How serious are we about protecting workers health? The case of diesel engine exhaust

Regulators frequently deviate from health-based recommendations when setting occupational exposure limits, but the impact on workers' health is rarely made explicit. We present a quantitative evaluation of the expected impact of recently proposed regulatory limits for occupational diesel engine exhaust (DEE) exposure on the excess burden of lung cancer (LC) in Europe.

We used a lifetable approach, basing our analyses on the DEE exposure distribution in a large general population study, as well as the 5% prevalence used in earlier DEE burden calculations. We evaluated the effects of intervention on DEE exposures according to a health based limit (1 ug/m³ of elemental carbon (EC)) and both Dutch (10 ug/m³) and European (50 ug/m³) proposed regulatory limit values. Results were expressed as individual excess lifetime risks (ELR), total excess number of cases and population attributable fraction of LC.

The ELR for the EU working population was estimated to be 341/10 000 workers based on our empirical exposure distribution and 46/10 000 workers based on the 5% prevalence. Implementing the proposed health based DEE limit would reduce the ELR by approximately 93%, while the proposed regulatory limits of 10 and 50 ug/m³ EC would reduce the ELR by 51% and 21%, respectively.

Although the proposed regulatory limits are expected to reduce the number of DEE related LC deaths, the residual ELRs are still significantly higher than the targets used for deriving health-based risk limits. The number of additional cases of LC in Europe due to DEE exposure, therefore, remains significant.