Respirable crystalline silica and lung cancer in community-based studies: impact of job-exposure matrix specifications on exposure-response relationships

Objectives The quantitative job -exposure matrix SYN-JEM consists of various dimensions: job -specific estimates, region -specific estimates, and prior expert ratings of jobs by the semi -quantitative DOM-JEM. We analyzed the effect of different JEM dimensions on the exposure-response relationships between occupational silica exposure and lung cancer risk to investigate how these variations influence estimates of exposure by a quantitative JEM and associated health endpoints. Methods Using SYN-JEM, and alternative SYN-JEM specifications with varying dimensions included, cumulative silica exposure estimates were assigned to 16 901 lung cancer cases and 20 965 controls pooled from 14 international community -based case -control studies. Exposure-response relationships based on SYN-JEM and alternative SYN-JEM specifications were analyzed using regression analyses (by quartiles and log -transformed continuous silica exposure) and generalized additive models (GAM), adjusted for age, sex, study, cigarette pack -years, time since quitting smoking, and ever employment in occupations with established lung cancer risk. Results SYN-JEM and alternative specifications generated overall elevated and similar lung cancer odds ratios ranging from 1.13 (1st quartile) to 1.50 (4th quartile). In the categorical and log -linear analyses SYN-JEM with all dimensions included yielded the best model fit, and exclusion of job -specific estimates from SYN-JEM yielded the poorest model fit. Additionally, GAM showed the poorest model fit when excluding job -specific estimates. Conclusion The established exposure-response relationship between occupational silica exposure and lung cancer was marginally influenced by varying the dimensions of SYN-JEM. Optimized modelling of exposure-response relationships will be obtained when incorporating all relevant dimensions, namely prior rating, job, time, and region. Quantitative job -specific estimates appeared to be the most prominent dimension for this general population JEM.