Inhalative exposure of roofers to 2-naphthylamine during hot application of tar adhesives

Status:

completed 01/2011

Aims:

In relation to occupational disease (BK) 1301, aromatic amines such as 2-Naphthylamine are regarded as a cause of cancer of the urinary tract (particularly of the bladder). 2-naphthylamine and other aromatic amines are constituents of coal tar products which up until the 1960s and 1970s were used as work materials in the plants of member companies of the German Social Accident Insurance Institution for the building trade. Known examples are the hot processing of road tar and the sealing of flat roofs with tar adhesives and tar papers. During searches performed in relation to reported cases of occupational disease, it was repeatedly established that measurement data for the past exposure of roofers was not available, making decisions difficult during the occupational medical evaluation of the cases to be ruled upon. The German Social Accident Insurance Institution for the building trade has therefore proposed that the tasks of roofers involving the use of tar adhesives be simulated under conditions comparable to those in the past, and the level of exposure to carcinogenic amines measured.

Activities/Methods:

The following procedure was planned; the performance of the individual steps was made dependent upon the result of the respective preceding step. The composition/formulation of tar adhesives used in the past was first identified (Step 1). Production of such a tar adhesive (Step 2) was then commissioned from a tar-processing company. Step 3 involved procurement of an old tar boiler and the contacting of an older roofer familiar with working methods employed in the past. Following worst-case measurements during heating of the tar adhesive in the tar boiler, high amine concentrations were observed. A roof area (wooden structure) was then fabricated and exposure measurements performed during bonding work.

Results:

In two measurement programmes conducted in July and October 2010, exposure measurements were performed for the aromatic amines 2-naphthylamine, o-toluidine, 4-aminobiphenyl and 2,4,5-trimethylaniline. The concentrations of polycyclic aromatic hydrocarbons were also measured. Measurements were performed both at the tar boiler and during the bonding work on the roof area. The samples obtained from the July measurement programme were analysed in three different laboratories. These were: 1. IFA; 2. Münster University of Applied Sciences; 3. Biochemical Institute for Environmental Carcinogens (BIU). Since the results varied within a relatively wide range and the individual laboratories had analysed different samples, it was unclear whether the variation was due to the natural scatter of samples taken in the open air or to differences between the analytical processes of the laboratories. For this reason, a part of the samples taken in the course of the second measurement programme in October was divided 50:50 and analysed in two laboratories (IFA and BIU). This led to results of satisfactory comparability. The variations between the individual samples were also substantially lower. For the exposure of a roofer during bonding of roofing felt with hot tar adhesives, an exposure concentration of 2.5 µg/m³ (double arithmetic mean) was measured. For the work at the tar boiler, a value of 14.8 µg/m³ (double arithmetic mean) was measured. Corresponding exposure doses can be deduced from these values in individual cases of formally recognized occupational disease.

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