Table 2.

Emerging chemical contaminants that may occur in water sources or treated drinking water [data from Richardson and Ternes (2011)], with the current state of information regarding their health effects.

Chemical group	Source	Chemicals	Suspected or known health effects
Algal toxins	Produced by algal blooms from an excess of nutrients (in agricultural runoff and wastewater discharges).	Microcystins (e.g., microcystin-LR), nodularins, anatoxins, cylindrospermopsin, and saxitoxins.	Microscystin-LR is hepatotoxic, genotoxic, and carcinogenic (IARC 2010).
Artificial sweeteners	Consumers > urban wastewater > natural waters > drinking-­water source.	Sucralose (Splenda®, SucraPlus™), acesulfame, saccharin, cyclamate, etc.	Unknown. Sucralose is a persistent chemical in the environment (half-life up to several years).
Brominated flame retardants	Used during many years in commercial products such as children’s sleepwear, foam cushions in chairs, computers, plastics, and electronics. Diet is a source of exposure because some are persistent and accumulate in fish, eggs, milk, and meat.	Several chemicals classified in different groups such as polybrominated diphenyl ethers (PBDEs), polybrominated biphenyl (PBB), hexabromocyclododecane (HBCD).	Neurotoxicity and thyroid disruption (Dingemans et al. 2011).
Benzotriazoles	Complexing agents widely used as anticorrosives and for silver protection in dishwashing liquids.	The two most common forms are benzotriazole and tolytriazole.	Unknown. Soluble in water, resistant to biodegradation, and only partly removed in wastewater treatment.
DBPs	Generated through chemical reaction between organic matter and a disinfectant (e.g., chlorine, chloramine, chlorine dioxide) in the treatment of drinking water and swimming pools.	More than 700 compounds identified to date, which together are estimated to account for ~ 50% of the total organic halogen content.	Genotoxic, carcinogenic, reprotoxic.
Ionic liquids	Organic salts with low melting point (< 100ºC) promoted as “green chemistry” replacements to traditional solvents in industry. They exhibit some unique properties, including tunable viscosity, miscibility, and electrolytic conductivity, which make them useful for many applications, including organic synthesis and catalysis, production of fuel cells, batteries, coatings, oils, and nanoparticles, as well as other chemical engineering and biotechnology applications.	The chemical structures typically involve a cationic or anionic polar head group with accompanying alkyl side chains. Cationic head groups include imidazolium, pyridinium, pyrrolidinium, morpholinium, piperidium, quinolinium, quaternary ammonium, and quaternary phosphonium moieties; anionic head groups include tetrafluoroborate (BF4–), hexafluorophosphate (PF6–), bis(trifluoromethylsulfonyl)-imide [(CF3SO2)2N–], dicyanamide [(CN)2N–], chloride, and bromide.	Different toxicity in animals (Pham et al. 2010). No human studies.
Illicit drugs	Found in surface waters, but generally removed by treatment in water utilities (Huerta-Fontela et al. 2008).	Several chemicals, including amphetamine-like compounds, benzodiazepines, cannabinoids, cocainics, lysergic acid diethylamine (LSD), opioids, and metabolites (Valcárcel et al. 2012).	The effect of the mixture is unknown.
Musks	Highly lipophilic chemicals widely used as fragrance additives in many consumer products including perfumes, lotions, sunscreens, deodorants, and laundry detergents.	Several chemicals. May have nitroaromatic structures [as in the case of musk xylene (1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene) or musk ketone (4-tert-butyl-2,6-dimethyl-3,5-dinitroacetophenone)] or polycyclic structures [as in the case of 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN; trade name, tonalide), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(g)-2-benzopyran (HHCB; trade name, galaxolide), 4-acetyl-6-tert-butyl-1,1-dimethylindan (ADBI; trade name, celestolide), dihydropentamethylindanone (DPMI; trade name, cashmeran), or 5-acetyl-1,1,2,3,3,6-examethylindan (AHMI, trade name phantolide)].	Endocrine disruption, according to animal evidence (Schreurs et al. 2004).
Naphtenic acids	Result from petroleum extraction. Occur naturally in crude oil deposits across the world (up to 4% by weight) and in coal.	Complex mixture of alkyl-substituted acyclic and cyclo-aliphatic carboxylic acids that dissolve in water at neutral or alkaline pH and have surfactant-like properties.	Liver toxicity in mammals (Rogers et al. 2002). No human studies.
Nanomaterials	Heterogeneous group of chemicals sized 1–100 nm, highly stable, strong, conductors, and with low permeability.	Several chemical groups and structures including fullerenes, nanotubes, quantum dots, metal oxanes, titanium dioxide, nanoparticles, nanosilver, and zerovalent iron nanoparticles.	Unknown.
Perfluorinated compounds (PFCs)	Used to make stain repellents (such as Teflon), and in the manufacture of paints, adhesives, waxes, polishes, metals, electronics, fire-fighting foams, and caulks as well as grease-proof coatings for packaging. Diet is the main route of exposure, followed by drinking water, house dust, and air.	Different types. The most common are perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS).	Liver, pancreatic, and testicular tumor in animals. Inmunotoxicity (DeWitt et al. 2012), thyroid function disruption (Boas et al. 2012; Melzer et al. 2010).
Pesticide transformation by-products	Result from the hydrolysis, oxidation, biodegration, or photolysis of pesticides. Can be present at higher levels than the parent compound and can be as toxic or more toxic. Diet is a source of exposure.	Several chemicals, such as alachlor ethanesulfonic acid (ESA), alachlor oxanilic acid (OA), acetochlor ESA, acetochlor OA, metolachlor ESA, metolachlor OA, 3-hydroxycarbofuran, and terbufos sulfone.	Unknown.
Pharmaceuticals	Human consumption > excretion > urban wastewater > natural waters > drinking-­water source.	Several chemicals, including antidepressants, antiviral drugs, glucocorticoids, antimycotics, antibiotics, beta-blockers.	The effect of the mixture is unknown.
Siloxanes	Used in cosmetics, deodorants, soaps, hair conditioners, hair dyes, car waxes, baby pacifiers, cookware, cleaners, furniture polishes, and water-repellent windshield coatings.	Cyclic siloxanes [octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), and tetradecamethylcycloheptasiloxane (D7)] and linear siloxanes.	Unknown.
Sunscreens/ultraviolet filters	Personal care products > urban wastewater > natural waters > drinking-­water source. Identified in drinking water (in Barcelona, Spain) with average concentrations up to 295 ng/L (Díaz-Cruz et al. 2012).	Several chemicals. The ones identified in drinking water are benzophenone-3 (BP3), octocrylene (OC), 2-ethylhexyl 4-methoxycinnamate (EHMC), 3-(4-methylbenzylidene) camphor (4-MBC), and 2-ethylhexyl 4-(dimethylamino) benzoate (OD-PABA).	Unknown.
Single chemicals
Dioxane	High-production chemical used as a solvent stabilizer in the manufacture and processing of paper, cotton, textile products, automotive coolants, cosmetics, and shampoos and as a stabilizer of 1,1,1-trichloroethane (a degreasing agent).	1,4-Dioxane. Regulated by U.S. EPA (50 mg/L).	Unknown.
Perchlorate	Highly stable and soluble chemical used in solid propellants in rockets, missiles, and fireworks as well as in highway flares. Can be found as a contaminant in sodium hypochlorite. Perchlorate can accumulate in plants and has been found in biological samples.	Perchlorate	Unknown. Perchlorate can cross the placenta.