Do Environmental Hazards Really Cause Disease

Pollution is civilization's oldest companion. The ancient Greeks and Romans spewed massive amounts of toxins into the air as they extracted silver from lead ore. During the Civil War an abandoned canal in Washington, D.C., was so clogged with animal carcasses and household waste that the stench permeated the White House.

In the past 45 years alone, more than 70,000 new chemical compounds—including many that cause cancer in laboratory animals—have been invented and spread throughout the environment. So how does this affect your risk of cancer, heart disease, and stroke as you creep beyond age 60? A lot more than you might think.

While estimates vary, some researchers believe that up to 25 percent of all cancers might be prevented if Americans reduced their exposure to smog, pesticides, secondhand smoke, and other hazards that we breathe, drink, eat, and absorb into our bodies, says Devra Lee Davis, Ph.D., senior fellow and program director at the World Resources Institute, an environmental research center in Washington, D.C. Reducing exposure to toxins also might prevent thousands of heart attacks and strokes each year, she says.

"Unlike some things that have been identified as causes of cancer, stroke, and heart disease that you can't control—like family history—environmental factors are often things you can do something about," Dr. Davis says. "Even after age 60, it represents an opportunity for prevention that, in many ways, is easy to achieve."

What We're Doing to Ourselves

All of us carry residues of a few toxins in our cells. DDT, for example, an insecticide suspected of promoting breast cancer, has been banned in the United States since 1972. Yet because traces of it can linger in food and water for more than 50 years, virtually all people in this country still have some DDT in their bodies, Dr. Davis says.

In most cases these minute amounts of toxins probably won't harm you. Only 30 chemicals, for instance, have been proven to cause cancer in humans. But at least another 400 have been shown to cause cancer in laboratory animals and are suspected of promoting tumors in us.

Here's a sampling of intriguing findings.

Pollution increases heart attack risk. Automotive air pollutants, such as carbon monoxide, can reduce the ability of the blood to carry oxygen and trigger heart attacks and angina in people over age 60, says Robert Morris, M.D., Ph.D., director of the Center for Environmental Epidemiology at the Medical College of Wisconsin in Milwaukee. Long-term exposure to carbon monoxide also may promote more blood clots in the arteries and possibly lead to stroke.

In his three-year study of 204,000 Medicare patients, 65 and older, in seven American cities, Dr. Morris found up to a 30 percent increase in hospital admissions for congestive heart failure as carbon monoxide levels rose.

"There's a steady increase in hospital admissions as carbon monoxide goes up," Dr. Morris says. "There's no question that if you're exposed to excessive amounts of carbon monoxide, your heart is going to have to work harder to deliver oxygen to the cells. So if an older person has an underlying heart condition, carbon monoxide can push the heart to a dangerous extent."

Breast cancer rates may be higher in industrial areas. Postmenopausal women in Nassau County, New York, who live within a mile of a chemical, petroleum, rubber, or plastics facility are 60 percent more likely to develop breast cancer than postmenopausal women who lived in other parts of Long Island, according to a study by New York State Department of Health researchers.

"This study adds credibility to the suggestion that environmental exposure may be important in the development of breast cancer," says Elizabeth Lewis-Michl, Ph.D., lead author of the study and a research scientist at the Center for Environmental Health at the New York State Department of Health in Albany.

Some cancers are more common among farmers who use pesticides. In a 16-year study of 70,000 Canadian farmers, those who routinely sprayed more than 250 acres with herbicide were 2.2 times more prone to develop prostate cancer than farmers who didn't use pesticides, says Howard Morrison, Ph.D., chief of behavioral risk assessment, Cancer Bureau, at Health Canada, the equivalent of the U.S. Department of Health, in Ottawa. In another 16-year study, 143,000 herbicide-using farmers, most of whom were at least in their sixties by the end of the study, were twice as likely to develop a life-threatening cancer of the lymphatic system known as non-Hodgkin's lymphoma than their colleagues who did not spray with herbicides.

Other studies have found that farmers who work with insecticides have higher rates of leukemia, bone marrow cancer, and brain cancer. Some of these same chemicals are used in lower doses by household gardeners, Dr. Davis says.

"It's absolutely established that many herbicides are carcinogens," says Philip Landrigan, M.D., director of environmental and occupational medicine at the Mount Sinai School of Medicine of the City University of New York in New York City. "It just doesn't make any sense to expose yourself to these compounds at any age."

Radon is linked to lung cancer. Swedish researchers found that people up to age 74 who lived in homes with high levels of radon were 80 percent more susceptible to lung cancer than those who lived in houses containing little or no radon. Radon is an invisible, odorless radioactive gas that seeps into homes from the decay of underground uranium deposits.

"Radon is clearly a carcinogen. There's no doubt about it, but the degree of risk of lung cancer from residential exposure is not clear," says Aaron Blair, Ph.D., chief of the occupational studies section at the National Cancer Institute in Bethesda, Maryland.

Many Questions Remain Unanswered

Although these studies strongly suggest the powerful impact of environmental hazards, scientists are still struggling to determine the thresholds at which many of these toxins cause trouble.

"That's the $64,000 question," says Jane Koenig, Ph.D., professor of environmental health at the University of Washington in Seattle. "In a lot of cases we don't have the answers yet."

A few, like carbon monoxide and asbestos, a potent carcinogen that causes a rare form of lung cancer, have no known safe exposure levels. For others, like radon, the Environmental Protection Agency (EPA) has set exposure limits. But in general, the magnitude of your risk depends on what you have been exposed to, how much and how often you are exposed to it, and your age.

Certain occupations, for example, can come back to haunt you, even if you have long been retired. Workers who installed asbestos insulation in the 1940s and 1950s have tremendously high rates of lung cancer. Textile workers who are exposed to benzidine-related dyes have unusually high rates of bladder cancer, according to Max Costa, Ph.D., chairman of the Norton Nelson Institute of Environmental Medicine at New York University Medical Center. Furniture workers who are exposed to wood dust may be susceptible to nasal and sinus cancers for up to 40 years after their first exposure. Some hobbyists who frequently use paints, solvents, and solders also are more prone to cancers than the general population, he says.

Toxins Carry More Clout As You Age

The damage that these hazards inflict on the body often increases as you get older. That's because as you age, your lungs, liver, kidneys, and other organs gradually lose much of their ability to rid the body of cell-damaging toxins, says Jonathan Samet, M.D., chairman of the Department of Epidemiology at Johns Hopkins University School of Medicine in Baltimore.

Although doctors still aren't sure how these toxins trigger cancer, heart disease, or stroke, they suspect that hazardous substances may cause gradual changes in DNA, the genetic building blocks that cells use to reproduce. Over decades, these changes might cause mutations in cells that may spark cancer and might accelerate atherosclerosis, hardening of the arteries, says Chris Schonwalder, Ph.D., assistant to the director of the National Institute of Environmental Health Sciences of the National Institutes of Health in Research Triangle Park, North Carolina.

These pollutants also may weaken the immune system so that it is less capable of destroying abnormal cells that eventually could become cancerous, says Mary Wolff, Ph.D., a toxicologist and professor of community medicine at the Mount Sinai School of Medicine of the City University of New York.

Keep Your Guard Up

Even if you have been exposed to massive amounts of environmental hazards in your lifetime, it's not too late, Dr. Landrigan says. If you eliminate an environmental hazard like pesticides from your life now, you may be able to prevent that one final exposure that would set you on a collision course with one of the three killers.

"Older people need to engage in prudent avoidance and try to minimize their exposure to environmental hazards," Dr. Davis says. "That doesn't mean you have to live in a bubble. But if you pay attention to your environment—as well as exercise regularly, eat well, and don't smoke—you will be healthier."

Here's a closer look at several environmental hazards that are known or suspected of causing the big three killers and what you can do about them.

Smoking Is Never Passive

Tobacco smoke is one of the most dangerous and most pervasive environmental hazards.

Fifty-three thousand people die of passive-smoking-related causes each year, according to Stanton Glantz, Ph.D., professor of medicine at the University of California, San Francisco, School of Medicine. That's because sidestream or secondhand smoke from burning tobacco emits virtually all of the same toxic chemicals and carcinogenic substances into the air that you get from taking a puff. A nonsmoker who regularly inhales these secondhand fumes has a 30 percent greater risk of developing lung cancer and heart disease and may be more likely to develop breast cancer than nonsmokers who live in smoke-free homes, he says.

"Passive smoking increases the need of the heart for oxygen and decreases the body's ability to use it effectively," Dr. Glantz says. "So if you already have some heart disease or atherosclerosis and then you throw in secondhand smoke, this could easily push you over the edge."

According to Dr. Glantz, studies have found:

* Exposure to secondhand smoke thickens artery walls and promotes the formation of artery-clogging plaque. It also lowers blood levels of HDL, the "good" cholesterol that normally would prevent plaque buildup in the arteries.

* If a heart attack occurs, previous exposure to sidestream smoke magnifies heart damage and complicates recovery.

In addition, at least 3,000 lung-related deaths among nonsmokers each year are attributable to secondhand smoke, according to the Environmental Protection Agency.

Persuading household smokers to quit is the best way to protect nonsmokers like young grandchildren. But until that happens, here are a few things you and your nonsmoking loved ones can do to reduce these risks.

Take it outside. Allow smokers to puff away outdoors only, says C. Barr Taylor, M.D., professor of psychiatry at Stanford University School of Medicine and author of The Facts about Smoking. As an alternative, designate a well-ventilated room in your home not normally used by others where they can light up. Ask your guests who smoke to use the room, too.

Create a breeze. If possible, open windows or install strong exhaust fans to quickly clear smoke out of your home, Dr. Taylor suggests.

Eat in self-defense. Eating at least seven servings a day of fruits and vegetables, such as apples, pears, carrots, and broccoli, that are rich in antioxidants may help a nonsmoker counteract some of the risks of breathing secondhand smoke, says James Scala, Ph.D., a nutritional biochemist and author of If You Can't/Won't Stop Smoking. Antioxidants fight off the effects of the free radicals found in tobacco smoke that rob cells of oxygen.

Air Pollution Steals Your Heart

Inhale. Exhale. You do that about 17,000 times in an average day. And what are you breathing? Carbon monoxide, sulfates, and other dangerous pollutants that can strain your heart and lungs to the breaking point.

"Studies have consistently shown that there are increased numbers of deaths associated with increasing levels of particulate material in the air. One to 3 percent of the deaths that occur on days with high levels of particulate material are due to cardiac problems in people over age 65," Dr. Koenig says.

Researchers have also found that people who live in cities with high air-pollution levels die an average of 2½ years earlier than those who live in the least-polluted areas, Dr. Koenig says.

"Air pollution is similar to secondhand smoke. The more you breathe it, the more toxic effects it is going to have on your body," Dr. Koenig says. "So you should do everything you can to reduce the amount of air pollution that you breathe, particularly if you're 60 or 70 and already have an underlying heart or lung condition that could be exacerbated by breathing dirty air," Dr. Koenig says. Here's how to lower your intake of air pollutants.

Stick to side streets. Regular exercise such as walking strengthens the heart. But avoid strolling along busy streets where carbon monoxide levels are higher. Head for a secluded park or neighborhood, Dr. Morris says.

Dodge rush hour. The more cars on the road, the more air pollution you are likely encounter. Try doing outdoor activities such as walking and gardening at off-peak times like the middle of the day so that you avoid being exposed to fumes from the morning and evening rush hours, Dr. Morris says.

Stay smoke-free. Tobacco smoke contains large amounts of heart-damaging carbon monoxide. "Certainly one of the biggest sources of carbon monoxide you can be exposed to is the end of a lit cigarette," says Dr. Morris. So avoid secondhand smoke, and if you smoke, quit, he says.

Snatch pollutants out of the air. Even indoors you can be exposed to air pollutants that seep into your home, Dr. Koenig says. Consider getting a high-efficiency particulate (HEPA) filter. About the size of a footstool, HEPA filters collect many of the worst pollutants. They are available at most hardware or building supply stores and cost less than $200.

Relax. Scan the newspaper or watch television weather reports for pollution alerts in your area. When a pollution alert is declared, stay indoors, cut back on your regular activities, and take more frequent rest breaks so that you reduce the amount of air you breathe and don't overexert your heart and lungs, Dr. Koenig says.

Pesticides: Look to Natural Alternatives

A foggy mist of DDT engulfing beaches, campgrounds, and parks once was a sure sign that summer had arrived.

Some trucks belching out this potent concoction actually displayed signs proclaiming, "DDT: powerful insecticide, harmless to humans."

But far from being harmless, DDT, now banned in the United States, and many other pesticides that are still in use like dimethoate can provoke cancers, Dr. Landrigan says.

"You're never so old that you're immune from the effects of pesticides," Dr. Landrigan says. "My advice to people is reduce their use as much as possible. If you must, use the minimal amount necessary and integrate other, more natural approaches into your effort to control pests."

In a study by Dr. Wolff, women who had elevated blood levels of DDE, a residual component of DDT, were four times more likely to develop breast cancer than women who had lower blood concentrations of the residue.

"The older you are, the more DDT you have," Dr. Wolff says. "We're still uncertain whether DDT actually causes breast cancer. But it's something that we need to understand better because there is still plenty of it around. Although it is banned in the United States, it is still widely used in Mexico and other Third World countries. So it can still get into this country."

Some researchers speculate that substances called xenoestrogens in DDT and other pesticides may promote breast, prostate, and other hormonally linked cancers, Dr. Wolff says.

These xenoestrogens may mimic sexual hormones in the body and fuel cancer development by damaging DNA or helping cancer cells form new blood vessels that are needed for tumor growth, Dr. Davis says.

Here's how you can battle back.

Load up on vegetables and soy. Broccoli, cauliflower, cabbage, and soy products like tofu have compounds that may enhance the body's ability to repair damaged DNA and fend off the worst effects of xeno-
estrogens, Dr. Scala says. Eat at least five servings of these foods a day, he suggests.

Lay off meat. Pesticides tend to accumulate in animal fats like in beef, pork, and chicken. Try to eat no more than one 3-ounce serving of meat a day, Dr. Scala says.

Do a striptease. Carefully wash and peel all fruits and vegetables before eating, says Dr. Schonwalder says. That should eliminate most of pesticide residues on the food.

Keep your kitchen pesticide-free. You may be unwittingly contaminating your meals if you use pesticides on kitchen counters and other food preparation areas, Dr. Davis says. Instead, keep your kitchen clean at all times and use less-toxic pest-control methods like boric acid dust, available at most hardware stores, which will slowly kill ants and cockroaches without harming you. Boric acid dust should be used carefully and not inhaled, says Jay Feldman, executive director of the National Coalition against the Misuse of Pesticides (NCAMP). For more information on other natural pest-control techniques, write NCAMP, 701 E Street SE, Suite 200, Washington, DC 20003.

Create a barrier. Skin barriers, a thin nonpenetrable solution similar to petroleum jelly, can prevent pesticides from soaking into your skin, Dr. Schonwalder says. Used by petrochemical workers, skin barriers are available in most drugstores.

Don't track in trouble. "Most houses are so airtight these days that once a pesticide gets into your home, it's there to stay," says Dr. Schonwalder. After applying pesticides, take off your shoes before entering your house. Remove all your clothing in an entryway and wash them in hot water as soon as possible. Then take a shower to remove any remaining residues from your body, he suggests.

Radon: Close the Door on This Cancer Culprit

After a construction engineer set off radiation detectors as he walked into a nuclear power plant in Limerick, Pennsylvania, in 1984, investigators narrowed their search for the contamination down to a startling culprit.

It was radon seeping into the man's home, exposing his family to 50 times the annual radiation levels allowed for uranium miners. Although the family quickly fixed the problem, they may have an elevated risk of developing lung cancer for years or decades, Dr. Landrigan says.

"Radon isn't a small problem," says Charles T. Hess, Ph.D., professor of physics at the University of Maine at Orono, who has studied the health effects of radon for more than 20 years. "It's in the air. It's in the water. It's one of the biggest sources of radiation exposure in the United States."

Radon is a naturally occurring gas produced by radioactive decay of uranium in soil and water throughout the country. It is the second most common cause of lung cancer after smoking, contributing to 10,000 deaths a year. Smoking and radon exposure more than doubles your risk of developing lung cancer, Dr. Landrigan says.

Because it is a gas, it can easily slip into a home through cracks in floors and walls, construction joints, and gaps around pipes. It also is commonly found in wells or municipal water systems that use groundwater, Dr. Hess says. Up to six million homes in the United States may exceed EPA standards for radon exposure.

"If you have excessive radon in your home, it is prudent to take corrective measures to get it out, no matter what your age. It's just a gas, and you can get rid of it very easily," says Dr. Landrigan, who is also co-author of Raising Children Toxic Free.

Be snoopy. Call the county or city health department and ask if they have received any reports of high radon levels in your neighborhood, says Richard Sextro, Ph.D., a staff scientist at the Lawrence Berkeley Laboratory at the University of California, Berkeley. Ask neighbors if they have taken recent radon measurements. Since radon levels can fluctuate dramatically from house to house, this isn't a foolproof method. But at least it will give you a better idea of whether you should test.

Check it out. Get a radon detector, available at many hardware stores, and place in the basement or lowest living areas of your home, Dr. Landrigan says. Detectors that accumulate radon for 2 to 90 days will give you a general idea of your risk. If that reading is high, get a detector that will measure radon levels for 6 to 12 months. Since radon levels can vary day to day, a long-term test will give you a better idea of your year-round radon exposure. When the detector is ready, you mail the device off to a lab that analyzes the contents and then sends you a report.

Radon is measured in units called picocuries per liter. If your test results are greater than 4 picocuries per liter, the highest exposure recommended by the EPA, you should consider ways to fix the problem. In most cases it can be done for $500 to $2,500, according to the EPA.

Stop those leaks. Seal large cracks in your basement with caulk to prevent radon from pouring in, Dr. Hess suggests. In basements with porous or cracked concrete, apply several layers of epoxy paint or masonry sealer to the floor or walls.

Get some fresh air. Open all the windows, particularly in the basement, and use a window fan to flush the radon out, Dr. Landrigan suggests.

Take it out before it gets in. Installing a 4-inch plastic pipe through the foundation and venting it to a small fan in the roof will suck the gas away before it gets in the house, Dr. Sextro suggests. You may want to consider having this done professionally, since pipe and fan size can be dependent on house size and local codes.

Bathe wisely. If you get your household water from a well, a long, hot shower can make radon levels in the your bathroom soar more than 28 times higher than normal, Dr. Hess says. That's because some wells and other groundwater sources are loaded with the radioactive gas.

When you bathe or shower, turn on the fan and water, then leave the room while the water warms or the tub fills, Dr. Hess suggests. Shower for no more than 5 minutes, grab a towel, and dry off in another room. That should reduce your radon exposure in the shower to about 20 percent. Be sure to close the bathroom door while you are showering or whenever you leave the room so that the gas won't seep into the rest of the house. Take warm rather than hot showers. Hot water releases more radon.

Prescription for Prevention

Radon, secondhand smoke, asbestos, and other environmental toxins can increase the risk of stroke, heart disease, and certain forms of cancer, especially after age 60. But even if you have lived or worked around hazardous materials for years, you can still make lifestyle changes to dampen your chances of getting ill.

Do:

* Make your home a smoke-free zone.

* Exercise in secluded parks or neighborhoods away from congested or busy streets that have high concentrations of carbon monoxide.

* Get a HEPA filter. It will eradicate many of the worst pollutants.

* Carefully wash and peel all fruits and vegetables before eating them. This should prevent you from inadvertently digesting pesticides.

* Get a radon detector. If levels of the gas in your home are high, open windows and seal all cracks in the foundation and basement flooring.

Don't:

* Exercise in morning or evening rush hours. Pollution is highest at those times.

* Use pesticides on kitchen counters. That can contaminate foods.

* Abuse pesticides. In large amounts, they can poison you. Follow label.