•;tools for addressing aggregate risk
from single agents yet multiple envi-
ronments (for example, work, home,
car, air) and cumulative risks from
multiple stressors
•;a more thorough incorporation of
cost-benefit analysis and life cycle im-
pacts on occupational exposures for a
better understanding of the economic
impacts of risk management decisions
•;improved techniques for studying how
perceptions affect the acceptability of
a particular risk
Driven by advances in science and
technology, these new risk analysis
methods are allowing health profes-
sionals, including industrial hygienists,
to tackle ever more complex problems
and make more informed decisions. For
industrial hygienists, this new era offers
several opportunities. Mastery of risk
analysis tools is one of our core compe-
tencies; staying ahead of the curve will
serve occupational and public health
well and increase our value.
Reducing Uncertainty
Uncertainty is inherent within a risk
assessment.2 If a dangerous condition
exists with little or no uncertainty, there
is no reason to assess risk; one moves
directly to controlling the hazards. Thus,
risk assessments must consider uncertainty during every phase of the process.
Uncertainties exist in the identification and measurement of hazards, the
estimation of exposures, the identification and measurement of health effects
associated with exposures, and the
method used to characterize population
and operational risks. Creating a risk assessment is an iterative process designed
to be refined until there is consensus on
the most important and most uncertain
factors affecting the results. How confident do decision makers need to be
regarding these important but uncertain
factors? The answer to this question
should determine the duration and complexity of the risk assessment. Perceptions of risk and the availability of data
influence estimates of health risk.
A major criticism of the risk assessment process concerns the impact of
uncertainty on the accuracy and us-ability of the findings. Uncertainty can
be thought of as absence of knowledge
on a specific issue, such as the toxicity
or physiochemical properties of a sub-
stance, or the distribution of exposures
among a group of factory workers. One
way to reduce the impact of uncertainty
is to include data within each step of
the risk assessment. The need for robust
sources of scientific data is a challenge
that must be overcome to ensure accurate, usable results.
Fortunately, promising scientific
advancements may help reduce uncertainty. For example, new toxicity testing
methods under development might offer
quicker and less expensive alternatives
to traditional bioassays. A groundbreak-ing 2007 NAS report outlined a framework for the continued development
and use of alternative testing methods
that aligns with the traditional risk assessment paradigm3 and generates data
needed to reduce uncertainty within the
hazard identification and dose-response
steps of a risk assessment. This information will help characterize chemicals’
properties and metabolism, define key
exposure pathways, and identify potential human effects of exposure. These
new sources of data will greatly enhance
industrial hygienists’ ability to conduct
effective occupational and environmental assessments. The challenge lies in
understanding and applying the new
data to reduce the impact of uncertainty
within the risk assessment process.
Shifting from Traditional Health
End Points
What health end point should serve as
the focal point for an occupational risk
assessment? Should transient reversible
or subclinical health effects be regulated
to the same level as irreversible effects,
such as cancer?
These questions are frequently debated among health professionals,
stakeholders and regulators. A review
of the documentation of available occupational exposure limits (OELs) quickly
demonstrates that a large majority of
the health-based recommendations focus
on irreversible health end points, such
as cancer, neurotoxicity or reproductive
effects. Advances in science and medicine now allow us to identify subclinical effects, such as genetic and immune
responses to certain chemical agents,
