Archives of Environmental & Occupational Health, Vol. 69, No. 3, 2014 C 2014 Taylor & Francis Group, LLC Copyright 

Response to Editorial

21st Century Exposure: An Opposing View Notwithstanding the enthusiastic reception surrounding the recommendations contained in the National Research Council report Exposure Science in the 21st Century: A Vision and A Strategy,1 efforts to define exposure science as an independent discipline are likely to fall short. Paradoxically, independence will be garnered by closer cooperation and integration with other disciplines to align the concept of exposure with outcomes and to supply effective tools to estimate and to characterize exposure. To achieve its potential, the field needs to integrate better with other fields and to develop standardized methods and procedures, and harmonized terminology that can describe exposures in terms of meaningful adverse effects or associations with the onset of disease. Rather than seek independence from epidemiology, toxicology, and risk assessment, exposure science should seek to forge even closer links to these disciplines through alignment with clinical sciences and systems biology. Failure to move in the direction of closer integration is likely to marginalize the field as a unique discipline, because it is not necessarily exposure scientists who are advancing the field. The field is advancing because of the demands placed on it by epidemiologists and risk assessors. Advances in multidisciplinary epidemiology studies are already revolutionizing the assessment of exposure, by defining the environment broadly in physical, economic, and social terms, and by employing a variety of modalities for estimation of exposure. In the absence of reliable and reproducible measurement methods and procedures, epidemiology will develop and test estimation methods to suit its needs. In the absence of reliable information about the frequency and duration of exposure for specific activities and events, risk assessment will continue to devise procedures to manage uncertainty. In the absence of measurement, methods will continue to be developed to characterize exposure for plausible scenarios to support sufficient regulatory decisions based on chemical structure-activity relationships, environmental fate models, and available data.2 2014, Vol. 69, No. 3

Embracing the ill-conceived concept of the “exposome” lends credence to suspicion about the field of exposure science, as does the atmosphere of sensationalism surrounding the detection of low-level exposures presenting dubious hazards. Hyped reports of nanogram or microgram exposure to industrial chemical residues of questionable health significance have had the opposite of the intended effect. Rather than vault exposure science to a level of importance on par with genetics and molecular toxicology, exaggeration of the potential significance of these findings has cast suspicion on the scientific merits of exposure science and its value in addressing public health and ecological problems. The impracticality, and lack of necessity, to characterize the so-called “exposome” (and in so doing to account for all exposure events ever encountered) impugns the credibility of exposure science in the eyes of scientists from other disciplines. Claims that nanogram or microgram exposures to industrial chemical residues are significant to health risk, without demonstrating an outcome or perturbation of biological processes, cause confusion among scientists and alarm the public unnecessarily. They also alienate colleagues from other scientific disciplines, who may legitimately question the significance of reported effects when there is a failure to show results that are consistent, unconfounded, and generalizable to other populations. The value of exposure science would be enhanced far more if the field developed rigorous standardized methods and procedures that characterized important routes of exposure over the life course and provided data about which toxicants at specific concentrations, alone or combined with other stressors, exert biological changes of significance in the causation or exacerbation of disease. Exposure science should make a priority of harmonizing terminology, using the same terms consistently, aligning its nomenclature with that used in other disciplines, dropping arcane terminology of little real significance (such as “near field” and “far field”), and replacing confusing terminology (such as “external exposure”). 129

In reality, seeking “independence” through separation has been detrimental, not beneficial, to exposure science: the field does not need more autonomy. Lack of orientation and standardization to the rest of life sciences has already limited the development of exposure science and diminishes its appeal. Closer alignment of exposure science with biology, clinical sciences, epidemiology, and toxicology, not less, will ultimately advance the field. Michael Dellarco, DrPH Senior Scientist, Eunice Kennedy Shriver National Institute of Child Health and Human Development


Disclaimer: The views expressed here are solely those of the author and do not reflect the policies of any component of the Federal Government.

References 1. National Research Council. 2012. Exposure Science in the 21st Century: A Vision and a Strategy. Washington, DC: National Research Council. Available at: id=13507. Accessed 5 July 2013. 2. The Health and Environmental Sciences Institute. Risk Assessment in the 21st Century. Institute for Life Sciences. Available at: Accessed 15 July 2013.

Archives of Environmental & Occupational Health

21st century exposure: an opposing view.

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