As Chemicals Proliferate in the Environment, a Science-Based Approach Is Needed to Protect Human Health
With chemical production and use on the rise, and continued evidence that many chemicals in everyday products are linked to health problems such as cancer, infertility, and neurodevelopmental conditions, an interdisciplinary group of scientific experts said changes are urgently needed to better protect people from harmful chemicals.
Despite advances in science and a greater understanding of chemical health harms, the scientists say, the U.S. Environmental Protection Agency’s (EPA) approaches to assessing and regulating human health risks of chemical exposures have not changed much since the 1970’s.
“Chemical pollution is a worldwide crisis that threatens global ecosystems, food security, and human health and reproduction. However, the manufacture and production of industrial chemicals has continued to increase…with low-wealth communities and communities of color often bearing disproportionate burdens of exposure,” write the scientists in the first in a series of five papers published together in Environmental Health.
“Regulatory agencies urgently need to improve the use of science in decision-making processes and ensure that populations are not exposed to harmful levels of chemicals or classes of chemicals,” the scientists say in A Science-Based Agenda for Health-Protective Chemical Assessments and Decisions: Overview and Consensus Statement.
“As chemical production and use continues to rise, regulatory bodies aren’t keeping up,” said Tracey J. Woodruff, PhD, former EPA senior scientist, professor and director of UCSF’s Program on Reproductive Health and the Environment, UCSF EaRTH Center, and lead author of the consensus statement.
We need to do a better job of protecting people and communities, especially those already exposed to higher levels of health-harming pollutants and chemicals.”
-Dr. Tracey Woodruff
The scientists, including several veterans of EPA, are affiliated with the Science Action Network for Health and the Environment (SANHE). They outlined five principles for using science in hazard and risk assessment to reflect real-world risks and make chemical policy more health-protective:
- Chemical producers must pay for data collection on the chemicals they produce or will produce
- Do not treat lack of data like a lack of hazard, exposures, or risks
- Better identify and protect populations that are disproportionately exposed and/or are more susceptible to harmful chemicals
- Do not assume there is a “safe” or “no-risk” level of chemical exposure in the diverse general population
- Evaluate and account for conflicts of interest in scientific studies used in hazard and risk assessments
These changes are critical to correct existing deficiencies in exposure, hazard and risk assessments that lead to insufficient information to identify risks, underestimates of risk, inequitable distributions of risk, and unconsented transfer of risks from manufacturers to the public.”
– A Science-Based Agenda for Health-Protective Chemical Assessments
and Decisions: Overview and Consensus Statement
In four accompanying papers, the scientists provide scientific recommendations to update risk assessment to better capture exposures and hazards, guide decision making, and protect the public’s health. They include for EPA to:
- Improve its inadequate approach to exposure assessments that have prevented the Agency from fully protecting communities
- Update methods to consider population variability and increase protection for people burdened by environmental exposures and/or social stressors such as poverty and racism
- Quantify non-cancer health outcomes to better reflect real-world health consequences of exposures and improve benefit-cost analyses of regulations, and
- Adopt a class-based approach to evaluate chemical risks rather than evaluating hazardous chemicals one at a time
Improving Exposure Assessment Methods
Understanding how we’re exposed to chemicals is critical to protecting the public’s health, however, EPA’s current approach to exposure assessment fails to recognize the extent of everyday exposures.
“EPA’s current approach to estimating exposure in risk evaluations is leaving many people unprotected,” said Laura Vandenberg, PhD, associate vice chancellor for research and engagement at University of Massachusetts Amherst and lead author of Addressing Systemic Problems with Exposure Assessments to Protect the Public’s Health. “EPA can protect more people – and protect people better – by updating risk evaluation methods to better quantify real-world exposure.”
The paper outlines four ways EPA can improve exposure assessments to make more health-protective decisions, including doing a better job of considering factors such as where people live or how they might be more susceptible (age, genetics, stress, pregnancy) to chemical harms. The authors caution that EPA should not wait for data to confirm that human and environmental exposures occur when a chemical is produced in high volumes.
Updating Population Variability Assessments
EPA’s current approach to chemical assessments assumes people are fairly similar. But our differences can determine who is most at risk of health harms.
“Just like pre-existing health conditions can make people more susceptible to a virus, so too can some health conditions make people more susceptible to the harmful effects of a chemical or chemical mixtures,” said Julia Varshavsky, PhD, assistant professor of environmental health at Northeastern University and lead author of Current Practice and Recommendations for Advancing How Human Variability and Susceptibility Are Considered in Chemical Risk Assessment. These factors can include the variety of chemicals a person is exposed to, their health status, life stage, and whether they have a disability. This paper explores emerging tools and data sources that better account for diversity in people and recommends updated methods to capture variability in chemical risks resulting from exposure to multiple chemical stressors and non-chemical stressors like poverty and racism.
Quantifying Non-Cancer Health Outcomes
In its evaluations of chemical risk, EPA assesses risk of cancer differently from risk of all other (non-cancer) health outcomes. The approach for non-cancer outcomes makes incorrect assumptions about “safe” levels of exposure in a way that doesn’t reflect the reality and diversity of the general population.
“EPA’s assumptions about how people are affected by exposure to harmful chemicals often lead to underestimating health risk in many, many of its chemical risk evaluations,” said Wendy J. Heiger-Bernays, PhD, clinical professor in environmental health at the Boston University School of Public Health and co-lead author with Greylin H. Nielsen, MPH, of Application of Probabilistic Methods to Address Variability and Uncertainty in Estimating Risks for Non-Cancer Health Effects. “The result is decision-making based on partial information because people at risk of some non-cancer health effects are undercounted or not counted at all,” said Nielsen.
The paper applies a method published by to the World Health Organization to estimate the neurological impact of a dry-cleaning chemical, perchloroethylene (PCE). This method better accounts for the extent of adverse effects in the exposed population compared to EPA’s outdated method.
Regulating Chemicals by Class
Despite more than 350,000 chemicals in use in the U.S., EPA continues to evaluate chemicals for risk one at a time. “This makes no sense and leaves people exposed and at risk,” said Maricel Maffini, PhD, an independent consultant and lead author of Advancing the Science on Chemical Classes, in which the scientists recommend that chemical regulation could be more efficient and effective by regulating chemicals by class, group, or family – categorizing chemicals by function or other properties.
The paper explains how the class concept has been used in regulatory decision making and how it could apply to EPA’s current activities. Using phthalates – a widely used class of chemical in many plastics and personal care products that nearly every person in the U.S. has in their body – as an example, the authors demonstrate how evaluating chemicals by class could protect people more efficiently and effectively. While each phthalate is different, several of the phthalates considered share properties that pose an increased risk to health. Most people are exposed to multiple phthalates, and several phthalates pose similar risks to human health, such as effects on the development of the male reproductive system.
Blogs about each of the four papers will be released throughout the month of January. All lead authors will participate in a webinar to discuss the papers on Thursday, February 2nd. Register here: bit.ly/san-jan23
Other blogs in this series: