NIGERIANS may be exposed to high levels of disinfection by-products in their drinking water, predisposing to cancers and other health problems, a study has warned.
In the study, experts found amounts of cancer-causing contaminants and toxic metals in drinking water and groundwater sources in the country at concentrations above threshold limits.
The study was carried out to determine the occurrence of chlorination by-products in drinking water from four watertreatment plants (WTPs) in Lagos and Ogun states.
It also evaluated the possible potential health risks associated with possible long-term exposure to levels of trihalomethanes (THMs) through drinking such water.
The 2017 study was published in the Journal of Environmental Public Health and entitled “Disinfection By-products in Drinking Water and Evaluation of Potential Health Risks of Long-Term Exposure in Nigeria.”
The researchers found that the average concentrations of chlorination disinfection by-products in drinking water exceeded 0.001 mg/L, the standard maximum contaminant levels stipulated by Standard Organisation of Nigeria.
In addition, higher average intake of chlorination disinfection by-products was observed in adults while the ingestion in children showed comparable values.
The researchers said this indicated that the treatment processes and handling at WTPs contributes a great deal to the formation of disinfection by-products in drinking water.
They stated: “This has to do partly with carefulness in the addition of chlorine, which is mostly used in all the watertreatment plants in the sampled areas. In addition to this are the processes of sedimentation/flocculation and the maintenance of the right amount of residual chlorine in the distribution system.”
Four potable watertreatment plants that utilise one of the two main treatment processes (chlorine-chlorine, chlorine-UV) used were selected for this study.
In addition, public and private WTPs in Lagos and Ogun states were selected and these include two public and two private watertreatment plants.
Several epidemiological studies have reported health complications, associated with liver, reproductive system, kidney, and central nervous system, as well as increased risk of cancer due to consumption of drinking water that contains chlorination disinfection by-products in excess of the maximum contaminant level.
They, however, suggested switching to chloramine as disinfectant and with ultraviolet light as the secondary disinfectant to reduce the concentrations of drinking water disinfection by-products to the barest minimum.
The use of chloramine as disinfectant has proven to produce very minimal amount of disinfection by-products (DBP) in countries like Europe, America, and Australia.
In Nigeria, approximately, 99.8 per cent of public and private drinking watertreatment plants in Nigeria use chlorine for disinfection because of its availability, relatively low cost, high efficiency, and convenience of application in water purification.
The disinfection of water is an essential treatment process for safeguarding the quality of drinking water but could create undesirable chemical risk due to the formation of DBP during the process.
Since early 70s, studies have revealed that chlorination produces potentially harmful DBPs with more than 600 DBPs detected and quantified in drinking waters.
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