To raise awareness of the particular dangers posed by BPA to children, the San Francisco-based Breast Cancer Fund (BCF) tested 12 canned-food items aimed at and consumed by children for the presence of the chemical, known to leach from the lining of food cans into the product inside. They found detectable amounts of BPA in every single sample tested, with Campbell's Disney Princess and Toy Story soups having the highest levels (www.breastcancerfund.org/asset/pdfs/publications/bpa-in-kids-canned-food.pdf).
Although the sample was small and limited to products sold in the US, recent studies suggest that BPA contamination of food is a global concern, with children everywhere consuming possibly harmful levels of this toxic chemical every day. Indeed, even minute levels of the chemical have been linked to a host of health effects, including abnormal reproductive development, aggressive behaviour and certain cancers.
In the BCF investigation, two cans each of six different canned-meal items-such as soups, ravioli and noodles-were sent to an independent lab for analysis. All products had been purchased from current stocks at regionally well-known grocery outlets in the Bay area and also in the greater Milwaukee, WI, metropolitan area; all products were well within their 'best-before' dates.
The results revealed BPA levels ranging from 10 parts per billion (ppb) to 148 ppb, with an average level of 49 ppb. These data are consistent with the results of a recent BCF review of previous BPA studies in the US and Canada, testing nearly 700 foods and beverages (www.breastcancerfund.org/assets/pdfs/publications/what-labels-dont-tell-us-1.pdf), which found that soups contained an average of 69 ppb of BPA, while meals averaged 36 ppb. Now, in the current report, the soups averaged 77.5 ppb and meals averaged 21 ppb. The Environmental Protection Agency (EPA) estimates a safe exposure level of 50 ppb/day.
The authors of the new report say that the levels of BPA discovered in the child-friendly canned foods are of great concern. "While a child-sized serving may result in BPA exposure at a level of concern, an adult-sized serving given to a child would result in even higher BPA exposure," they said, pointing out that the labels on the tested cans recommended serving sizes based on adult caloric intakes. What's more, the authors noted that pairing the foods tested with other canned goods such as fruits or vegetables, as if often the case, would lead to even higher BPA exposure.
Consuming canned goods beyond a single serving on a regular basis, they warned, could lead to the levels of BPA associated with numerous health effects, such as abnormalities in breast development, and a higher risk of breast and other cancers, as well as adverse effects on brain and reproductive development, puberty onset, body weight and gender-related behaviours.
BPA and its health effects
The evidence has been stacking up for some time now that BPA is a potent hormone-disrupting chemical with damaging effects on the body-even at miniscule concentrations.
According to the US public-health and environmental watch-dog, the Environmental Working Group (EWG), whose own investigations have detected BPA in the majority of canned foods tested, "[F]ew chemicals have been found to consistently display such a diverse range of harm at such low doses".
In one recent review, researchers Dr Frederick vom Saal, at the University of Missouri, and Dr Claude Hughes, at East Carolina University in NC, found over 90 studies-albeit in animals, so the findings may not necess-arily apply to humans-confirming BPA toxicity at surprisingly low doses. In 31 of the studies, "significant effects" were seen with exposures below the supposedly 'safe' or reference dose of 50 mcg/kg/day.
At some of the lowest doses, BPA caused permanent changes in breast and prostate cells that can lead to cancer, insulin resistance (a hallmark of type 2 diabetes), chromosomal damage linked to recurrent miscarriage and a wide range of birth defects, including Down's syndrome.
The scientists also noted that "rate of growth and sexual maturation, hormone levels in blood, reproductive organ function, fertility, immune function, enzyme activity, brain structure, brain chemistry, and behaviour are all affected by exposure to low doses of BPA", as demonstrated in a wide range of laboratory animals (Environ Health Perspect, 2005; 113: 926-33).
Interestingly, where traditional toxicology asserts that the higher the dose, the greater the harm, BPA tests show that low doses may be the most toxic of all. In one laboratory test, a low dose of BPA produced a 70-per-cent higher growth rate in human prostate cancer cell cultures vs higher doses (Molec Cancer Ther, 2002; 1: 515-24). A possible explanation is that such minute doses of BPA fall below the 'radar' of the body's own natural detoxifying mechanisms, thereby allowing more damage to be done.
BPA and children
A handful of human studies support the worrying animal and test-tube evidence of BPA effects. In women, higher blood levels of the chemical have been linked to polycystic ovarian syndrome (Endocr J, 2004; 51: 165-9), recurrent miscarriage (Hum Reprod, 2005; 20: 2325-9) and complex endometrial hyperplasia-where the womb lining becomes thickened-a condition generally considered a precursor of endometrial cancer (Endocr J, 2004; 51: 595-600). In men, BPA exposure has been associated with poor sperm quality (Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi, 2009; 27: 741-3).
However, fetuses, infants and young children are the most vulnerable to BPA toxicity, as their still-developing brains and other organs are especially sensitive to chemical exposures (Philos Trans R Soc Lond B Biol Sci, 2009; 364: 2079-96). Any disruption of their hormonal systems during critical developmental stages can cause permanent changes and set the stage for later-life diseases.
In one of the latest BPA studies, researchers found that the sons of Chinese workers exposed to BPA during pregnancy had a shorter distance between their genitals and anus-or anogenital distance (AGD)-compared with boys whose parents were not exposed to BPA in the workplace. A shorter AGD has been linked to infertility, and to lower sperm counts and quality (PLoS One, 2011; 6: e18973).
The association between maternal BPA exposure and AGD was particularly strong, and showed a dose-response relationship-the greater the BPA exposure during pregnancy, the shorter the boy's AGD (Birth Defects Res A Clin Mol Teratol, 2011; 91: 867-72).
According to lead investigator Dr D.K. Li, "This finding indicates that BPA may interfere with testosterone function during fetal development because the shortened AGD indicates under-developed male genitalia, likely due to an abnormal testosterone function."
One US study has linked prenatal BPA exposure to early childhood behaviours. Data from 249 mothers and their children revealed that women with higher concentrations of BPA in their urine during pregnancy were more likely to have hyperactive and aggressive two-year-olds. The association was especially strong in girls, whose behaviour appeared to be more like that of boys at that age (Environ Health Perspect, 2009; 117: 1945-52).
Early life exposures to BPA
may also have an effect on the developing immune system. US researchers found that the urinary BPA levels in children at ages 3 and 7 years were associated with increased odds of asthma. These results add to an earlier, animal study which reported that maternal BPA exposure triggered experimental asthma in mouse pups (Environ Health Perspect, 2010; 118: 273-7).
Such damning evidence-and particularly concerning its effects in children-has led a number of regulatory authorities around the world to ban the sale of baby bottles, sippy cups, and other re-usable food and drink containers that contain the chemical. However, there are no such regulations for BPA use in food-can linings.
BPA in can liners create a barrier between the metal and the food to protect against bacterial contamination. However, as the latest BCF investigation shows, BPA leaches from the can lining into the food inside. Similar findings have been reported by the US Food and Drug Association (FDA), which recently reported detectable levels of BPA in 71 of 78 popular canned foods (J Agric Food Chem, 2011; 59: 7178-85), while the UK's Food Standards Agency found BPA in 37 of 62 canned items (Food Addit Contam, 2002; 19: 796-802).
Happily, some manufacturers have started to replace BPA or are, at least, looking into alternatives. US company Eden Foods, for example, began moving away
from BPA in 1999, and now uses what was used in cans long before BPA was introduced. This lining, made of oleoresinous c-enamel, is a combination of oil and resin extracted from various plants such as pine and balsam fir.
But not all companies are as transparent about what alternatives they're using. As the BCF points out, "switching out a chemical we know is harmful for one that's unknown and untested is not the solution customers are looking for."
A far safer solution is to avoid canned foods altogether and opt for fresh food wherever possible. Indeed, a recent study by the BCF and the Silent Spring Institute in Newton, MA, looked at the impact of swapping canned or plastic-wrapped foods for fresh food on BPA levels. Participants ate their usual diet, followed by three days of fresh foods, and then returned to their usual diet.
During the fresh-food stage, BPA levels dropped by an average of 66 per cent whereas, on return-ing to their normal diets, BPA levels reverted to pre-intervention levels (Environ Health Perspect, 2011; 119: 914-20).
So, as eating canned or plastic-wrapped food is a major source of BPA expo-sure, switch-ing to fresh food should help to reduce the risk of serious health issues.
Factfile: BPA body burden
Manufacturers and regulatory agencies defend the use of BPA by claiming that it's rapidly and efficiently cleared from the body. But a ground-breaking new study suggests otherwise.
Researchers at the University of Missouri analyzed BPA concentrations in mice given a steady diet supplemented with BPA throughout the day-a situation designed to mirror real-world exposures-and compared the results with BPA levels in mice given a single (bolus) exposure, the more usual test method. What they found was an increased uptake and accumulation of BPA in the mice fed BPA throughout the day.
"Our data may explain how, although humans can rapidly eliminate BPA when it is provided as a single bolus, continuous external BPA exposure appears to lead to sustained concentrations that are detectable in serum or plasma of humans who have not been knowingly exposed to this endocrine-disrupting chemical," the researchers said (Environ Health Perspect, 2011; 119: 1260-5).
WDDTY VOL 22 NO 8