Operators may be exposed to a pesticide when opening containers, mixing/loading or preparing the product for use, during application of the product, cleaning up spills, maintaining equipment and re-entering treated areas. The main routes of exposure are dermal and inhalation. Risk assessments are carried out for all scenarios of exposure that can be expected to occur through the use of the pesticide. Both acute (immediate) and chronic (long-term) risks need to be considered.
Risk with the use of the pesticide product can be mitigated through engineering controls (such as closed application systems) and/or personal protective equipment (such as gloves or respirators).
The FAO Pesticide Registration Toolkit also provides guidance on Mitigation measures.
The outcome of the risk assessment determines whether occupational exposure to a pesticide when used in accordance with the instructions for use would be likely to be harmful or would not be likely to be harmful to the operator.
What this table contains
This table summarises the principles applied during the risk assessment to determine whether the human health risk criteria in relation to occupational risks are acceptable.
Summary analysis
Two methods are used to determine whether the human health risks in relation to occupational exposure are acceptable: a health-based exposure limit (used in the EU) or a margin of exposure approach (US, Canada, Australia). Both methods rely on at least a 100-fold safety factor although these are applied at different steps of the risk assessment process.
Exposure assessment may be based on measured user exposure or estimated using surrogate data and data models. The reader should also be aware that regulators recognise the limitations in data contained in exposure models particularly as agricultural production practices (including engineering controls) change over time. Exposure models are continuously being improved and further developed and regulators will use the most current information should be used for occupational exposure assessments as it becomes available. Some proprietary data models such as the US Agricultural Handler Exposure Taskforce (a consortium of pesticide industry companies) may only used for regulatory decisions for those members of the taskforce that have sponsored the research.
It is critical that worker exposure scenarios and work practices (including personal protective equipment - use and availability - and engineering controls) must be relevant and appropriate to the country/agricultural practice where the pesticide is to be used.
Aspect | Description |
Links to risk assessment guidelines, manuals and science policy documents | APVMA risk assessment manual Human Health, March 2019 |
Hazard assessment and end-point selection | - The output of the hazard assessment is the identification of the NOAEL
- The toxicological studies are re-viewed to assess the most suitable NOAEL that best represents the use scenarios of the product.
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Setting of toxicological reference values and the use of assessment factors | n.a. |
Exposure assessment | - The exposure assessment may be based on measured user exposure, or from extrapolation based on surrogate data or suitable data models.
- Exposure scenarios using different levels of engineering controls and/or personal protective equipment are considered.
Exposure during use: - The input variables that are considered in estimating in-use exposure using models include:
- concentration of active constituent in the formulated product, maximum application rate, work rate and quantity of each active ingredient handled each day
- dermal absorption factor
- inhalation absorption factor
- bodyweight
Post-application exposure: - The input variables that are considered in estimating post-application exposure using models include:
- transfer coefficient
- dislodgeable residues
- dissipation rate
- exposure duration
- bodyweight
- NOAEL
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Risk assessment and acceptability criteria | The criteria for acceptable risk is based on calculating an MOE. The MOE is calculated by dividing the NOAEL with the estimated likely exposure.
A MOE > 100 is generally considered as an acceptable risk. |
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Aspect | Description |
Links to risk assessment guidelines, manuals and science policy documents | |
Hazard assessment and end-point selection | - A margin of safety approach is used for toxic end points that have threshold effects. A NOAEL is selected for a toxic end point observed in animals that is relevant to humans and it is usually from a study in which animal exposure is representative of the route, frequency and duration of human exposure. The NOAEL forms the basis for establishing reference values (ARfD, ADI, target MOE for occupational and non-occupational exposure).
- A quantitative risk assessment approach is used for for non-threshold effects such as cancer. Data from laboratory and animal studies together with mode of action studies are used to decide if a pesticide is likely to pose a cancer risk. Statistical models are used to estimate potential cancer risk in humans.
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Setting of toxicological reference values and the use of assessment factors | n.a. |
Exposure assessment | The exposure assessment may be based on measured user exposure or estimated using surrogate data and data models.
Canada uses an approach similar to the US EPA using exposure values derived from compensable Agricultural Handler Exposure Taskforce (AHETF) database scenarios or, where these are not yet available, from the Pesticide Handler Exposure Database (PHED).
As AHETF data for new exposure scenarios become available, they supersede existing data.
More detailed information on the most current data used to assess occupational exposure and risk can be found through the US EPA website at:
https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/occupational-pesticide-handler-exposure-data
Other types of data considered:
- Dermal absorption
- Dislodgeable residues
- Turf transferable residue
- Dust-off (seed treatment)
- Air monitoring
- Transfer coefficients
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Risk assessment and acceptability criteria | For threshold effects the criteria for acceptable risk is based on calculating an MOE. The MOE is calculated by dividing the NOAEL with the estimated likely exposure.
A MOE > 100 is generally considered as an acceptable risk, unless the target MOE is higher (e.g. 300).
Non-threshold effects (cancer) risk to humans is estimated using mathematical models. These provide an assessment (expressed as a probability) of the excess risk of cancer resulting from exposure to the pesticide. A calculated risk of 1 in 1,000,000 generally is considered acceptable for the general public. Higher estimate levels may be considered acceptable for some occupational exposures. (e.g. 1 in 100,000). |
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Aspect | Description |
Links to risk assessment guidelines, manuals and science policy documents | http://www.chinapesticide.org.cn/fxpg/index.jhtml (in Chinese) |
Hazard assessment and end-point selection | - The most sensitive endpoints relevant to humans are selected.
- Generally, data form sub-acute or sub-chronic dermal and inhalation toxicity studies can be used.
- In the absence of studies for a particular exposure route, oral toxicity studies of corresponding duration may be used as an alternative.
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Setting of toxicological reference values and the use of assessment factors | The AOEL is derived using uncertainty factors to account for inter-species differences and intra-species differences. |
Exposure assessment | - Calculation of operator exposure takes into account formulations, application methods and equipment, crop characteristics, environmental conditions and other factors.
- Operator exposure is derived by using the unit exposure method specific to a scenario.
- The COPrisk Model is used, however this model contains exposure data for knapsack sprayer application only.
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Risk assessment and acceptability criteria | - A tiered risk assessment approach is used.
- Results from the hazard assessment and exposure assessment are analysed and compared to determine whether the health risk during application is acceptable
- Acceptability criteria is based on the calculation of a risk quotient.
- If RQ<= 1, the risk is considered acceptable
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Aspect | Description |
Links to risk assessment guidelines, manuals and science policy documents | |
Hazard assessment and end-point selection | - The output of the hazard assessment is the identification of the NOAEL for the critical effects.
- The most appropriate NOAEL is selected on a case-by-case basis
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Setting of toxicological reference values and the use of assessment factors | - The NOAEL forms the basis for establishing a health-based exposure limit - the AOEL
- the AOEL is derived by applying a 100-fold safety factor (comprising a 10-fold factor for interspecies variability and a 10-fold factor for intra-species variability) to the relevant NOAEL.
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Exposure assessment | - The aim of the exposure assessment is to consider realistic and high exposure scenarios that can be compared with appropriate toxicological reference values
- A range of approaches and models for pesticide exposure assessment are available and used
- Standardised first tier methods of exposure assessment are used where available. These methods have been defined for the most commonly occurring scenarios specified by:
- the category of individual exposed
- the formulation type
- the operations that will be carried out ad the equipment to be used
- the intended use
- For scenarios that are not covered by the standardised methods, risk assessor follow an ad hoc approach that is judged to be the most appropriate.
- Detailed guidance is provided on the most suitable models and inputs at:
https://efsa.onlinelibrary.wiley.com/doi/epdf/10.2903/j.efsa.2014.3874 |
Risk assessment and acceptability criteria | - The risk assessment considers the outcomes of the exposure assessment (including engineering controls, personal protective equipment and/or re-entry interval as relevant) and compares it with the established AOEL.
- The criteria for acceptable risk is that exposure is within the AOEL.
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>> back to overview
Aspect | Description |
Links to risk assessment guidelines, manuals and science policy documents | |
Hazard assessment and end-point selection | - A margin of safety approach is used for toxic end points that have threshold effects. A NOAEL is selected for a toxic end point observed in animals that is relevant to humans and it is usually from a study in which animal exposure is representative of the route, frequency and duration of human exposure.
- A quantitative risk assessment approach is used for for non-threshold effects such as cancer. Data from laboratory and animal studies together with mode of action studies are used to decide if a pesticide is likely to pose a cancer risk. Statistical models are used to estimate potential cancer risk in humans.
- When sufficient data are available a benchmark dose approach involving dose-response modelling may be used to better define dose/response levels at the low end of the observable range of data
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Setting of toxicological reference values and the use of assessment factors | n.a. |
Exposure assessment | Worker exposure scenarios and work practices determine the worker exposure.
The exposure assessment may be based on measured user exposure or estimated using surrogate data and data models.
Exposure values derived from compensable Agricultural Handler Exposure Taskforce (AHETF) database scenarios or, where these are not yet available, from the Pesticide Handler Exposure Database (PHED).
As AHETF data for new exposure scenarios become available, they supersede existing data.
More detailed information on the most current data used to assess occupational exposure and risk can be found at:
https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/occupational-pesticide-handler-exposure-data |
Risk assessment and acceptability criteria | The risk assessment considers the outcomes of the hazard assessment and characterisation in conjunction with the exposure expected when the product is used in accordance with the label instructions (including engineering controls, per-sonal protective equipment and/or re-entry in-terval as relevant).
For threshold effects, the criteria for acceptable risk is based on calculating an MOE. The MOE is calculated by dividing the NOAEL with the estimated likely exposure.
A MOE > 100 is generally considered as an acceptable risk.
Non-threshold effects (cancer) risk to humans is estimated using mathematical models. These provide an assessment (expressed as a probability) of the excess risk of cancer resulting from exposure to the pesticide. A calculated risk of 1 in 1,000,000 generally is considered acceptable for the general public. Higher estimate levels may be considered acceptable for some occupational exposures. |
>> back to overview
The principles and policies followed in the hazard assessment and end-point selection for occupational risks is similar across regulatory frameworks and can be applied in any country.
Worker exposure scenarios and work practices are key to determining worker exposure. It is critical that the worker exposure scenarios and work practices used in an occupational risk assessment are relevant to the country/agricultural area where the pesticide is to be used.
Exposure assessment may be based on measured user exposure or estimated using surrogate data and data models. A range of models for pesticide exposure are used by regulators. It is important that the regulator understands the scope and limitations of models they intend to use. It is critical that relevant and appropriate input variables are considered when exposure is estimated using surrogate data and data models.
Two methods are used in occupational risk assessments. The EU policy is to use of health-based exposure limits. Other regulators use a margin of exposure approach. It is a matter of choice whether an occupational risk assessment uses a health-based exposure limit or a margin of exposure approach. The outcomes from either method will be the same as the factors considered are the same.
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