As a researcher in the field of exposure science, I have applied systems thinking and a convergence approach to understand how exposure agents move through our environment, how humans interact with these agents, and the implications for health. My work has focused on characterizing exposures associated with anthropogenic activities, spaces, and places to build the scientific basis for designing healthier environments. As the Editor-in-Chief of the Journal of Exposure Science and Environmental Epidemiology for the last 8 years, I have had the opportunity to observe the larger evolution in the field as well as common themes that have remained foundational.

Exposure science is the study of our contact, by breathing, ingesting, or touching, with environmental agents and stressors. Chemicals and microbes in the air we breathe, water we drink, and food we eat can affect our health. Low-level and prevalent environmental exposures to contaminants, noise, and extreme temperatures in the places we live, study, work, and play may contribute substantially to the burden of common complex diseases. As such, exposure science is a key requirement for assessing human health risk, and a sparsity of exposure information has been consistently identified by policymakers as a barrier to addressing our most pressing environmental health challenges [1,2,3]. Understanding the relationships between environmental exposures and health outcomes requires integration of a wide range of factors over the human lifespan.

Convergence research [4] is inspired by the need to address specific challenges that arise from pressing societal needs. These compelling problems require contributions and deep integration across disciplines. By drawing on perspectives and expertise, problems are attacked from multiple vantage points and solutions arise at the intersections that may not have been discovered from any one angle. Exposure science is by its very nature interdisciplinary, and the questions that exposure scientists pursue require a convergent research approach. As scientists around the world tackle vexing problems in environmental health and aspire to impact solutions that protect and promote health, I would like to share the six principles of exposure science that I see are fundamental to our field and critical to translating scientific advances in adjacent fields for use by decision makers.

1. Both naturally occurring and anthropogenic agents and stressors impact health. For centuries, societies around the world have extracted and adopted natural materials, including metals, dyes, and fibers to create functional, durable, and beautiful products. The last several decades have seen rapid growth in industries that manufacture and use man-made chemicals to provide many of these same functions. Exposure scientists have made significant contributions to understanding how exposures to both these ancient and modern compounds and contaminants may cause adverse health effects [5, 6]. Designers today are exploring new uses for traditional materials while deriving inspiration from structures and processes in nature to advance healthy alternatives. Exposure scientists can contribute to premarket evaluation of these innovative technologies along-side engineers who test performance. Understanding exposure science principles will enable early concepts and prototypes for new materials and products that anticipate consequences and support safer designs.

2. Exposure sources can be located outdoors and indoors. Awareness of the critical impacts and health hazards of environmental pollution and outdoor sources of exposure was manifest by a series of events, including the 1962 publication of Silent Spring [7] and the 1969 Cuyahoga River Fire [8]. Yet it is only in recent years that the public has come to understand the potential for significant indoor sources of exposure. Natural disasters, including the COVID-19 pandemic [9] and wildfire events [10], focused attention on how the indoor and built environment can both contribute to and provide refuge from exposures to hazardous agents. Exposure scientists have actively contributed expertise to characterize exposure sources and pathways outdoors and indoors. The field has also been instrumental in implementing and evaluating interventions. Today, the healthy building movement is focused on innovations that support the health and well-being of occupants and communities. Exposure science is integral to the success of this movement and can enable architects, builders, and city planners to optimize and connect indoor-outdoor spaces that are clean and safe.

3. Exposure agents move through connected systems, interact, and change in form. The fate and transport of agents in environmental and biological systems is a function of the properties of the agents and the characteristics of the system. These properties and characteristics can be measured experimentally and predicted with QSAR (quantitative structure–activity relationship) tools. Using this information, exposure scientists have been at the fore applying mechanistic-based modeling approaches to identify significant sources, pathways, and toxicokinetics of exposure to agents [11, 12] ranging from toxics in air and pesticides in food to semi-volatile organic compounds in house dust. This first-principles-based modeling approach is broadly applicable in a variety of systems and informs understanding of factors with the greatest influence on exposure and dose. For more complex agents and chemistries that persist and migrate globally, including the “forever chemicals” or PFAS (per- and polyfluoroalkyl substances), properties and transformations may be challenging to estimate, and occurrence in environmental media may be difficult to predict. Advanced nontargeted analytical methods and sensors are enabling measurement and discovery of emerging contaminants. In partnership with chemists and data scientists, exposure scientists are exploiting these new collection methods, along with geospatial information and machine learning approaches, to identify predictors of chemical occurrence in exposure media. Fusing mechanistic and data-driven modeling will provide rapid exposure information to efficiently screen for new agents and ensure safe air, water, and food [13].

4. Exposure is determined by context, including time, place, and culture. Environmental conditions may increase or reduce exposures to agents of concern, as may human behavior. Time scales and spatial scales of both environmental conditions and human behavior mediate exposures. It is this intersection between environment and human behavior that distinguishes exposure science from related environmental health disciplines. The complexity of these linked, open physical and social systems has challenged environmental health practitioners and risk assessors who aspire to characterize and predict potential exposures under a wide range of real-world contexts [14]. Simulating representative patterns of life that take a systems approach and consider the broad scope of activities and influences is required to improve exposure modeling that underlies the understanding of environmental contributions to health [15]. Today, convergence research integrating diverse expertise from the physical, biological, and social sciences will progress understanding of complex physical and societal systems. Exposure science can inspire the development and application of emerging tools, including agent-based models and knowledge graphs, to support thoughtful innovation and provide resilient solutions across time and space.

5. Important exposures to vulnerable people may occur across the lifespan and lifecycle. Exposure agents are generated and emitted during the manufacture, use, and disposal phases of the product lifecycle, resulting in potential exposures to workers, consumers, and fence-line communities. Individuals may be particularly susceptible or resilient to health impacts associated with exposures to given agents depending on the developmental stage of organ systems and metabolic capacity. These windows overlay important life stages characterized by developmental changes in behavior that may influence the intake of these agents. It is important to consider sensitive windows during the lifecourse of human development [16], as well as significant exposure conditions along the lifecycle of manufactured products [17], to identify and protect people who may be at highest risk. Exposure scientists develop and curate information required to assess exposure from the vantage point of exposed individuals and groups, as well as from sources of agents. Innovations in sustainable development that prevent pollution and enable circular economy initiatives [18] will depend on exposure science to inform assessments that include prospective exploration of unintended consequences, including burden shifting and regrettable substitutions.

6. The impact of exposures on health is determined by biology. Biologically relevant exposure metrics are those that can be directly associated with key events in a disease process and with an individual’s exposure profile. Individuals, communities, and populations may have underlying vulnerability and resilience associated with psychosocial factors that modify the health impact of exposure to environmental agents. As early as 1999, Groopman and Kensler [19] highlighted the challenges associated with developing biomarkers and interpreting biomarker data to sort out the interactions of multiple chemicals, multiple exposures, and the relation of these to health outcomes. The exposome concept, introduced by Chris Wild in 2005, encompasses all environmental exposures from preconception through death that influence health and disease [20]. Exposomics [21] include the ensemble of technologies, methodological approaches, and biological research strategies that investigate the exposome to characterize exposures, identify biomarkers, and establish mechanistic links between environmental factors and health outcomes. Today, environmental health researchers are dedicated to systematically mapping the exposome by cataloging the myriad exposures, including psychosocial stressors, that individuals encounter throughout their lives [22]. The objective is to enable the discovery of exposure-disease links and, importantly, translate these insights for use by decision makers. It is incumbent on exposure scientists to rise to this challenge, contribute their unique domain expertise, and ensure the success of this endeavor.

The goal for exposure science writ large is to provide the scientific basis for decisions and actions that foster innovation to solve critical problems while sustaining and promoting a healthy environment. Opportunities abound for exposure scientists to embrace state-of-the-art advances, including environmental and personal sensors, nontargeted chemical analysis, multi-omics biomonitoring, and artificial intelligence as we contribute to this end. Considering these six principles of exposure science will ensure new technologies created and deployed today secure the wellbeing of future generations as we work together to repair the world and build a healthy future for all.