Disinfection Byproducts in Rajasthan, India: Are Trihalomethanes a Sufficient Indicator of Disinfection Byproduct Exposure in Low-Income Countries?

Abstract

The implementation of chlorine disinfection in low-income countries reduces the risk of waterborne illness but initiates exposure to disinfection byproducts (DBPs). Like high-income countries, low-income countries typically are adopting regulations focusing on trihalomethanes (THM4) as an indicator of overall DBP exposure. However, the use of impaired water sources can decouple the formation of THM4 from other DBP classes that are more potent toxins. The documentation of DBP species other than THM4 is rare in low-income countries, where water sources may be degraded by inadequate sanitation infrastructure and other uncontrolled wastewater discharges. We measured THM4 and 21 unregulated DBPs in tap waters and laboratory-treated source waters from two cities in northwestern India. The contribution of each DBP class to the cumulative toxicity was estimated by weighting each species by metrics of toxic potency; haloacetonitriles typically were the dominant contributor, while the contribution of THM4 was negligible. THM4 concentrations did not correlate with the total toxic potency-weighted DBP concentrations. Although THM4 rarely exceeded international guidelines, DBPs of greater toxicological concern were observed in high concentrations. The total toxic potency-weighted DBP concentrations in some waters were elevated compared to conventional drinking waters in high-income countries and more closely resembled chlorine-disinfected wastewater effluents. Artificial sweeteners confirmed widespread contamination of both surface and groundwaters by domestic sewage. The results suggest that THM4 may not be an adequate indicator of overall DBP exposure in impaired water supplies prevalent in some low-income nations.

Potential spreading risks and disinfection challenges of medical wastewater by the presence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) viral RNA in septic tanks of Fangcang Hospital

“…Nevertheless, it was an over-dosage and resulted in a significant level of DBPs in the effluents, which was about 15 times higher than other hospital wastewater (Luo et al, 2020). The four detected chloroform and trihalomethanes accounted to the majority of total DBPs in wastewaters (Furst et al, 2019) and their composition was similar as previous studies (Luo et al, 2020;Zhong et al, 2019). They show high ecological risks and challenge the surrounding environment receiving disinfected medical wastewater, possessing threats to ecological system and human health (Ding et al, 2020;Li et al, 2019).…”

Temporospatial variation and health risk assessment of trihalomethanes (THMs) in drinking water (northwest Iran)

“…The World Health Organization (2017) have also established drinking water guideline values for each THM species: CF, BDCM, DBCM, and BF levels should not exceed 300 µg/l, 60 µg/l, 100 µg/l and 100 µg/l, respectively, and the sum of the ratio of each compound to its MCL should not exceed 1 (see Eq 1 below), where C is concentration and GV is guideline value. Measurements of DBPs levels in drinking water have been carried out regularly worldwide (Abbas et al 2014;Furst et al 2019;O'Driscoll et al 2018;Yao et al 2019). In Iran, a number of studies (Ahmadi and Ramavandi, 2014;Alipour and Ghanbarnejad, 2014;Babaei et al 2015;Ghoochani et al 2016;Kalankesh et al 2019;Mohammadi et al 2019;Mohammadi et al 2016;Nadali et al 2019;Ramavandi and Asgari, 2012) have investigated THMs formation potential, THMs concentrations in tap drinking water and related health risks in different parts of the country.…”

Waterborne pathogen monitoring in Jaipur, India reveals potential microbial risks of urban groundwater supply

“…Disinfection with chlorine might be considered, but the high concentrations of halides and organic contaminants observed in the groundwater increase the likelihood of forming disinfection byproducts 38 . This risk is verified by a recent study of tap water in Jaipur that detected both regulated and unregulated disinfection byproducts that could pose significant risks to public health 44 . Additionally, disinfection using chlorine would be less effective against protozoan pathogens Giardia and Cryptosporidium, which we detected via molecular assays 26,27 .…”