 89-94.

5. Fagan, J. et al. (2002) Self-reported increase in asthma severity after the September 11 attacks on the World Trade Center - Manhattan, New York, 2001. Morbidity and Mortality Weekly Reports, 51, 781-784.

6. Pope, C.A. III et al. (2002) Lung cancer, cardiopulmonary mortality, and long-term exposure to fine particulate air pollution. Journal of the American Medical Association, 287, 1132-1136.

7. United States Environmental Protection Agency. (1997) Mercury concentrations in the top ten types of fish/shellfish consumed by U.S. residents. Mercury Report to Congress, http://www.epa.gov/ttn/oarpg/t3/reports/volume1.pdf.

8. U.S. Department of Health and Human Services, National Toxicology Program. (2002) 10th Report on Carcinogens. http://ehp.niehs.nih.gov/roc/toc10.html

9. World Health Organization. (2001) Climate and health. WHO Fact Sheet No. 266, Geneva. http://www.who.int/inf-fs/en/fact266.html

10. U.S. Environmental Protection Agency. (2003) America's Children and the Environment: Measures of Contaminants, Body Burdens and Illnesses, 2nd edition. http://www.epa.gov/envirohealth/children/ace_2003.pdf

11. U.S. Environmental Protection Agency, Risk Assessment Forum. (2003) Supplemental guidance for assessing cancer susceptibility from early-life exposure to carcinogens. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=55446

12. U.S. Environmental Protection Agency. (2003) Aging initiative: protecting the health of older Americans. http://www.epa.gov/aging/index.htm

13. World Health Organization. (2001) Occupational and community noise. WHO Fact Sheet No. 258, Geneva. http://www.who.int/inf-fs/en/fact258.html

The Center for the Advancement of Health is an independent nonprofit organization that promotes greater recognition of how psychological, social, behavioral, economic and environmental factors influence health and illness. The Center advocates the highest quality research and communicates it to the medical community and the public. The fundamental aim of the Center is to translate into policy and practice the growing body of evidence that can lead to the improvement and maintenance of the health of individuals and the public. The Center was founded by the John D. and Catherine T. MacArthur Foundation and the Nathan Cummings Foundation, which continue to provide core funding. Funding for this series was provided by the Robert Wood Johnson Foundation.

For Information Contact:
Kristina Campbell
Editor, Health Behavior News Service
Center for the Advancement of Health
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