Do Immune System Diseases Have an Environmental Cause?
Nearly 20 years ago, as a young graduate student, Canadian wildlife biologist Peter Ross investigated a massive die-off of harbor seals in the Baltic Sea. The problem, it turned out, was their immune systems. Their habitat was so full of polychlorinated biphenyls (PCBs), that the seals could not fight common viruses anymore.
The more PCBs the seals had in their bodies, the greater damage scientists found. PCBs wreak havoc on the delicate balance between hormones and the immune system, Ross says. Now, scientists are studying similar effects of toxic chemicals in humans.
A Clear Link
Researchers are uncovering a definite link between environmental pollutants and a growing number of autoimmune diseases. Disorders like lupus, multiple sclerosis (MS) and Type I diabetes are on the rise, says Glinda Cooper, an epidemiologist with the National Institute of Environmental Health Sciences (NIEHS). "It’s very likely that environmental factors play a role in the development of these diseases," Cooper says.
About eight percent of the U.S. population, or 22 million people, have one of the 24 most common forms of autoimmune disease, National Institutes of Health officials estimate. "You have to look at these diseases together to really get the magnitude of the problem," says Virginia Ladd, president of the Detroit-based American Autoimmune Related Disorders Association (AARDA). Few people have heard of these disorders because, individually, they are rare, Ladd says. Since AARDA lobbied to classify them as a group, government officials are providing more research dollars.
Autoimmune diseases are the medical equivalent of friendly fire in the military. They cause a person’s immune system to go haywire and attack healthy tissue. The site of attack varies: In MS, it’s nerve cells; in rheumatoid arthritis, it strikes the joints; lupus targets the kidneys, joints, heart or lungs. Scientists are beginning to understand the cause. It’s partly genetic. But a person also must encounter something in the environment (a virus, a chemical or a heavy metal) before symptoms appear.
Living with this kind of war raging inside your body can take its toll. Autoimmune patients (75 percent are women) endure severe fatigue, swollen joints and mysterious skin rashes. They live with constant discomfort and unpredictable flare-ups. Many must give up careers they love, stop exercising (or even climbing stairs), and have to let someone else take care of their children much of the time. So little is known about these diseases, there are few treatments.
Recent studies show many of the same chemicals that cause cancer and reproductive problems in both humans and wildlife can also aggravate autoimmune disease. In some cases, toxics set the disease in motion even before an infant is born. Other scientists say it may take a combination of factors. Here are their findings:
" Environmental estrogens/endocrine disrupters. According to World Wildlife Fund scientist Theo Colborn, any substance that might act like hormones can influence the immune system. Bisphenol A (BPA) is one such chemical. It’s in everything from computers to polycarbonate baby bottles. Past studies showed BPA—which acts like estrogen—may increase breast cancer risk. Now, scientists say it also may activate autoimmune responses.
Early evidence comes from a series of Japanese animal studies, in which lab mice with a genetic tendency to get lupus developed telltale signs of the disease when exposed to BPA. Meanwhile, Ansar Ahmed, a Virginia Tech immunologist, found prenatal exposure to the drug DES (another estrogen-like chemical) caused mice to develop lupus symptoms—but not until later in life. When Kansas endocrinologist Virginia Rider exposed immune cells of human lupus patients to estrogen, the disease activity increased.
" Pesticides. Since many pesticides act like hormones, they also appear to play a role in autoimmune disease. For example, Dr. Eric Sobel, a University of Florida rheumatologist, exposed lab mice to chlordecone (a pesticide in ant and roach traps). The mice came down with lupus.
" Mercury. At California’s Scripps Research Institute, K. Michael Pollard says mice with a lupus gene will develop the disease when exposed to the level of mercury most of us carry in our bodies every day (0.04 micrograms). "It’s certainly a concern if you are someone with a family background of autoimmune disease," Pollard says. "If you eat a lot of fish, you might want to be careful about it." Similar experiments showed lupus-prone mice developed the disease after taking a very high dose of thimerosal, the mercury-based preservative in some vaccines. Pollard says no one has studied how thimerosal might affect children with a family history of autoimmune disease. But he believes the benefits of vaccines outweigh the risk.
Mice with the lupus gene also got the disease after receiving mercury-based dental fillings. While the debate over the safety of dental amalgam in general continues, people with a genetic risk for autoimmune disease could be more sensitive to it, Pollard says.
" Work-related exposures. Occupational studies show stone workers and miners have more rheumatoid arthritis, lupus, MS and scleroderma. These people inhale silica dust. Auto workers and military staff who use a lot of solvents also have higher rates of rheumatoid arthritis and MS. Several lawsuits are underway that could implicate pesticides, asbestos and radioactive bomb fallout.
Based on this new information, people with a family history of autoimmune disease should take certain precautions, health experts say. While it’s impossible to avoid all toxics, here are a few ways to protect yourself:
" Get tested. If you’re concerned, get an immune profile from a specialist.
" Ask about estrogen. Tell your doctor about your family history before you start hormone therapy or the birth control pill. Estrogenic chemicals can leak from plastic in the microwave, so use glass instead.
" Go veggie. Fatty meats and dairy products carry the most dioxin and PCBs. Chicken contains estrogen.Vegetarian meals contain less toxins.
" Filter. Drinking water may contain solvents and other contaminants.
" Go organic. Avoid as many chemicals as possible. Buy organic produce, unbleached paper products and greener cleaners; skip weed killer and bug sprays.
" Manage stress. Intense emotional stress makes autoimmune diseases flare.
" Watch what you swallow. Herbs like Echinacea can be harmful if your immune system already is in overdrive. Check with a doctor first.
The more scientists learn about environmental triggers, the more they will be able to prevent autoimmune disease. Meanwhile, government agencies and conservation groups must work to keep harmful pollutants out of the environment in the first place, says seal researcher Ross, now with the Canadian Department of Fisheries. "It’s very hard to predict what impact these chemicals are going to have when they end up i
n our waterways and food supply," Ross says. "It speaks to the need for wise chemical design and regulations."
MELISSA KNOPPER is a Colorado-based freelance writer.