New direction urged to better assess public health risks

Most health conditions that are the focus of risk assessment are caused by multiple factors: stressors from multiple sources contribute to a single disease, and a single stressor can lead to multiple adverse outcomes.

Recent scientific and technological advances have the potential to improve the assessment of public health risks posed by chemicals, yet questions remain how best to integrate the findings from the new tools and methods into risk assessment.

A new National Academies of Sciences, Engineering & Medicine report recommends approaches for using 21st-century science to evaluate the many factors that lead to health risks and disease, laying the groundwork for a new direction in risk assessment that acknowledges the complexity of disease causation.

This report, published Jan. 5, builds on the findings from two earlier National Academies reports: "Toxicity Testing in the 21st Century: A Vision & a Strategy," which recommended a path whereby testing chemicals relies primarily on high-throughput in vitro tests and computational models based on human biology to evaluate potential adverse effects of chemical exposures rather than on animal testing, and "Exposure Science in the 21st Century: A Vision & a Strategy," which urged a transformational change in the breadth and depth of exposure assessment that would improve its integration with and responsiveness to toxicology and epidemiology, an announcement explained.

The committee that conducted the study and wrote the report considered the benefits of many new tools in exposure science, toxicology and epidemiology. For example, personal sensors and other sampling techniques now offer unparalleled opportunities to characterize individual exposures, particularly in vulnerable populations, and computational tools have the potential to provide exposure estimates where exposure-measurement data are not available.

Other advances include the further development of cell-based assays that can be used to evaluate various cellular processes and responses and the creation of transgenic animals from gene editing techniques that can be used to investigate specific questions, such as those related to susceptibility or gene/environment interactions.

Furthermore, "-omics" technologies have substantially transformed epidemiology and advanced molecular epidemiology fields that address underlying biology and complement empirical observation.

To ensure that these tools and methods are being used to their full potential, the report calls for a collaborative approach among scientists in the relevant fields.

“This report builds on the conceptual foundation established by the two earlier reports and indicates ways that findings from these new reports can be used in practice,” said Jonathan Samet, distinguished professor and the Flora L. Thornton chair at the department of preventive medicine at the University of Southern California. “It also identifies critical challenges to be addressed in using 21st-century science to better characterize the risks of chemicals for human health.”

The advances in exposure science, toxicology and epidemiology described in the report support a new direction for risk assessment — one based on biological pathways rather than on observations from lab experiments of effects in animals, and one incorporating the more comprehensive exposure information emerging from new tools and approaches, the National Academies said.

The new direction emphasizes that most diseases that are the focus of risk assessment are caused by multiple factors; that is, stressors from multiple sources can contribute to a single disease, and a single stressor can lead to multiple adverse outcomes. Conditions intrinsic to an individual, such as genetic makeup or life stage, or conditions acquired from one’s environment, such as psychosocial stressors and nutritional status, can contribute to a disease. The new direction in risk assessment acknowledges this complexity.

The four agencies that requested the study — the U.S. Environmental Protection Agency, U.S. Food & Drug Administration, National Institute of Environmental Health Sciences and National Center for Advancing Translational Sciences — are all involved with application of these 21st-century scientific approaches, including their use in various components of risk assessment, particularly hazard identification and exposure assessment.

Assessment of risks from chemicals and other agents provides needed information to decision-makers who must find solutions to protect public health. The scientific growth highlighted in this report will lead to better information for answering pertinent questions about the complex health problems that society faces.

The committee emphasized that technological growth is outpacing the development of approaches to analyze, interpret and integrate the diverse, complex and large data sets in these fields. The report proposes an agenda for enhancing use of the findings from these emerging technologies that includes developing case studies that reflect various situations of decision-making and data availability, testing case studies with multidisciplinary panels and cataloguing evidence evaluations and decisions that have been made on various agents so expert judgments can be tracked and evaluated.

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