BPA—science controversies

BPA was recognised to have estrogenic properties in the late 1930s, yet was approved for food contact uses more than 40 years ago. Only after studies showing low-dose impacts of BPA in laboratory animals were published in the late 1990s did concerns about the chemical increase significantly. Particular concern has been raised for applications that may expose children and the developing fetus.

Research and controversy regarding BPA toxicity have increased significantly. A search for ‘bisphenol a’ in an article title in the Medline database found 1089 published articles since January 2001, with more than 100 in 2010. Only 143 were published prior to 2001.

Laboratory studies have associated BPA exposure with a wide range of end points such as reproductive impairments, damage to the fetus, attention-deficit problems, obesity and diabetes.3 Unconjugated BPA in blood and conjugated BPA in urine samples have been found in biomonitoring throughout the world.4 Despite the number of studies demonstrating human and environmental exposures and identifying hazards in animal and cellular models, there is still uncertainty as to the major sources and significance of exposure, pharmacokinetics of exposure, and to what extent the effects in animal models are transferable to humans.5 There is little epidemiology to support or refute BPA toxicity in humans.

This uncertainty has led to vigorous debate in the scientific and regulatory community about the toxicity of BPA. While a number of scientific, government and industry panels have weighed the same set of data (though there have been significant debates over which studies are acceptable for risk assessment),6 they have come up with different opinions as to the safety of BPA. Some industry bodies and food safety regulatory authorities have stated that concerns regarding BPA toxicity in food contact applications are low at current exposures, given uncertainties and ‘the lack of consistency among some of the measured end points or results between studies.’7

A WHO panel concluded that ‘Establishing a “safe” exposure level for BPA continues to be hampered by a lack of data from experimental animal studies that are suitable for risk assessment …. Continued research into the toxicokinetics of BPA and its estrogenic and other mechanisms of action will be needed before it is possible to determine the appropriate points of departure … for human risk assessment with confidence.’8

Yet, a 2007 National Institutes of Health (NIH) consensus panel that reviewed the whole of the evidence on BPA toxicity found that ‘the published scientific literature on human and animal exposure to low doses of BPA in relation to in vitro mechanistic studies reveals that human exposure to BPA is within the range that is predicted to be biologically active in over 95% of people sampled. The wide range of adverse effects of low doses of BPA in laboratory animals exposed both during development and in adulthood is of great concern with regard to the potential for similar adverse effects in humans.’3

Nonetheless, most groups have recommended the same action: more study. The 2007 panel concluded ‘the fact that very few epidemiological studies have been conducted to address the issue of the potential for BPA to impact human health is a concern and more research is clearly needed.’3

Governments and companies act in the face of uncertainty

Advocates meanwhile have pressed for state, federal and market policies to restrict BPA. The increased media attention demonstrates the success of this advocacy, with more than 400 news articles mentioning BPA published since 2008. Nineteen US states have proposed legislation that would regulate BPA use in children's articles, with policies being passed in eight states and several cities. In 2008, the Canadian government restricted BPA use in baby bottles and, more recently, declared BPA toxic. The French, Danish, Swedish and German governments have taken action to restrict BPA; and in November 2010, the European Union restricted BPA in baby bottles. A January 2010 US Food and Drug Administration statement noted reasons for some concern about the low-dose effects of BPA and recommended lowering exposures where possible.7 The US Environmental Protection Agency established an action plan for BPA that includes research on alternatives to BPA in thermal tape.

The market-place has moved much quicker than government policy. For example, in a matter of 2 years, and despite the earlier assurances of BPA safety, several major manufacturers and retailers of polycarbonate water and food containers have all but eliminated polycarbonate plastic.

Focus on problems not solutions

While millions of dollars have been invested in studying detailed aspects of BPA exposure and toxicity, little funding has been allocated to the study of alternative materials. A Medline search revealed no studies on BPA alternatives, with the majority of available information coming from corporate websites, limited government studies and research by advocates. Policy actions have focused primarily on removing BPA, not on transitioning to safer alternatives. For example, one of the main alternatives to BPA in food containers is Tritan, a co-polyester. Tritan's use has skyrocketed with BPA concerns and while the company's research has indicated that it is not estrogenic or androgenic,9 there is relatively little public information on the long-term safety of this alternative. Numerous examples exist where actions to restrict a particular chemical without thinking about the alternatives have led to risk shifting.10 11

Lessons learnt

The BPA example highlights a large problem in our current approach to chemical assessment and management: a focus on characterising problems in terms of causes and mechanisms as the basis for subsequent action. This approach leaves open the door to extended debates over study design, mechanisms of action, duelling scientists and scientific panels and ultimately inaction. Given the large number of unassessed chemicals and large uncertainties, such an approach can never be efficient or fully preventive and may actually lead to unintended consequences.

We propose a new approach to chemical assessment and management that marries science and action, called the sustainable solutions agenda (SSA).12 The SSA approach seeks not only to characterise the evidence on hazards and exposures but also to identify possible pathways to solutions. In the face of scientific uncertainty regarding chemical toxicity, the SSA moves discussions away from characterising risks and towards rapid screening, prioritisation and assessment of alternatives, to ensure that preventive actions enhance health and sustainability. It asks if given the whole of the evidence at hand, including the availability of alternatives, is there a reasonable basis to take preventive actions? Such an approach is consistent with Sir Bradford Hill's proclamation that uncertainty ‘does not confer upon us a freedom to ignore the knowledge we already have, or to postpone the action that it appears to demand at a given time.’13 It is consistent with the way that businesses make decisions. Companies do not need perfect information to avoid risks and do not need a particular chemical or material but rather its functionality or ‘service’. For example, through research on alternatives and technical assistance to firms, the state of Massachusetts has reduced the use of trichloroethylene, a degreaser and probable human carcinogen, in manufacturing by 95%.12 Hence, the search for safer alternatives can cause a convergence of interests around innovation in reducing toxic chemical use, whereas the current model almost automatically leads to growing controversy and inaction that benefits neither health nor the private sector.