No short-term cytogenetic consequences of Hungarian red mud catastrophe

Red mud is an industrial waste produced in the process of alumina extraction from bauxite with concentrated NaOH. When the red mud-containing reservoir collapsed in Ajka Alumina Plant Hungary in October 2010, the most serious immediate effects were caused by the high alkalinity (pH ≥ 13) of the flood. Many persons suffered burn-like damage to tissues and contact with caustic desiccated ultra-fine dust with traces of toxic metals also caused irritation of upper respiratory tract and eyes. This catastrophe was unique from the point of view of genotoxic effects as well. Therefore cytogenetic examinations were carried out on inhabitants, either with burns (17 persons) or on those inhaling desiccated caustic dust (42 persons). Chromosomal aberration (CA) analysis and bleomycin (BLM)-sensitivity assays, as possible markers of effects, were studied in peripheral blood lymphocytes of persons within 4-6 weeks following the catastrophe. Controls were matched for age, sex and smoking habits, and also places of residence with different constituents of air pollution either from rural (59 persons), or from urban environments (59 persons). Neither spontaneous rate of CAs (1.47% vs. 1.69%) nor BLM-induced in vitro chromosomal breakage (0.79 vs. 0.83 break/cell) showed elevated rates when cytogenetic biomarkers of genotoxicity were compared between controls and exposed persons. Time spent in cleaning did not affect cytogenetic changes either (R(2) = 0.04). BLM-induced mutagen sensitivity was similar in exposed and control persons (27.1% vs. 30.5%). It seems that the red mud exposure does not appear to pose an immediate genotoxic hazard on residents when measured with cytogenetic methods. We recommend, however, that those involved in clean-up activities should be followed closely not only for overall health, but also for further genotoxic risk assessment, because the long-term hazards of ultra-fine fugitive dust particles with alkalinity of residual NaOH in red mud are still unknown.