The German Bitumen Forum--cooperation in partnership.

Some substances are familiar only to those who work in certain industries. Bitumen is something that we have all seen applied in road repair, and we may be aware of less obvious uses. Studies on it are frequently reported in this journal, often with emphasis on polyaromatic hydrocarbon exposure (e.g. Burstyn et al., 2002; McClean et al., 2004a,b; Väänänen et al., 2005). In June 2006, bitumen is the subject of a conference in Dresden organized by ACGIH and a Commission of the Deutsche Forschungsgemeinschaft (DFG) (http://www.acgih.org/events/course/ asphalt.htm). In Germany, the substance has become an example of cooperative venture between industry and regulators, and in this commentary we attempt to summarize what has taken place. One consequence is a wide-ranging study of exposure, a total of 1272 samples of vapours and aerosols of hot bitumen gathered between 1991 and 2005, which is reported in this issue (Rühl et al., 2006). We will follow the European convention of using ‘asphalt’ to refer to a mixture of organic binder (‘bitumen’) and filler such as sand or gravel. In Germany the legally binding standards are the limit values and classifications published in the TRGS (Technical rules for hazardous substances). For a long time, bitumen was classified in the TRGS as a suspected carcinogen, which meant that it was also automatically included in the DFG’s annual ‘List of occupational exposure limit (MAK) and biological monitoring guidance (BAT) values’, where it was listed as a suspected carcinogen from 1977 onwards. However, it did not appear in the European Union carcinogen lists. In the mid-1990s this national carcinogenicity classification was examined, and also the exposure limits in air for vapours and aerosols released from work with hot bitumen. The new German threshold limits for vapours and aerosols of bitumen were assigned in autumn 1996. The Hazardous Substances Committee (AGS) decided that the threshold limit of 15 mg m 3 for working outside would be reduced to 10 mg m 3 on 1 January 2000 unless measurement results were presented by 30 June 1999 which showed the reduction to be not feasible. The basis of the limits was not completely agreeable to all parties in 1996. The database was not satisfactory. Also, this limit was a technical guidance value—which reflected technical state-of-the-art in control, not primarily toxicological findings—and for a non-carcinogenic substance this also caused confusion.