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Thursday
Jan162014

Concerns Over Cans and BPA

BPA, or bisphenol A, is an industrial chemical used in polycarbonate plastics and epoxy resins that has come under scrutiny for potential harmful health effects. Developed as a synthetic estrogen in the 1890's and granted "GRAS" (generally recognized as safe) status by the FDA in 1963, it is widely present in both food packaging, such as aluminum can linings, and nonfood materials, such as medical devices, paper receipts, and printer toner. Six million tons are produced yearly. Concern about BPA lies in its possible action as an endocrine disruptor. This is a category of chemicals that can alter normal hormone-dependent physiology. Small amounts of BPA leach from containers into the foods and beverages that they hold, especially when those contents are acidic, high in fat, or heated (like canned tomatoes, Chef Boyardee, and warmed baby formula, respectively).

It's hard to avoid BPA. In fact, the CDC has documented its presence in the urine in 93% of Americans older than 6 years of age. [1] Less clear are the actual health effects of BPA exposure. Up until recently, research consisted mostly of lab animal and in vitro studies. In the past year, however, the number of epidemiologic studies exploring the effects of BPA exposure in humans has doubled. A recent review of this literature supports associations between BPA exposure with decreased fertility, altered male sexual function, childhood neurobehavioral problems and asthma, cardiovascular disease, and type 2 diabetes. [2]  

Significant questions remain. Does adult BPA exposure matter, or is childhood and fetal exposure what's critical? Since BPA has a short 6-hour half-life in humans, how can we determine longer term exposure? Without the type of controlled studies that would be obviously unethical, particularly during pregnancy and over large swaths of time, is it possible to assess causation versus correlation? How do we quantify and define "low dose" exposure?  [3] Some researchers say the "low doses" associated with toxicities are still much greater than humans are exposed to in practical terms, whereas others believe "low doses" may be more harmful than higher amounts and that dose-response isn't demonstrable. [4]

As consumer awareness and demand grow, BPA-free food packaging is increasing. Alternative can linings, such as polyester coatings, have been developed, but their safety is not certain, either. One promising technology is oleoresins, which are made from natural plant sources, but they can be used only with non-acidic foods. 

Some brands have eliminated BPA from all or some of their cans. Amy's Kitchen has eliminated BPA in all cans. Eden Foods canned beans are BPA-free. Whole Foods states that 27% of their canned goods are BPA-free, but don't specify which. They do report that they will no longer accept new canned products that contain BPA.

Glass jars and Tetra-paks (boxes) are a viable option, particularly for acidic foods. Eden Foods offers crushed tomatoes in glass jars, Bionaturae makes tomato paste in glass jars, and Pomi makes chopped tomatoes in Tetra-paks. Many brands of tomato sauces are available in jars, and Hunts now sells tomato sauce boxes.

Broths and soups are widely available in Tetrapaks. Pacific Natural and Imagine Foods make many options from potato quinoa spinach soup to chicken stock to vegetarian pho base.

If you do use canned foods, rinsing the food well with running water may decrease ingestion of BPA.

Of course, the surest way to minimize dietary BPA intake would be to avoid all packaged foods. More realistically, work toward limiting canned goods and choosing more fresh, frozen, or dried foods. If you have more fresh vegetables than you know what to do with (including broccoli, green beans, cauliflower, zucchini), steam them lightly and then freeze them in glass jars. Dried beans can be prepared in large batches and frozen for future use. Look for pre-cooked frozen beans such as lentils, garbanzos, and soy beans. Frozen vegetables and fruits are wonderful alternatives to fresh, are just as nutrient-rich, and contain less sodium and added sugar than canned. As for canned soda… well, do you really need another reason to avoid it? 

Cans aside, lessen BPA exposure by using glass or ceramic instead of plastic in the microwave, keeping plastic water bottles away from extremes of temperature (eg, the dishwasher) and direct prolonged sunlight, and replacing plastic containers that become cracked or chipped. 

As always, consider the big picture. If your workday lunch options are a quick greens salad with canned artichokes and beans—or fried chicken and Doritos—the choice should still be obvious. Minimize BPA cans where you can, but use your own judgment in making sound, healthy choices. 

 

1. Calafat A, Ye X, Wong L, Reidy J, Needham L. Exposure of the US population to bisphenol A and 4-tertiary-octylphenol: 2003-2004. Environ Health Perspect 2008;116:39-44.

2. Rochester JR. Bisphenol A and human health: A review of the literature. Reprod Toxicol 2013;42:132-55.

3. Teeguarden J, Hanson-Drury S. A systematic review of Bisphenol A “low dose” studies in the context of human exposure: A case for establishing standards for reporting “low dose” effects of chemicals. Food Chem Toxicol 2013;62:935-48.

4. The National Workgroup for Safe Markets. No silver lining: an investigation into bisphenol A in canned foods, 2010.

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