When we talk about the health risks of toxic chemical exposure, we tend to focus on the chemicals themselves — how much, how long, how often. But the research my colleagues and I published last week in Journal Of Exposure Science And Environmental Epidemiology argues that this picture is incomplete in ways that matter enormously, especially for the communities most affected by environmental pollution.
Our study conducts a comprehensive review of the scientific literature on how non-chemical stressors — things like poverty, discrimination, and limited access to healthcare — interact with chemical exposures (chemical stressors) to affect health outcomes. What we found is clear: social and economic conditions don’t just exist alongside chemical risk, they can amplify it.
This has real consequences for how health risk is assessed and regulated. Current frameworks often evaluate single chemicals and without accounting for the compounding stressors many people face. Someone navigating chronic stress, economic insecurity, or systemic barriers to care may be more vulnerable to the same chemical exposure than standard assessments assume.
To understand the full scope of this issue, we conducted what’s known as an “overview of reviews” — a rigorous synthesis of existing research — to map the body of evidence on this topic and lay the groundwork for more equitable, evidence-based approaches to cumulative risk assessment.
Where we go from here
This work also reveals how much remains to be done. We found a clear need for additional rigorous systematic reviews that assess the certainty of the evidence – reviews that examine both chemical and non-chemical stressors and evaluate not just whether non-chemical stressors affect health outcomes, but also the quality of their findings and confidence in their conclusions. We also need research that captures a wider range of both chemical and non-chemical stressors, so that risk assessment frameworks can reflect the true complexity of people’s lived environments.
Getting this right isn’t just a scientific question. It’s a matter of ensuring that the communities bearing the heaviest burden of environmental exposure are seen and protected by the policies designed to keep them safe.
Authors and affiliations:
- Jessica Trowbridge, PhD, MPH – Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology, and Reproductive Sciences, UC San Francisco
- Emily Lasher, MSPH – Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology, and Reproductive Sciences, UC San Francisco (present address: Stanford University)
- Xing Gao, PhD – Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology, and Reproductive Sciences, UC San Francisco (present address: Health Sciences Research Institute, UC Merced)
- Nicholas Chartres, PhD, MHumNutr – School of Pharmacy, Faculty of Medicine and Health, The University of Sydney
- Rashmi Joglekar, PhD – Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology, and Reproductive Sciences, UC San Francisco (present address: Stanford University)
- Tracey J. Woodruff, PhD, MPH – Program on Reproductive Health and the Environment, Department of Obstetrics, Gynecology, and Reproductive Sciences, UC San Francisco (present address: Department of Epidemiology and Population Health & Woods Institute for the Environment, Stanford University)
About the Author
Jessica Trowbridge, PhD, MPH, is an Associate Research Scientist at PRHE. She studied Environmental Health Sciences at the University of California, Berkeley.
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