Screening of toxicity and genotoxicity in wastewater by the use of the Allium test.

Wastewater was collected from two municipal wastewater treatment plants and twelve different industries representing five lines of business (chemical, metallic, petrochemical, pulp- and paper, and textile dye industries). Effect on the growth of Allium roots was measured after five days of exposure. Growth inhibition values, EC50 and EC30, showed no toxic effect for eight of the fourteen plants. The most toxic effect was found in wastewater from one of the pulp- and paper plants. Allium root tip cells were analyzed for chromosome aberrations after 24 h of exposure. Wastewater from nine of the fourteen plants was able to induce chromosome aberrations at a statistically significant level. The textile dye industry was the only line of business which did not show any genotoxic effect. Three of the plants (municipal wastewater, metallic, and pulp- and paper) showed genotoxicity in spite of being nontoxic in the growth inhibition experiment.