BISPHENOL-A (BPA) everywhere? no, but here’s a list…

Not to be an alarmist, but the more research I do on the topic of human exposure to bisphenol-A (BPA), the more concerned I have become.   The list of potential exposures is long, but we certainly have a choice to limit these.  And as consumers, we must make our preferences known to lawmakers and manufacturers.  Unfortunately, the FDA opted not ban the use of BPA in food packaging on 3/30/12, but stated that they will continue to evaluate the risks of BPA to human health.

Here’s a list of the most common (known) sources of BPA:

CANNED FOOD –most canned food has lining containing BPA; more manufacturers are starting to use BPA free cans (see Mark’s Daily Apple for specific brands); canned food is considered a significant source of BPA

THERMAL PAPER RECEIPTSeg. ATM, gas station, store receipts; large amount of BPA–in the order of 60-100mg, as opposed to nanogram amounts leached from polycarbonate bottles!

POLYCARBONATE BOTTLES  (labeled #7 or #3)–including water coolers at work, older Nalgene water bottles (newer Nalgene and Camelbak bottles are BPA free)

SODA AND BEER CANS –BPA is particularly soluble in alcohol, so opt for bottled beer

METAL WATER BOTTLES–such as Sigg (prior to their admission of BPA lining and exchange program in 2008/9);  Kleen Kanteen has no BPA and Sigg’s newer containers are BPA free

TUPPERWARE  (if labeled #7)

PLASTIC WRAP –no pthalates since 2006; now made with LDPE, which has fewer contamination concerns; best not to microwave.

BABY BOTTLES and PACIFIERS –look for BPA- free bottles and pacifiers; some states have outlawed the use of BPA in baby bottles (as have other countries including Canada, EU, United Arab Emirates, China, Malaysia)

DENTAL SEALANTS and FILLINGS (see post BPA and sealants)

MOUTHGUARDS  (check w/ manufacturer)

PIZZA BOXES –many are made from recycled newspaper and receipts, which both contain BPA

Here are some helpful resources:

http://www.marksdailyapple.com/are-your-canned-foods-safe-to-eat-a-bpa-free-buying-guide/#axzz1rlCNu5Kf

http://www.ewg.org/bisphenol-a-info

http://healthychild.org/blog/comments/how_to_avoid_the_sneakiest_sources_of_bpa

http://www.cleveland.com/healthfit/index.ssf/2012/01/top_bpa_sources.html

 

 

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Bisphenol-A (BPA) and dental sealants

This is a tough one.  Right now I can tell you I have no easy answer for anyone out there worrying about the potential health risks of dental sealants and composite filling materials due to Bisphenol-A (BPA) exposure.  I would highly recommend reading an article from 2010 reviewing this topic in Pediatrics (available free online http://pediatrics.aappublications.org/content/early/2010/09/06/peds.2009-2693).  Even if you have no medical background, this article summarizes the findings thus far in easy to understand terms (just ignore the chemical structures if you prefer).

Having discussed some of the evidence supporting my concerns surrounding BPA in another post, I will focus on dental sealants and filling materials in this post.  Because the greatest potential risk for exposure to BPA is in infants, small children and fetuses, the idea of using a plastic that can leach BPA for an elective procedure seems unsettling to many.  Dental resins (such as bis-DMA and bis-GMA) are primarily composed of BPA derivatives, and hydrolyzed by salivary enzymes into BPA.  Studies thus far have only detected spikes of BPA in patient saliva (not blood) immediately (<3 hrs) after a dental procedure.  The studies have shown conflicting patterns, possibly due to differences in assays (testing methods) used.  Most studies have shown that bis-GMA does not hydrolyze into BPA, but bis-DMA does.  It is important to ask your dentist about the specific components of the dental sealant or composite filling material–though some sealants have a combination of ingredients such as BPA ethoxylate dimethacrylate (bis-EMA)  and other urethane-modified bis-GMA, that may have some estrogenic activity but have not been investigated.  Table 1 in the Pediatrics article summarizes sealant components for 90% of the US Market.

Since there is so much uncertainty regarding this topic, it is best to proceed with common sense and use your best judgment.  Ask yourself these questions:  What are the risks for development of dental caries (be realistic)?  If you or your child will need dental repair of cavities, what will be the exposure to BPA at that point? (likely greater than with sealants)  Also consider that since >93% of the US population has measurable urinary BPA (presumably due to food packaging, other daily exposures), how bad is a one time spike in salivary BPA relative to a longer term exposure?  It is believed that BPA has a short half-life and is quickly removed from the body, though the metabolism of BPA is still under investigation.  Precautionary measures can reduce dental exposure to BPA:

1) Choose a bis-GMA sealant if possible–see Table 1 from Pediatrics article.  Keep in mind that there is still a great deal of uncertainty regarding other monomers used in sealants and fillings.

2) Avoid resin placement if pregnant or nursing (if necessary, use precautions to contain saliva that may contain BPA, see below)

3) Gargle water for 30 seconds after resin placement (other measures to reduce exposure to BPA:  rub sealant surface after application with cotton ball & pumice, rinse with an air-water syringe, use a rubber dam during application)

Most dentists are familiar with this topic and should be able to answer the questions you may have about sealants/fillings and exposure to BPA.

BOTTOM LINE:  My children have dental sealants as do I.  I’m just crossing my fingers…

Bisphenol-A (BPA)

Human exposure to Bisphenol-A (BPA) has caused a great deal of alarm in the popular media as well as the scientific community.  Surveys have shown that >93% of the US population has measurable levels of BPA metabolites in their urine—likely due to exposure from food (canned goods), water (PVC pipes), copy paper (cash register receipts), and dental materials.  It was previously thought that BPA is rapidly metabolized and excreted from the body, but the pharmacokinetics are not entirely clear—and now it is thought that low levels of BPA may be stored in and released from our adipose tissue (fat cells).

Why the concern about BPA?

Numerous animal studies have demonstrated effects of BPA on different tissues—breast tissue growth, neuroblastoma development, neurobehavioral changes,  dopaminergic system changes, thyroid dysfunction, testicular cancer, prostate cancer, reproductive disorders, and many others.  In vitro studies have also shown similar estrogenic effects to cell lines exposed to BPA and its derivatives.   Epidemiologic studies indicate a causative link between occupational BPA exposure and polycystic ovary syndrome (PCOS) in women, low follicle- stimulating hormone (FSH) levels in men, high testosterone levels in men and women as well as chromosomal defects and low birth weights due to prenatal exposure to BPA.  One large study revealed that  BPA may be associated with increased risk for cardiovascular disease, elevated liver enzymes and diabetes.  Considering the widespread exposure of the US population to BPA and BPA derivatives, these findings are greatly concerning.

Why the controversy?

Thus far, the study of BPA and human health has been limited—though several in vitro and animal studies have shown a clear correlation between BPA and hormonal disruption, demonstrating its estrogenic effects.  Several scientific panels (EU and US) have evaluated the current data and have come to a consensus that there is “some” concern for neural, behavioral and hormonal effects on humans at current levels of exposure, particularly for fetuses, infants and small children.  This unfortunately has been insufficient to sway large corporations to alter their use of BPA in food manufacturing or the FDA to approve a ban on the use of BPA in food packaging (rejected 3/30/12).  Several states in the US (as well as Canada, EU, China, United Arab Emirates) have banned the use of BPA in baby bottles.  BPA has been used since the 1940s to harden plastics and to manufacture the epoxy resin that lines food and beverage containers, and in countless other products.  An  estimated six billion pounds of BPA are produced globally each year, and can enter the environment by leaching from plastic and metal waste in landfills as well as ocean-borne plastic trash.  Some industry groups argue that the low level of BPA exposure is below a threshold, and is not necessarily a cause for alarm.  Current research does show, however, that even low doses of this estrogenic compound can have adverse effects on human health—and some scientists recommend lowering the EPA’s reference range for “acceptable exposure” to <10 micrograms/kg body weight (currently 50 micrograms/kg).

BOTTOM LINE:  I personally limit BPA exposure by avoiding canned food (or using BPA free cans such as Eden Foods), using BPA free water bottles (such as Kleen Kanteen or Nalgene BPA free) and crossing my fingers with regard to my dental sealants and fillings.  We also filter our drinking water with a reverse osmosis water filtration system.

To read more, please see BISPHENOL-A (BPA) dental sealants