Presented by: Philippa Gibson, WorkSafe NZ at OHSIG 2014, Wednesday 10/9/14, NZI Room 4, 2.15pm

1. Philippa Gibson
OCCUPATIONAL HEALTH RISK ASSESSMENT –
LEGAL COMPLIANCE AND UNCERTAINTIES
PREPARED FOR OHSIG September 2014

2. HEALTH AND SAFETY REFORM BILL (2014)
Duty to manage risk Section 22
1. eliminate risks
2. minimise risks
WORKSAFE NEW ZEALAND September 2014 2

3. RISK MANAGEMENT –
AS/NZS/ISO 31000:2009 Principals and guidelines
Risk
the effect of uncertainty on objectives
Risk management
coordinated activities to direct and control an
organization with regard to risk
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4. AS/NZS ISO 31000:2009 Risk management
WORKSAFE NEW ZEALAND MAY 2014

5. Risk assessment - AS/NZS ISO 31000:2009
Identification
(ID and describe)
Analysis
(nature and level)
Evaluation
(magnitude, acceptable/not)
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6. OCCUPATIONAL HEALTH RISK ASSESSMENT
• informs (is part of) the risk management process
• You must consider the strengths, uncertainties and
assumptions that affect on the overall risk assessment
Source: Environmental Health risk assessment Guidelines for assessing human
health risks from environmental hazards (Commonwealth of Australia, 2012)
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7. UNCERTAINTIES IN HEALTH RISK ASSESSMENT
RISK IDENTIFICATION
• what are the exposures?
• routes of exposure
• people exposed
• sensitive individuals
RISK ANALYSIS
• variation in exposure
• error – systematic and
random
RISK CRITERIA
• Workplace Exposure
Standards
• absence of exposure
criteria
RISK EVALUATION
• are results comparable
to criteria
• uncertainty and
variability in data
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8. RISK ANALYSIS UNCERTAINTIES – airborne exposure
Quantitative exposure assessment
• varied methods
• instrument limitations
• systematic error- sampling and analysis
• random error - variation in exposure
Qualitative exposure assessment e.g.
control banding
• model limitations
• modelling assumptions
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9. WES = 100 ppm
VARIATION IN EXPOSURE
140
120
100
80
60
40
20
0
Ethyl benzene exposure
0 10 20 30 40 50 60 70
Ethyl benzene concentration (ppm)
Sampling day
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10. RISK EVALUATION UNCERTAINTIES
(risk analysis + risk criteria)
Workplace Exposure Standard as risk criteria
• Compliance with the designated value does not
guarantee that all workers are protected from
discomfort or ill heath – (individual susceptibility)
• e.g. certain genetic variations increase risk of
developing occupational asthma from HDI isocyanate
• e.g. genetic polymorphisms give rise to varying risk of
developing cancer. e.g. variation in DNA repair genes,
differences in metabolism, enzyme polymorphisms
• Basis for the WES often ignored – health end point e.g.
dichloromethane - acutely toxic, skin and eye irritant, CNS,
suspected carcinogen, hepatotoxic, nephrotoxic, produces
carboxyhaemoglobin
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11. UNCERTAINTIES
“Lack of, or imperfect knowledge concerning the present
or future state of an organism, system, or
(sub)population under consideration, which may affect
its accuracy or relevance.
Uncertainty can be reduced, at least in principle,
by improving the quality and/or amount of
information.”
(Source: WHO, “Guidance Document on characterizing and
communicating uncertainty in exposure assessment”, 2008)
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12. HEALTH RISK ASSESSMENT
• Each step in the risk assessment process
introduces uncertainty
• We need to consider the effect of those
uncertainties on the risk evaluation
• What do we need to do to manage those
uncertainties to improve the risk assessment?

13. worksafe.govt.nz
0800 030 040