Internal and external exposure to polycyclic aromatic hydrocarbons (PAH) at the workplace -: the German PAH study

During a period of nearly three years we investigated altogether 270 employees from seven different industrial branches concerning their external and internal exposure to PAH (ambient and biological monitoring). In 20 % (range: 6 to 30 %) of the air samples benzo[a]pyrene concentrations above the relevant technical exposure limit (German TRK value) were observed. The internal exposure was determined by means of the urinary metabolites of monohydroxylated phenanthrenes and 1-hydroxypyrene. We hereby found 1-hydroxypyrene median levels (mug/g creatinine) of 1.51 (coal tar distillation - TD), 4.30 (coking plants - KK), 5.17 (installation of fire proof materials - FFV), 8.65 (graphite electrode plants - GE) and 11.27 (production of fire proof materials - FFH). The corresponding concentrations of the sum of five isomeric hydroxyphenanthrenes were 6.87 (GE), 7.05 (TD), 9.81 (FFH), 10.29 (KK) und 15.75 (FFV) mug/g creatinine. This study showed that ambient monitoring apart does not assure an adequate protection from health hazards as a result of occupational PAH exposure. This is due to the fact, that PAHs are absorbed through the skin to a considerable extent. In order to objectify this non-inhalative PAH absorption we introduced the "relative internal burden" (RIB).