Challenges of the 21st Century - Science For Environmental Protection: The Road Ahead - page 21

An area of increasing recognition is that of cumulative effects from the
built and social environment on health and well-being. Multiple exposures and
social factors can interact to increase risks and affect community health status.
The role of the built environment in community health is analogous to the role
of habitat change in ecologic quality. Effective environmental protection takes
into consideration all environments that are valuable to humans and natural sys-
tems, and EPA can continue to have significant impacts in this area of research.
Today and in the future, EPA will be challenged to maintain and consider
an expanding list of chemicals and potential adverse environmental health ef-
fects. Because people are being exposed to many different types of stressors that
may interact antagonistically or synergistically and because chemicals can affect
different populations in different ways, EPA will also be challenged to refine
methods to evaluate cumulative effects (EPA 2011b). New approaches to under-
standing and managing risks and to measuring health outcomes would support
more informed environmental-policy decisions.
Biomonitoring and Emerging Concerns about Exposure and Health
Biomonitoring for human exposure to chemicals in the environment has
provided a new lens for understanding population exposures to toxicants. The
Fourth National Report on Human Exposure to Environmental Chemicals
measured 212 chemicals in the US population, including 75 for the first time
(CDC 2009). The results indicated some declining loads of historical pollutants,
such as lead and polychlorinated biphenyls, but also indicated widespread popu-
lation exposure to previously unmeasured and potentially toxic chemicals. For
example, bisphenol A, which potentially has reproductive and endocrine effects,
was found in the urine of over 90% of those sampled. Bioaccumulated polybro-
minated diphenyl ethers were found in the serum of almost the entire population,
as were several polyfluorinated compounds used to impart nonstick characteris-
tics to surfaces. The report also provided improved data on pervasive exposures
to historically recognized toxicants, such as arsenic and mercury.
The “exposome” is a measure of all exposures that a person accrues in a
lifetime (see Chapter 3). It is exceedingly difficult to measure all exposures that
a person accrues in a lifetime because of the enormous variability in exposure
over space and time and to an ever-changing set of chemicals that are used by
society. Measuring such exposures in an entire population is even more difficult.
Yet the exposome is a useful concept that will be increasingly important in com-
ing years and allow the exploration of the progression of disease from an ab-
sorbed dose to a targeted health outcome, including the influence of genetic in-
formation on susceptibility and biomarkers.
Novel understanding of population exposure brings new challenges for envi-
ronmental health science. The report Biomonitoring for Environmental Chemicals
(NRC 2006) indicates the analytic methods for detecting exposures have outpaced
the science of interpreting the potential implications for human health. As the list
of biomarkers grows, EPA will face constant challenges to interpret health and