Health Risks of Chlorination - is there a Problem? (original) (raw)
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Disinfection By-Products in Chlorinated Drinking Water and Their Adverse Health Effects : A Review
All drinking water sources contain natural organic matter (NOM) and addition of chlorine to drinking water results in the formation of various chlorinated disinfection by-products (DBPs). Some of these DBPs are carcinogenic and are regulated in most developed countries. This paper is a review of the current levels of understanding about DBP toxicity and the magnitude of risk due to exposure to DBPs. Various routes of exposure have now been examined and the latest findings prove that ingestion of chlorinated drinking water is no longer the major route of exposure. THM levels in blood were far higher after exposure to chlorinated drinking water via dermal absorption and inhalation during showering, bathing or swimming. Evidence of DBP toxicity comes mainly from animal toxicity studies and to a smaller extent from epidemiological studies. Two common methods of studying toxicity are by feeding the chemical of concern to animals (generally rodents) via drinking water or gavage (force-fee...
Journal of Water and Health, 2015
This study reports the baseline data of chlorination disinfection by-products such as trihalomethanes (THMs) and their associated health risks in the water distribution network of Islamabad and Rawalpindi, Pakistan. THM monitoring was carried out at 30 different sampling sites across the twin cities for 6 months. The average concentration of total trihalomethanes (TTHMs) and chloroform ranged between 575 and 595 μg/L which exceeded the permissible US (80 μg/L) and EU (100 μg/L) limits. Chloroform was one of the major contributors to the TTHMs concentration (>85%). The occurrence of THMs was found in the following order: chloroform, bromodichloromethane > dibromochloromethane > bromoform. Lifetime cancer risk assessment of THMs for both males and females was carried out using prediction models via different exposure routes (ingestion, inhalation, and dermal). Total lifetime cancer risk assessment for different exposure routes (ingestion, inhalation, and skin) was carried out. The highest cancer risk expected from THMs seems to be from the inhalation route followed by ingestion and dermal contacts. The average lifetime cancer risk for males and females was found to be 0.51 × 10 À3 and 1.22 × 10 À3 , respectively. The expected number of cancer risks per year could reach two to three cases for each city.
Water Research, 2009
Seven water treatment works were selected to compare disinfection by-products (DBPs) formed when using chlorination and chloramination. DBPs measured included trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), trihalonitromethane, iodinated THMs and nitrosamines. Generally treatment works that used chloramination were able to meet the European THM regulatory limit of 100 mg L À1 whereas the chlorinated works found it significantly more difficult. There were no significant differences in the levels of nitrogenous DBPs between the treatment works using chlorination or chloramination with the exception of the nitrosamine N-nitrosodimethylamine (NDMA) which was present at one treatment works in one season. (S.A. Parsons).
Undesirable effects of drinking water chlorination by-products
The fundamental objective of water treatment is the protection of consumers from pathogenic microorganisms. Chlorination of drinking water is essential to prevent waterborne disease. However, chlorine reacts with organic matter present in surface waters to form various by-products suspected of being carcinogenic. In the last decade, several epidemiological studies have been conducted to determine the connection between exposure to these chlorination by-products and human health defects. The purpose of this paper is to evaluate the genotoxicity of drinking water of Annaba city. The study have been carried out in different points of water distribution and in the station of treatment, using two tests of determination of genotoxic risk by means of SOS chromotest (using the strain Escherichia coli PQ37). SOS chromotest showed genotoxic effect of the sample collected from the exit of treatment station.
WATER CHLORINATION AND ITS RELEVANCE TO HUMAN HEALTH
Climatic conditions are fundamental to life on earth and their destruction or disturbance by direct or indirect human activities is the greatest threat to human health. Human life on earth is directly associated with environmental factors such as "air" and "water." Pollution of air by toxic substances by the activities of mankind has shown to cause serious health issues, including damage to the immune, respiratory, neurological, and reproductive systems, and other health problems like cancer. Water intended for human consumption should be free from microorganisms and toxic substances. The impact and drastic effects of chlorinated water and their impact on human health are poorly studied. Chlorination is an inexpensive and effective process for disinfecting water worldwide. During the disinfection, the chlorine generates hundreds of different by-products called chlorination by-products such as trihalomethanes and halo acetic acids (HAA's) at low levels. In this article we address the action of two HAA's, tri-and di-chloroacetic acid and their impact on the progression of cancer, respiratory disorder, and neurological anomalies.
Chlorination byproducts, their toxicodynamics and removal from drinking water
Journal of Hazardous Materials, 2007
No doubt that chlorination has been successfully used for the control of water borne infections diseases for more than a century. However identification of chlorination byproducts (CBPs) and incidences of potential health hazards created a major issue on the balancing of the toxicodynamics of the chemical species and risk from pathogenic microbes in the supply of drinking water. There have been epidemiological evidences of close relationship between its exposure and adverse outcomes particularly the cancers of vital organs in human beings. Halogenated trihalomethanes (THMs) and haloacetic acids (HAAs) are two major classes of disinfection byproducts (DBPs) commonly found in waters disinfected with chlorine. The total concentration of trihalomethanes and the formation of individual THM species in chlorinated water strongly depend on the composition of the raw water, on operational parameters and on the occurrence of residual chlorine in the distribution system. Attempts have been made to develop predictive models to establish the production and kinetics of THM formations. These models may be useful for operational purposes during water treatment and water quality management. It is also suggested to explore some biomarkers for determination of DBP production. Various methods have been suggested which include adsorption on activated carbons, coagulation with polymer, alum, lime or iron, sulfates, ion exchange and membrane process for the removal of DBPs. Thus in order to reduce the public health risk from these toxic compounds regulation must be inforced for the implementation of guideline values to lower the allowable concentrations or exposure.
DANGER OF USING CHLORINE IN THE TREATMENT OF WATER.docx
Water is life, without it life cannot be sustained either domestically or industrially. This paper examine the use of chlorine in the treatment of water and its harmful effect. Chlorine is used in the chlorination process because of the effectiveness in fighting against water-borne diseases both at the water treatment plant and distribution system. It was found out that chlorine reacted with organic matter in water and form dangerous, carcinogenic trihalomethane. Carcinogenic trihalomethane is a cancer-producing compound. It was suggested that the water should be filtered with activated carbon before use.
Occupational and Environmental Medicine, 2000
Objectives and methods-Chlorination has been the major disinfectant process for domestic drinking water for many years. Concern about the potential health eVects of the byproducts of chlorination has prompted the investigation of the possible association between exposure to these byproducts and incidence of human cancer, and more recently, with adverse reproductive outcomes. This paper evaluates both the toxicological and epidemiological data involving chlorination disinfection byproducts (DBPs) and adverse reproductive outcomes, and makes recommendations for future research. Results and conclusions-Relatively few toxicological and epidemiological studies have been carried out examining the eVects of DBPs on reproductive health outcomes. The main outcomes of interest so far have been low birth weight, preterm delivery, spontaneous abortions, stillbirth, and birth defects-in particular central nervous system, major cardiac defects, oral cleft, and respiratory, and neural tube defects. Various toxicological and epidemiological studies point towards an association between trihalomethanes (THMs), one of the main DBPs and marker for total DBP load, and (low) birth weight, although the evidence is not conclusive. Administered doses in toxicological studies have been high and even though epidemiological studies have mostly shown excess risks, these were often not significant and the assessment of exposure was often limited. Some studies have shown associations for DBPs and other outcomes such as spontaneous abortions, stillbirth and birth defects, and although the evidence for these associations is weaker it is gaining weight. There is no evidence for an association between THMs and preterm delivery. The main limitation of most studies so far has been the relatively crude methodology, in particular for assessment of exposure. Recommendations-Large, well designed epidemiological studies focusing on well defined end points taking into account rel-evant confounders and with particular emphasis on exposure characterisation are ideally needed to confirm or refute these preliminary findings. In practice, these studies may be impracticable, partly due to the cost involved, but this is an issue that can be put right-for example, by use of subsets of the population in the design of exposure models. The studies should also reflect diVerences of culture and water treatment in diVerent parts of the world. To identify the specific components that may be of aetiological concern and hence to fit the most appropriate exposure model with which to investigate human exposure to chlorinated DBPs, further detailed toxicological assessments of the mixture of byproducts commonly found in drinking water are also needed. (Occup Environ Med 2000;57:73-85)
Mutation Research/Genetic Toxicology and Environmental Mutagenesis, 2004
A battery of in vitro short-term tests revealing different genetic end-points was set up in order to study surface-water genotoxicity after disinfection with different biocides: sodium hypochlorite (NaClO), chlorine dioxide (ClO 2 ) and peracetic acid (PAA). The surface water both before and after disinfection was concentrated by adsorption on C 18 silica cartridges and the concentrates containing non-volatile organics were divided into different portions for chemical analyses and biological assays. The following in vitro tests were conducted on the water concentrates dissolved in DMSO: the Salmonella mutagenicity assay with S. typhimurium strains TA98 and TA100; the SOS Chromotest with Escherichia coli, the Microtox ® and Mutatox ® assays with Vibrio fischeri; and gene conversion, point mutation and mitochondrial DNA mutability assays with D7 diploid Saccharomices cerevisiae strain. The results show that the SOS Chromotest and the yeast assays are highly sensitive in detecting genotoxicity. The surface-water extracts were very often toxic to most of the test organisms considered, partially masking their potential mutagenic activity. Therefore, the assays with E. coli and with S. cerevisiae are more likely to show a mutagenic effect because these organisms are generally less sensitive to most toxic compounds. Among the tested disinfectants, NaClO and ClO 2 increased water genotoxicity, whereas PAA was able to slightly reduce raw water activity. However, because the organic compounds in the lake water varied with the season of the year, the disinfection processes, at times, both increased and decreased the raw water activity.