Improving the prevention and control of hazardous substance exposures: a randomized controlled trial in manufacturing worksites.

Background: New measures of exposure prevention (EP) activity were used to evaluate the effectiveness of a 16-month management-focused intervention addressing hazardous substance exposures in manufacturing work settings.

Methods: EP efforts were assessed using a rating scheme developed for this study. The rating scheme yields a set of measures of exposure potential and protection, which are combined into an overall EP summary rating. A randomized, controlled design was used to assess intervention effectiveness. Fifteen large manufacturing worksites completed the 16-month intervention and follow-up assessments. Analyses were conducted on the 107 production processes assessed at both baseline and final.

Results: Patterns of improvement within the intervention condition were consistent with the intervention emphasis on upstream or source-focused intervention; whereas patterns in controls were consistent with prevalent practice (more downstream, worker-focused). A mixed model analysis of variance showed greater improvement in EP ratings in intervention versus controls, but the difference in improvement was moderate and statistically non-significant.

Conclusions: This study has demonstrated that EP efforts in the manufacturing sector can be systematically assessed across the full range of hazardous substances in use, and that such assessments can serve both needs assessment and effectiveness evaluation functions. Findings suggest that more sustained or intense management-focused intervention would significantly improve EP activity in manufacturing settings.