These days, turning on the nightly news is enough to make your heart race--or self-diagnose yourself with the latest health plague. The media's not intentionally trying to scare you, but a little shock value really livens up a regular broadcast. The problem is that viewers are much more likely to remember the shock and ignore the real science. Before you make back-to-back appointments with every specialist your insurance plan covers, take a minute to sort out the facts. These five historic health scares are proof that some headlines simply don't hold up.
Support: In 1993 David Reynard went on Larry King Live saying a cellphone was responsible for his late wife's fatal brain tumor. Media hype surrounding the interview led to a flood of studies on the link between cellphone use and brain cancer, none of which found any significant correlation. A 2004 study from the Karolinska Institute in Stockholm added a little meat to the claim: Researchers looked at self-reported data from about 750 people and found that those with brain tumors who had habitually held their phone on one side of their head were more likely to experience tumors on that same side.
The Truth: The 2004 study was flawed from the beginning because of something called recall bias, says John Moulder, Ph.D, a professor of radiation oncology at the University of Wisconsin-Madison. "They were asking people about their cellphone behavior a decade earlier," he says. "Realistically, could you accurately report how much you talked on the phone10 years ago, how you held your phone, and where in the house you were having your conversations?" What's more, your cellphone, which gives off about the same amount of radiation as an AM radio or a television, has never been proven to cause cancer. Only one study in mice found a connection between exposure to radio waves and cancer, and all 17 attempts to replicate the results have failed. "We've asked ourselves if radio frequencies cause any changes in human cells that would make you suspect they cause cancer," Moulder says. "The answer is no. As far as we can tell, they don't do anything." If you're still not convinced, switch to the service provider with the most towers. If you have a good signal, your cellphone won't have to work as hard to prevent dropped calls (and therefore won't dump as many frequencies into your head).
Bottom line: Keep talking. A 2009 study tracked the incidence
of brain tumors from 1974 to 2003 and found there was no significant increase
with the introduction of cellphones in the 1990s.
The Claim: Vaccines Cause Autism
Support: In 1998 the British medical journal the Lancet published a study linking the common MMR vaccine (for measles, mumps, and rubella) to the onset of autism. The study's author, Andrew Wakefield, had worked with children on a normal developmental track who suddenly acquired disabilities (developmental and social) along with the onset of digestive diseases. Wakefield concluded that the vaccine given to the children caused undigested nutrients to "leak" out of the intestine into the blood stream and to the brain, causing damage. "The response to the study was quite swift and strong," says Lisa Miller, M.D., director of the Disease Control and Environmental Epidemiology Division for the Colorado Department of Health, who has researched autism risk factors. "The Centers for Disease Control and Prevention and the National Institutes of Health convened a panel of experts in the fall of 2000 to examine vaccine safety issues." Celebrities like Jenny McCarthy spoke out against the vaccine. The public outcry affected the behavior of parents, Miller says, with MMR vaccinations in England dropping and the incidence of measles rising--from only 56 in 1998 to 884 in 2008.
The Truth: The Lancet officially retracted Wakefield's study in February 2010 as a result of his questionable moral code. Two more reasons to disregard the results: The sample size was only 12 children, and blood samples were purchased from friends of the researcher's son at a birthday party. What's worse, Wakefield had a patent for a rival measles vaccine he declared far safer than the MMR vaccine, so there was also a financial incentive in play. Parents concerned that their child may develop autism (one in every 110 children will, according to the CDC) can re-embrace the idea of vaccination--it's an important tool in the prevention of disease.
Bottom line: Inoculate swiftly, and inoculate often. "There have been many scientific studies from around the world that have looked for a relationship between vaccines and autism," Miller says. "They haven't found it."
Support: In 1970 the journal Nature published a study saying that rodents were contracting cancer from eating nitrosamines--a mix of protein and nitrite that forms when cured meat (meat that's been treated with salt and nitrate or nitrite to keep it from going bad) is cooked at high temperatures (like that of your grill). A wave of food-additive legislation immediately followed, bringing nitrites into question. "A 1979 report in Science suggesting that nitrite alone caused cancer caught much media attention and started a public uproar to ban nitrite and nitrate," says Andrew Milkowski, Ph.D an adjunct professor with the Food Research Institute at the University of Wisconsin-Madison, who has authored a recent study on dietary nitrate compounds. "[The report] was later found to be flawed, but that was not nearly as well-publicized."
The Truth: Nitrite in your diet might not even be that bad for you--after all, it's in fruits and vegetables, and our body naturally produces it every day. "The human body makes about 70 to 100 milligrams of nitrite in metabolism per day for a 150- to 220-pound adult," Milkowski says. "By contrast, a cooked hotdog has about 0.5 to 1.0 milligrams of nitrite left in it." Even so, in 1925 the USDA limited the amount of nitrite allowed in cured meats to 200 parts per million--less than one percent of the content. As a result, nitrosamine is virtually a thing of the past.
Bottom line: If nitrite caused cancer, people would be advised to avoid swallowing since saliva contains nitrite. You'd have to eat about 100 hot dogs just to take in the same amount of nitrite that your body naturally produces each day.
The Claim: Mercury in Fish is Dangerous
Support: In 2004 the Environmental Protection Agency and the Food and Drug Administration released an advisory saying women of childbearing age (a small and specific population) shouldn't eat four specific fish: shark, swordfish, king mackerel, and tilefish. These fish have higher mercury levels than others, and years of research have presented some evidence that exposure to mercury in the womb may cause brain damage in fetuses and infants. In 1997 one hallmark study on fish consumption in the Faroe Islands showed that higher mercury levels in the womb were correlated with less capacity for memory, attention, language, and visual space perception.
The Truth: Risks of fish consumption don't apply to the general population. "The risks are very focused and very specific," says Dariush Mozaffarian, M.D., an assistant professor in the Department of Epidemiology at the Harvard School of Public Health. "The targeted attention to risks has somehow been dramatically warped in the public's mind." In reality, it is much more of a risk--nay, a tragedy--to not eat fish. "Our country's misplaced fear and resulting low seafood consumption is one of the major causes of preventable death from cardiovascular disease," Mozaffarian says. For the average adult, one to two servings of fish per week could cut risk of heart disease by 36 percent, according to a review conducted by Mozaffarian's team that appeared in the June 2009 Journal of Environmental Research and Public Health. Switch up your seafood meals to enjoy all the benefits, and encourage your pregnant or nursing wife to eat a variety as well--the DHA in fish is good for your baby's brain development, according to a wave of new research.Bottom line: The benefits of fish consumption far exceed the risks. "It's really a scare that's far out of proportion as to what the actual evidence shows and what the recommendations are," Mozaffarian says.
Support: A cardinal study published in 1998 in Toxicology and Industrial Health found that low doses of bisphenol A, a chemical used in the production of hard plastics and the coating of aluminum cans, caused reproductive and developmental abnormalities in rats. These findings spawned a Consumer Reports article blasting the substance, and the floodgates opened for terrifying headlines. Various research groups found that BPA was migrating from plastic containers into food and water, causing a maximum average intake of one-tenth of a microgram per day (the EPA has set an "acceptable daily intake" level at 3.6 micrograms per day, based on a 160-pound male). Then in January, the FDA proposed a review of BPA concerns and potentially removing BPA from plastic baby bottles entirely.
The Truth: Not all plastic is created equal. BPA-containing materials have a recycling number of 7 (look for the little triangle). The soft, disposable bottles that carry your water and soda are made with polyethylene terephthalate (PET). They're marked with a recycling number of 1 and are not suspected to contaminate your drink.
Since most of the research on BPA has used rats as subjects, results are poorly replicated in humans. We metabolize BPA much more efficiently than rats, so whatever effect might be seen in the little critters will be decreased in us. Additionally, the acceptable daily intake of BPA for humans is one one-thousandth of the amount it takes to show any effect in rats, according to the EPA (that effect, by the way, is decreased body weight). "Adverse effects have never been observed in humans," says Michael Karmin, Ph.D, a toxicology professor emeritus at Michigan State University. "If you look at the various groups and government organizations all around the world, they almost all agree with the conclusion that there isn't anything that they see happening."
Bottom Line: "Everything is toxic. It's the first rule of toxicology," Karmin says. The important thing is to set safe limits. The amount of BPA that we take in each day is negligible, and we have no reason to believe that greatly exceeding those amounts could cause harm.
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