Evaluation of Formation and Health Risks of Disinfection by-Products In Drinking Water Supply of Ggaba Waterworks, Kampala, Uganda
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Date
2021-07-27
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Addis Ababa University
Abstract
In developing countries, the evaluation of DBPs has been neglected because most water utility
companies focus on microbial elimination. As a result, this study aimed at evaluating THMs
formation, their concentration, the effect of other water quality parameters and estimation of the
associated potential health risks in drinking water. The study considered evaluation of THMs
because they are the most common, and are used as indicators for total DBPs concentration. The
USEPA 524.2 method was used to quantify THMs in water while utilizing the headspace purge
and trap coupled with a GC-MS technique. The THMs identified were chloroform in the
concentration ranging from 11.87-33.98 μg/L and 11.23-39.30 μg/L at the treatment plant and
along the distribution system respectively. Bromodichloromethane was in the range from 0.78-
9.43 μg/L and 0.89-9.49 μg/L at the treatment plant and along the distribution system, respectively.
The concentrations of THMs found in water were within NWSC, WHO and USEPA guidelines.
Running a Pearson correlation, to find the relation between water parameters; TOC, UV254,
bromide concentration, temperature had a positive and significant correlation, pH had a positive
but non-significant correlation while the residual chlorine had a negative but significant
correlation. Potential health risk was evaluated using the WHO index and the USEPA risk
estimation model. WHO index was 0.4104 which was less than unity indicating no
noncarcinogenic risk to human health in the study area. The human lifetime carcinogenic risk of
THMs due to the oral ingestion, dermal and inhalation were 2.54 × 10-5, 9.08 × 10-6 and 8.29 ×10-
6 for females and 2.44 × 10-5, 1 × 10-5 and 7.96 ×10-6 for males, the values were within the USEPA
acceptable low risk range of 1× 10-6 < CR< 5.1 × 10-5. Also, the hazard quotient was less than
unity, indicating no adverse health effects due to exposure to THMs in Kampala western zone.
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Keywords
Evaluation, Formation, Health Risks, Disinfection by-Products, Drinking Water Supply, Ggaba Waterworks, Kampala, Uganda