A review of the data leaves the door open on an answer.

According to the World Health Organisation (WHO) there are some 80,000 man-made chemicals floating around planet earth since the beginnings of the Industrial Revolution.

Some of these, including lead, arsenic, polychlorinated biphenyls (PCBs), dioxins and pthalates have been classified as endocrine disrupting chemicals (EDCs) because of their known effects on endocrine organs. The WHO says EDCs can “…alter function of the endocrine system and consequently cause adverse health effects in an intact organism, or its progeny, or (sub) populations.” 1

EDCs are a hot topic for research at the moment with an ever-widening search for products with specific ill-health effects. Some have been shown to have direct effects on brain function, others on changing the balance of gut microbiome, which has indirect effects on a range of issues, including obesity.

Bisphenol A (BPA) is a ubiquitous chemical used to make plastic bottles and in the epoxy resin lining of metal cans to increase food preservation. Its use is gathering increasing attention as a potential EDC, because of its possible links with diabetes and obesity.

Humans come into contact with BPA through industrial waste in water, air and soil. But the most common contact occurs through consumption of food stored in plastic containers or tin cans lined with BPA, particularly if these are exposed to microwaves or heat.

Yet despite growing concerns about its toxicity, the demand for BPA in products is on the increase, partly because of the growing industrialization in China and other rapidly developing countries.

Data from the US National Health and Nutrition Examination Survey (NHANES) in 2003-2004 showed that around 90% of the US population older than 6 years of age had detectable levels of BPA in their urine. Children and adolescents had higher levels than adults, consistent with their greater exposure to the chemical.

The fact that several national bodies have banned BPAs in infant food containers because of neurological damage, is suggestive of concern at all levels. But various food authorities and the WHO suggest that amounts are insignificant to cause problems in adults.

In a comprehensive review of the data to date, two medical researchers from the University of Indiana are not so sure.2 They looked at several epidemiological studies that show associations between BPA and both obesity and Type 2 diabetes in a number of different sub-groups (healthy US adults, Chinese children, overweight peripubertal girls etc).

The majority of these show positive associations between obesity, diabetes, and urinary BPA. However association doesn’t imply causality and this is where human data are currently lacking. The physiological effect of BPA has been linked to a number of molecular targets with relevance to metabolic health and function and effects have been shown in animals on insulin resistance, Beta cell functioning and blood sugar levels.

While we wait for further evidence, what can be done to reduce any possible risk? A prudent approach would be to advise the avoidance of BPA exposure such as through:

• Minimising plastics use (which can have an added positive environmental effect)
• Avoiding placing plastic and tinned food (where BPA levels are not marked on labels) in microwaves
• Not keeping plastics or tinned food containers in extreme heat (eg. inside a closed car)
• Discarding plastic bottles with scratches, as these can lead to greater release of BPAs
• Using glass or stainless steel cookware as an alternative to plastic and cans with unknown BPA content
• Encouraging exercise to eliminate BPA and other EDCs through sweating
• Not storing vegetable oils and/or salt solutions in plastic containers as these can cause BPAs to leach into the food.

While the evidence for the effects of BPAs as an Endocrine Disrupting Chemical is clearly not definitive, the potential links with obesity and diabetes (BPA in mice leads to greater food intake), make these of particular interest in a lifestyle approach to health. Together with other EDCs in the air, soil and water, BPAs are likely to attract some genuine research interest in the future.

1. WHO. State of the science of endocrine disrupting chemicals.
   www.who.int/ceh/publications/endocrine/en/index.html
2. Mirmira P, Evans-Molina C. Bisphenol A, obesity and type 2 diabetes mellitus: genuine concern or unnecessary preoccupation? Translational Research, 2014;164:13-21.

Source:_Medical Observer