By Jennifer Ruffing
Bisphenol A, commonly referred to as BPA, is a clear, odorless, organic compound derived from petrochemicals that is used to make polycarbonate plastics and epoxy resins. It is widely used in food containers in its polycarbonate form and used as an epoxy liner in canned foods and beverages. If you have consumed canned foods or beverages (with a few notable exceptions), you've been exposed to BPA.
In my opinion, BPA in canned foods is the most pernicious source of this plasticizer, as heating the cans during the canning process causes the chemical to leach out in greater quantity than if it had not been exposed to heat. As reported by CBS News1, a study published in the Journal of American Medical Association found that "people who consumed one serving of canned soup a day for five days had a more than 1,000 percent increase in urinary BPA over people who consumed fresh soup for five days." Granted, the study used one brand of soup, Progresso, and had a cohort of 75 volunteers. Still, it's probably fair to extrapolate the data and assume that any canned food with BPA in the liner that has been exposed to heat during the canning process will deliver a whacking great dose of the chemical.
Why not consume BPA? BPA is what's known as an endocrine disrupting chemical (EDC), interfering with the body's system of hormone-secreting glands and cellular receptors that regulate many internal functions. One way that BPA does this is by acting as an estrogenic chemical in the body, meaning that it mimics naturally occurring estrogen. Estrogen is dandy stuff, in the quantities that the average human body produces naturally. Even males have some natural estrogens floating around. But exposure to amounts coming from outside the body sends an overwhelming message to your estrogenic receptor sites and causes your body to react in harmful ways. Estrogenic chemicals can contribute to increasing breast cancer and testicular cancer rates and obesity (feed lot cattle are dosed with estrogen to promote weight gain). While BPA has been identified as an EDC, I believe that further studies will prove that other plasticizers will be endocrine disrupting as well (I'm looking at you, phthalates).
A recent study from Spain2 has highlighted the direct effect of BPA on humans. To quote the authors, "Our findings suggest that BPA behaves as a strong estrogen via nuclear ERβ and indicate that results obtained with BPA in mouse β-cells may be extrapolated to humans. This supports that BPA should be considered as a risk factor for metabolic disorders in humans." After some well-controlled messing about with mice, proving the deleterious effects of BPA in mouse tissue, the study's authors went on to replicate their findings in humans. They found that the amount of BPA normally found in humans caused nearly twice the insulin release in human pancreatic tissue: "The action of 8 mM glucose was enhanced almost two fold by the presence of 1 nM BPA." That's a very large increase, and does point the finger at BPA as a cause of obesity, type II Diabetes, and the kind of vascular degradation responsible for heart disease and strokes. Adipose tissue stores fat in an insulin dose-dependent fashion. That means if more insulin is present, more fat will be stored. That's why one of the symptoms of diabetes is unexplained weight loss — no insulin means no fat storage. It would be an easy way to diet if it also didn't wreak havoc on the body's vascular systems.
What can average consumers do to protect themselves against these harmful chemicals? Food manufacturers have been very coy about the presence of BPA in their products. As a shopper, I've noticed that baby food manufacturers have trumpeted the lack of BPA in certain plastic containers, while not addressing that canned formulas still are exposed to BPA in the can liner. All soda cans have BPA liners. So, even though aluminum is easier to recycle than plastic, I've switched to plastic soda bottles when having a soda not available in glass.
I would also recommend talking to food producers about their canning practices. I recently called Eden Foods and asked them about BPA in their canned foods. They openly state that their canned tomatoes still contain some BPA in the epoxy liner, because of the acidic nature of tomatoes, but that their other canned foods are BPA-free. They use an "oleoresinous c-enamel" that is derived from plants. Both Muir Glen and Tuttarosso canned tomato products have epoxy liners that leach detectable amounts of BPA into the contents of the can.
There are other measures consumers can employ to protect themselves from estrogenic or other endocrine-disrupting chemicals in their food. The best method is to be old-fashioned about food — look for canned foods in glass jars, just like your grandparents used to put up. A few food manufacturers are offering foods in glass jars, even though there's an increase in transport cost due to breakage and weight – glass is heavy stuff. Avoid foods wrapped in plastic. Most plastic wraps used today do not contain BPA, but manufacturers use a host of other plasticizers to make plastic wraps flexible. The precautionary principle would lead me to suspect all food-grade plastic to be capable of creating hormonal harm when its chemical components leach into food and are ingested. In other words, guilty until proven innocent, especially if the plastic has been exposed to heat and/or acids in the food preparation process.
Granted, this cuts out a lot of foods in the modern American diet. Most processed frozen meals are packed and then cooled in their little plastic trays (heat exposure), and most fast foods are intimate with plastic food containers in at least one stage of their production. I do have to acknowledge plastic's role in contributing to food safety in that it has helped to prevent a lot of food spoilage. But now that we know more about the hormonal havoc that plasticizers can wreak in our bodies, we need to minimize risk. This article is too short to detail the ways plasticizers in our air and water have contributed to other species' hard times, but these risks are clear and documented.
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