CrossFit and Paleo: Plastics, Obesity and Diabetes

This post covers one of the problems posed by endocrine disruptors (ECDs) that I don’t think has gotten a lot attention, or at least broad enough attention. This is the issue of estrogen-mimics.  These are also known as Xenoestrogens.    A lot of people seem to be aware of BPA and take steps to avoid it. However, BPA is a relatively small part of the story. Plastics labeled BPA-free may not be Estrogen Activity-Free at all (Yang et al. 2011). Normal estrogen acts by docking at an estrogen-receptor, like a lock fitting into a key, and turns on various biochemical pathways.  These pathways play important roles in maintaining normal function in various tissue, allow girls to develop normally through puberty, make reproduction possible, organize behavioral responses and neurological function among other things.

The problem with xenoestrogens is that the body can’t tell the difference between these molecules and natural estrogen.  Its an issue of molecular structure or shape (Katzenellenbogen 1995).  That means biochemical pathways can be turned on at inappropriate times, upsetting the normal course of development, including brain development.  It may also mean that more estrogen activity is happening because estrogen-regulated cell activity is ramped up.  This might mean more cell division and change in estrogen-sensitive tissue, which can increase risk of breast cancer. There is also evidence that xenoestrogens can harm male development as well (Ogura et al. 2007).  

A normal three-year old performs with her toy cat
Many chemicals have estrogen-activity.  Some chemicals are more estrogenic than others.  Household products, dusts, plastics, cosmetics, personal care products may all contain estrogenic chemicals.  Note that, dust aside, there are products that don’t contain estrogenic chemicals.  For example, plastics can be produced that do not have estrogenic activity. 
It may just be hard to find them.  For example, the only company I know of that produces a plastic water bottle that is independently certified as Estrogen Activity Free is a small company called The Water Geeks.  The Headline on the Link says BPA-Free, but these are Estrogen-Activity Free as well.  A small company, Certichem, run by a bunch of University of Texas professors, certifies chemicals as Estrogen-Actity Free.  They also test things for androgen and anti-androgen activity as well.  
BPA-Free is great, but BPA bottles and cans are not necessarily Estrogen-Activity Free.  I try to use glass, which is not always practical or even permitted in some situations.  We probably don’t want to see fields of pee-wee soccer players running around with glass bottles, and a lot of boxes probably don’t want to see exhausted athletes staggering around with glass either. 
The Environmental Working Group provides a website that will help you identify products that contain fewer ECDs.  They also have a lot of other well-written and informative material on the topic of chemicals in the environment.  You can read more about Endocrine Disruption and the concerns of the scientific and medical communities in this pdf published by The Endocrine Society.

Katzenellenbogen JA (1995). The structural pervasiveness of estrogenic activity. Environmental health perspectives, 103 Suppl 7, 99-101 PMID: 8593885 

Yang CZ, Yaniger SI, Jordan VC, Klein DJ, & Bittner GD (2011). Most plastic products release estrogenic chemicals: a potential health problem that can be solved. Environmental health perspectives, 119 (7), 989-96 PMID: 21367689 

Ogura Y, Ishii K, Kanda H, Kanai M, Arima K, Wang Y, & Sugimura Y (2007). Bisphenol A induces permanent squamous change in mouse prostatic epithelium. Differentiation; research in biological diversity, 75 (8), 745-56 PMID: 17459086

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