Inhalation study on exposure to bitumen fumes Part 2: Analytical results at two exposure levels

During the hot application of bitumen-containing materials, e.g. in road pa ving or roofing, fumes are emitted that contain traces off polycyclic aroma tic compounds (PACs), Although worker's exposure to these fumes is low, it might lead to health problems. For studying DNA adduct formation as a conse quence of inhalation of bitumen fumes we developed and validated an inhalat ion system (a dynamic fume generator plus a nose only inhalation chamber), This paper presents and discusses the analytical results from the different laboratories involved in this study on the fumes sampled in the inhalation chamber during three series of experiments where the animals were exposed to fumes at the 5 mg/m(3) and 50 mg/m(3) level, coming from bitumen heated at 200 degrees C and, as a positive control, fumes from coal tar, heated to 110 degrees C at the 5 mg/m(3) level. The following parameters were contro lled: temperatures at different key places in the generator; humidity of th e chamber; the bitumen or coal tar flow rate; and Total Particulate Matter (TPM), Analyses were performed for Benzene Soluble Matter (BSM), the EPA po lycyclic aromatic hydrocarbon (PAH) mixture and for a number of heteroatom- containing PACs, The data show that the coal tar fumes produced at 110 degrees C were very v olatile and that most of the differences in particulate matter found betwee n the laboratories can be attributed to evaporative losses. The bitumen fum es boil 25-50 degrees C higher and contain higher boiling compounds. A comparison is made between the PAC exposure profiles for bitumen experime nts aimed at 5 and 50 mg/m(3) Although the same molecules are found in both fumes their proportion is dramatically different. This effect is largest w ith the 2- and 3-ring PACs, the ratio of the concentrations found in the 50 mg/m(3) TPM concentration to that in the 5 mg/m(3) experiment gradually de clines from 5500 for acenaphthene to 500 for pyrene, for the 5-ring PACs th is ratio is 20-30. As function of their vapour pressure, the ratios of the concentrations of the hetero PACs follow the same trend as that of the 16 E PA PAHs and are of the same order of magnitude. In conclusion, for the compounds investigated, the equipment delivers: a fu me atmosphere in a reproducible manner. The 50 mg/m(3) bitumen fumes ape no t representatives of field fumes. The reason for these quantitative differe nces is unclear and further work would be needed to clarify this. Neverthel ess it was felt that these fumes at 50 mg/m(3) might be a useful tool for q ualitative detection of DNA adducts in an animal exposure study. (C) 2000 B ritish Occupational Hygiene Society. Published by Elsevier Science Ltd, All rights reserved.