Is Bisphenol A (BPA) - is the cure as bad as the curse?

We hear a lot about BPA. It has become the poster child of negative health impacts of packaging. But is it as bad as they say?

BPA has definable health impacts, but it is also an example of where some have sought to exploit the environmental awareness of consumers to their advantage by providing solutions that may solve some of the specific health impacts of BPA, but lead may lead to other health or environmental issues.

Bisphenol A (BPA) is an organic compound with the chemical formula (CH₃)₂C(C₆H₄OH)₂ . Mostly commonly BPA is into a hard plastic called polycarbonate (Vogel, 2009) used in electronics, safety equipment or food containers.    It is also used to make epoxy resins which are used in a wide range of industrial applications such as paints, adhesives, and electrical systems and it is also used as a plasticiser additive to  Polyvinyl Chloride (PVC) (Teuten, 2009). In 2009 2.2 million tons was produced with 72% going to polycarbonate plastic and 21% going to epoxy resins and 5% going to food contact applications. (U.S. Department of Health and Human Services, 2007).

This report seeks to understand the chemical processes involved in the BPA lifecycle, some of the environmental impacts, alternatives that have been used to try to address some of these impacts, the reasons for these alternatives, and ultimately how appropriate these alternatives have been.  The report demonstrates that while proving the impacts of a particular compound is complex and controversial, and attempting to replace it can compound and confuse the issue even further.

Description of the chemical process in question

Bisphenol A (BPA) was first synthesized in 1891, as a synthetic estrogen by Dianin. (University of Minnesota, 2008) As it was not seen as a strong candidate for estrogen it was forgotten until it was re-discovered in the 1950’s as polycarbonate and epoxy resin.

BPA is produced by condensation of phenol and acetone in the presence of HCL or other catalysts (such as Amberlyst  121 Wet) (Rohmihaas, 2010) , (University of Minnesota, 2008).

Polycarbonates are made of strings of BPA molecules and are derived through the reaction of BPA and COCl₂ . They are easily worked, moulded and thermoformed and have many applications.

There are three points of the BPA lifecycle when exposure to the chemical can occur : in production; in use; and in disposal of associated products,  either via leeching of landfill or burning.  There is limited literature on the environmental impacts in the production process. It has been suggested that some of those most at risk are working in the high volume production of BPA (Vogel, 2009). In most BPA production processes bioreactors are used to reduce environmental damage (Cho, 1987).

There is significant data on direct ingestion of BPA via consumer goods and various food and beverage containers.  A study by Copper (et al 2011) evaluated the migration of BPA into water from within water bottles containing BPA as well as aluminium cans lined with epoxy resin (which contains BPA). The migration from Aluminium was potentially higher but much more variable (.08-1.9 mg L^-1) than water bottles (0.2-0.3 mg L^-1).  Heat made a significant difference to the BPA leakage from the epoxy lined aluminium bottles. Dermal absorption is also possible, and is particularly prevalent through thermal paper or carbonless copy paper (Raloff, 2009).

There is also significant literature around the release of BPA in the disposal of products that use the chemical.  Detection of BPA in landfill leachate has been reported in concentrations from ten to ten thousand ug ^-1  which is much higher than those in municipal sewage effluents implying untreated leachates from landfills are potentially significant sources of BPA (particularly for the aquatic environment)  (Teuten, 2009). When BPA is used as additive then it is easily released due to its hydrophilic character in early stage of landfill.  Fu (2010) found that the level of BPA in the atmosphere ranged from 1-17400 pg m^-3  with a range over 4 orders of magnitude depending on where in the world it was being measured.  There was a positive correlation in the study between high BPA and plastic burning of domestic waste, suggesting this is a major source. 

BPA does not generally persist in the environment or in humans but exposure is generally continuous (Saal, 2007) . BPA is broken down in soil with a 1-10 day half life. In a study of aquatic environments it was found that BPA degraded within 18 days in rivers, however this did depend on the particular microorganisms present in any particular environment. Some research suggests that it can bioaccumulate in circumstances such as pregnancy (Saal, 2007). There is  a wide range of exposure levels within humans : .3-4.4 ng ml ^-1 ppl (Saal, 2007).  There does seem to be significant consensus that the vast majority of humans (between 90-95%) are exposed to BPA (Saal, 2007) (Cooper, 2011).  Complete degradation (mineralisation) has only been achieved under aerobic conditions. (Teuten, 2009).

Analysis of the environmental impact of the original process

There is significant debate around the impact of BPA on human health.  This is a 6 billion pound , (and growing)  industry (Vogel, 2009), which means that suppliers and lobby groups have strong interest in defending the safety of the product. They point to the large body of evidence that mostly suggests that as BPA is not persistent in the environment or in humans, and current levels measures in humans are acceptable.  This has lead to a large number of Safety authorities ruling that BPA is currently acceptable for use (Polycarbonate/BPA Global Group of the American Chemistry Council , 2009).  United Kingdom’s food safety authority  commented on a study saying : “This corroborates other independent studies and adds to the evidence that BPA is rapidly absorbed, detoxified, and eliminated from humans – therefore is not a health concern.".

 On the other hand a group in the US in 2006 released the : “Chapple Hill Consensus Statement” which suggested that the amounts of BPA found in humans is “associated with organizational changes in the prostate, breast, testis, mammary glands, body size, brain structure and chemistry, and behaviour of laboratory animals." (Vogel, 2009). Vogel goes on to argue that part of the reason for confusion is the definition of acceptable concentration is based on the understandings that dose-response reaction monotonic (ie that higher doses produce proportional results). There is also the often cited argument that studies commonly focus on whether the compound bio-accumulates rather than researching the fact that most people have constant, low level exposure. More recent studies have demonstrated that temperature is a major determinant of exposure (hot beverage can cause BPA to see up to 55 times faster (University of Minnesota, 2008)),  and recent studies have argued it that it is a metabolite of BPA produced when BPA is broken down by the body that “binds itself much more strongly to the estrogens receptor than the BPA itself” (Science Daily, 2012), potentially  explaining the correlation between BPA and health issues.  There has also been a great body of evidence linking higher risks at early developmental stages.

Summary of possible changes, reason for changes and their environmental impact

There are many potential alternatives to BPA.  These can be categorised into solutions that either: improve the environmental impact of the BPA lifecycle; substitute directly for BPA; or present alternative ideas to BPA related products all together.  The following table outlines many of these concepts.

Table 1 : Review of alternatives

Alternative	Description	Potential Issues
Oleoresin	A mixture of oil and a resin extracted from plants such as pine . 14 percent more expensive. Reasonably non-toxic. Not carcinogenic. Substitute for epoxy resins.	Some toxicity identified, both oral and dermal.
Tritan™	Used in baby bottles and other bottles as alternative to Polycarbonate BPA. Does not seem to be carcinogenic or EDC.  Manufactured utilizing three monomers, di-methylterephthalate (DMT), 1,4-cyclohexanedimethanol (CHDM), and 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO). Note that CBDO is the direct substitute for BPA. Claimed to be recyclable however not available in recyclable form.	New on the market and requires further testing.  Tests from Plastipure and CertiChem indicate estrogenic activity. This is disputed by manufacturer. (Eastman, 2012). CHDM appears to have some toxicicity (Environmental Protection Agency, 2007).
Copolyester plastic	Made by altering polyesters to give them attributes of plastic. Tritan is an example (above), however there are many others.	Similar to Tritan there is little long term documented evidence on health or environmental impacts.
Uncoated stainless steel	Steel alloy with minimum of 10.5% chromium content by mass. Benefits are that they are 100% recyclable.	Expensive. No significant toxicity in use (Sanoteen, 2010). Mining of Chromium may be carcinogenic (Goleman, 2012) and if it is not recycled it is highly persistent.
Aluminium lined with EcoCare™.	EcoCare is BPA-Free and Phthalate-Free, as well as being free of any VOCs (volatile organic compounds)	Have had some examples of liner chipping away (non peer reviewed source) (Jeremiah, 2009) Biggest issue is lack of transparency as to the chemical make-up.
Tetra Pak	Made of 70% paperboard combined with low density polyethylene and aluminium.	Aluminium is seen as toxic and is highly energy intensive to produce.  Some studies show leaching of estrogenic substances.
PET	Polyethylene Terephthalate (PET) are recyclable and non carcinogenic. Thermoplastic polymer resin of the polyester family.	Usually only applied to single use applications. May lead to endocrine disruptors (Sax, 2010).
Polypropylene	Used in most reusable food storage containers. Recently used in baby-bottles. Non carcinogenic and made of least hazardous monomers.	Very resistance to biodegradation.
High density Polyethylene (HDPE)	Used in non-re-usable containers for beverages	Single use. Very resistant to biodegradation. .1% of carbon transformed to CO2 per year.
Glass	Glass can be used for baby bottles and other BPA related applications. They do not contain chemicals that can get into contents of bottles or containers. 40-70% recycled.	Energy intensive to produce. 40% higher global warming impact than PET. (Isaac, 2012)

There are many attributes that must be considered when trying to emulate a product. In replacing BPA related products, the key driver  is to emulate many of the benefits such as flexibility, ability to mould, toughness, biodegradability and price while removing the negatives such as its propensity to leech, and characteristic as a EDC.

Appropriateness of chosen alternatives

It appears that when BPA became a major concern, there was such a general suspicion with plastics that “green-wash” emerged with substitute products. Being BPA free implied risk free and environmentally friendly .  Unfortunately , as outlined in Table 1, many of the alternatives, particularly those that were developed specifically to ride the wave of concern over BPA, led to either other issues, or contain chemicals that do not yet have significant enough testing conducted to provide confidence of their environmental or health outcomes. In some cases, as with EcoCare, it is impossible to find any detailed information about the chemicals used. In others, such as with Tritan™ you can find information (Eastman, 2012) however when you look at areas such as toxicological information, ecological information (including persistence) and disposal considerations, the response for over twenty areas is “no data available”. Even when Tritan™ claimed to be fully recyclable, the claim is mitigated as not being “currently in recyclable form”. 

Also, as you uncover more about the supply chain of many products you realise that they are not as environmentally sensitive as they appear. For example, although Stainless Steel bottles appear to be an obvious choice as a replacement for BPA, the supply chain impact of production would mean that you would need to replace 50 plastic bottles to have benefit from a climate perspective, and 500 times from a holistic environmental analysis (Goleman, 2012).

Conclusion

BPA was a revolutionary compound that had many significant industrial applications, and remains a huge industry today. It is a example of where the precautionary principle has meant that a lack of consensus on the environmental and health impacts has not stopped consumer action, and corporate reaction from leading to significant change. Unfortunately it is also an example of where some have sought to exploit the environmental awareness of consumers to their advantage by providing solutions that may solve some of the specific health impacts of BPA, but lead may lead to other health or environmental issues. This is the danger where a label such as “BPA Free” is used in place of a more comprehensive industry wide environmental and health and safety labelling system.

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