Addressing systemic problems with exposure assessments to protect the public’s health

Abstract

Background Understanding, characterizing, and quantifying human exposures to environmental chemicals is critical to protect public health. Exposure assessments are key to determining risks to the general population and for specific subpopulations given that exposures differ between groups. Exposure data are also important for understanding where interventions, including public policies, should be targeted and the extent to which interventions have been successful. In this review, we aim to show how inadequacies in exposure assessments conducted by polluting industries or regulatory agencies have led to downplaying or disregarding exposure concerns raised by communities; that underestimates of exposure can lead regulatory agencies to conclude that unacceptable risks are, instead, acceptable, allowing pollutants to go unregulated; and that researchers, risk assessors, and policy makers need to better understand the issues that have affected exposure assessments and how appropriate use of exposure data can contribute to health-protective decisions. Methods We describe current approaches used by regulatory agencies to estimate human exposures to environmental chemicals, including approaches to address limitations in exposure data. We then illustrate how some exposure assessments have been used to reach flawed conclusions about environmental chemicals and make recommendations for improvements. Results Exposure data are important for communities, public health advocates, scientists, policy makers, and other groups to understand the extent of environmental exposures in diverse populations. We identify four areas where exposure assessments need to be improved due to systemic sources of error or uncertainty in exposure assessments and illustrate these areas with examples. These include: (1) an inability of regulatory agencies to keep pace with the increasing number of chemicals registered for use or assess their exposures, as well as complications added by use of ‘confidential business information’ which reduce available exposure data; (2) the failure to keep assessments up-to-date; (3) how inadequate assumptions about human behaviors and co-exposures contribute to underestimates of exposure; and (4) that insufficient models of toxicokinetics similarly affect exposure estimates. Conclusion We identified key issues that impact capacity to conduct scientifically robust exposure assessments. These issues must be addressed with scientific or policy approaches to improve estimates of exposure and protect public health.

Blood Levels of Organochlorine Contaminants Mixtures and Cardiovascular Disease

“…Integrating multiple chemical exposures provides a more realistic estimate of risk than exposures to single specific compounds and is more meaningful for health risk assessment, public health prevention, or interventions. 25,26 Herein, we used an improved method for environmental chemical mixtures within epidemiological studies to account for the cooccurrence of multiple components present in the real world as a complex mixture. 27 Thus, using quantile g-computation, we examined the joint mixture association of the most prevalent OCPs and PCBs congeners with the incidences of MI and ischemic stroke in 2 population-based cohorts, using a prospective nested case-control design.…”

“…While elevated blood concentrations of both PCBs and OCPs have been associated with incident stroke in Nordic and Korean populations, the association with incident MI is unexplored, as is the impact on these end points of the joint toxic effect of several compounds. Integrating multiple chemical exposures provides a more realistic estimate of risk than exposures to single specific compounds and is more meaningful for health risk assessment, public health prevention, or interventions …”

Systems for rating bodies of evidence used in systematic reviews of air pollution exposure and reproductive and children’s health: a methodological survey

“… Further aspects specific to reproductive and children’s health, including generally longer expected lifespans and long latency periods, life course perspectives (e.g., developmental origins of disease), trans-generational effects, among others, necessitate a tailored approach [ 24 ]. Challenges related to exposure assessments are generally an issue in observational vs. experimental studies, where exposures are not controlled by investigators, and in particular, in environmental health studies [ 14 , 27 ]. Exposure assessments regarding air pollution are characterized by specific challenges (e.g., differences in the availability of air monitoring data, seasonal variations in exposure patterns, etc.)…”

“…Exposure assessments regarding air pollution are characterized by specific challenges (e.g., differences in the availability of air monitoring data, seasonal variations in exposure patterns, etc.) [ 17 , 27 ], potentially increasing misclassification, also with regard to relevant developmental periods, such as gestational trimesters. Also, there are additional considerations with regard to reproductive and children’s health: Due to differences in body size and behaviors, among others, exposure patterns are different for developing fetuses, children, and pregnant persons vs. non-pregnant adults (e.g., relative exposure doses, exposure routes and settings, timing and duration of exposure in relation to windows of susceptibility) [ 24 , 27 – 29 ].…”

Multigenerational Effects of a Complex Human-Relevant Exposure during Folliculogenesis and Preimplantation Embryo Development: The FEDEXPO Study

“…Investigations on those alternatives are currently less substantial than for BPA but they have already reported numerous negative findings regarding female reproductive function [ 10 ], which makes them a potentially regrettable substitution. The management of these emerging chemicals adds to the yet numerous questions raised in the human risk assessment of EDCs [ 11 ].…”