Uncertainties and disagreement during risk assessment can lead to safe chemicals being unnecessarily banned and harmful chemicals remaining insufficiently regulated.
Science and chemical controversy
BPA is the poster-child of fractured consensus on how evidence of a potential chemical risk to health should be assessed and acted upon: the French food safety authority ANSES has recommended that tight restrictions be placed on the use of BPA while the European Food Safety Authority’s 2015 opinion on BPA more-or-less recommended the regulatory status quo be maintained.
Other risk assessors go either one way or the other, with the UK Food Standards Agency espousing the same opinion as EFSA, while Danish authorities have recently been followed by the US Food and Drug Agency in banning BPA in infant food contact materials. Swedish authorities have gone even further, announcing restrictions even on the use of BPA in thermal paper.
For a more detailed overview of these controversies and how we can use systematic review methods to help resolve them, see our paper Whaley et al. 2015. – open access.
It is a puzzle as to how such pronounced differences in opinion as to the safety of BPA can come about. Is one body more or less aware of evidence of harm than any of the others? Has one body carried out a more objective evaluation of that evidence than another, incorporating more data in a fairer way? Or are different bodies requiring different standards of evidence before recommending regulatory action?
While the answers to these questions are unclear, the diversity of views on offer demonstrates a great deal of uncertainty within the regulatory authorities and society at large about the safety of BPA. This is a problem: policy which is based on uncertainty either incurs economic costs through unnecessary restrictions on safe chemicals, or fails to protect public and environmental health if harmful chemicals are allowed onto the market.
Making best use of the best evidence
Evidence-based medicine (EBM) was a response to the discovery that, with the best of intentions, medical advice was often doing more harm than good. Some of the worst cases included prescription of diethylstylbestrol, which caused cancer instead of preventing miscarriage, heart antiarrhythmia drugs which prematurely ended the lives of more American men per year than the entire Vietnam war, and advice to sleep infants on their fronts rather than their backs, causing thousands of cases of cot death.
We argue that chemical risk assessors can take a lead from medicine, using systematic review methods to help resolve scientific debates. Read our blog about this at Elsevier Connect.
Of particular importance was the realisation that in each case there was a sufficient body of data to direct doctors towards the correct treatment which, if acted upon, would have saved a great many lives. The problem was, this evidence was not informing decision-making.
To remedy this, EBM promotes two basic principles: first, of ensuring all the evidence relevant to answering a question is at hand when it is being answered; second, that a transparent, replicable process is followed when data is reviewed. These two principles are the defining features of systematic review, the evaluation of all the available evidence using a thorough, methodical process which anyone can in principle repeat. Arguably the most famous feature of EBM, a systematic review should constitute as objective and unbiased an evaluation of the significance of the complex body of evidence as is reasonably possible.
EBM has been tremendously successful: systematic reviews are now the most-cited papers in the medical literature, while conducting a systematic review is often even a prerequisite of performing new clinical research. The benefits have been the identification of ineffective treatments which either harm health or waste money, and a reduction in unnecessary research when there is already sufficient evidence to answer a given question. The reasons for disagreement, be they based in values, error of interpretation or need for more research, are much more easily laid bare, providing the foundations for consistency in interpreting data and the resolution of conflict in opinion.
Because the lessons concern methodology for assessing evidence, rather than the specifics of medical experiments, many of the principles put forward to ameliorate the play of bias in medicine should be highly pertinent to chemicals policy. By using EBM as an example of best practice in evidence evaluation and learning from its motives and its techniques for ameliorating the play of bias, we should better understand the relative shortcomings and merits of current practice in chemicals risk assessment, and therefore be able to devise a strategy for making chemicals safety assessment more objective and more logical.
This website provides a venue for highlighting various efforts to facilitate the development and implementation of systematic review methods in chemical risk research, in which Lancaster Environment Centre is pleased to be involved.
The site is maintained by Paul Whaley, an environmental science consultant, researcher into how systematic review methods can be applied to chemical risk assessment, and Associate Editor for Systematic Reviews at the journal Environment International.