Professional exposure to basaltic rock dust: assessment by the Vibrio fischeri ecotoxicological test

BACKGROUND A recent study demonstrates that inhalation of airborne particulate from Mount Etna eruptions may induce fibrotic lung disease. The occupational exposure of construction workers from the Etna area, who excavate building sites and use basalt dust to make mortar, has never been assessed. METHODS Samples of basalt, volcanic ash, basalt + cement and cement dust were collected on the construction site of a subway tunnel, ground to dust and subjected to the Microtox(®) solid-phase test to evaluate the toxicity of dust suspensions. Samples were investigated by scanning electron microscopy equipped with energy dispersive X-ray analysis (EDX). Minerals were identified and characterized by their morphology and elemental composition. RESULTS The elements found most frequently were C, Na, Mg, Al, Si, K, Ca, Ti, Mn, Fe and O. All four dusts were toxic: basalt and ash were significantly less toxic than basalt + cement and cement, which shared a similar and very high degree of toxicity. Higher Fe, Ca and Mg concentrations were associated with greater toxicity. CONCLUSIONS The risk related to long-term occupational exposure to various dusts on constructions sites in the Mount Etna area should be further assessed.