Disinfecting water is considered as a main public health conquering since it considerably decreased waterborne illness and augmented life expectancy [1]. Nevertheless, a not planned sequel was the formation of disinfection by-products (DBPs), which are generated via the reaction of disinfectants (chlorine, chloramine, ozone, chlorine dioxide, ultraviolet (UV)) with natural and anthropogenic organic matter, bromide, and iodide [2] [3] [4]. Such compounds are produced for any specific objective but are generated throughout water treatment [5] [6] [7]. Until now, more than 700 DBPs have been defined, and of those, around only 100 have been strictly examined for their existence, generation, and quantitative analytical biological toxicity [8] [9] [10].

In the early 1970s, at most a few of DBPs were investigated, foremost trihalomethanes (THMs) [11] [12]. Later, such THMs were observed to be prevalent in chlorinated water and were as well discovered to be carcinogenic in laboratory animals [1] [13]. Consequently, the earliest DBP regulations were announced [14] [15] [16]. The emerging U.S. Environmental Protection Agency (EPA), which was instituted in 1970, started to regulate THMs (chloroform, bromoform, bromodichloromethane, and chlorodibromomethane) below the 1979 Safe Drinking Water Act [1]. Subsequently, more toxicity facts were acquired for five haloacetic acids, bromate, and chlorite; and these were attached to the regulation below the Stage 1 and Stage 2 [17] [18] [19]. The World Health Organization, European Union, and many different nations also have guidelines or regulations for some DBPs in drinking water [1].

This work focuses on the hard challenges in dealing with the disinfection by-products (DBPs). Fundamental interrogations relating DBPs monitoring are presented. The fact that regulating DBPs is important or not is also discussed.

Richardson and Plewa [1], well-known experts in the DBPs field, posted a relevant question: “Are we controlling the right DBPs?” Previous researches on human epidemiology support the plan of regulating and controlling DBPs since numerous investigations noted a hazard of bladder cancer, colorectal cancer, miscarriage, and birth defects [1] [20] [21].

One more matter in question is that water is not as it was consumed seventy years earlier [1] [22] [23]. It is ever-changing [24] [25] [26]. During the time that regulations and ecological protection actions greatly enhanced the protection of water, potable water is unlike what it was a half-century ago [14] [27] [28].

If in the end all the different DBPs were as well decreased with the regulated DBPs, the situation would be better [1]. In fact, the more poisonous iodo-DBPs and nitrogen-containing DBPs (N-DBPs) [29] could be produced at much greater degrees when plants change to chloramine [30]. A change to ozone could as well lead to an augmented generation of bromate, as well as unregulated halonitromethane, haloaldehyde, haloketone, and haloacid DBPs, with secondary chlorination [15] [31] [32]. Paradoxically, UV could response with natural organic matter (NOM) to augment the production of considerably hazardous halonitromethanes if secondary chlorine is implemented [33] [34] [35]. Since ozone and UV do not provide a residual disinfectant, chlorine or chloramine is frequently injected as an additional disinfectant to keep disinfection in the distribution system [36] [37] [38].

Additional elements also influence water sources like population increases, climate change, water usage, and wastewater reuse [39] [40] [41]. As an example, climate change increases wastewater pollutants in water sources, as well as concentrates NOM, bromide, and iodide, constituting circumstances for worsening the hazardous effects on water [1] [42] [43] [44] [45].

Since the earliest DBP poisoning investigations launched five decades ago, more than 100 additional DBPs were rigorously analyzed for cytotoxicity, genotoxicity, endocrine disruption, and carcinogenicity [46] [47] [48]. Several unregulated DBPs were found more dangerous than regulated ones [1] [49] [50].

More technical details can be found in the excellent discussion performed by Richardson et al. [1] and references cited in.

Finally, treatment master plans must be adopted to avoid the formation of DBPs, whether regulated or unregulated [51] [52] [53]. Viable techniques involving the usage of granular activated carbon or membranes to retain DBP precursors (then injecting a smaller injection of chlorine for killing pathogens), utilizing UV pursued by a smaller dosage of chlorine [1] [14] [54] (Figure 1).

Considered as the latest technique, post-disinfection is extremely crucial for the classical potable water treatment [55] [56] [57]. Disinfection target is to kill microorganisms that cause diseases in water to make certain the potable water security [58] [59] [60]. But, the quality of the fountainhead water becomes worse and worse due to rising natural and artificial water contaminations [61] [62] [63]. DBPs are generated at what time disinfectants (chlorine, chlorine dioxide, chloramines or ozone) interact with NOM, anthropogenic contaminants, bromide, and iodide in the potable water treatment chain [64] [65] [66]. As well the regulated DBPs (such as THMs, HAAs, bromate and chlorite), several additional unregulated DBPs have been detected [67] [68] [69]. Nitrosoamines are the elements of these new DBPs, which are strongly carcinogenic, mutagenic, and teratogenic [70] [71] [72]. The main points drawn from this review may be drawn as:

1) The first objective of water treatment is to render water secure to consume by making certain that it is without of pathogens and poisonous compounds; the second target is to render it a desirable drink by eliminating unwanted turbidity, tastes, colors, and odors [73] [74] [75]. Considering the first objective render

water without pathogens and toxic matters, it is obvious that disinfecting by injecting chemicals is an impossible compromise since disinfection kills microorganisms but forms DBPs [76] [77]. Consequently, injecting chemical products into water must be avoided even if the mentioned reason is disinfecting water [14] [15].

2) Instead of chemical therapy, sure techniques such as physical processes like distillation and membrane processes should be urgently adopted to remove pathogens and organic compounds [14] [15].

3) Finally, at the COVID-19 period, this study arrives at its time since the Environmental Engineers and the Green Chemistry specialists have largely opened the discussion about polluting industry and preserving nature [78] [79] [80] [81].

This research has been funded by the Research Deanship of University of Ha’il, Saudi Arabia, through the Project RG-191190.

The authors declare no conflicts of interest regarding the publication of this paper.

Ghernaout, D. and Elboughdiri, N. (2020) Disinfection By-Products Regulation: Zero ng/L Target. Open Access Library Journal, 7: e6382. https://doi.org/10.4236/oalib.1106382