Building Science for Environmental Protection in the 21st Century - Science For Environmental Protection: The Road Ahead - page 123

thinking” to characterize where a particular product, action, or decision may
shift effects somewhere in the life cycle of a product or activity and how those
effects can be minimized or prevented. For example, a simple chemical substitu-
tion may result in the use of a new product that may be safer for consumers but
may cause effects on workers far upstream in the production process. In addi-
tion, LCA is an inherently comparative tool because it considers the life-cycle
implications of multiple products or processes that achieve the same end use.
This so-called functional unit determination is intended to be broad and to en-
courage innovation in the development of solutions by focusing on what a con-
sumer needs from a product rather than on the product itself. Box 4-3 outlines
the opportunities that LCA or life-cycle thinking can provide to enhance systems
thinking about complex problems.
Cumulative Risk Assessment
The advent of new science tools and techniques means that the suite of
traditional tools need to be reviewed and enhanced for 21st century challenges
and opportunities. Quantitative risk assessment has been central to many aspects
of EPA's mission for decades. The risk-based decision-making framework pro-
posed in Science and Decisions: Advancing Risk Assessment (NRC 2009) offers
an opportunity, and detailed recommendations, for the agency to revisit and re-
vamp its current practices. In particular, this would encourage linkages between
risk assessment and various solutions-oriented approaches. In addition, as dis-
cussed in Chapter 3, a host of rapidly evolving health and ecosystem assessment
tools (for example, “-omics” and the exposome) can be applied, with appropriate
deliberation, to enhance risk assessment further.
Beyond enhancements in traditional single-chemical risk assessment,
many of the trends in both science and risk-assessment practice in recent years
involve moving from a single-chemical perspective to a multistressor perspec-
tive. EPA has grappled with chemical mixtures for some time, and cumulative
risk assessment has come to the forefront of the agency's thinking over the last
decade, although the agency has rarely used it. Multiple recent NRC committees
have addressed cumulative risk assessment extensively (NRC 2008, 2009), and
the present committee concurs with the prior recommendations. Moreover, the
committee supports the growing emphasis in EPA on this topic (which includes
both intramural and extramural research), noting that these efforts have increas-
ingly emphasized community-based participatory approaches, applications in
disadvantaged communities, and use of epidemiologic insight. Nonetheless, al-
though much of the emphasis of previous NRC reports has been on cumulative
risk assessment for human health effects, it is possible that insights and ap-
proaches from ecosystem-based cumulative impact analyses (required under the
National Environmental Policy Act [NEPA]) could be adapted to cumulative
risk assessment for human health effects.