Curb Exposure to BPA and Phthalate Through Diet
by Sarah (Steve) Mosko, PhD
- E-Magazine as “You Are What You Eat: Reducing chemical exposures through diet,” Sept/Oct 2011
- Surf City Voice, 17 June 2011
Endocrine disrupting chemicals (EDCs) are synthetic substances known to play havoc with hormone and organ systems in lab animals, and it’s well-documented that the urine of most Americans tests positive for an alarming number of them. EDCs are found in a wide array of everyday consumer products and also find their way into air, dust and even foods.
A new study confirms for the first time that dietary practices – like whether you select fresh versus canned fruits & vegetables, microwave foods in plastics, or drink from plastic bottles – have a rapid and hefty impact on one’s body burden of at least two EDCs known to interfere with normal organ development in animals and maybe humans: bisphenol A (BPA) and di-ethylhexyl phthalate (DEHP).
BPA is a key component of shatter-proof polycarbonate plastic items, like many personal sports bottles or 2-5 gallon water bottles, as well as the epoxy lining of canned foods and soda. BPA is known to migrate into the contents of such containers, and it is well-established that BPA mimics the hormone estrogen.
A large body of evidence pointing to a possible role of BPA in such diverse medical conditions as obesity, diabetes, infertility and breast & prostate cancers has led to legislation in a number of states to reign in human exposure, especially in infants and young children who are thought to be most vulnerable to developmental derailments from EDCs. In the European Union, BPA is classified as a reproductive toxicant.
DEHP is another EDC produced in high volume and found in many consumer goods, including food packaging like some food wrap films. It is commonly used as a softening agent in plastics made of polyvinyl chloride, and because it is not chemically bonded to the plastic polymer, it too is free to migrate out during routine use.
Effective 2009, the U.S. federal government banned the use of DEHP (and other phthalates) in children’s toys and child care products, and several states have passed similar restrictions to reduce exposure in youngsters based on research showing that DEHP can inhibit testosterone synthesis and might disrupt the development of the male sexual tract and impair semen quality.
While most research on BPA and DEHP has, by necessity, been conducted on lab animals – leaving the impact on humans uncertain – it is appropriate that health-conscious consumers and parents have an interest in limiting their own and their families’ exposure to known EDCs while scientists sort out the actual threat to humans.
BPA and DEHP are well-suited for a study of how dietary choices impact human exposure to EDCs because both can be monitored through the urine. Furthermore, their biological half-lives (a measure of how quickly the body gets rids of them) are short enough that the effects of a manipulation should show up in the urine within a few days.
Researcher Ruthann Rudel of the Silent Spring Institute in Massachusetts headed the study which followed five families of four (two parents and two children each, aged 3-12 years) during a three-day dietary intervention designed to eliminate obvious food-related sources of BPA and DEHP. Exposure levels to BPA and DEHP were determined for a few days just before, during and right after the three-day intervention by measuring BPA and the breakdown products (i.e. metabolites) of DEHP in daily urine samples.
The families were all from the San Francisco area and were selected based on the likelihood that they were being exposed to BPA or DEHP in their usual diet by way of consuming canned foods/sodas or at least two of the following: drinking from personal water bottles or 2-5 gallon polycarbonate bottles in office coolers; microwaving foods in plastic; or eating restaurant food.
Families maintained their usual eating habits for two days before and for three days after the intervention period. During the intervention, they ate a uniform menu from a caterer who prepared meals from fresh and organic fruits, vegetables, grains and meats and without use of plastic utensils or non-stick cookware. Glass storage containers were used in which microwaving was allowed too, but only after the plastic lid (non-BPA) had been removed.
Coffee made with a French press or ceramic drip was allowed but not from a plastic coffee maker or from a café.
Because there was considerable person-to-person variability in the baseline concentrations of the EDCs detected in the urine samples, the researchers arrived at an estimate of the “typical” level by using a conservative measure of the group’s “average” called the geometric mean which is designed to compensate for such variability.
The most impressive findings of the study were that, during the intervention, BPA in the urine of adults and children fell by about two-thirds and the metabolites of DEHP were reduced by more than half. The individuals whose exposure to BPA and DEHP was highest while eating their routine diet showed the greatest drops during the intervention.
BPA in the urine reverted back to nearly pre-intervention levels as soon as families were free to resume their usual diets, and the metabolites of DEHP also rose again within a few days but not yet to the point of a statistically significant difference at the time of the final urine collection.
The upshot of this study is that food ingestion seems to be a major source of human exposure to BPA and DEHP and, because the body is able to eliminate these chemicals in a matter of days, moving to a “fresh foods” diet can have a pretty rapid and measureable impact. The study authors surmised that plastic food packaging and restaurant meals were the most likely dietary sources of BPA and DEHP for the participants in their study.
Perhaps the other take home message is that the old adage “you are what you eat” still holds but with the unhappy twist that, because synthetic chemicals have come to define most aspects of everyday modern life, unless you choose foods mindfully you’re probably eating plenty of questionable stuff you didn’t bank on.
The study was published in the online 30 March 2011 issue of Environmental Health Perspectives. For six easy steps to avoid BPA and phthalate in foods, visit The Silent Spring Institute