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Notini, M. J. Fish. Res. Board Can. 1978, 35, 745-753. Ganning, B.; Billing, V. In Ecological Aspects of Toxicity Testing of Oils and Dispersants; Wiley: New York, 1974; pp 53-61. Scott, B. F.; Wade, P. J.; Taylor, W. D. Sei. Total Environ. 1984, 35, 191-206. UNESCO GESAMP Reports and Studies; UNESCO: Paris, 1980; No. 11, 22 p. Gilfillan, E. S. In Proceedings Conference Prev. Contr. Oil Spills; American Petroleum Institute: Washington, DC, 1973; pp 691-695. Byme, C. J.; Calder, J. A. Mar. Biol. (Berlin) 1977, 40, 225-231. Roesijadi, G.; Anderson, J. W. In Marine Pollution Functional Responses; Vernberg, W. B.; Calabrese, A.; Thurberg, F. P.; Vernberg,F. J., Eds.; Academic: New York, 1979; pp 69-83.
(36) Stekoll, M. S.; Clement, L. E.; Shaw, D. G. Mar. Biol.
(Berlin) 1980,57, 51-60. (37) Augenfeld,J. M.; Anderson, J. W.; Woodruff, D. L.; Webster, J. L. Mar. Environ. Res. 1980, 4 , 135-143. (38) Gilfillan, E. S.; Mayo, D.; Hansson, S.;Donovan, D.; Jiang, L. C. Mar. Biol. (Berlin) 1976, 37, 115-123. (39) Thomas, M. L. H. J. Fish. Res. Board Can. 1978, 35,
707-716. (40) Gilfillan, E. S.; Vandermeulen, J. H. J. Fish. Res. Board Can. 1978, 35, 630-636. Received for review January 16,1986. Revised manuscript received June 26,1986. Accepted November 24,1986. This work was supported by grants from Exron Production and Research Division and the Swedish Environmental Research Institute (IVL).
Importance of Sample pH on Recovery of Mutagenicity from Drinking Water by XAD Resins H. Paul Rlnghand," John R. Meler, Frederick C. Kopfler, Kathy M. Schenck, William H. Kaylor, and Donald E. Mltchell Toxicology and Microbiology Division, Health Effects Research Laboratory, US. Environmental Protection Agency, Cincinnati, Ohio 45268
Sample pH and the presence of a chlorine residual were evaluated for their effects on the recovery of mutagenicity in drinking water following concentration by XAD resins. The levels of mutagenicity in the pH 2 concentrates were 7-%fold higher than those of the pH 8 concentrates, suggesting that acidic compounds accounted for the majority of the mutagenicity. The presence of a chlorine residual had little effect on the levels of mutagenicity at either pH. Comparisons of the mutagenic activity for the pH 2 resin concentrates vs. pH 8 concentrates prepared by lyophilization further indicated that the acidic mutagens were products of disinfection with chlorine and not artifacts of the sample acidification step in the concentration procedure. Introduction The finding of mutagenic and carcinogenic organic compounds in source water ( I ) and drinking water (2) has caused concern as to their potential effect on human health. Mutagenic activity in source water has generally been attributed to contamination by industrial waste, to agricultural run-off, and to a lesser extent to naturally occurring substances. Comparison studies of raw water vs. finished drinking water, by Glatz et al. (3)and Hooper et al. (4),suggested that chlorination may play a major role in the production of organic mutagens in potable water. Subsequent laboratory experiments by Cheh et al. (51, in which a drinking water treatment process was simulated, clearly demonstrated that nonvolatile mutagens were produced by chlorine disinfection. While the practice of chlorination is known to produce volatile halogenated organic compounds such as the trihalomethanes (6, 7), little is known about the potential health effects of the nonpurgeable chlorinated organic compounds that are produced. Because risk estimates for regulatory use are currently dependent on toxicological testing of individual substances, one is ultimately faced with identifying those substances responsible for the bio382 Environ. Sci. Technol., Vol. 21, No. 4, 1987
logical response. However, because most organic contaminants are present at microgram per liter (ppb) levels or less in drinking water, a concentration step is necessary prior to the analytical identification of individual contaminants of toxicological importance. Drinking water concentrates for mutagenesis testing have typically been prepared by liquid-liquid extraction (8), freeze-drying (9), or resin adsorption (3, 4 ) . These methods, like other concentration procedures, fail to provide a totally representative concentrate since one or more classes of organic compounds are not recovered efficiently. Consequently, the knowledge of whether the mutagenic activity in chlorinated drinking water is associated with acidic, basic, or neutral compounds is therefore important in developing an effective concentration procedure. The work of several investigating groups (10-14) has suggested that acidic substances as well as neutral compounds may contribute significantly to the mutagenic activity of finished drinking water. Because oxidation is the principal reaction of organic chemicals with hypochlorous acid and hypochlorite (1.9, the formation of acidic organic mutagens from polar and semipolar contaminants may be anticipated. Chlorination of humic material, a common natural component in drinking water sources, has been shown to result in the formation of a substantial number of acidic reaction products (16, 17). The significance of acidic mutagens in drinking water, however, is still somewhat questionable since it has also been shown that mutagenic artifacts arise from the reactions of XAD-4 resin with residual chlorine (18). In addition, the necessity of lowering sample pH in order to be able to efficiently recover the acidic mutagens in their nonionized form on XAD resins may have a direct effect on artifact formation. This adjustment of pH is also of particular concern because different chlorine species, with widely varying reactivities, predominate a t different pH values (19). Because of the possibility of artifact formation and because of the potential importance of sample pH on the recovery of acidic mutagens, we decided to further
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investigate the effects of sample pH and the presence of a chlorine residual on the preparation of concentrates for mutagenicity testing.
Materials and Methods XAD Resins. Amberlite XAD-2 and XAD-8 resins were obtained from Rohm and Haas, Philadelphia, PA. The resins were purified by consecutive 24-h Soxhlet extractions with methanol, acetone, and methanol. Resin purity was checked by gas chromatography/mass spectroscopy (GC/MS) analyses of acetone extracts of representative portions of the resins. No impurities were noted other than trace amounts of diacetone alcohol and mesityl oxide, which are condensation products of acetone. The resins were stored in methanol at ambient temperature. Prior to use, the XAD resins were batch rinsed with distilled water to remove methanol, Water Samples. Water samples from the Ohio and Mississippi Rivers were obtained from a pilot plant operation at the California Plant of the Cincinnati Water Works, Cincinnati, OH, and the Jefferson Parish Plant, Jefferson, LA, respectively. The Ohio River sample was clarified by presettling, coagulation-flocculation, sedimentation, and rapid sand filtration. Treatment of the raw Mississippi River water included clarification with diallyldimethylammonium chloride and/or dimethylamine-type cationic polymers (20). After settling and fluoridation, the clarified water was filtered through pressure sand filters. Distilled water that was filtered through a series of granular activated carbon (GAC) cartridges wag used as a control sample. The sample had a total organic carbon (TOC) concentration of
