Invited Editorial Long-term Trends in Occupational Exposure: Are They Real? What Causes Them? What Shall we do with Them?

The Beatles already knew it in 1967 when they sang ‘‘It’s getting better all the time’’. Scientific evidence that this holds true for occupational exposures has only been obtained very recently (Symanski et al., 1998a,b). Circumstantial evidence has been around for much longer. Just a chat with an experienced worker or a glance at old workplace photographs conveys the same notion. Symanski et al. reviewed the literature for longi-tudinally collected sets of data that allowed them to quantify long-term trends in exposure to chemical agents. On the basis of 696 data sets published over a 30-year period (1967–1996), they observed a me-dian annual trend of ÿ6 % with an inter-quartile range of ÿ1 % to ÿ11%. Such a trend results ap