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A random selection of 186 water utilities was used for this study in which raw and finished water samples were collected from each facility five times throughout a year and analyzed for iron and aluminum by atomic absorption techniques. The water samples were categorized by the supply source (ground, surface, or a combination of both), the type of water (raw, finished, or untreated distribution samples), and the type of coagulation used in the treatment process (aluminum sulfate, ferric chloride, other coagulants such as cationic polymers, or no coagulant). The samples were also categorized according to the 10 US Environmental Protection Agency regions and 4 population categories. The results indicate that aluminum is more likely to exist in surface waters than in groundwaters and that there is a 40-50 percent chance that alum coagulation increases the aluminum concentration of finished water above its original concentration in the raw water.

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Chlorination of humic and fulvic acid results in the formation of direct-acting mutagenicity, detectable in the Salmonella/microsome assay (Ames test). This mutagenicity is being characterized as part of an overall effort aimed at evaluating potential health risks associated with the presence of mutagenic chemicals in drinking water. A number of chlorinated organic compounds, including several known mutagens, have been identified and quantified in diethyl ether extracts of chlorinated humic acid solutions. However, the total mutagenicity of these compounds accounts for only about 7% of the original mutagenicity. Synergistic or antagonistic interactions among the identified components have been ruled out as possible explanations for the failure to account for a higher percentage of the activity. Recent progress has been made to separate the activity into neutral and strong acid fractions. Further isolation of the strong acids by high-pressure liquid chromatography (HPLC) has resulted in the purification of the mutagenicity into a major peak of activity with a specific mutagenicity of about 20,000 TA100 revertants per milligram. Several trichlorohydroxyfuranone isomers have been tentatively identified in this fraction. The contribution of these types of compounds to the mutagenicity of chlorinated humic acid is under investigation.

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