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expert reaction to editorial about regulating toxic chemicals for public and environmental health

An editorial, published in PLOS Biology, looks into regulation of toxic chemicals for public and environmental health.


Dr Camilla Alexander-White, Programme Manager for Environment and Regulation, Royal Society of Chemistry, said:

“This editorial, and the forthcoming collection of papers in PLOS Biology, focuses on the situation for chemicals regulation in the USA and expresses the views of scientists operating in that area.  It is important to understand that the way the USA regulates chemicals under TSCA (the Toxic Substances Control Act) is very different from the way the UK and EU regulates chemicals within EU REACH (Registration, Evaluation, Authorisation and restriction of Chemicals); and other parts of the world – for example Canada, Australia, Korea, Japan also have their own diligent approaches to chemicals management.

“The EU has a ‘no [safety] data, no market’ approach and follows the precautionary principle.  As the authors allude to, the USA does not follow this approach and assumes all chemicals are safe until evidence arises that reveals the threat of harm or actual harm has happened.  It is not the case that all regulations are failing.  Over the past decade by EU law, those wishing to manufacture and import chemicals and products into the EU have had to collate and generate safety data for thousands of chemicals already on the EU market, as well as new chemicals.  They have to provide evidence to regulators, according to agreed EU guidelines, that these chemicals on the market do not present an unacceptable risk to human health and the environment.  There are formalised ways to prioritise chemicals of high concern for further investigation.

“This article suggests that scientists may have particular frustrations with policymakers in the USA not acting upon scientific evidence.  It is important for all policymakers to take account of scientific evidence, as one strand of many lines of evidence to be considered when proposing an outright ban to a chemical.  In the case for chlorpyrifos, in the UK there is not an outright ban but, since new data emerged in the EU in 2016, a significant restriction exists on its authorised use in highly specific agricultural settings, which includes ways to mitigate risks through controlling chemical exposures.

“In many cases it is possible to protect health and the environment – whilst at the same time retaining benefits of chemicals to society and industry – if pragmatic and viable solutions can be found to control and manage human and environmental exposures to hazardous chemicals.

“This piece highlights a US perspective on chemicals regulation and draws upon a few examples of scientific research to illustrate the views made in the editorial.  It does highlight the need for increased international cooperation and collaboration – and where possible through international agreements, the sharing of existing safety data on chemicals – to make sure all of the available evidence from authoritative international sources is included in decision-making.”


Dr Simon Wilkinson, Staff Scientist in the Medical Toxicology Centre, Institute of Cellular Medicine, Newcastle University, said:

“Although these articles concentrate on the US regulatory landscape, they offer an important message that is relevant worldwide: as our understanding of the harmful effects of a combination of chemicals at low concentrations and throughout the human lifespan increases, scientists must re-examine long-held beliefs regarding the relationship between exposure and effect, and ensure that policy makers understand the significance of these findings.”


Prof. Tony Dayan, Emeritus Toxicologist, said:

“This editorial is very specifically directed at regulations and large unregulated areas in the United States.  Regulatory controls and procedures in Europe, still including Britain, are quite different and so is the nature and control of the legal purposes of the risk assessment and management processes on this side of the Atlantic.

“That is not to deny that low-level contamination by chemicals in the environment may be a potential risk to humans and other living systems, as well as to the environment, but in looking at the very brief conclusions of the PLoS articles mentioned in the editorial it seems likely that certain fundamental differences may make some of the printed conclusions either irrelevant to Europe or possibly of less significance.

“In particular, many of the laboratory tests on which it is likely that the conclusions of the papers have been reached [NB I have not seen the detail of those papers] will be based on extrapolation from results indicating a possible hazard, i.e. the potential of a substance or mixture to cause harm.  What really counts for us and for the environment is the risk, i.e. consideration of the relationship between dose and effect.  If the dose is sufficiently low there is unlikely to be any harm in real life circumstances.

“Some of the papers are said to refer to the results of epidemiological studies in humans and no doubt other living systems.  Whether they indicate harm relevant to circumstances in Europe must depend on whether those chemicals are employed here and whether the exposure, i.e. the dose and duration, to those substances is relevant to European circumstances.

“There is good evidence that environmental exposures to certain chemicals may really be harmful to humans, other living systems and to the environment in general and those substances must be carefully controlled to prevent damage occurring.

“The greatest need is to ensure that there are the resources both to develop robust methods of predicting harm, i.e. risk and not hazard, and to ensure that proper weight is given both to the risk and to whatever benefit may be obtained from use of those chemicals.

“The latter judgement is a complex process involving politics, economics, social philosophy and toxicology.  Attitudes to the first three of those factors in the USA have often differed from Europe particularly under the present American administration.”


Prof. Alastair Hay, Professor of Environmental Toxicology, University of Leeds, said:

“The articles to be published in the journal later this week will raise difficult issues for regulators, but not ones that have never been considered; multiple exposures to chemicals is just one of these.  Our ability to assess the toxic effects of exposure to many chemicals at the same time is very limited, yet this is how most of us are exposed.  And with exposure to mixtures how do you know for certain which one is the problem?  Or could it be all of them?

“Methods for assessing the effects of exposure to mixtures are still in their infancy.  And this is why most regulation deals with exposure to individual chemicals where evidence is unequivocal.  The driver for regulation is evidence of harm.  And the evidence needs to be robust.

“Yet, there is often good evidence from epidemiological studies implicating exposure to whole classes of chemicals, such as agriculturally applied pesticides, as harmful.  Reducing exposures to industrial chemicals is good hygiene practice anyway, and there are sound public health reasons for considering significant buffer zones between residential areas and where pesticides are spread to take account of spray drift, or any inadvertent contact.”


* ‘Regulating toxic chemicals for public and environmental health’ by Liza Gross and Linda S. Birnbaum et al. published in PLOS Biology on Monday 18 December 2017.


Declared interests

Dr Simon Wilkinson: “I have no connections with any of the authors or their funding bodies.  I am funded by the National Institute for Health Research under two of their Health Protection Research Units; the views expressed are my own and not necessarily those of the NHS, the NIHR, the Department of Health or Public Health England.  I currently sit on the Defra Expert Committee on Pesticides.”

Prof. Tony Dayan: “I have previously worked both as a regulatory adviser to the UK and various international organisations as well as for a large number of chemical, agrochemical, food and pharmaceutical companies but I have not been actively involved with any of those for the past 10 years.”

Prof. Alastair Hay: “Alastair Hay was formerly involved in chemicals regulation for the UK Health and Safety Executive from 1989 to 2014 and for the EU from 2006 to 2014.”

None others received.

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