In 2009, an Endocrine Society scientific statement announced that the planet had passed a surprising statistical point: There are now more people in the world who are overweight than are undernourished. In the US, the proportion of obese and extremely obese adults has grown from 26% to 40% in the past 20 years, says the CDC. Adding in the 33% of overweight people means excess body fat impacts nearly three-quarters of our population, increasing the risk of metabolic syndrome, diabetes, cardiovascular disease, and other illnesses.
But the usual suspects — sedentary lifestyle and easy access to food — aren’t enough to account for the rocketing numbers of too-heavy people, say recent papers in Endocrinology and other peer-reviewed scientific journals. That’s because people in developed countries are generally eating less than they did several decades ago; they’re also are exercising a reasonable amount, thanks to school activities, gym memberships, government programs touting exercise, and the like. Yet their bodies are ballooning, along with those of inhabitants in poor parts of the world, who may experience food shortages.
Too-high calorie intake doesn’t entirely explain what’s going on — nor why the phenomenon occurred so quickly and universally — say the papers’ authors. We can’t blame a few Big Macs, or even a lot of Big Macs. And the rate at which obesity shot up is too fast to fault genetic changes, the researchers note. Instead, these scientists and those who wrote the Endocrine Society statement point to worldwide exposure to powerful chemicals — including ingredients in plastics, pesticides, and personal-care products — that interfere with the hormones that make up your endocrine system. The substances affect many functions, including the way you metabolize and store fat. Your body should normally be able to maintain a habitual weight for years, and this ability to regulate weight could be disturbed as well. Scientists have dubbed these dangerous materials endocrine disrupting chemicals, or EDCs.
More and more, the things you’ve been doing all along to keep yourself healthy — eating right, exercising regularly, getting enough shut-eye, keeping up with your medical tests and doctor’s visits — aren’t enough. You also have to be well informed about the obstacles to your wellness that may be lurking in the world around you. That way, you can take sensible steps to avoid them.
Substances that mess with your hormones are not there purposely to do you harm. But bisphenol A (or BPA), phthalates, triclosan, and more are ingredients in a huge number of products you come into contact with every day, such as food storage containers, soaps, shampoos, cosmetics, carbonless cash register receipts, dental sealants, newspaper ink, and the timed-release coatings for some drugs. Additional chemicals, including dioxins, PCBs, and DDT, have been banned, but they persist in soil and water, becoming part of the meat, fish, dairy, and produce you eat.
When you eat, drink, breathe, and touch all those EDCs out there, they become incorporated into your bones, blood, and other tissues. Two plastics ingredients, BPA and phthalates, are in just about all Americans: 93% and 100%, respectively. Dioxins are found in many Americans as well. Because your body is exquisitely sensitive to hormones (or hormone mimics), it responds to tiny amounts — often more dramatically than it does to large amounts. A graph produced by a leading endocrinologist shows that during the 20th century the growth in ordinary daily exposure to synthetic chemicals parallels the rise in the number of overweight individuals. Backing up this point of view are animal studies showing that certain EDCs change the way the body metabolizes fat — increasing the number and size of fat cells and raising their lipid uptake. Research on human cells produced similar results.
But what about research on humans? You can’t give people doses of dangerous materials and see what happens. However, epidemiological studies that compare types of chemicals in human beings with their health problems suggest that people respond to EDCs as animals do. Published data on men that was collected for NHANES 2002 linked exposure to phthalates with both abdominal obesity and insulin resistance.
Research on DES exposure also helps confirm the dangers of EDCs. DES is a synthetic estrogen that was given to pregnant women between 1948 and 1971 in order to prevent miscarriage; it caused vaginal tumors in the women’s female children, and now that they have grown to adulthood, breast cancer. Experiments in mice predicted the breast cancer outcome 25 years ahead of time, reassuring scientists of the validity of animal endocrine research in forecasting human results, says the Endocrine Society.
And by the way, BPA and DES are chemically very similar, says Frederick vom Saal, PhD, professor of biology at the University of Missouri and member of an FDA committee that assessed risk from this EDC, which is used in food-can linings, plastic containers marked “7” in the recycling icon, and other items. “BPA is an unstable estrogen, and we make food containers out of it,” vom Saal says. “This is, not surprisingly, a problem.”
EDCs like BPA may not just make you fat, they may also interfere with other essential processes, says the Endocrine Society report. Often they impact the reproductive system. Epidemiological studies have found connections between EDCs and recurrent miscarriage, ovarian disease, breast tumors that do not respond to treatment, abnormal genital anatomy in males and females, low sperm quality and quantity, sexual dysfunction in men, and more.
However, your hormones signal many complicated interactions, says the Endocrine Society, so non-reproductive systems can be impaired as well. For example, NHANES data on adult men and women analyzed for a 2008 JAMA article pointed to cardiovascular harm from EDC exposure. And obesity isn’t the only rapidly growing modern problem with an EDC connection. NHANES and other studies have linked EDCs to diabetes, attention deficit disorder, and hyperactivity — more as-yet-unexplained modern epidemics. The younger you are when you’re exposed (including fetal and early childhood exposure), the more likely you’ll be damaged.
HOW WE GOT HERE
“Better living through chemistry,” the slogan of the DuPont corporation, became a mantra for the mid- to late 20th century and the many lifestyle conveniences produced then. Medicine shifted from cures that relied heavily on natural substances, including herbs, to pharmaceuticals that zapped illness and symptoms with just the active ingredient of the old-time remedies. The industries that supplied nitrogen-based bomb-making materials during World War II began to use nitrogen to make fertilizers for the giant new farms, or agribusinesses, that displaced many of the small pre-war family operations. “Plastics” were the secret to financial success, Dustin Hoffman’s character, Benjamin, learned in The Graduate.
The race was on to better our lives through artificial products of all kinds. Growing up in the second half of the 20th century, you played with plastic toys rather than your grandmother’s wooden ones. Today, you eat food stored in plastic rather than ceramic or glass; you live in a home built and furnished with man-made materials; you wash with soaps and put on makeup that’s packed with unpronounceable materials.
All those items appear to profoundly, and negatively, alter the way your body works, say vom Saal and other endocrinologists. However, getting rid of a chemical on a nationwide basis is very difficult. Once an agency like the FDA or EPA approves its use in medicine, industry, or agriculture, it almost never changes its mind. When the EPA was told in 1998 to screen the American population for endocrine disruptors on a wide scale and determine if they were causing disease, it simply didn’t do it, says Gina Solomon, MD, MPH, who served on the committee that set up the testing protocols.
That’s why public-health advocates were amazed — and cheered — by the FDA’s recent second look at its BPA approval, after the committee vom Saal was on tabulated ill effects in about a dozen recent human studies, hundreds of human-cell experiments, and hundreds more animal investigations. Even this much research isn’t usually enough to bring a substance under scrutiny, much less get it banned, so the FDA’s reaction was groundbreaking, says vom Saal. The substance isn’t forbidden yet, but at least we’re looking at it, he says.
Meanwhile — as scientists, government officials, and chemical-industry lobbyists wrangle about what to do about BPA and other EDCs — there are plenty of easy things you can do to protect yourself.
• Don’t eat canned food, advises vom Saal. “I have no cans whatsoever in my home,” he says. “Anything acidic, such as tomatoes, is especially bad. It leaches out the BPA.” When Japan banned BPA from the linings of food cans there, blood levels of the substance fell in the people the government tested, vom Saal reports.
• Never use plastic food containers marked “7” in the triangular recycling icon. And don’t buy food that comes in them (including plastic ½-gallon orange-juice containers).
• Don’t keep cash register receipts (which are printed via a process that involves biologically active amounts of BPA, according to vom Saal), if you don’t have to. Place receipts you do collect immediately into an accordion file or storage box, then wash your hands. At tax time, when you have to handle lots of receipts, wear thin plastic gloves, which can be purchased cheaply from the hardware store.
• For this one, you’ll need to take a cheat sheet to the store: Check labels on personal-care products, from deodorants to hand creams, and avoid those that contain the phthalates DBP, DEP, and BzBP.
• Avoid items with a reference to “fragrance” on the label, as this may mean phthalates.
• Don’t use plastic food containers marked “3” and “6,” which include phthalates and other EDCs.
• Never microwave in plastic, as this pulls dangerous substances out of the material.
• To avoid dioxin, go flexatarian, says Michael J. DeVito, PhD, senior toxicologist with the National Institute of Environmental Health Sciences of the NIH. Dioxin accumulates in fatty tissues, so is present in meat, fish, and dairy products with fat. Eat lots of fruits and vegetables to reduce exposure, DeVito says. And of course, you’ll do a good turn for your heart while you’re at it.
• This thyroid-disrupting pesticide is used as an antibiotic in antibiotic soaps and other personal-care products. However, it has no antibiotic effect unless you wash with it for, say, 20 minutes or more.
• A 2007 study in Toxicological Science found that arsenic may act as an EDC that contributes to prostate cancer risk. Men should look for the green-and-white USDA organic label when buying chicken, as arsenic is the antimicrobial of choice in many of the giant operations that produce non-organic poultry. A label proclaiming “No antibiotics” is meaningless, as antibiotics may not be employed anyway. Arsenic exposure has long been linked to other cancers as well, which means women should be shopping for organic birds too.
c. Stephanie Woodard.
c. Stephanie Woodard.