Transcript Health Effects of Air Toxics

Air Toxics Exposure:
Relevance to Risk
Assessment
TCEQ/NUATRC Air Toxics Workshop
October 17, 2005
Tina Bahadori, D. Sc.
Long-Range Research Initiative
American Chemistry Council
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GPRA Goals (source: EPA Air Toxics
Research Strategy draft 2002)
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“By 2010, reduce air toxics emissions by
75% from 1993 levels.”
“By 2020, eliminate unacceptable risks of
cancer and other significant health
problems from air toxics emissions for at
least 95% of the population, with particular
attention to children and other sensitive
subpopulations…”
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Risk Assessment/Risk Management Framework
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Foundation for Decision-Making
MACT Std’s
Residual Risk Std’s
Urban Area Source Std’s
Community Initiatives
Utility Determination & Actions
Mobile Source Std’s
Combustion Std’s
NATA
HEALTH RISK INFORMATION
Is it sufficient?
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The Conundrum
Facility
SOURCE 1
SOURCE 2
SOURCE 3
“Individual” Air Toxics
 188 CAA
 34 NATA
 21 Mobile Source
 18 Indoor Air
8-9 Yr after MACT:
Residual Risk? Ample
margin of safety test.
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Sources of Air Toxics
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Linear MultiStage Model
RfC
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Lifetime continuous
exposure
Adverse effects unlikely in
sensitive groups
NOAEL/BMD (human
adj)/UF’s: NOAEL,
interspecies, intraspecies,
chronic, database
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Lifetime continuous
exposure
Upper bound excess
lifetime cancer risk
Risk unlikely to exceed
upper bound
Risk likely to be
somewhere between 0
and upper bound
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Current and Future Needs
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Improve risk assessment methodologies
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consideration of real-world exposures (e.g., dose-rate,
intermittent)
reduced reliance on generic defaults,
harmonization of cancer and noncancer methods
Expand research on complex mixtures of air toxics
Use available health information in state-of-the-science
assessments, in time for regulatory use
Prioritize and fill chemical-specific health data gaps in context
of the risk “wheel”
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The ACC’s Long-Range Research
Initiative (LRI)
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Goal: Provide fundamental research essential to
improving chemical testing and risk assessment
practices and policies
Research independence
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PIs select chemicals
PIs “own” data and publish in peer-reviewed literature
without ACC approval
Research conducted according to
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MOU with CIIT Centers for Health Research
Competitive RfP program, often with other federal
agencies
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LRI Air Toxics Program
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Human Exposure Studies
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Atmospheric formation of air toxics mixtures, with
identification of toxic components (UNC)
Measurement of indoor, outdoor, and personal
exposures to VOCs in several areas of Boston
and Detroit (Harvard,U.MI)
Improve air toxics exposure models (EOHSI with
EPA/NERL & OAQPS)
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LRI Air Toxics Program
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Dose Studies
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Respiratory tract dosimetry modeling, reactive
gases and particles (CIIT)
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Animal-to-human extrapolation
Human age models
Age-dependent pharmacokinetic modeling for
systemically acting chemicals (CIIT, ENVIRON)
Chlorine dosimetry (CIIT)
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LRI Air Toxics Program
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Health Effects and Assessment Studies
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Chlorine dose-response modeling (CIIT)
Mechanisms of acute lung injury (CIIT)
Lung biomarkers (CIIT)
Methods for developmental effects (EPA, Cornell,
TNO, CIIT)
Chloroform computational modeling (CIIT)
Functional genomics (CIIT)
BB-DR modeling (CIIT, Colorado State, Gradient)
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For more
information on LRI
www.uslri.org
[email protected]
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Far More Advanced Assessment
Methods Available, if Database Rich
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Noncancer
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Expert judgment (e.g., EPA ozone)
Advanced BMD and Bayesian analyses (e.g., EPA Mn)
Probabilistic UF’s (e.g., pubs, mostly for RfD’s)
1999/2003 EPA’s Draft Revised Cancer
Guidelines
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Mode of action
Biologically-based dose-response modeling
Margin of exposure
2003 supplement for early-life exposure
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Research Causes Evolution of
Formaldehyde Cancer Assessment
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Early 80’s, nasal cancers
in rodents, >6ppm
Later
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rat-human nasal dose
models
mode of action (DPX &
CRCP)
2-stage clonal growth
model link of DPX & CRCP
with tumors
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