COMPARING THE PRESENCE, POTENCY, AND POTENTIAL HAZARD OF GENOTOXINS EXTRACTED FROM A BROAD RANGE OF INDUSTRIAL EFFLUENTS

We examined the genotoxicity of dichloromethane extracts from 50 final effluent samples collected from 42 industries, including pulp and pap er, chemical manufacturing, metal refining, metal surface treatment, a nd municipal waste water treatment. Effluents were initially fractiona ted into dissolved substances, and substances adsorbed to suspended pa rticulate matter. Acid/base partitioning was used to further fractiona te aqueous extracts. Genotoxicity was measured using the SOS Chromotes t. Genotoxicity of extracts was found to be related to sample type, in dustry type, metabolic activation status, and extract fluorescence (38 0 nm excitation, 430 nm emission). S9 metabolic activation reduced gen otoxic potency in over 90% of the extracts examined. Expression of pot ency values per equivalent unit of original sample revealed that efflu ent particulate matter is, on average, almost four orders of magnitude more potent than aqueous filtrates. Suspended particulate matter from organic and inorganic chemical production, petroleum and metal refini ng, and from metal surface treatment facilities, provided extracts tha t were significantly more genotoxic than those from sewage treatment a nd pulp and paper facilities. Aqueous filtrates from inorganic and org anic chemical production, metal refining, and surface treatment facili ties were significantly more genotoxic than those emitted by aluminum and petroleum refineries. Overall, the results suggest that pulp and p aper mills emit mostly soluble genotoxins, while petroleum and aluminu m refineries emit predominantly particle-associated genotoxins. Althou gh some extracts elicited a strong SOS response, the potency of the ex tractable residues was low when compared to highly potent pure substan ces such as benzo(cr)pyrene. On average, a mg of dichloromethane-extra ctable residue has an SOS genotoxicity equivalent to 0.1 - 1.0 mu g of benzo(a)pyrene. Predicted Ames mutagenic potency values corresponded reasonably well with industrial waste mutagenic potency values publish ed by other researchers. Genotoxic loading values were calculated to q uantify the total daily genotoxic emission and potential hazard of eac h industry. Highest loadings were from sewage treatment, pulp and pape r, and metal refining facilities. Highest loading values were the SOS genotoxic equivalent of over 30 kg of benzo(a)pyrene per day. The ulti mate hazard of genotoxic emissions is not known. Actual hazard assessm ent is complicated by a poor understanding of the postemission behavio r of genotoxins. Exposure of downstream biota is likely substantial. ( C) 1996 Wiley-Liss, Inc.