Job-exposure matrix for historical exposure to rubber dust, rubber fumes, and n-nitrosamines in the british rubber industry

In 1982 IARC concluded that there was sufficient evidence for a causal association between occupational exposures in the rubber manufacturing industry and urinary bladder cancer and leukaemia. To enable evaluations of exposure-response associations in a cohort of men age 35+ employed in the British rubber industry in 1967 with a 49 year mortality followup (n=40,867), we created a quantitative historical job-exposure matrix (JEM) covering the period 1915–2000 based on personal and area measurements previously collated within the EU-EXASRUB project for rubber dust (n=4,187), rubber fumes (n=3,852), and n-Nitrosamines (n=10,215). These data were modelled by job function using linear mixed-effects models with sample year and industry sector as explanatory factors and a random factory intercept.Variations in exposure levels over time between compounds and department were observed. For example, rubber dust exposures ranged from −8.8%/yr (crude materials and mixing, p<0.001) to +0.5%/yr (curing, p=0.01) while rubber fumes exposures declined between −8.3%/yr (crude materials and mixing, p<0.001) and −0.2%/yr (finishing, assembly, and miscellaneous, p=0.218).JEM-estimates were linked to all cohort members for each year worked to calculate average annual and lifetime cumulative exposures (AAE, LCE), thereby allowing quantitative evaluation of exposure-response associations between 50 year occupational exposure and cancer mortality. AAE rubber dust exposures ranged between 0.3 mg/m3 (curing) and 36.3 mg/m3 (crude materials and mixing). Rubber fumes exposures range between 0.3 mg/m3 (finishing, assembly, and miscellaneous) and 5.4 mg/m3 (crude materials and mixing). LCE trends mirrored AAE results.JEM-estimates will allow for quantitative exposure-response association assessments between long-term occupational exposure and cancer mortality.