When a new drinking water regulation is being developed, the USEPA conducts a health risk reduction and cost analysis to, in part, estimate quantifiable and non-quantifiable cost and benefits of the various regulatory alternatives. Numerous methodologies are available for cumulative risk assessment ranging from primarily qualitative to primarily quantitative. This research developed a summary metric of relative cumulative health impacts resulting from drinking water, the relative health indicator (RHI). An intermediate level of quantification and modeling was chosen, one which retains the concept of an aggregated metric of public health impact and hence allows for comparisons to be made across "cups of water," but avoids the need for development and use of complex models that are beyond the existing state of the science. Using the USEPA Six-Year Review data and available national occurrence surveys of drinking water contaminants, the metric is used to test risk reduction as it pertains to the implementation of the arsenic and uranium maximum contaminant levels and quantify "meaningful" risk reduction. Uranium represented the threshold risk reduction against which national non-compliance risk reduction was compared for arsenic, nitrate, and radium. Arsenic non-compliance is most significant and efforts focused on bringing those non-compliant utilities into compliance with the 10 μg/L maximum contaminant level would meet the threshold for meaningful risk reduction.

The increased mutagenicity of disinfection by‐products (DBPs) containing bromide (Br−) and nitrogen requires a renewed evaluation of best available treatment technologies for DBP control. The aim of this article is to document the removal of organic nitrogen during granular activated carbon (GAC) treatment and to illustrate how GAC treatment alters DBP speciation. Rapid small‐scale column tests (RSSCTs) with GAC were conducted on pretreated surface water sources to evaluate the simultaneous removal of carbonaceous and nitrogenous DBP precursors: dissolved organic nitrogen (DON), dissolved organic carbon (DOC), organics absorbed by ultraviolet light at 254 nm (UV254), and Br−. Simulated distribution system tests were conducted with RSSCT effluent samples throughout natural organic matter breakthrough, and free chlorine was used to evaluate the formation of halogenated carbonaceous and nitrogenous DBPs. GAC preferentially removed UV254‐absorbing material over DOC, which was removed more effectively than DON. Br− was not removed. Consequently, effluent ratios of Br− to DOC and Br− to DON changed during GAC treatment, and the ratio of brominated DBPs to chlorinated DBPs shifted during the GAC breakthrough cycle; brominated DBPs dominated earlier in the breakthrough of DOC. Neither DON nor nitrogenous DBP precursors were removed efficiently during GAC treatment.

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Optimizing granular activated carbon (GAC) operation can reduce costs for removing disinfection byproducts or their precursors. This article investigates prechlorination to enhance the removal of total trihalomethane (TTHM) precursors and reduce TTHM concentrations in finished water. Rapid small‐scale column tests (RSSCTs) and pilot tests using virgin and reactivated GAC were conducted on water with and without prechlorination. Prechlorination (1 or 2 mg Cl2/L) increased (by 15 and 30%, respectively) the number of bed volumes treated by GAC. On the basis of size exclusion chromatography, prechlorination followed by GAC preferentially removed low‐molecular‐weight dissolved organic carbon by GAC. Simulated distribution system (SDS) chlorination tests on GAC effluent showed lower TTHM concentrations with prechlorination. Prechlorination lowered the bromine incorporation factor values in GAC effluents after SDS tests, which suggests a reduction in toxicity potential from trihalomethanes. RSSCT results were validated by pilot testing, showing that RSSCTs can be used to optimize the prechlorination process.

Polymorphism is an important characteristic which affects the activity, solubility and other physical properties of a compound and can be induced by varying temperature, pressure and solvent. The presence and conversion of α to β polymorphic forms of an anti‐rheumatic drug leflunomide have been studied by temperature‐dependent and in situ Raman observations. Both α and β polymorphs were found to co‐exist in the temperature interval 367–372 K. The α form alone exists below 367 K and the β form alone above 373 K. The CO stretching band clearly demonstrates the α → β conversion because of breaking of N–H···O bond and formation of N–H···N bond. On cooling the Raman spectra suggest the irreversibility of this conversion. Thermodynamic stability, crystal parameters and surface morphology of both forms in the leflunomide powder used for the present study have been verified by differential scanning calorimetry, X‐ray powder diffraction and scanning electron microscopy. Copyright © 2015 John Wiley & Sons, Ltd.