Bisphenol A and endocrine disruption: Cause for concern?

Image by nerissa's ring | flickr.com

Image by nerissa's ring | flickr.com

To ban or not to ban? That is the question regulatory agencies should be prioritizing regarding the widely used chemical, Bisphenol A, or BPA. Both non-profit agencies and industry are debating notable safety claims of this ubiquitous chemical, yet it still remains on the market, so what gives?

Synthesized in the 1930s to be used as a synthetic estrogen, BPA was outcompeted by more apt pharmaceuticals and soon made its way into plastics and epoxy resins. To date, seven billions pounds of BPA are produced worldwide and its global market is expected to reach 20 billion U.S. dollars by 2020.

Considering its history, it should come as no surprise that research findings point to BPA as an endocrine disruptor (that is, a chemical interfering with regular hormone function) by acting as a weak estrogen. Studies have shown that high (and even low) exposure to BPA is associated with a variety of health problems including harmful reproductive effects, birth defects, cancer, neurobehavioral function, and even autism.

Yet despite these findings, BPA remains ubiquitous in our everyday lives. It can be found in certain baby bottles, food and beer can linings, thermal receipt paper, toys, medical devices, and in many other plastic products with few regulations limiting its use.

Ideally, we want decision makers to be informed with the best available science when making their policy decisions. Is this happening in the case of BPA? Though a plethora of studies show linkages, it’s hard to point the finger at the multi-billion dollar market for multiple reasons. As there is a gap in chronic toxicity data, some claim that we simply don’t know enough about the potential long-term effects of BPA. Others claim that we simply aren’t exposed to a concentration large enough to cause adverse effects. Because people are exposed in different amounts depending on their environment and lifestyle choices, causality is a difficult claim to make.

Talking Toxicokinetics

You have probably heard of the famous Paracelsus’ phrase that underlies the first principle of toxicology: the dose makes the poison. However, the age and timing of these doses can also determine toxicity. There is evidence that suggests possible age-dependent effects of BPA, which is why some policy makers have gone as far to ban BPA from baby bottles.

Research affirms that BPA is prevalent, found widely both in waters and in humans but it is important to note that the toxicological relevance of current exposure levels is the subject of an intense debate within and between industry, academic and public health.

According to the European Food Safety Authority (EDFA), the toxicokinetics, or what happens to a substance once it enters the body, of BPA are well characterized. However, there is controversy over how much free BPA is eliminated after metabolism (or processing within the body) occurs. After it is ingested, BPA is absorbed and is processed in the liver to form BPA-glucuronide, the unharmful major BPA metabolite. For their regulatory decisions, the EDFA uses the premise that in humans, this metabolite is then rapidly eliminated in the urine, with a half-life of less than 6 hours. On the contrary, numerous other studies have detected free BPA eliminated in both humans and rats (ie. the BPA compound was eliminated before being converted to the safer metabolite, BPA-glucuronide). This may justify cause for concern.

What about BPA-free alternatives?

After years of consumer demands, manufacturers started to address public concern with the use of BPA alternatives. However, these alternatives have not been well tested and can be just as bad (if not worse) in their endocrine disrupting properties. It turns out that bisphenols make up quite the family, however dysfunctional it may be.

BPA’s siblings, Bisphenol S and Bisphenol F, are now having their chance to enjoy the limelight. What’s probably in your confidently purchased BPA-free plastic is either BPS or BPF. Recent research has implicated these two chemicals in having the same negative effects as BPA, though research in the area is sparse.

In 2010, Canada became one of the first countries to declare BPA as a toxic substance and banned the use of BPA in baby bottles.  Nearly half a dozen states in the United States have banned BPA in children’s products, but no federal policy has been implemented due to lack of evidence of human harm. If one thing remains clear, it is that more studies need to be done on the long-term human health effects of the bisphenol family. Until a final ruling is made that incorporates all relevant data, ultimately, it is up to the consumer to weigh the evidence and decide if BPA’s bad rapport is actually warranted, or just another case of chemophobia.

If you look at the bottom of any plastic container in your home, you may see the symbols 7 or 3. This signifies that it probably contains BPA. These codes are called resin identification codes and they identify what material is used to make plastic. Type 7 is the ‘catch all’ code that most likely contains BPA or BPA alternatives. Type 3 may contain BPA in flexible PVC materials, but not in rigid PVC plastics such as pipes.

You might be asking yourself what you can do to avoid BPA. Here are some simple tips to minimize your exposure.  

1. Avoid over-handling receipts

Yes, this includes grocery receipts and even movie tickets. A study found that handling receipts after using hand sanitizer could increase BPA absorption by 100-fold.

2. Drink out of stainless steel or glass containers

These containers are becoming increasingly popular and are widely available. Check out this Starfish post about choosing which products are best for you.

3. Avoid reheating leftovers in plastics

Heating alters the chemical integrity and makes BPA more prone to leeching. If you must store in plastic, transfer your food to a glass or ceramic dish to reheat in instead.