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Risk Assessment
Risk Assessment / Overview of Assessment of Ecological and Human Health Risk
Evaluation of Media for Inclusion into a Risk Assessment
Evaluation of Risk Assessments
Computer Software for Multimedia Assessments
References
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Risk Assessment
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Risk assessments can be extremely complex and
encompass numerous variables and areas well
outside the expertise of many permit writers. It is
therefore recommended that the permit writer
consult with risk assessment staff early and often in
the permit process, so that the risk assessment may
be focused towards solving the appropriate questions
and conducted in the most expedient and
efficient manner. The information provided in this
chapter is intended as a primer for those permit
writers who have little or no experience in this area
and as a resource for those with more extensive
knowledge.
Whenever possible, specific examples are provided
of the kinds of requirements a permit writer might
specify in an NOD to assist permit writers in identifying
the types of requirements they may impose.
Because a wide variety of issues are associated with
the interpretation of risk assessments, the examples
provided are not exhaustive.
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Risk Assessment / Overview of Assessment of Ecological and Human Health Risk
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| Risk Assessment |
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Description: For many types of Subpart X units, particularly
mechanical units such as shredders, crushers and
filter presses, a risk assessment may not be necessary.
This is especially true in cases where the unit is
fully enclosed in a containment structure such as a
building, which could essentially prevent releases to
environmental media. The applicant must be able to
justify that an risk assessment is unnecessary. |
| Overview of Assessment of Ecological and Human Health Risk |
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Description: As set forth in 40 CFR §264.601, “Permits for
miscellaneous units are to contain such terms and
provisions as necessary to protect human health and
the environment...”. Assessment of potential risk to
human health and the environment for permitting of a
combustion unit includes assessment of releases of
chemicals through air emissions and migration of
waste or residues to groundwater, surface and
subsurface soil, surface water, and wetlands. |
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Evaluation of Media for Inclusion into a Risk Assessment
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| Evaluation of Media for Inclusion into a Risk Assessment |
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Description: From the combustion unit, chemicals may be
transported through storm-water runoff,
volatilization, wind-suspended particulates, and
infiltration and percolation. Direct releases to the
soil also are considered. The media potentially
affected by those release mechanisms are surface
water, sediments, air, groundwater, and soil. |
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Evaluation of Risk Assessments
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| Evaluation of Risk Assessments |
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Description: This section consists of several subsections that
outline direct and indirect exposures to both human
and ecological receptors that permit writers must
consider when reviewing permit applications, for
combustion units, as well as a methodology that
should be followed to ensure consistent evaluation of
such units. Each subsection describes risk
assessment components necessary to support the
permit application for a combustion unit and
provides specific tools and information required to
support both screening and detailed human health
risk assessments. The final subsection describes the
uncertainty assessment that should be conducted for
the permitting process. |
| Data Evaluation |
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Description: Data to support quantitative assessment of risk at
combustion units usually are limited, but some
sources are available from which screening level
data can be collected. |
| Exposure Assessment |
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Description: Exposure Assessment is a key component of conducting a risk-based
screening evaluation is identification of potential
exposures. An exposure assessment includes an
evaluation of potential human and ecological
receptors that may contact chemicals originating
from the site, as well as routes, magnitude,
frequency, and duration of exposure. |
| Toxicity Assessment |
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Description: The toxicity assessment focuses on chemicals that
pose the greatest threat to human and ecological
receptors. Standard toxicological methodologies for
assessing the toxicity of contaminants require
quantification of dose-response relationships for
adverse human health effects associated with
exposure to specific chemicals. |
| Risk Characterization |
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Description: Risk characterization combines exposure estimates
and toxicity values to calculate numerical estimates
of risk and hazards to human health. |
| Uncertainty Assessment |
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Description: Because risk characterization is a bridge between
risk assessment and risk management, it is important
that the major assumptions, professional judgments,
and estimates of uncertainties be described in the
risk assessment. |
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Computer Software for Multimedia Assessments
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| Computer Software for Multimedia Assessments |
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Description: EPA has published modeling equations for
estimating concentrations of chemicals in plants and
animals, as well as transfer between media. The
equations range from simple to complex, as more
site-specific information is used or the need for a
more precise estimate is recognized. |
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References
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| References |
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Description: This section contains references to Risk Assessment. |
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