THE enHEALTH RISK MANAGEMENT FRAMEWORK

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THE enHEALTH RISK MANAGEMENT FRAMEWORK

• Brian G. Priestly
• Director ACHHRA

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
2
ACHHRA What is it?

• Consortium of four Australian Universities
• Monash DEPM Flinders Env.HlthUQ EnTox
  Griffith Env Hlth
• Core funds PHERP Innovations program
• Broad spectrum of expertise in public
  environmental health risk assessment
• Key priorities workforce development
  innovative research

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
3
The concept of SAFETY

• The absence of risk?or
• A concept which relies on the efficacy and
  reliability of CONTROLS over risk?

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
4
enHEALTH Council what is it?

• Subcommittee of the National Public Health
  Partnership
• Comprised of Commonwealth/State/Territory senior
  officials representing environmental health
  programs
• Key publications include National
  Environmental Health Strategy (1999 under
  review) National Environmental Health Strategy
  Implementation plan (2000) Environmental health
  risk perception in Australia (2001) Directories
  of environmental health data, standards
  guidelines Developing National Environmental
  Health Indicators (2002)

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
5
enHealth Council what is it?
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
 
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enHEALTH RISK MANAGEMENT FRAMEWORK
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
7
enHEALTH RISK MANAGEMENT FRAMEWORK

• OBJECTIVES
• Establish a national framework for risk
  assessment
• Encourage the use of consistent risk assessment
  methodology
• Adopt risk assessment methodology consistent with
  international best practice
• Deliver consistent and reproducible outcomes (?)
• Provide a mechanism for the application of risk
  assessment outcomes to standard setting and other
  risk management strategies

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
8
CONCEPTUAL FRAMEWORK

• Risk assessment should represent a vigorous
  adaptive and interactive process of evaluating
  the nature, and to maximum extent possible, the
  quantitative character of risks.
• Risk management should represent an interactive
  design, planning, negotiation and/or regulation
  process aimed at reducing identified risks to
  levels which can be tolerated by potentially
  affected parties or by society overall Hrudey
  (1996)

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
9
KEY ELEMENTS OF THE DOCUMENT

• Summary of risk assessment objectives
  significance
• Concise statement of the key principles in
  environmental health risk assessment (HRA)
• Glossary of HRA terminology
• Guidance on community consultation and risk
  communication
• Individual chapters outlining the components of
  HRA hazard, dose-response, exposure, risk
  characterisation, guidance and standards for
  different exposure media
• Drafted by Australias leading experts on HRA

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
10
There is another enHEALTH risk assessment
document out for consultation
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
11
EnHEALTH has also published reviews of individual
air toxics
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
12
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
13
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
14
DESIRABLE RISK ASSESSMENT OUTCOMES

• Estimates of baseline, existing, new or exotic
  risks, at a point of time and changes in risk
  over time
• Evidence-based health guideline values to assist
  the risk manager and/or guide clean-up processes
• Supporting risk management decisions on whether
  interventions are needed or risk policies
  reconsidered
• Prioritisation of issues according to their
  levels of risk
• Identification and comparative analysis of
  factors which may mitigate risk
• Greater transparency in risk management and risk
  communication to the community

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
15
STEP 1 HAZARD IDENTIFICATION

• Is the airborne toxic a gas, vapour or dust?
• Will it produce mainly systemic or local toxic
  effects?
• What is the nature of the toxicological
  database? - animal studies - epidemiological
  studies - occupational exposure studies
• Are the dose-response relationships adequately
  defined
• Have exposure standards been set (or can they be
  set)? - TLV, ADI, MPC
• Are these standards relevant to airborne
  exposures?

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
16
AIRBORNE TOXICS PRODUCE BOTH SYSTEMIC AND LOCAL
TOXIC EFFECTS
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
17
TOXICITY TESTS BASIC ASSUMPTIONS

• As dose increases, so does the severity of the
  toxic effect and the probability of observing it
• Toxic mechanisms are common across tissues and
  species differences in response relate mainly
  to different target tissue concentrations
• The toxic endpoint is recognisable as a distinct
  patho-physiological change
• The use of safety factors overcomes the
  uncertainties inherent in trans-species
  extrapolation

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
18
TERMINOLOGY DEFINITIONS

• Acceptable Daily Intake (ADI)the daily intake
  which can be ingested for an entire lifetime (70
  years) without appreciable health risk (on the
  basis of information available at the
  time)units mg/kg body wt/day

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
19
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
20
STEP 2 EXPOSURE ASSESSMENT
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
21
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
22
EXPOSURES MAY BE VARIABLE
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
23
Do the data allow for conversion between routes
of exposure?
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
24
POTENTIAL CONSEQUENCES ASSOCIATED WITH INADEQUATE
UNDERSTANDING OF EXPOSURE PARADIGMS
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
25
Is there a better way of integrating point
estimates of exposure?
Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
26
MONTE CARLO TECHNIQUES

• PROS- inherently more representative of variable
  exposures- avoids bias associated with outlier
  or extreme point estimates- enables exposure
  pathways to be appropriately ranked
• CONS- complex, data-rich requirements to define
  probability distributions- difficult to
  distinguish between variability and
  uncertainty- need to define acceptable
  exposure in terms of a probability cut-off
  (e.g. 1 in 20 persons would exceed exposure
  level)- the models may portray a level of
  precision which is misleading- the distribution
  extremes (e.g 99th percentile) are still
  estimated with some uncertainty

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
27
EXPOSURE MODELLING

• Some inputs required to achieve an estimate of
  concentrations at each receptor point (enHealth
  2002 table 2 A2)
• release point locations stack height/diameter
• mass emission rates for cmpds stack
  velocity/temperature
• concs. Of individual substances geographic
  features
• rural or urban site classification local
  meteorological data
• receptor locations
• frequency/duration of short-term releases

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
28
USE OF DEFAULT VALUES

• Safety factors in extrapolating from animal to
  human
• Benchmark dose approach to establishing a
  safe level of exposure to carcinogenic soil
  contaminants (NHMRC EH21 1999))
• The use of tables of physiological
  parameterse.g. in December 2003 Exposure draft,
  see tables for - respiratory rates in infants,
  children adults standardised and
  activity-related - activity-related respiration
  volumes - air exchange ratios - particle
  deposition and filtration factors - examples of
  dust size-frequency distribution patterns -
  activity summaries time spent in different
  microenvironments

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment
29
SOME CLOSING REMARKS

• Whenever data gaps occur, assumptions must be
  made before the risk assessment process can be
  completed. When these assumptions are
  unrealistic, or eventually prove to be incorrect,
  the risk assessment supports an interpretation
  diametrically opposed to reality Gregory
  (1992) Cancer risk - does anyone really
  care? Reg. Toxicol. Pharmacol. 15, 271-277

Department of Epidemiology Preventive Medicine
ACHHRA
Australian Centre for Human Health Risk Assessment