Hydraulic fracturing wastewaters discharged to surface water have led to elevated bromide and iodide levels, as well as enhanced formation of brominated trihalomethanes, haloacetic acids, haloacetonitriles, and iodo-trihalomethanes at downstream drinking water treatment plants, in chlorinated effluent from wastewater treatment plants, and in controlled laboratory studies. This enhanced formation of brominated and iodinated disinfection byproducts (DBPs) raises concerns regarding human health, because they are much more toxic than chlorinated DBPs. This study represents the first nontarget, comprehensive analysis of iodinated DBPs formed in chloraminated produced waters associated with hydraulic fracturing of shale and conventional gas formations. Fifty-six iodo-phenolics were identified, comprising three homologous series of mono-, di-, and tri-iodinated phenols, along with two new classes of DBPs: iodomethylphenols and iododimethylphenols. Four iodo-phenolics (2-iodophenol, 4-iodophenol, 2,4,6-triiodophenol, and 4-iodo-2-methylphenol) were investigated for mammalian cell cytotoxicity. All were cytotoxic, especially 2,4,6-triiodophenol, which was more cytotoxic than all trihalomethanes and most haloacetic acids. In addition, geogenic organic compounds present in the oil and gas produced waters, including methylphenol and dimethylphenol, were found to be potential precursors to these iodo-DBPs.

•Emerging environmental contaminants are reviewed.•Sources, occurrence, and issues of emerging contaminants are discussed.•Transformation in the environment and upon disinfection can occur.•Climate change can result in concentration of contaminants in rivers.•Engineering solutions are proposed to minimize these contaminants in the environment.While our current generation continues to make efforts to remediate and minimize traditional pollutants in the environment, other “emerging” environmental contaminants are now warranting attention. These include perfluorinated compounds, nanomaterials, pharmaceuticals, illicit drugs, antibacterials, hormones, flame retardants, disinfection by-products (DBPs), artificial sweeteners, benzotriazoles, 1,4-dioxane, and algal toxins, as well as emerging contaminants on the horizon: prions and ionic liquids. Wastewater effluents are a major source for many of these emerging contaminants, due to their use in products we use in our households, from pharmaceuticals, detergents, fabric coatings, foam cushions, lotions, sunscreens, cosmetics, hair products, foods and beverages, and food packaging. After use, these chemicals are released in wastewater, and because many are incompletely removed in wastewater treatment, they enter our rivers and drinking water supplies. Surface run-off and agricultural run-off can also be important sources of their entry into the environment. Moreover, many of these contaminants can transform in the environment, from such processes as microbial degradation, photolysis, and hydrolysis, and they can also react with disinfectants in drinking water or wastewater treatment to form disinfection by-products. Issues surrounding these emerging contaminants, include widespread occurrence, bioaccumulation, persistence, and toxicity. Climate change can also serve to exasperate their effects by concentrating them in rivers during times of drought and by causing resuspension of some (like nanomaterials) during floods. This review will discuss these issues surrounding emerging contaminants and also propose some engineering solutions for the future.Download high-res image (528KB)Download full-size image

Disinfection by-products (DBPs) are a complex mixture of compounds unintentionally formed as a result of disinfection processes used to treat drinking water. Effects of long-term exposure to DBPs are mostly unknown and were the subject of recent epidemiological studies. However, most bioanalytical methods focus on a select few DBPs. In this study, a new comprehensive bioanalytical method has been developed that can quantify mixtures of organic halogenated compounds, including DBPs, in human urine as total organic chlorine (TOCl), total organic bromine (TOBr), and total organic iodine (TOI). The optimized method consists of urine dilution, adsorption to activated carbon, pyrolysis of activated carbon, absorption of gases in an aqueous solution, and halide analysis with ion chromatography and inductively coupled plasma-mass spectrometry. Spike recoveries for TOCl, TOBr, and TOI measurements ranged between 78% and 99%. Average TOCl, TOBr, and TOI concentrations in five urine samples from volunteers who consumed tap water were 1850, 82, and 21.0 μg/L as X−, respectively. Volunteers who consumed spring water (control) had TOCl, TOBr, and TOI average concentrations in urine of 1090, 88, and 10.3 μg/L as X−, respectively. TOCl and TOI in the urine samples from tap water consumers were higher than the control. However, TOBr was slightly lower in tap water urine samples compared to mineral water urine samples, indicating other sources of environmental exposure other than drinking water. A larger sample population that consumes tap water from different cities and mineral water is needed to determine TOCl, TOBr, and TOI exposure from drinking water.Download high-res image (217KB)Download full-size image

Lead contamination in the City of Flint, MI has been well documented over the past two years, with lead levels above the EPA Action Level until summer 2016. This resulted from an ill-fated decision to switch from Detroit water (Lake Huron) with corrosion control, to Flint River water without corrosion control. Although lead levels are now closer to normal, reports of skin rashes have sparked questions surrounding tap water in some Flint homes. This study investigated the presence of contaminants, including disinfection by-products (DBPs), in the hot tap water used for showering in the homes of residents in Flint. Extensive quantitative analysis of 61 regulated and priority unregulated DBPs was conducted in Flint hot and cold tap water, along with the analysis of 50 volatile organic compounds and a nontarget comprehensive, broadscreen analysis, to identify a possible source for the reported skin rashes. For comparison, chlorinated hot and cold waters from three other cities were also sampled, including Detroit, which also uses Lake Huron as its source water. Results showed that hot water samples generally contained elevated levels of regulated and priority unregulated DBPs compared to cold water samples, but trihalomethanes were still within regulatory limits. Overall, hot shower water from Flint was similar to waters sampled from the three other cities and did not have unusually high levels of DBPs or other organic chemicals that could be responsible for the skin rashes observed by residents. It is possible that an inorganic chemical or microbial contaminant may be responsible.Download high-res image (284KB)Download full-size image

Pools and spas are enjoyed throughout the world for exercise and relaxation. However, there are no previous studies on mutagenicity of disinfected spa (hot tub) waters or comprehensive identification of disinfection byproducts (DBPs) formed in spas. Using 28 water samples from seven sites, we report the first integrated mutagenicity and comprehensive analytical chemistry of spas treated with chlorine, bromine, or ozone, along with pools treated with these same disinfectants. Gas chromatography (GC) with high-resolution mass spectrometry, membrane-introduction mass spectrometry, and GC-electron capture detection were used to comprehensively identify and quantify DBPs and other contaminants. Mutagenicity was assessed by the Salmonella mutagenicity assay. More than 100 DBPs were identified, including a new class of DBPs, bromoimidazoles. Organic extracts of brominated pool/spa waters were 1.8× more mutagenic than chlorinated ones; spa waters were 1.7× more mutagenic than pools. Pool and spa samples were 2.4 and 4.1× more mutagenic, respectively, than corresponding tap waters. The concentration of the sum of 21 DBPs measured quantitatively increased from finished to tap to pool to spa; and mutagenic potency increased from finished/tap to pools to spas. Mutagenic potencies of samples from a chlorinated site correlated best with brominated haloacetic acid concentrations (Br-HAAs) (r = 0.98) and nitrogen-containing DBPs (N-DBPs) (r = 0.97) and the least with Br-trihalomethanes (r = 0.29) and Br–N-DBPs (r = 0.04). The mutagenic potencies of samples from a brominated site correlated best (r = 0.82) with the concentrations of the nine HAAs, Br-HAAs, and Br-DBPs. Human use increased significantly the DBP concentrations and mutagenic potencies for most pools and spas. These data provide evidence that human precursors can increase mutagenic potencies of pools and spas and that this increase is associated with increased DBP concentrations.

Toilet flushing with seawater results in saline wastewater, which may contain approximately 33–50% seawater. Halogenated disinfection byproducts (DBPs), especially brominated and iodinated DBPs, have recently been found in chlorinated saline wastewater effluents. With the occurrence of brominated and iodinated DBPs, the adverse effects of chlorinated saline wastewater effluents to marine ecology have been uncertain. By evaluating the developmental effects in the marine polychaete Platynereis dumerilii directly exposed to chlorinated saline/freshwater wastewater effluents, we found surprisingly that chlorinated saline wastewater effluents were less toxic than a chlorinated freshwater wastewater effluent. This was also witnessed by the marine alga Tetraselmis marina. The toxicity of a chlorinated wastewater effluent to the marine species was dominated by its relatively low salinity compared to the salinity in seawater. The organic matter content in a chlorinated wastewater effluent might be partially responsible for the toxicity. The adverse effects of halogenated DBPs on the marine species were observed pronouncedly only in the “concentrated” chlorinated wastewater effluents. pH and ammonia content in a wastewater effluent caused no adverse effects on the marine species. The results suggest that using seawater to replace freshwater for toilet flushing might mitigate the “direct” acute detrimental effect of wastewater to the marine organisms.