BPA – a journey from industry to human exposure & health risks
I recently completed an Environmental Health unit as part of my Masters course. One of the environmental hazards I studied and wrote a paper on was BPA. This chemical is widely distributed across the environment and capable of having far reaching impacts on human health.
BPA has been in the media in recent times – due to concern over baby milk bottles made with BPA. Widespread awareness of the potential for harm from BPA has lead to the banning of BPA bottles in many countries over recent years.
So let’s take a look at BPA in more detail and explore the issues concerning this chemical.
Bis-phenol A (BPA) is one of the chemicals known as endocrine disruptors that are now considered ubiquitous in the environment. BPA is one of the highest volume chemicals produced worldwide. Current estimates indicate that more than 8 billion pounds of BPA are produced annually and approximately 100 tons may be released into the atmosphere each year.
Where Does BPA Come From?
Additional uses for BPA include items that we come in contact with daily in domestic and workplace environments including the coating of CDs, DVDs, electronic equipment, automobiles, recycled paper and carbonless paper often used in register receipts.
Additionally, BPA has been measured in freshwater, seawater, landfill leachates, air, and dust particles. The widespread existence of BPA in the environment means humans and other species are at risk of exposure. BPA was detected in the urine samples of 92.6% of participants in one US study and BPA has been measured in human blood, breast milk, amniotic fluid and placental tissue.
How Do We Absorb It?
BPA can enter the body through different exposure routes. The majority of human exposures come through the oral or ingested route. Ingesting foods and drinks that have been stored in BPA lined packaging is the primary source of ingested BPA amongst children and adults.
There is evidence that acidic foods have a higher capacity to leach BPA and also heating of foods and drinks can increase the leaching from the packaging into the food. Long term storage and reusing of plastic water bottles is also thought to increase the potential for leaching through breakdown of the plasticizers. It is important to note that breastfed infants are also exposed through maternal colostrum and breast milk. A study found BPA in the breast milk of all 23 healthy women they examined.
Dental materials can also be a source of ingested BPA with the potential for leaching of the chemical out of composite dental materials. We are also exposed via the skin through handling carbonless cash register receipts and electrical equipment that use BPA.
What Happens Once BPA Gets In The Body?
Once BPA enters the body through ingestion of contaminated foods and drinks, it is rapidly metabolised by the gut and absorbed into the bloodstream. Active forms of BPA are more likely through skin and air exposures – when the chemical is absorbed directly into the bloodstream and thus bypasses gut breakdown.
Many studies of the health effects of BPA have focused on its well-documented oestrogenic activity with the chemical having an affinity with the oestrogen receptor. Chemicals that can bind to oestrogen receptors can elicit an oestrogenic action much like our own oestrogen does. While BPA is generally thought to only be a weak stimulant – the fear is that chronic long term low level exposure can still have serious health impacts.
The major at risk populations for the known harmful endocrine effects of BPA on the sensitive reproductive system are considered to be the foetus, infants, young children and potentially adolescents.
Some of the known health associations of high BPA concentrations include:
- Cardiovascular disease
- Liver dysfunction
- Thyroid issues
- Cancer (particularly breast & prostate)