Application of semipermeable membrane device for assessing toxicity in drinking water.

Semipermeable membrane devices (SPMDs) mimic passive diffusive transport of bioavailable hydrophobic organic compounds through biological membranes and their partitioning between lipids and environmental levels. Our study was developed on a surface water treatment plant based in Turin, Northern Italy. The investigated plant treats Po River surface water and it supplies about 20% of the drinking water required by Turin city (about one million inhabitants). Surface water (input) and drinking water (output) were monitored with SPMDs from October 2001 to January 2004, over a period of 30 days. The contaminant residues, monthly extracted from SPMDs by dialysis in organic solvent, were tested with the Microtox acute toxic test and with the Ames mutagenicity test. Same extracts were also analyzed with gas chromatography--mass spectrometry technique in order to characterise the organic pollutants sampled, especially Polycyclic Aromatic Hydrocarbons (PAHs). Although the PAHs mean concentration is about one hundred times lower in the output samples, the mean toxic units are similar in drinking and surface water. Our data indicate that the SPMD is a suitable tool to assess the possible toxicity in drinking water.