Select the relevant component
TRA contains separate worker, consumer and environmental models. Occupational assessment uses the Worker component. Its conservative first-tier approach supports scenario assessment with a relatively limited set of structured inputs. A result requiring refinement does not automatically establish an unacceptable measured exposure, but it cannot simply be disregarded. Use within REACH does not turn the tool into a complete assessment of every workplace hazard or every potentially exposed person.
What a PROC describes
Process categories describe ways in which substances are used. Selection should follow the operation and its conditions, rather than a company’s commercial description. Activities with different release characteristics, such as transferring a substance and applying it to a surface, may need separate consideration. Choosing a more favourable category merely to reduce the predicted value misrepresents the scenario. The reason for selection must be supported by observations of actual work.
Inputs that shape the estimate
The Worker 3.2 manual includes physical state, volatility or dustiness, concentration, duration, ventilation and controls. It also defines criteria for industrial and professional use. A factory location alone does not justify automatically selecting industrial use. The assessor must check whether the organisation, equipment and controls described in the manual are actually present. Missing information should be investigated or addressed through justified conservative assumptions, rather than filled with convenient defaults.
Keep exposure and risk characterisation consistent
The tool differentiates inhalation and dermal estimates and uses reference values to characterise risk. Route, units and averaging period must match: a daily value and a short-term value answer different questions. A DNEL used in a REACH scenario should not be treated automatically as the applicable national occupational exposure limit. Incorrect inputs can generate apparently precise results that do not address the exposure situation being assessed.
Turn screening into a defensible decision
A useful record retains the software version, each PROC, assumptions and reasons for the controls selected. A control not yet installed represents a proposed scenario; its implementation must subsequently be verified. Where conditions lie outside the model’s scope, information is insufficient or refinement is indicated, review the scenario, use another appropriate approach or plan measurements. Repeatedly adjusting inputs until the output looks favourable is not a valid assessment strategy.
When reviewing a supplier’s scenario, compare its operational conditions with those at the workplace. If it assumes enclosed transfer but actual dosing is manual, investigate the discrepancy. A result calculated for different conditions does not become applicable merely because it accompanies the same product’s safety information or appears in an approved document.
