Evidence Evaluation of Early Warnings to Protect Health

Scientists are trained to question and probe uncertainties, which is valuable for scientific progress, but not necessarily helpful for clear communication of the evidence to support protective policies and timely action.

In early 2021 I was very pleased to join with two friends and colleagues, David Gee (Brunel University, London UK) and Dr. Nicholas Chartres (Program on Reproductive Health and the Environment, PRHE, University of California San Francisco, USA) to co-host a gathering of thought leaders in environmental health science and policy.

Scientists are trained to question and probe uncertainties, which is valuable for scientific progress, but not necessarily helpful for clear communication of the evidence to support protective policies and timely action. Thus, the purpose of the Workshop was to gather scientists with expertise in policy, to identify some of the barriers to conducting transparent and timely evaluations and propose solutions for translating scientific evidence of harm into health-protective actions.

The “Workshop on Conducting Evaluations of Evidence that are Transparent, Timely and Lead to Health-Protective Actions” was held in webinar format over four days in mid-February. The Workshop Robust Proceedings contains the summary of our discussions and the presentations of the experts. Below are some highlights.

Late Lessons, Early Warnings

The idea and initial planning of the Workshop came from David Gee, well-known for his lifetime of work devoted to improving the use of early hazard warnings to improve health protections. He is the Editor and author of two books on, “Late Lessons from Early Warnings” (Volume One in 2001, and Volume Two in 2013).

The ‘Late Lessons from Early Warnings’ books, which included case studies from roughly 100 authors, documented dozens of examples of hazardous chemicals where effective risk reduction actions came decades after scientists and others issued early warnings about the harm likely to be caused by those chemicals. That  was far too late for many workers, fence-line communities (situated adjacent to polluting industries) and Environmental Justice communities (low-income communities and communities of color experiencing the cumulative effects of multiple chemical and non-chemical stressors that contribute to persistent environmental health disparities).  Failure to act on early warnings can result in illnesses like organ damage, asthma and respiratory illnesses, reproductive harm, neurological damage, cancer, and premature deaths that may have been prevented.

With so many examples of this problem, why are early warnings from scientists still not sufficient to spur early action and pollution controls to avoid harm?

When Uncertainty Is Weaponized: The Triumph of Doubt

Health-protective actions are often delayed by the heavily-funded efforts of the affected industry—particularly the chemical industry—to raise doubt in the minds of policy makers whether health protections are needed. Examples of these are detailed and documented in the pages of two books by Dr. David Michaels: “Doubt Is Their Product: How Industry’s Assault on Science Threatens Your Health” (2008), and, “The Triumph of Doubt: Dark Money and the Science of Deception” (2020). A book review in the scientific journal Nature sums up Michael’s documentation of “when uncertainty is weaponized”: “[Michaels] takes on per- and polyfluoroalkyls, widely used in non-stick coatings, textiles and firefighting foams; the harmful effects of alcohol and sugar; the disputed role of the ubiquitous glyphosate-based pesticides in cancer; and the deadly epidemic of addiction to prescribed opioid painkillers. In each case, Michaels records how the relevant industry has used a toolbox of methods to downplay the risks of its products, spreading disinformation here, hiding evidence of harm there, undermining authorities—all tactics from the tobacco industry’s playbook.”

In our workshop, experts also used chemical case studies to demonstrate where—and why—there was a divergence of perspectives on the scientific evidence, including air pollution, PFAS forever chemicals, and Monsanto’s glyphosate-based herbicides. Comparisons of approaches across US federal and state regulators, the European Union, and international scientific agencies were especially informative.

Overcoming Uncertainty: Scientific Evaluations That Lead to Health-Protective Actions

Our Workshop convened just over one hundred science and policy experts each day to discuss the reasons for the divergent evaluations, and how to minimize and render them more transparent, consistent, and supportive of timely action. 

Transparency: Community engagement is essential

The opening presentation was Dr. Mark Mitchell, a US-based physician and expert on addressing pollution and disease in Environmental Justice communities. Dr. Mitchell presented his experience working with a neighborhood heavily contaminated with hexavalent chromium from industrial facilities, where the residents were predominantly Black, with a high level of poverty. Governments and others have repeatedly failed these communities, even with the most basic protections afforded under the law.Dr. Mitchell noted that in their current form, risk assessments and regulations are often outdated, calibrated for healthy white males, and fail to incorporate the cumulative impacts of overlapping environmental and social threats including systemic racism and poverty.

Dr. Mark Mitchell

Workshop participants consistently identified the need for representation and meaningful participation by affected communities throughout the decision-making processes, including community representatives, local health care workers, local schools and parents, community organizations, and others. Early and ongoing engagement with community members could help avoid repeating the practices that have failed fence-line and environmental justice communities for so long. 

Many workshop participants stressed the need for policy guidelines or frameworks that address how evidence is interpreted and integrated. For example, the evaluation and integration of evidence can be done with more consistency across regulatory agencies by applying systematic review frameworks that are consistent with established best practices, including University of California San Francisco’s Navigation Guide (UCSF NavGuide), the U.S. National Toxicology Program’s Office of Health Assessment and Translation method (NIEHS NTP-OHAT) and the Systematic Review and Integrated Assessment of endocrine disrupting chemicals (SYRINA). Further, when divergent evaluations of the same body of evidence are made, the reasons for such divergence are more transparent, and can be readily identified.

Timely: Scientific rigor is needed, not rigor-mortis

A class approach to chemicals—evaluating groups of related chemicals—such as phthalates, PFAS or dioxins—instead of one-by-one, is one important way to ensure that more timely action is taken to address toxic chemical pollution and contamination. In addition, it can be a way to bridge information from the better-studied chemicals to related ones that are less well characterized.

Community engagement contribute valuable ‘citizen science’, such as fence-line and community air monitoring, health surveys, and local knowledge. This can be used to fill in data gaps, inform decision-making, and speed the deliberation process. Better use of these information resources can also facilitate the identification and incorporation of social determinants that amplify the impact of hazardous agents, as well as provide more realistic assessments of the experiences of workers, and impacted communities.

Scientists should avoid insisting on such a high degree of scientific rigor that it leads to rigor-mortis, thus further delaying much-needed health-protections.   

Dr. Kristi Pullen Fedinick

Health-Protective Action: Decisions delayed are protections denied

Workshop participants noted that it is important to move ahead with timely evaluations, even if they lack precision. Data gaps, uncertainties, and scientific complexities are unavoidable, but they should not be insurmountable.


We recognize that chemical hazard evaluations and risk assessments are only a small part of decision-making. Important additional factors include structural racism, sexism, socioeconomic disparities, and other systems that uphold inequities and injustices. These will have a much greater impact on the ability to deliver the health protections that are human rights.

The time has never been better to modernize the practice of evaluating chemicals, to ensure the best science and assessment methods are used to address the long-running injustice of uncontrolled pollution and chemical contamination. 

The Workshop offered a productive space to identify common hurdles that hinder health protection, as well as best practices for moving forward with the ongoing work to protect people around the world from toxic chemicals.

(see the Workshop Proceedings for details)

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