Retrospective exposure assessment for carcinogenic agents in bitumen waterproofing industry in Finland and denmark

The purpose of the study was (i) to identify the carcinogenic agents that may cause confounding when studying the exposure-response relationship between bitumen fume exposure and cancer among roofing membrane-manufacturing workers and roofers and (ii) to assess exposures to the identified carcinogens and bitumen fume in roofing membrane manufacturing and roofing in Finland and Denmark from 1950 to 2005.

Information on the use of carcinogenic agents and other relevant data were collected through semi-structured interviews of senior employees in the industry. Semi-quantitative exposure assessments were made on the basis of available measurement data and information obtained from the interviews and literature.

Most of the production line workers in roofing membrane plants in Finland were exposed to asbestos until the mid-1970s. Also, some of the mixer operators in the plants were exposed to asbestos in Finland during the 1970s and in Denmark from the mid-1960s to the mid-1980s. In both countries, coal tar pitch was used in roofing membrane manufacturing until the mid-1960s, and consequently, exposure to polycyclic aromatic hydrocarbons (PAHs) in the plants was high in the 1950s and still significant in the early 1960s. Exposure of production line workers to quartz dust was high until the 1980s and is still relatively high compared with current occupational exposure limit values. Bitumen roofers' exposure to coal tar-derived PAHs may have been significant in both countries until the end of 1960s. Roofers' exposure to asbestos and quartz was estimated to have been near background level.

The estimated average annual exposures to asbestos, coal tar-derived PAHs and quartz dust in the bitumen waterproofing industry in Finland and Denmark were significant in the past but have a clear declining trend. Exposure to bitumen fume was found to follow a similar trend.