11.3 Factors t hat influence t he form at ion of disinfect ion byproducts

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1 CHAPTER DISINFECTION BYPRODUCTS Chemical drinking water disinfection with substances such as chlorine has been applied for more than a century. During the seventies, scientists discovered the possibility of origination of disinfection byproducts by means of gas chromatography testing. Disinfection byproducts can be harmful to human health. After this discovery, extensive research took place on the origination of disinfection byproducts, on the health effects and on procedures to prevent the formation of these products during the disinfection process Nature of disinfection byproducts Disinfection byproducts are chemical, organic and inorganic substances that can form during a reaction of a disinfectant with naturally present organic matter in the water Formation of disinfection byproducts Disinfection byproducts can form when disinfectants, such as chlorine, react with naturally present compounds in the water. The formation of these products mainly takes place during reactions in which organic substances, such as humic acid and fulvine acid, play a part. These materials end up in water during the decomposition of plant matter. In 1971 the American scientist Bellar discovered that chloroform was absent in the Ohio river water which was used for drinking water production. However, chloroform appeared to be present in drinking water originating from drinking water purification plants. This proves the formation of disinfection byproducts during chlorination. Little information can be found on the chemical structures of humic acids and fulvine acids. The mechanism of formation of disinfection byproducts therefore remains unclear. Research is difficult, because of the extensive number of substances that make up organic matter Factors t hat influence t he form at ion of disinfect ion byproducts The types of disinfection byproducts that are formed depend on a number of influential factors: - The type of disinfectant - The disinfection dose - The disinfection residue When the dose and residue of the disinfectant are higher, more disinfection byproducts are formed. To prevent halogenic disinfection byproducts from forming, alternative disinfectants are applied today. However, disinfection byproducts may still form. - Circumstances of disinfection: reaction time, temperature and ph When the reaction time is shorter, higher concentrations of trihalomethanes (THM) and halogenic acetic acids (HAA) may be formed. When the reaction time Chapter 11 55

2 is longer, some temporary forms of disinfection byproducts may become disinfection end products, such as tribromine acetic acid or bromoform. Haloacetonitrils (HAN) and haloketons (HK) are decomposed. When temperatures increase, reactions take place faster, causing a higher chlorine concentration to be required for a proper disinfection. This causes more halogenic disinfection byproducts to form. An increase in temperatures also enhances the decomposition of tribromine acetic acids, HAN and HK. When ph values are high, more hypochlorite ions are formed, causing the effectiveness of chlorine disinfection to decrease. At higher ph values, more THM is formed, whereas more HAA is formed when ph values are lower. At high ph values HAN and HK are decomposed by hydrolysis, because of an increase in hydrolysis reactions at higher ph values. The levels of trihalomethanes in drinking water are often higher in the distribution network than at drinking water production companies. When hydrolysis takes place many disinfection byproducts become trihalomethanes. Fig Trihalomethane formation (trichloromethane, brominedichloromethane, dibromomethane and tribromomethane), consequentially to contact time - The constituents of water - Concentrations and properties of naturally present organic matter (NOM) in the water NOM is the predecessor of a disinfection byproduct. The level of organic matter is usually registered as the "total organic carbon" concentration or the "dissolved organic carbon" concentration. The composition and concentration of naturally present organic matter determine the types and concentrations of disinfection byproducts that will eventually be formed. Naturally present organic matter contains compounds, such as humic acids, fulvine acids, hydrophobic acids, hydrophobic neutral substances, transfilic acids, transfilic neutral substances, hydrophilic acids and hydrophilic neutral substances. Chapter 11 56

3 Fig 11.2 organic carbon concentration influencing the formation of various types of trihalomethanes at various bromine concentrations Seasons influence the naturally present organic carbon concentration, causing the concentrations of disinfection byproducts to vary. The concentrations of disinfection byproducts in surface water and groundwater may be different. Table Disinfection byproducts of various disinfectants disinfectant organohalogenic disinfection byproducts inorganic disinfection byproducts non-halogenic disinfection byproducts chlorine (Cl 2 )/ hypochlorous acid (HOCl) trihalomethanes, halogenic acetic acids, haloacetonnitrils, chlorine hydrates, chloropicrin, chlorophenols, N- chloramines, halofuranones, bromohydrins chlorate (particularly the application of hypochlorite) aldehydes, alkanic acids, benzene, carboxylic acids Chlorine dioxide (ClO 2 ) chlorite, chlorate unknown chloramines (NH 3 Cl etc.) haloacetonnitrils, cyano chlorine, organic chloramines, chloramino acids, chlorohydrates, haloketons, nitrite, nitrate, chlorate, hydrazine aldehydes, ketone Chapter 11 57

4 ozone (O 3 ) bromoform, monobromine acetic acid, dibromine acetic acid, dibromine acetone, cyano bromine chlorate, iodate, bromate, hydrogen peroxide, hypobromic acid, epoxy aldehydes, ketons, ketoacids, carboxylic acids 11.4 Health effects of Disinfection byproducts Drinking water disinfection, for example by chlorine, has decreased the number of waterborne diseases dramatically. In the last thirty years the potential health risk of chemical disinfectants for drinking water has gained a lot of attention. Since the discovery of chloroform in chlorinated drinking water, several epidemiological and laboratory studies have been carried out. These studies show that chloroform is carcinogenic for laboratory animals when exposure to large doses takes place. Many disinfection byproducts are bio accumulative. They are not destroyed by the body and can accumulate in body tissues. Research on health effects of disinfection byproducts aims at the following themes: - Health effects on humans that drink disinfected drinking water. The research is carried out through epidemic studies. These are mostly concerned with long-term effects. Humans are exposed to small concentrations of disinfection byproducts for many years. - Toxicity of separate disinfection byproducts and mixtures of disinfection byproducts. This research is carried out on laboratory animals. The research on laboratory animals comes across several difficulties. There is a great number of disinfection byproducts. Cancer can develop in different ways. Various laboratory animals react differently on disinfection byproducts. Research on laboratory animals aims mainly on disinfection byproducts with the highest human exposure rate and the highest toxicity rate. Most researches carried out on reproduction effects of disinfection byproducts aim at birth defects and spontaneous abortion. Little research has been carried out on effects on male reproduction. An American research shows that bromodichloromethane (BDCM) and chloral hydrate (CH) lower the speed and mobility of sperm in laboratory rats. The effect of BDCM at low concentrations is stronger than the effect of CH or other disinfection byproducts that lower sperm speed. (Klinefelter, 1996) In 2002 American researchers looked at the carcinogenetic of a mixture of disinfection byproducts on rats. Aim of this research was to see whether the carcinogenetic of different disinfection byproducts would be increased in a mixture and what the effect was of long-term exposure to low concentrations disinfection byproducts. Eker rats, which are sensitive to effects of renal carcinogenic substances, were used. Both male and female rats were exposed to disinfection byproducts dichloromethylhydroxyfuranone (MX), potassium bromate (KBrO 3 ), chloroform (CHCl 3 ) and bromodichloromethane (BDCM) in drinking water during 4 to 10 months. These disinfection byproducts were chosen, because they are proven renal carcinogenic or poisonous to kidneys. Both low and high Chapter 11 58

5 concentrations were used. Mixtures of disinfection byproducts and separate disinfection byproducts were used. There seemed to be a relation between dosage and the origination of renal cancer. There was no difference in the amount of tumors in kidneys, uterus or spleen between the mixture of disinfection byproducts or the disinfection byproduct with the largest effect. This research shows that a mixture of these disinfection byproducts does not have a higher risk of cancer than the disinfectant with the greatest effect (Hooth, 2002) 11.5 Effect s of chlorine dioxide, chlorit e and chlorat e on laborat ory animals A survey of available research results on acute and long time exposure of rats, mice, chickens to chlorine dioxide, chlorate and chlorite in drinking water show that all these animals experienced alterations in their blood cells. These effects were dose related and occurred only at high concentrations (up to 1g/L). With these long time studies rats were supplied with chlorine dioxide concentrations up to 1 g/l and sodium chlorite or -chlorate concentrations up to 100 mg/l during 30 or 60 days. At chlorite concentrations of 100 mg/l or more, the amount of red blood cells and haemoglobin decreased. After exposure of 90 days these effects decreased. The results for mice were comparable. Furthermore chlorine dioxide, chlorite and chlorate alter DNA in testes and kidneys. This may imply that these substances have effects on reproduction. The outcome of these researches can not directly be transferred to people. More research has to be carried out. (Couri, 1982) 11.6 Chloroform Chloroform, a disinfection byproduct of chlorine, is one of the most investigated trihalomethanes. Toxicological research (Larson, 1994a) shows that chloroform causes damage to liver and finally causes cancer when it is daily directly applied into the stomach of laboratory animals. The amount of chloroform is too big for the liver to break down completely. The liver is damaged and death of cells and regenerative cell growth occur. The risk on cell mutation and cancer in exposed organs is increased. Another research was carried out in which laboratory animals were exposed to the same amount of chloroform dissolved in drinking water. They did not develop cancer. This was probably due to the fact that throughout the day animals were exposed to small amounts of drinking water with chloroform. The liver was able to break down the chloroform without getting damaged. (Larson et al., 1994b) Butterworth et al., 1998). The Environmental Protection Agency (EPA) concludes that as long as exposure to chloroform remains under given threshold values that cause cell damage, the risk for cancer is very low. Standards set for chloroform in drinking water are far below these values. (EPA, 1998) Besides experiments with laboratory animals (rats and mice) there are also epidemical studies on effects of exposure of humans to disinfection byproducts in drinking water. At first the relation of death because of cancer and the use of chlorinated or non-chlorinated drinking water were investigated. Subsequently studies showed that chlorinated drinking water increases the risk on bladder and anal cancer. The risk did not decrease when other factors, smoking, residence and work were investigated as well. The risk of intestinal cancer was not significant, but increased at higher concentrations disinfection byproducts. (Morris, 1992) Chapter 11 59

6 The health effects of halogenated disinfection byproducts can be divided in two groups. They can be carcinogenic or have effects on reproduction and development: In the 1960's new methods, gas chromatography and mass spectrometry, were developed to identify chemical substances at very low concentrations. Awareness of the large amount and diversity of chemical substances in air and water was born. In 1974 EPA enacted a list of 187 organic substances that are found in drinking water. Some of these substances are carcinogenic or mutagenic. Only a few substances, including trihalomethanes chloroform, bromoform, dichloromethane and dibromomethane, were found in all chlorinated drinking water. A large amount of studies were carried out on the development of cancer caused by drinking water. Most studies use population data to find a relation between geographical drinking water distribution and the risk on death as a result of cancer. Other studies investigated water sources that were used by people who developed cancer and water sources that were used by people who died as a result of another disease. Because no direct measurements were used, variables were taken for surface water versus groundwater, chlorinated versus nonchlorinated water and river water carrying industrial pollutions versus river water without pollutions. These studies show there is a relation between drinking water quality and bladder-, intestinal- and anal cancer. (Cantor, 1980) 11.7 Disinfection byproducts are non-carcinogenic according to World Health Organization (WHO) In 1991 the WHO's International Agency for Research on Cancer (IARC) evaluated the carcinogenic health risk of chlorinated drinking water based on toxicological laboratory studies and human epidemical researches. This study showed that it is hard to find a relation between the development of cancer and drinking of chlorinated water. The risk is small and cannot be proved with epidemical evidence. With all researches the estimations of exposure to disinfection byproducts were inaccurate. Furthermore, all kinds of factors are important for developing cancer, for example smoking, food, alcohol, socio-economic status and hereditary predisposition. (Disinfectants and Disinfection Byproducts, WHO,2001) A meta-analysis of several researches shows that there is a positive correlation between exposure to disinfection byproducts in drinking water and human bladder and anal cancer. Nine percent of all cases of bladder cancer and fifteen percent of anal cancer are attributed to chlorinated drinking water and disinfection byproducts. This comes down to 10,000 cases annually. (Morris, 1992) Risk of bladder cancer increases after lengthy exposure to chlorinated drinking water In 1990 and 1991 in Colorado (United States) a population research was carried out on the relation between disinfection of drinking water with chlorine or chloramines and the occurrence of bladder cancer. 327 people with bladder cancer were compared to 261 people suffering from another type of cancer. On the basis of interviews and data of the Health Organization a drinking water exposure profile was created. This study showed that a relation exists between years of exposure to chlorinated drinking water and the development of bladder cancer. This risk increased after more years of exposure. After exposure of thirty years the risk on bladder cancer was 1.8 times bigger than when no exposure had occurred. The concentration trihalomethanes, nitrate and residual chlorine were not associated with the risk on bladder cancer. (McGeehin, 1993) Chapter 11 60

7 Fourteen to sixteen percent of bladder cancer cases is caused by disinfection byproducts Research on lengthy exposure to disinfection byproducts in drinking water and the occurrence of bladder cancer carried out in Ontario (Canada) shows that there is a relation between lengthy exposure to disinfection byproducts and the risk on bladder cancer. The risk increased after lengthy exposure and trihalomethane concentrations of 50 g/l or more. Fourteen to sixteen percent of all bladder cancer cases can be attributed to exposure to disinfection byproducts. (King, 1996) Connection between exposure to disinfection byproducts and bladder cancer In Finland research is carried out on the connection of lengthy exposure to mutagenic and carcinogenic substances in drinking water and cancer. For this study the exposure of 732 bladder cancer patients, 703 renal cancer patients and 914 other people to drinking water was determined on data on residence, water sources and historical data on water quality and water treatment. For men there was a relation between exposure and the risk on renal cancer. For women this relation was non-significant. For both men and women the connection between exposure and bladder cancer was significant. (Koivusalo, 1998) Risk of bladder cancer is im portant because of the large am ount of people exposed to chlorinated drinking water A comparison of different studies to individual consumption of chlorinated drinking water and the association of bladder cancer shows there is a connection between lengthy exposure to chlorinated drinking water and bladder cancer. This risk increases after exposure for many years. This risk is not very big, but because many people are exposed to chlorinated drinking water for many years, this risk is significant because cases of bladder cancer can be attributed to disinfection byproducts. (Kogevinas, 2003) Risk of intestinal cancer due to the formation of disinfection byproducts Research on the connection of intestinal cancer and disinfection byproducts in drinking water show that there is an elevated risk on intestinal cancer when chlorinated drinking water is used. Marret and King examined 5000 people in Ontario (Canada), of which 950 were bladder-, intestinal or anal cancer. Data on the concentration of trihalomethanes in water were used. Other factors, including eating habits were investigated as well. This study proved that people who were exposed to concentrations of 50 g/l or more had 1.5 times bigger risk to develop intestinal cancer. (Marret en King, 1995). Too little evidence on elevated risk of intestinal cancer In 1998 a study was carried out on 685 intestinal cancer patients in Iowa (Canada) people suffering from another form of cancer were used as a control group. The concentration of trihalomethanes in drinking water were estimated. These estimations were adjusted on basis of other factors. This study showed no elevated risk on intestinal cancer. The different result of these studies can be a coincidence or be caused by another composition of the drinking water or other factors. In this study there is too little evidence for a relation between exposure to disinfection byproducts and an elevated risk on intestinal cancer. (Mills, 1998) Chapter 11 61

8 Disinfect ion byproduct s elevate t he risk of anal cancer aft er long-period exposure to chlorinated drinking water A study carried out in Iowa (USA) in 1986 and 1989 with data from intestinal and anal cancer patients shows there is no elevated risk on intestinal cancer after long time exposure to chlorinated drinking water or trihalomethanes. For anal cancer there is an elevated risk however. This risk is even bigger for people who eat little fibrous food. A lack of physical exercise also elevates the risk on anal cancer. (Hildesheim, 1998) 11.9 Influence of disinfection byproducts on the reproduction and development of humans Most attention on health effects of disinfection byproducts is on cancer caused by lengthy exposure to disinfection byproducts in drinking water. Standards that are being used for permitted concentrations of disinfection byproducts are based on carcinogenic abilities of these substances. (Singer, 1999) Connection between effects on laboratory animals and humans Laboratory tests with animals show that exposure to disinfection byproducts during pregnancy influence reproduction and development and induce birthdefects and spontaneous abortion. With humans these effects have been investigated with population data on drinking water quality, water treatment and birth data. The concentrations disinfection byproducts that cause these effects are in most cases many times bigger than concentrations that can cause cancer after lengthy exposure. To regulate disinfection byproducts in drinking water all potential health effects have to be considered. (Singer, 1999) Research of the effects on reproduction and development of humans The number of epidemiological studies on exposure to disinfection byproducts and the influence on reproduction and birth defects is small. However, these studies show there is a connection between exposure to trihalomethanes and spontaneous abortion, birth defects and growth delay. (Wigle, 1998) Relation bet w een chlorine dioxide byproduct s, low birt h-weight and premature birth To prevent the formation of chlorinated carcinogenic disinfection byproducts, other disinfectants are used. These disinfectants also produce disinfection byproducts that can be harmful for human health. Chlorine dioxide for example produces disinfection byproducts chlorite and chlorate, which have health effects on vulnerable people as newborn babies. Disease and death rates of newborns in two communities were studied. In one community water was disinfected with chlorine, the other used water disinfected with chlorine dioxide. The relation between exposure to water treated with chlorine dioxide of the mother during pregnancy, premature birth and a low birth weight was significant. There was no difference in the number of birth defects and still births. (Tuthill, R. 1982) Exposure rate to be determined more adequately On the basis of available epidemiological data research has been carried out on the relation between disinfection byproducts in drinking water and effects on Chapter 11 62

9 reproduction and development. The epidemiological evidence on a relation between exposure to disinfection byproducts and development is weak. If a connection is found, one has to be careful in drawing any conclusions. The research methods being used are very diverse and it is difficult to compare results. Future studies have to use enhanced methods to determine exposure. This can be achieved by using exposure markers and taking seasonal and annual differences in concentrations of disinfection byproducts through different transmission routes into account. Furthermore population research is required to determine male and female fertility, growth delay and specific birth defects. (Reif, 1996) Connect ion bet w een exposure to chlorinat ed drinking w at er and low birth weight A research was carried out on exposure during pregnancy to chlorinated drinking water with a high amount of natural organic matter and non-chlorinated drinking water with a small amount of natural organic matter. Birth data from 137,145 Norwegian births between 1993 and 1995 were used. The study showed no connection between exposure to chlorinated drinking water and a risk for low birth weight and small body length. The risk on premature birth was slightly smaller with exposure to chlorinated drinking water than non-chlorinated drinking water. (Jaakkola, 2001) Risk of birt h defect s aft er exposure t o disinfect ion byproducts in drinking water In Norway a research was carried out on the relation between specific birth defects and the occurrence of natural organic matter and disinfection byproducts in drinking water. Birth data from 285,631 births in Norway from were used. The risk on birth-defects and more specific heart-, breathing and urine tract defects were associated with exposure to disinfection byproduct during pregnancy. The risk on abdominal wall defects increases significantly after higher exposure. (Bing-Fang, 2002) Effect s of exposure to t rihalom ethanes in drinking w at er on foetal development Data from 56,513 births in Massachusetts (USA) in 1990 were used to investigate the effect of exposure to trihalomethanes in drinking water on foetal development. Exposure causes a low birth weight and small body length, also known as foetal growth delay. Comparison of trihalomethane concentration show that 80µ g/l or more lower the birth weight with 32 gram. No evidence was found on exposure to trihalomethanes and premature birth. (Wright, 2003) Evidence for an influence of disinfect ion byproduct s on reproduction For this research the epidemiological and toxicological evidence of studies on effects of disinfection byproducts on reproduction were weighed. There was too little evidence on a relation between exposure to disinfection byproducts in drinking water during pregnancy and effects on foetal development. Effects that were investigated were birth weight, premature delivery, some congenital defects and early death of the newborn. There was little evidence for defects on the central nervous system, spinal cord, spontaneous abortion and stillbirth. There was sufficient evidence for a relation between growth delay, and defects on urine tracts and exposure to disinfection byproducts. The epidemiological research that Chapter 11 63

10 has been carried out so far is in-efficient in proving a connection between disinfection byproducts and reproduction effects. To see if there is an evidence the true amount of water and disinfection byproducts that women consume has to be measured. (Graves, 2001) Other scientists reached this same conclusion. (Nieuwenhuijsen, 2000) Measurable risk of environmental pollutions on birth defects Research on the development of birth defects as a result of exposure to chemical environmental pollutions (drinking water pollutions, pesticides, waste, industrial pollutions, food pollutions and disasters with a large emission of chemical pollutions) show that it very difficult to determine the potential risk for birth defects caused by exposure to environmental pollutions. To prevent birth defects exposure to all chemical environmental pollutions should be prevented. (Dolk, 2003) Relat ion betw een exposure t o brom odichlorm et hane, chloroform and birth defects On the basis of birth data of births in Nova Scotia (Canada) from 1988 to 1995 and results of water monitoring tests research has been carried out on birth effects of bromodichlormethane and chloroform. Exposure during pregnancy to bromodichloromethane concentrations of 20 or more µg/l were associated with an elevated risk on defects on the neural tube. Exposure to chloroform points out to an elevated risk of chromosomal defects. The results of this study show that research on the relation between specific disinfection byproducts and birth defects is needed. (Dodds, 2001) Relat ion betw een exposure t o t rihalom et hanes and chlorine dioxide and birth defects In 2001 in Sweden a research was carried out on the relation between heart- and artery defects in children and trihalomethane concentrations in drinking water before and during pregnancy. 753 out of 59,422 children suffered from heart and artery defects. The risk on these effects was elevated when both chlorine dioxide and hypochlorite were used. This risk was more high than when solely hypochlorite was used. Chlorine dioxide seems to increase the risk on heart and artery defects. This can also be caused by the composition of the water, which might have been more polluted. All water investigated had trihalomethane levels lower than the standard levels. This points out that even below these concentrations effects on reproduction take place. (Cedergren, 2001) I nfluence of physical param et ers on chlorine dioxide or hypochlorite disinfectants In Italy research was carried out on physical parameters at birth and the relation with drinking water disinfected with chlorine dioxide or hypochlorite. This research was done because of earlier publications on birth effects of disinfectants and disinfection byproducts. Data of 548 women from Genua (Italy) giving birth from 1988 or 1989 and using water disinfected with sodium hypochlorite or chlorine dioxide were used. Data from 128 women from nearby Chiavari, were used as a control group. Their drinking water was not disinfected. Other factors influencing birth-defects were also investigated. There was a relation between drinking water disinfected with chlorine dioxide and small body length and cranial span. A hypothesis for this result is that the immunity of women exposed to chlorine dioxide is decreased. (Kanitz, 1996) Chapter 11 64

11 The outcome of this study can be questioned, because most Italians use bottled water, which is disinfected with ozone. The chlorine dioxide, chlorite and chlorate concentration has not been measured, and no dose-effect relationship can be established Reliability on the studies of reproduction effects The results of these studies show that there is probably a relation between exposure to (chlorinated) disinfection byproducts before and during pregnancy and birth-defects. A low birth weight and growth delay are mostly found. The evidence for spontaneous abortion, birth-defects and still-birth is not very consequent. The evidence is not strong enough to show a dose effect relation. This can be caused by research methods and techniques being used Implications of new studies The amount of water that women use has to measured. Then the concentration disinfection byproducts can be determined more accurately. It would even be better to determine the concentration disinfection byproducts from the tap. The composition and concentration of disinfection byproducts can be changed under influence of ph, temperature and contact time in water distribution network compared to the concentration and composition at the water company. It is not clear yet whether all disinfection byproducts cause health effects and whether their effects differ. Further research is required. Other factors, like smoking and exposure to environmental pollutions have to be investigated as well Recom m endat ions m ade for future research on healt h risks of disinfection byproducts in drinking water The microbiological quality of drinking water should be maintained while preventing the formation of disinfection byproducts. Efficient disinfection is preferred. Health risks of disinfection byproducts are small compared to health risks of waterborne diseases. This is proven by the cholera-epidemic that occurred in Peru in This epidemic was caused by inadequate drinking water disinfection. Worldwide attention for disinfection byproducts and the great number of scientific articles on disinfection byproducts caused many drinking water suppliers in South-America to stop drinking water chlorination. The acute health risk of pathogenic micro-organisms in drinking water is much higher, about to times higher than the risk of long-term exposure to disinfection byproducts. The cholera-epidemic spread to all 19 South-American countries and caused patients and deaths. (WHO, 1994) Health risks of disinfection byproducts are very low at concentrations found in drinking water. Nevertheless these risks can not be ignored, because of the large number of people exposed to disinfection byproducts. There are still a lot of disinfection byproducts that must be identified. Health risks must be researched, as well. The effects of mixtures of disinfection byproducts must be researched. Some disinfection byproducts may be mutagenic and must be researched, as well Methods to be used to control disinfection byproducts Changing the point of disinfectant application, using an alternative disinfectant, removing natural organic matter that produces disinfection byproducts in combination with disinfectants and removal of disinfection byproducts after disinfection can be used to control disinfection byproducts. Chapter 11 65

12 In general it is best to remove as much organic matter as possible from water, before disinfection is applied. This can be achieved with existing water treatment techniques. Coagulation is used to remove particles and turbidity. Active coal can be used to absorb organic substances. Membranes can be applied to remove organic matter from water. Alternative disinfectants, for example ozone, chlorine dioxide, potassium permanganate and chloramines can also be used to prevent the formation of disinfection byproducts. However all disinfectants produce disinfection byproducts. Chlorinated disinfection byproducts are researched more thoroughly than other byproducts. (Singer, 1999) Standards for disinfection byproducts Some disinfection byproducts are considered harmful for public health (chloroform, dibromochloromethane and bromoform are probably carcinogenic and dichlorobromomethane, dichloroacetonitrile and chloral hydrates are possibly carcinogenic). Health institutions worldwide have set standards for the maximum concentration of disinfection byproducts in drinking water. EU In the European Drinking Water Directive 98/83/EC (1998) the maximum standard for trihalomethanes is set to 100 g/l. If possible countries should strive for lower concentrations. WHO The WHO describes separate standards for three trihalomethanes: - bromodichloromethane (BDCM) 60 g/l - bromoform 100 g/l - chloroform 200 g/l. USA The EPA is concerned with regulation on disinfection byproducts in the United States since In 1996 the Safe Drinking Water Act was revised and the Congress asked EPA to set new standards for disinfectants and disinfection byproducts. This revision aims at lowering the health risk of disinfection byproducts, while protecting microbiological quality of the water. In 1998, EPA promulgated the Stage 1 Disinfectants and Disinfection Byproducts Rule. The standard on total trihalomethane concentration is 80 g/l and for halogenated acidic acid 60 g/l. The guideline also states that advanced coagulation must be used to remove organic matter. (EPA, 2001) Chapter 11 66

13 Table WHO's Guidelines for Drinking-water Quality, set up in Geneva, 1993, are the international reference point for standard setting and drinking-water safety. Element/ substance Symbol/ formula Normally found in fresh water/surface water/ground water Health based guideline by the WHO Aluminium Al 0,2 mg/l Ammonia NH 4 < 0,2 mg/l (up to 0,3 mg/l in No guideline anaerobic waters) Antimony Sb < 4 g/l mg/l Arsenic As 0,01 mg/l Asbestos No guideline Barium Ba 0,3 mg/l Berillium Be < 1 g/l No guideline Boron B < 1 mg/l 0,3 mg/l Cadmium Cd < 1 g/l 0,003 mg/l Chloride Cl 250 mg/l Chromium Cr +3, Cr +6 < 2 g/l 0,05 mg/l Colour Not mentioned Copper Cu 2 mg/l Cyanide CN - 0,07 mg/l Dissolved oxygen O 2 No guideline Fluoride F < 1,5 mg/l (up to 10) 1,5 mg/l Hardness mg/l CaCO 3 No guideline Hydrogen sulfide H 2 S No guideline Iron Fe 0,5-50 mg/l No guideline Lead Pb 0,01 mg/l Manganese Mn 0,5 mg/l Mercury Hg < 0,5 g/l 0,001 mg/l Molybdenum Mb < 0,01 mg/l 0,07 mg/l Nickel Ni < 0,02 mg/l 0,02 mg/l Nitrate and nitrite NO 3, NO 2 50 mg/l total nitrogen Turbidity Not mentioned ph No guideline Selenium Se < < 0,01 mg/l 0,01 mg/l Silver Ag 5 50 g/l No guideline Sodium Na < 20 mg/l 200 mg/l Sulfate SO mg/l Inorganic tin Sn No guideline TDS No guideline Uranium U 1,4 mg/l Zinc Zn 3 mg/l Chapter 11 67

14 Organic compounds Group Substance Formula Health based guideline by the Chlorinated alkanes Chlorinated ethenes Aromatic hydrocarbons Chlorinated benzenes Miscellaneous organic constituents WHO Carbon tetrachloride C Cl 4 2 g/l Dichloromethane C H 2 Cl 2 20 g/l 1,1-Dichloroethane C 2 H 4 Cl 2 No guideline 1,2-Dichloroethane Cl CH 2 CH 2 Cl 30 g/l 1,1,1-Trichloroethane CH 3 C Cl g/l 1,1-Dichloroethene C 2 H 2 Cl 2 30 g/l 1,2-Dichloroethene C 2 H 2 Cl 2 50 g/l Trichloroethene C 2 H Cl 3 70 g/l Tetrachloroethene C 2 Cl 4 40 g/l Benzene C 6 H 6 10 g/l Toluene C 7 H g/l Xylenes C 8 H g/l Ethylbenzene C 8 H g/l Styrene C 8 H 8 20 g/l Polynuclear Aromatic Hydrocarbons (PAHs) C 2 H 3 N 1 O 5 P g/l Monochlorobenzene (MCB) C 6 H 5 Cl 300 g/l Dichlorobenzenes (DCBs) 1,2- Dichlorobenzene (1,2-DCB) 1,3- Dichlorobenzene (1,3-DCB) 1,4- Dichlorobenzene (1,4-DCB) C 6 H 4 Cl 2 C 6 H 4 Cl 2 C 6 H 4 Cl g/l No guideline 300 g/l Trichlorobenzenes (TCBs) C 6 H 3 Cl 3 20 g/l Di(2-ethylhexyl)adipate (DEHA) C 22 H 42 O 4 80 g/l Di(2-ethylhexyl)phthalate (DEHP) C 24 H 38 O 4 8 g/l Acrylamide C 3 H 5 N O 0.5 g/l Epichlorohydrin (ECH) C 3 H 5 Cl O 0.4 g/l Hexachlorobutadiene (HCBD) C 4 Cl g/l Ethylenediaminetetraacetic acid (EDTA) C 10 H 12 N 2 O g/l Nitrilotriacetic acid (NTA) N(CH 2 COOH) g/l Organotins Dialkyltins R 2 Sn X 2 No guideline Tributil oxide (TBTO) C 24 H 54 O Sn 2 2 g/l Chapter 11 68

15 Pesticides Substance Formula Health based guideline by the WHO Alachlor C 14 H 20 Cl N O 2 20 g/l Aldicarb C 7 H 14 N 2 O 4 S 10 g/l Aldrin and dieldrin C 12 H 8 Cl 6 / 0.03 g/l C 12 H 8 Cl 6 O Atrazine C 8 H 14 Cl N 5 2 g/l Bentazone C 10 H 12 N 2 O 3 S 30 g/l Carbofuran C 12 H 15 N O 3 5 g/l Chlordane C 10 H 6 Cl g/l Chlorotoluron C 10 H 13 Cl N 2 O 30 g/l DDT C 14 H 9 Cl 5 2 g/l 1,2-Dibromo-3-chloropropane C 3 H 5 Br 2 Cl 1 g/l 2,4-Dichlorophenoxyacetic acid (2,4-D) C 8 H 6 Cl 2 O 3 30 g/l 1,2-Dichloropropane C 3 H 6 Cl 2 No guideline 1,3-Dichloropropane C 3 H 6 Cl 2 20 g/l 1,3-Dichloropropene CH 3 CHClCH 2 Cl No guideline Ethylene dibromide (EDB) Br CH 2 CH 2 Br No guideline Heptachlor and heptachlor epoxide C 10 H 5 Cl g/l Hexachlorobenzene (HCB) C 10 H 5 Cl 7 O 1 g/l Isoproturon C 12 H 18 N 2 O 9 g/l Lindane C 6 H 6 Cl 6 2 g/l MCPA C 9 H 9 Cl O 3 2 g/l Methoxychlor (C 6 H 4 OCH 3 ) 2 CHCCl 3 20 g/l Metolachlor C 15 H 22 Cl N O 2 10 g/l Molinate C 9 H 17 N O S 6 g/l Pendimethalin C 13 H 19 O 4 N 3 20 g/l Pentachlorophenol (PCP) C 6 H Cl 5 O 9 g/l Permethrin C 21 H 20 Cl 2 O 3 20 g/l Propanil C 9 H 9 Cl 2 N O 20 g/l Pyridate C 19 H 23 ClN 2 O 2 S 100 g/l Simazine C 7 H 12 Cl N 5 2 g/l Trifluralin C 13 H 16 F 3 N 3 O 4 20 g/l Chlorophenoxy herbicides 2,4-DB C 10 H 10 Cl 2 O 3 90 g/l (excluding 2,4-D and MCPA) Dichlorprop C 9 H 8 Cl g/l Fenoprop C 9 H 7 Cl 3 O 3 9 g/l MCPB C 11 H 13 Cl O 3 No guideline Mecoprop C 10 H 11 ClO 3 10 g/l 2,4,5-T C 8 H 5 Cl 3 O 3 9 g/l Chapter 11 69

16 Disinfectants and disinfectant by- products Group Substance Formula Health based guideline by the WHO Disinfectants Chloramines NH n Cl (3-n), 3 mg/l where n = 0, 1 or 2 Chlorine Cl 2 5 mg/l Disinfectant by-products Chlorine dioxide ClO 2 No guideline Iodine I 2 No guideline Bromate - Br O 3 25 g/l Chlorate - Cl O 3 No guideline Chlorite - Cl O g/l Chlorophenols 2-Chlorophenol (2-CP) C 6 H 5 Cl O No guideline 2,4-Dichlorophenol (2,4- DCP) C 6 H 4 Cl 2 O No guideline 2,4,6-Trichlorophenol C 6 H 3 Cl 3 O 200 g/l (2,4,6-TCP) Formaldehyde HCHO 900 g/l MX (3-Chloro-4-dichloromethyl-5-hydroxy- C 5 H 3 Cl 3 O 3 No guideline 2(5H)-furanone) Trihalomethanes Bromoform C H Br g/l Chlorinated acetic acids Dibromochloromethane CH Br 2 Cl 100 g/l Bromodichloromethane CH Br Cl 2 60 g/l Chloroform CH Cl g/l Monochloroacetic acid C 2 H 3 Cl O 2 No guideline Dichloroacetic acid C 2 H 2 Cl 2 O 2 50 g/l Trichloroacetic acid C 2 H Cl 3 O g/l Chloral hydrate (trichloroacetaldehyde) C Cl 3 10 g/l CH(OH) 2 Chloroacetones C 3 H 5 O Cl No guideline Halogenated acetonitriles Dichloroacetonitrile C 2 H Cl 2 N 90 g/l Dibromoacetonitrile C 2 H Br 2 N 100 g/l BromochloroacetonitrileCH Cl 2 CN No guideline Trichloroacetonitrile C 2 Cl 3 N 1 g/l Cyanogen chloride Cl CN 70 g/l Chloropicrin C Cl 3 NO 2 No guideline Chapter 11 70

17 The EU standards are more recent (1998), complete and strict than the WHO standards (1993). Some examples are: - Bromate (Br): Not mentioned by the WHO, 0.01 mg/l guideline in the EU standards. - Manganese (Mn): Guideline reduced from 0.5 to 0.05 mg/l. - Cyanide (CN): Guideline reduced from 0.07 to mg/l. But in some cases the EU guidelines are less strict than the WHO guidelines. - Cadmium (Cd): Guideline value increased from to mg/l. Following Table provides a comparison of WHO standards with EU standards, for both dissolved chemicals and microorganisms: Table 11.3 WHO/EU drinking water standards comparative table WHO standards EU standards Suspended solids No guideline Not mentioned COD No guideline Not mentioned BOD No guideline Not mentioned Oxidisability 5.0 mg/l O2 Grease/oil No guideline Not mentioned Turbidity No guideline (1) Not mentioned ph No guideline (2) Not mentioned Conductivity 250 micros/cm 250 micros/cm Color No guideline (3) Not mentioned Dissolved oxygen No guideline (4) Not mentioned Hardness No guideline (5) Not mentioned TDS No guideline Not mentioned cations (positive ions) Aluminium (Al) 0.2 mg/l 0.2 mg/l Ammonia (NH4) No guideline 0.50 mg/l Antimony (Sb) mg/l mg/l Arsenic (As) 0.01 mg/l 0.01 mg/l Barium (Ba) 0.3 mg/l Not mentioned Berillium (Be) No guideline Not mentioned Boron (B) 0.3 mg/l 1.00 mg/l Bromate (Br) Not mentioned 0.01 mg/l Cadmium (Cd) mg/l mg/l Chromium (Cr) 0.05 mg/l 0.05 mg/l Copper (Cu) 2 mg/l 2.0 mg/l Iron (Fe) No guideline (6) 0.2 Lead (Pb) 0.01 mg/l 0.01 mg/l Manganese (Mn) 0.5 mg/l 0.05 mg/l Mercury (Hg) mg/l mg/l Molibdenum (Mo) 0.07 mg/l Not mentioned Nickel (Ni) 0.02 mg/l 0.02 mg/l Nitrogen (total N) 50 mg/l Not mentioned Chapter 11 71

18 Selenium (Se) 0.01 mg/l 0.01 mg/l Silver (Ag) No guideline Not mentioned Sodium (Na) 200 mg/l 200 mg/l Tin (Sn) inorganic No guideline Not mentioned Uranium (U) 1.4 mg/l Not mentioned Zinc (Zn) 3 mg/l Not mentioned anions (negative ions) Chloride (Cl) 250 mg/l 250 mg/l Cyanide (CN) 0.07 mg/l 0.05 mg/l Fluoride (F) 1.5 mg/l 1.5 mg/l Sulfate (SO4) 500 mg/l 250 mg/l Nitrate (NO3) (See Nitrogen) 50 mg/l Nitrite (NO2) (See Nitrogen) 0.50 mg/l microbiological parameters Escherichia coli Not mentioned 0 in 250 ml Enterococci Not mentioned 0 in 250 ml Pseudomonas aeruginosa Not mentioned 0 in 250 ml Clostridium perfringens Not mentioned 0 in 100 ml Coliform bacteria Not mentioned 0 in 100 ml Colony count 22oC Not mentioned 100/ml Colony count 37oC Not mentioned 20/ml other parameters Acrylamide Not mentioned mg/l Benzene (C6H6) Not mentioned mg/l Benzo(a)pyrene Not mentioned mg/l Chlorine dioxide (ClO2) 0.4 mg/l 1,2-dichloroethane Not mentioned mg/l Epichlorohydrin Not mentioned mg/l Pesticides Not mentioned mg/l Pesticides - Total Not mentioned mg/l PAHs Not mentioned mg/l Tetrachloroethene Not mentioned 0.01 mg/l Trichloroethene Not mentioned 0.01 mg/l Trihalomethanes Not mentioned 0.1 mg/l Tritium (H3) Not mentioned 100 Bq/l Vinyl chloride Not mentioned mg/l (1) Desirable: Less than 5 NTU (2) Desirable: (3) Desirable: 15 mg/l Pt-Co (4) Desirable: less than 75% of the saturation concentration (5) Desirable: mg/l (6) Desirable: 0.3 mg/l Chapter 11 72