Harris et al1 provide useful new data for evaluating which occupational hazards are most deadly, and how this has changed over time. They have estimated excess deaths for different occupational groups, presumably exposed to specific hazards, via calculation of proportional mortality ratio (PMRs) (observed vs expected deaths) from death certificates, for causes of death strongly associated with occupations. Excess deaths (observed minus expected) over three study periods (1979–1990, 1991–2000 and 2001–2010) are presented (excess/observed deaths is the attributable fraction (AF) among the exposed). For some causes resulting solely from occupational exposures, there are no expected deaths without exposure, so all observed deaths across all occupations are considered excessive (eg, asbestosis, coal miner's pneumoconiosis). Among the more striking findings were the drop in excess deaths in exposed occupations from chronic bronchitis/emphysema, and in deaths from injury and poisoning.

There are a number of limitations to the method, most of which are noted by the authors. Change in annual excess deaths over time conflates improved working conditions/lower exposures, fewer people working in specific occupations (and hence fewer deaths), and declining overall mortality in the population over time. To zero in on improved working conditions/lower exposure, it might be best to emphasise the PMR itself, although clearly excess deaths are an important public health measure.

A large …