Assessment of exposure to oak wood dust using gallic acid as a chemical marker.

Objectives: The American Conference of Governmental Industrial Hygienists (ACGIH) has classified oak dusts as human carcinogens (A1), based on increased sinus and nasal cancer rates among exposed workers. The aims of this study were to investigate the use of gallic acid (GA) as chemical marker of occupational exposure to oak dusts, to develop a high-performance liquid chromatography–diode array detector (HPLC–DAD) method to quantify it, and to apply the method in the analysis of oak dust samples collected in some factories.Methods: A high performance liquid chromatography (HPLC) method was developed to detect GA in oak wood dust. The method was tested on field, and GA was extracted from oak wood dust sampled in the air of five wood-working plants where only oak wood is used. Results: A total of 57 samplings was taken in the dust concentration range 0.271-11.138 mg/m3. Five of these exceeded the Italian threshold limit value of 5 mg/m3, and 30 exceeded the ACGIH TLV of 1 mg/m3. GA concentrations were in the range 0.017-4.178 µg/m3. The total oak dust sampled was correlated with GA contents with a coefficient of 0.95. Conclusions: The GA in tannic extracts of oak wood turned out to be specific for this type of wood, showing that its concentration in wood dust sampled in the work environment is useful in assessing true exposure to carcinogenic oak dust.