1. What is an OEL, what is its goal, and what is the OEL for asbestos?
OEH = occupational exposure limits
Used as a tool for occupational health risk assessment. There are differing levels
of data and risk assessments, resulting in a patchwork of OELs.
Key points:
- Exposure limit guidance is often absent, and existing OELs vary
quantitatively
- Differences in OELs reflect differences in risk policy and science
methodology
o E.g., health-based regulations or technical considerations
- Harmonization can contribute to consistent use
Hierarchy of OELS
When an OEL is not available, alternative methods can be used to develop risk
benchmarks (Figure 1). These alternative techniques may be adequate for
preliminary assessment, screening or specific risk assessment. The lower rungs
are designed to facilitate the development of benchmarks (risk decisions,
precautionary measures).
Reasons for OEL variability:
1. Problem formulation
The goal of problem formulation is to design a risk assessment that can answer
specific risk management questions, thereby influencing the value of an OEL.
2. Risk science decisions
Point of departure (POD)
No-Observed-Adverse-Effect Level (NOAEL)
Lowest-Observed-Adverse-Effect Level (LOAEL)
Benchmark Dose (BMD)
, Used as a basis for the calculation of OEL. Besides the different points of
departure available, there are also different methods to decide on them, such as:
Timing of assessment (older vs. newer data might give different values)
Availability of literature (open access, industrial research)
Transparency of documentation
Quality of studies (e.g., animal-based, human data)
Application of uncertainty factors
Many OELs account for variability, uncertainty, or weakness in a substance-
specific literature database by using a combination of uncertainty and
adjustment factors selected from a standard set of values.
Not every organization selects/applies the same uncertainty factors. OEL-setting
organizations provide little quantitative guidance, resulting in varied choices and
inconsistent OELs.
Weight-of-evidence evaluation methods
Organizations can have different research methods and different ways to
implement the results of this research. They can also have different ways of
handling conflicting data or in using supporting studies to help resolve
uncertainty.
3. Risk policy decisions
Organizations can have different acceptable risk levels (e.g., 1 in 100 vs. 1 in
10.000). The OELs can also differ because of feasibility concerns: what is the
precautionary goal for the OEL? Economic, health, technical? Impacts the
strictness, etc.
- National legal, cultural, or industrial differences
- Differences in hazard coverage
OEH = occupational exposure limits
Used as a tool for occupational health risk assessment. There are differing levels
of data and risk assessments, resulting in a patchwork of OELs.
Key points:
- Exposure limit guidance is often absent, and existing OELs vary
quantitatively
- Differences in OELs reflect differences in risk policy and science
methodology
o E.g., health-based regulations or technical considerations
- Harmonization can contribute to consistent use
Hierarchy of OELS
When an OEL is not available, alternative methods can be used to develop risk
benchmarks (Figure 1). These alternative techniques may be adequate for
preliminary assessment, screening or specific risk assessment. The lower rungs
are designed to facilitate the development of benchmarks (risk decisions,
precautionary measures).
Reasons for OEL variability:
1. Problem formulation
The goal of problem formulation is to design a risk assessment that can answer
specific risk management questions, thereby influencing the value of an OEL.
2. Risk science decisions
Point of departure (POD)
No-Observed-Adverse-Effect Level (NOAEL)
Lowest-Observed-Adverse-Effect Level (LOAEL)
Benchmark Dose (BMD)
, Used as a basis for the calculation of OEL. Besides the different points of
departure available, there are also different methods to decide on them, such as:
Timing of assessment (older vs. newer data might give different values)
Availability of literature (open access, industrial research)
Transparency of documentation
Quality of studies (e.g., animal-based, human data)
Application of uncertainty factors
Many OELs account for variability, uncertainty, or weakness in a substance-
specific literature database by using a combination of uncertainty and
adjustment factors selected from a standard set of values.
Not every organization selects/applies the same uncertainty factors. OEL-setting
organizations provide little quantitative guidance, resulting in varied choices and
inconsistent OELs.
Weight-of-evidence evaluation methods
Organizations can have different research methods and different ways to
implement the results of this research. They can also have different ways of
handling conflicting data or in using supporting studies to help resolve
uncertainty.
3. Risk policy decisions
Organizations can have different acceptable risk levels (e.g., 1 in 100 vs. 1 in
10.000). The OELs can also differ because of feasibility concerns: what is the
precautionary goal for the OEL? Economic, health, technical? Impacts the
strictness, etc.
- National legal, cultural, or industrial differences
- Differences in hazard coverage
