December 17, 2017
A Hard Look at BPA

A Hard Look at BPA

by Berkeley Wellness  |  

When the chemi­cal BPA (bisphenol A) first came on the horizon as a health concern, about six years ago, the big worry was about potential risks posed by traces of this industrial chemical released from polycarbonate plastic baby bottles and sippy cups. In response to consumer pres­sure, manufacturers stopped using BPA-containing plastics for these baby products. In 2012, in order to reassure consumers, the FDA ruled that BPA could no longer be used in such products, though it continued to say that the chemical is safe. Since then, many companies have voluntarily found replacements for other BPA-containing plastic products, such as those nearly inde­structible water bottles favored by hikers.

Are BPA Substitutes Safe?

Amid ongoing health concerns about the chemical bisphenol A (BPA), you can find more and more "BPA-free" items for sale. The problem is that the sub­stances being used to replace BPA may be just as bad.

Despite these measures, BPA hasn't gone away, and it's likely that our overall exposure to it has not gone down. Billions of pounds of the chemical are produced annually. It's still used in many hard plastic products such as eyeglass lenses, automo­bile parts, helmets, plastic tableware, com­pact discs, and even in some dental compounds.

The main concern now is its continued use in polycarbonate food containers, metal cans for food and beverages, and paper receipts, which appear to be the three major ways BPA gets into our bodies. Studies have found that at least 90 percent of Americans have BPA in their urine, with higher concentrations typically seen in women and children. Meanwhile, research has been accumulating in the past few years about the potential dangers of BPA for adults as well as children.

Many concerns, many uncertainties

Most of the potential problems with BPA relate to the fact that it mimics estrogen and is thus classified as an endocrine disrup­tor—that is, a chemical that can interfere with hormonal functions. Exposure to endocrine disruptors is especially worrisome for fetuses, infants, and small children. The question is whether the levels of BPA to which we are typically exposed have adverse health effects.

Most of the research on BPA has been "test tube" or animal studies, augmented by human observational studies. While not always consistent, the research suggests that BPA exposure in the womb and in infancy, even at very low levels, causes cel­lular changes that may have many long-term consequences, such as developmental, reproductive, and behavioral problems, altered immune function, increased body fat, and early puberty—and possibly even adverse effects in adulthood. Notably, sev­eral recent studies have linked high prenatal or early childhood BPA exposure to an increased risk of childhood asthma.

Many (though not all) observational studies, following up on lab research, have found associations between elevated BPA in people (as measured in urine or blood) and dozens of disorders—from cardiovascular disease, elevated blood pressure, obesity, type 2 diabetes, reproductive problems, and prostate cancer to sexual dysfunc­tion and impaired immune, liver, kidney, and thyroid function. For instance, a 2014 study in PLOS ONE found that men with prostate cancer had higher levels of urinary BPA than men without cancer.

Of course, what happens in test tubes and lab animals may not occur in people, and observational studies don't prove that BPA causes health problems. For instance, elevated BPA levels may simply be a marker for increased consumption of less-healthful packaged foods and higher calorie intake (though researchers usually adjust for such factors) or for expo­sure to other hormonally active compounds that may be the main culprits.

BPA and Endocrine Disruptors

Bisphenol A (BPA) is one of many known or suspected "endocrine disruptors"—compounds that mimic or interfere with estrogen and other hormones. But it's hard to assess their health effects precisely because we're exposed to so many of them.

Moreover, the presence of BPA in urine doesn't necessarily mean it is harmful. BPA is rapidly metabolized to an inactive form and excreted from the body, which has led some scientists to question the proposed risks or at least the significance of one-time testing. In addition, most research has looked at urinary levels of BPA rather than blood levels; the latter are a more important measure of exposure and potential risk. Finally, there's much debate about which cutoffs for BPA exposure (and for urinary and blood levels of the chemical) should be used by regulators.

How BPA gets into your body

Polycarbonate plastic. Since the 1960s, BPA has been used as a hardener in countless hard lightweight polycarbonate plastic products. Polycarbonate is still used for many hard reusable food containers and other consumer goods; they may be marked "PC." The recycle number "7" in a triangle usually (but not always) indicates polycar­bonate. Note: Disposable plastic water, soda, and juice bottles are typically made from polyethylene (PETE, identified by the number "1" on the bottom) and do not contain BPA.

Cans. BPA is used in the epoxy resin that lines most food and beverage cans to prevent cor­rosion; trace amounts can migrate into the foods and beverages they contain. Acidic foods, such as tomatoes, cause more leaching of BPA from cans than other foods. A Harvard study in the Jour­nal of the American Medical Association found that people who ate 12 ounces a day of canned soup for five days had a 10-fold increase in urinary BPA levels, compared to when they ate fresh soup.

Similarly, in a Korean study in the journal Hypertension, older women who drank two cans of soy milk had a 16-fold increase in urinary BPA two hours later, compared to when they drank the same amount of soy milk from glass bottles. What made headlines was that the women also had higher systolic blood pressure after they drank from the cans than when they drank from bottles. Actually, soy milk low­ered blood pressure whatever the container, but the drop was smaller (3 vs. 8 points) when the women drank from the cans.

Thermal paper. This thin smooth paper is coated with heat-activated printing developers, usually either BPA or the related chemical BPS (see "Are BPA Substitutes Safe?", above). Such paper is used for many kinds of receipts (notably from cash registers, ATM machines, gas pumps, and credit card terminals) and tickets (for airlines, movies, or lotteries, for instance). You can tell it's thermal paper if scratching the printed side pro­duces a dark mark.

The BPA on the surface of thermal paper is in the free form so it easily rubs off on your hands and can then get on food you handle. It can also be absorbed through the skin, which may be more dangerous than oral absorption because the BPA would enter the circulatory system and go directly to tissues before being metabolized in the liver. A small study in the Journal of the American Medical Association found that when people handled thermal receipts for two hours, urinary BPA increased three- to five-fold over 24 hours. This is obviously a concern for cashiers and others who han­dle the paper frequently at work.

But even briefly handling thermal paper may be a problem under some cir­cumstances. This was seen in a series of small experiments done at the University of Missouri and published in PLOS ONE, which got lots of press. In one test, participants held thermal paper for up to four minutes either with dry hands or with hands wet with an alcohol-based sanitizer. About 100 times more BPA was trans­ferred to the wet hands (almost none to the dry hands).

Then in what might be a worst-case sce­nario—though one that may occur in a fast food restaurant—some participants used the hand sanitizer, immediately handled thermal receipts with wet hands, and then ate French fries. This led to a dramatic increase in skin and oral absorption of BPA in most of them (especially the women), as seen in urine and blood tests over the next 90 minutes.

Why did hand sanitizer worsen mat­ters? Like some other skin care products, such as moisturizers and sunscreens, it con­tains chemicals that enhance penetration of accompanying ingredients through the skin. Thus the sanitizer, especially because it was still wet, greatly increased the trans­fer and absorption of BPA. Some experts criticized the study for not testing what would have happened if the sanitizer had been allowed to dry (as instructions on products advise). Clearly, less BPA would have been transferred from the receipts and then absorbed.

Dental materials. Traces of BPA are found in some dental sealants and resin composites (called bis-GMA and bis-DMA) used for fillings, which have been replacing silver amalgam fillings. Studies have found elevated BPA in saliva and urine in the hours after people get new composite fillings. There’s some concern that BPA can also be released when these materials undergo wear and tear. At least two studies have found that children with BPA-containing composite fillings are at elevated risk for behavioral problems.

On the other hand, some research has found that the amount of BPA released from these composites is minuscule com­pared to various proposed daily exposure limits. The American Dental Association states that such levels of BPA are extremely low and "pose no known health threat."

There are potential safety questions about nearly every new dental material, but that shouldn't keep you from getting the den­tal restoration work you need. Still, to err on the side of caution, pregnant women should probably minimize elective restorations.

Government Agencies' Take on BPA

In contrast to some consumer advocacy groups that warn about bisphenol A (BPA), most government agencies con­tinue to be reassuring about the safety of this industrial chemical.

Containing the risk

Given all the concerns about BPA, what's a consumer to do? Keep in mind that much about BPA remains unknown and uncer­tain, and that it is just one of many poten­tially problematic chemicals in consumer products. Still, limiting exposure makes sense, especially for young children and pregnant or breastfeeding women.

Here are steps you can take to reduce your exposure to BPA:

  • Instead of polycarbonate bottles and food containers, use glass, stainless steel, or aluminum. Or look for other, presumably safer, plastics, such as polyethylene.
  • If you do use polycarbonate contain­ers or are not certain what type of plastic they are made of, do not put very hot food or boiling liquid in them, since that can cause the plastic to break down and greatly increases the release of BPA, even during subsequent uses. Similarly, do not put the containers in the dishwasher; wash them by hand with mild detergent and warm water. Do not microwave plastic containers unless they are labeled microwave-safe.
  • Limit your intake of canned foods. When possible, opt instead for foods in jars or cartons or, better yet, fresh or frozen food. This will reduce your exposure not only to BPA but also to other chemicals that can migrate into foods and beverages. Some companies have switched to "BPA-free" cans, but the replacement chemicals may not be better. However, if avoiding BPA leads you to eat less of the healthful foods you usually buy canned (like fish or beans), that's a bad tradeoff. If you are feeding a baby, pow­dered infant formula is a safer choice than canned liquid formula, unless you know the cans contain no BPA or BPS (talk to your doctor before changing formula).
  • If you handle thermal paper receipts, wash your hands with soap and water after­wards, especially before handling food. Or don’t take the receipts if you don't need them. If you do keep them, put them in an envelope or plastic bag, not in your pocket or purse, where the BPA can rub off on other items. To be on the safe side, the receipts should be kept away from small children, and pregnant women should handle them as little as pos­sible. Most important, don't touch thermal receipts right after using alcohol-based hand sanitizer or hand lotion—or even if your hands are greasy or wet with water. If your job requires frequent contact with thermal paper, wear disposable gloves.