Occupational health and safety assessment

Last update 9 October 2017

The aim of occupational health and safety assessments is to determine the potential risk to the health and safety of workers. This is achieved by assessing the health hazards and physico-chemical properties of the chemical, estimating exposure and characterising risk.

For new industrial chemicals, the occupational health and safety risk assessment is conducted based on hazards of the chemical and possible exposure scenarios. For existing chemicals atmospheric monitoring or biomonitoring data may be available for use in characterising exposure.

Exposure assessment

An exposure assessment is conducted by establishing the use pattern of the chemical and identifying the sources of occupational exposure.

Exposure is then estimated by taking into account workplace activities, the routes of exposure, the frequency and duration of exposure, and any measured workplace (monitoring) data (for example, atmospheric and/or biological monitoring results). Information is needed for each situation in which workers are potentially exposed.

We consider the reliability of the measured data, and its ability to be representative, when assessing. If insufficient measured data are available, then model calculations are used to estimate typical and reasonable worst case exposure levels. Where necessary, default values are used for certain input parameters in the model calculations (for example, inhalation rate, body weight and skin surface area).

Exposure estimates are conducted using internationally accepted modelling methods (for example, a modified United Kingdom Estimation and Assessment of Substance Exposure model).

Where exposure levels have been determined using both measured data and modeled data, we prefer measured data, provided they are reliable and representative.

For new chemicals, the occupational exposure assessment is usually qualitative, as measured data are unlikely to be available and there is often insufficient information to reliably quantify workplace exposures. Where quantitative assessment is required to determine risk, realistic worst case assumptions are used in the absence of data.

Risk characterisation

The health risk of the chemical to workers is characterised by integrating exposure and potential hazards.

For brief or short-term exposures, human data and information from acute toxicity studies are taken into account to determine the risk of adverse health effects such as acute respiratory effects and skin irritation.

For repeated, longer-term exposures, the health risk is first characterised by comparing exposure estimates with no-effect levels (eg a NOAEL) from toxicity studies to give a margin of exposure (MOE), and then deciding whether the MOE provides cause for concern.

Matters taken into account when characterising the risk include the uncertainty arising from the variability in the experimental data and inter- and intra-species variation, the nature and severity of the health effect and its relevance to humans, and the reliability of the exposure estimates.

Where an exposure estimate is higher than, or equal to, the NOAEL, we consider the chemical to be of concern.

Where the exposure estimate is lower than the NOAEL, other matters—such as those mentioned earlier in this section—are taken into account before deciding if the chemical is of concern. For example, the margin of exposure may be based on a human NOAEL, leading to greater certainty in risk characterisation.

Conversely, if a LOAEL is used in the absence of a NOAEL, the degree of uncertainty would be higher and a higher margin of exposure would be required. Expert judgment is required to weigh these individual parameters case-by-case, and the approach needs to be transparent and justifiable.

Where it is not possible to determine a NOAEL or LOAEL—for example, where there are not enough suitable data—risk is evaluated on the basis of qualitative or quantitative exposure relevant to the human population under consideration.

Where effects are deemed to pose greater risk to certain sensitive populations in the work force—for example pregnant women—an additional safety factor may be introduced.

Risk management

We assess current risk-reduction strategies and, if the risk characterisation shows cause for concern, further control measures are recommended. For example, applicable workplace exposure standards) are appraised for adequacy. Overall, the hierarchy of controls is used to formulate measures that can be applied directly to the workplace to reduce adverse health risks.

Risk management also includes considering standards of current hazard communication. Information on (Material) Safety Data Sheets and labels are assessed against respective codes of practice.

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