Titanium Dioxide (TiO2) exposure among workers in German manufacturing plants: research on lung cancer Mortality (TiMo)

Status:

ongoing

Aims:

The study aims at investigating the risk of lung cancer mortality among workers exposed to titanium dioxide particles. The project is based on an already completed historical cohort of approximately 4.700 German workers in TiO2 production plants. The German cohort was part of a European pooling study (Boffetta et al. 2004).

1. A reanalysis of the German cohort data will be conducted. The confounding effect of smoking habits will be directly and indirectly accounted for. TiMo included an analysis of the mortality among TiO2-workers in comparison to a reference population. Furthermore, an internal dose-response-analysis to estimate hazard ratios for selected causes of death will be conducted.
2. The mortality-follow-up of the German cohort with TiO2-workers ended in December 1999. TiMo will assess the feasibility of a record linkage between cohort members and federal cancer registries in order to expand the SMR-analysis with those workers who died after 12/1999.

Activities/Methods:

The cohort included approximately 4,700 male workers employed between 1927-1999 in three TiO2-production plants (Leverkusen, Krefeld, Nordenham). In 12/1999, a total of 73.4% were still alive (21.1% deceased workers). Information on cause of death could not be retrieved for 106 deaths. Information on smoking habits are available for 55% of the cohort.

1. In the external analysis, the mortality observed in the cohort will be compared with that from the general German population by computing age-standardised mortality ratios (SMR) based on individual person-years at risk. To account for missing death certificates, observed numbers of deaths were corrected according to a method proposed by Rittgen and Becker. For the dose-response analysis fractional polynomials will be used. Multiple imputation methods will be applied for the smoking variable. Furthermore, indirect methods will be used to account for the confounding effect of smoking.
2. A prerequisite for a record linkage with federal cancer registries are comprehensive data protection policies. The feasibility study aims to develop these policies and detailed standard operation procedures in cooperation with the eligible cancer registries.

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