As with the presidential campaign, serious debate on the subject of chemicals that can interact with the human endocrine system is often sidetracked by a tendency by some to engage in the politics of identity, branding anyone with a different perspective to be in industry’s pockets. Such ad hominem attacks are a serious impediment to progress and must stop. The question is, how did we get here in the first place?
In 1991, Theo Colborn convened a group of international scientists to discuss concerns about the trans-generational effects of persistent chemicals on predator species in the Great Lakes. During the following 25 years, Colborn’s and her colleagues’ work inspired hundreds of research studies into modes of action and potential health effects of so called endocrine disrupting chemicals (EDCs).
Even now, scientists are still trying to provide concrete answers to some of the same basic questions about exposures to low doses of chemicals. Do they meet the definition of an EDC? Are there safe levels of exposure? Should certain chemicals be banned, or can they be managed safely?
25 years of endocrine disruptor research
This week, the National Institute of Environmental Health Sciences (NIEHS) is hosting a conference to “celebrate the people and the science” investigating links between chemicals and the human endocrine system. Some participants will undoubtedly highlight what they perceive to be problem chemicals but the big questions still remain: how far has the science truly advanced, and can all stakeholders engage in constructive dialogue so that the science can continue to move forward?
Through the efforts of the U.S. Environmental Protection Agency (EPA), academia and others, considerable progress has already been made to develop methods, tests and data that are answering questions about chemicals’ interaction with the endocrine system. For example, scientists now know that some chemicals can interact with the endocrine system temporarily, but do not illicit harmful effects. They are “endocrine active” but not “endocrine disrupting” chemicals.
Although the development and implementation of EPA’s Endocrine Disruptor Screening Program (EDSP) arguably represents the most significant accomplishment in terms of preventing future harm from EDCs, it is not as though EPA was doing nothing before the EDSP’s creation to protect human and wildlife health.
For many years, EPA officials have required for pesticide approval a battery of animal tests designed to detect a chemical’s ability to cause a range of adverse health effects, including cancer and reproductive and developmental disorders, and they and other regulatory agencies established safe levels of exposure based on the most sensitive endpoint detected.
Another significant accomplishment has been the development of a globally agreed upon definition of an EDC. This arose as part of a seminal “state of the science” report issued by the World Health Organization in 2002. That definition requires that a chemical both “alter the function(s) of the endocrine system and consequently cause adverse effects in an intact organism, or its progeny, or (sub) populations.”
Although there is widespread agreement on this definition, some stakeholders while acknowledging it, are also trying to subvert it. They want to conflate endocrine activity, like that which occurs naturally in response to activities like drinking coffee, with endocrine disruption, without demonstrating a consequent adverse health effect. This is problematic for many reasons, not the least of which it would falsely identify many chemicals as EDCs and confuse the public and marketplace.
Beyond the development of EDSP and the definition of an EDC, agreement on progress in other areas is harder to find, like the confidence in the body of evidence linking chemical exposures to certain health effects, whether safe levels of exposure to EDCs can be established, and the appropriate weight that should be accorded data derived from un-replicated, new novel testing approaches versus those from internationally agreed upon animal testing protocols.
Opportunity for NIEHS on EDCs
Looking forward, it is difficult to be optimistic that many of these differences can be resolved soon, that is, unless stakeholders can engage frankly on the science. At a minimum, the upcoming NIEHS conference does present an opportunity to foster a more objective and inclusive atmosphere for serious discussion of topics that many scientists still regard as unresolved. Setting an appropriate tone will be critical.
Stakeholders, particularly consumers whose health we are all trying to protect, but also industry who is trying to meet society’s growing unmet needs, are best served by a system that is science and risk-based, transparent and that delivers a positive safety evaluation and determination on chemicals – before they come to market.
It would therefore be helpful if NIEHS would publicly endorse EPA’s EDSP program and the WHO/IPCS definition of an EDC and emphasize the importance of having a program that not only detects chemicals that are truly EDCs, but also determines with confidence chemicals that are not EDCs.
That, indeed, would be something to celebrate.
Dr. Gregory G. Bond is an epidemiologist and adjunct professor of environmental health sciences at The University of Michigan. He founded Manitou View Consulting, LLC, a boutique scientific consulting firm, in 2014.