In recent issues of OEM, the authors of two articles in “ergonomic epidemiology” stress several necessary qualities of exposure data: they must be accurate and precise;¹ and the method of exposure measurement must be reliable.² All epidemiologists in occupational epidemiology would agree with that: absence of systematic or random error is important, stability of the measure if repeated under identical conditions is important too. Among the expected qualities of exposure data one could add “relevant”; we expect that the exposure data are consistent with what is known (or suspected) about the mechanisms underlying their effect on disease. This is less obvious than it seems; for example, in many situations one can wonder whether the relevant exposure is that of today, or that of last week, or that of 20 years ago, or the cumulative exposure over the last 20 years. Another quality (or limit) has to do with feasibility. If exposure assessment, at an individual level, is very expensive (in terms of money or time), alternative solutions have to be found if the study sample is large.

All this is common to all the fields of occupational epidemiology. However, is there something specific to the assessment of biomechanical exposures? Are the problems met …