Trends in inhalation exposure--a review of the data in the published scientific literature.

As part of a larger study aimed at identifying the long-term changes in inhalation exposure for selected hazardous substances in a number of industrial sectors within the UK, we have reviewed the published literature on temporal changes in inhalation exposure. Scientific papers and reports of interest were identified using standard literature review techniques. Most studies did not express the results as relative annual trends in exposure, and so where possible the data were reanalysed using regression methods to produce estimates of the average annual percentage change in concentration. In the majority of instances, there were significant reductions in exposure, with percentage yearly declines up to 32%. In many studies, information about changes in the working environment, process conditions or other factors that may have influenced the change in exposure over time was lacking. Factors commonly cited as being responsible for exposure reductions included the introduction of new standards and response to regulatory requirements as well as changes in production methods. A large number of exposure measurement datasets exist for many industrial sectors for most of the second half of the 20th century and this resource has allowed us to identify trends in occupational exposure. It is most important that longitudinal exposure data continue to be collected along with relevant contextual information to enable future changes to be adequately assessed.