On the Dose-Response Relationship between Occupational Exposure to Diesel Engine Emissions and Lung Cancer Risk—A Critical Appraisal of the Current Stage of Epidemiological Research

The Diesel Exhaust in Miners Study (DEMS) played a decisive role in the classification of diesel engine emissions as a Group 1 carcinogen by the International Agency for Research on Cancer. However, the statistical analysis of this extensive cohort study and the interpretation of the results have been widely criticized. Recently, a comprehensive systematic review was published whose meta-analysis revealed a statistically significant positive linear dose-response relationship. The results of the case-control approach from the DEMS contributed significantly to this result. However, the contradictory results of the mortality analysis for the entire cohort were not mentioned. The method for estimating the linear dose-response relationship in the studies included in the aforementioned systematic review must also be scrutinized from a methodological point of view. Meanwhile, the follow-up of the DEMS-cohort has been extended by 18 years, which has significantly strengthened the database for the analysis. The results of this important data material and its effects on the meta-analysis are discussed. Ultimately, the meta-analysis was reanalyzed, corrected for the shortcomings identified.