Appendix 2 World Health Organization Drinking Water Guidelines

Transcription

1 Appendix 2 World Health Organization Drinking Water s The following tables present the most recent (2004) World Health Organization drinking water guidelines (for those parameters for which guideline values have been established). The guidelines are updated periodically by the WHO, and the reader should always consult the most up to date set of guidelines. Table A2.1 Organisms values for verification of microbial quality a value All water directly intended for drinking E. coli or thermotolerant coliform bacteria b,c Must not be detectable in any 100-ml sample Treated water entering the distribution system E. coli or thermotolerant coliform bacteria b Must not be detectable in any 100-ml sample Treated water in the distribution system E. coli or thermotolerant coliform bacteria b Must not be detectable in any 100-ml sample a Immediate investigative action must be taken if E. coli are detected. b Although E. coli is the more precise indicator of faecal pollution, the count of thermotolerant coliform bacteria is an acceptable alternative. If necessary, proper confirmatory tests must be carried out. Total coliform bacteria are not acceptable indicators of the sanitary quality of water supplies, particularly in tropical areas, where many bacteria of no sanitary significance occur in almost all untreated supplies. c It is recognized that in the great majority of rural water supplies, especially in developing countries, faecal contamination is widespread. Especially under these conditions, medium-term targets for the progressive improvement of water supplies should be set. Water Wells and Boreholes B. Misstear, D. Banks and L. Clark # 2006 John Wiley & Sons, Ltd. ISBN:

2 Table A2.2 values for naturally occurring chemicals that are of health significance in drinking-water value a Chemical (mg l 1 ) Remarks Arsenic 0.01 (P) Barium 0.7 Boron 0.5 (T) Chromium 0.05 (P) For total chromium Fluoride 1.5 Volume of water consumed and intake from other sources should be considered when setting national standards Manganese 0.4 (C) Molybdenum 0.07 Selenium 0.01 Uranium (P,T) Only chemical aspects of uranium addressed limited; T, provisional guideline value because calculated guideline value is below the level that can be achieved through practical treatment methods, source protection, etc.; C, concentrations of the substance at or below the healthbased guideline value may affect the appearance, taste or odour of the water, resulting in consumer complaints. Table A2.3 values for chemicals from industrial sources and human dwellings that are of health significance in drinking-water value Inorganics (mg l 1 ) Remarks Cadmium Cyanide 0.07 Mercury For total mercury (inorganic plus organic) value a Organics (mgl 1 ) Remarks Benzene 10 b Carbon tetrachloride 4 Di(2-ethylhexyl)phthalate 8 Dichlorobenzene, 1, (C) Dichlorobenzene, 1,4-300 (C) Dichloroethane, 1,2-30 b Dichloroethene, 1,1-30 Dichloroethene, 1,2-50 Dichloromethane 20 Edetic acid (EDTA) 600 Applies to the free acid Ethylbenzene 300 (C) Hexachlorobutadiene 0.6 Nitrilotriacetic acid (NTA) 200 Pentachlorophenol 9 b (P) Styrene 20 (C) Tetrachloroethene 40 Toluene 700 (C) Trichloroethene 70 (P) Xylenes 500 (C) limited; C, concentrations of the substance at or below the health-based guideline value may affect the appearance, taste or odour of the water, leading to consumer complaints. b For non-threshold substances, the guideline value is the concentration in drinking-water associated with an upper-bound excess lifetime cancer risk of 10 5 (one additional cancer per of the population ingesting drinking-water containing the substance at the guideline value for 70 years). Concentrations associated with estimated upper-bound excess lifetime cancer risks of 10 4 and 10 6 can be calculated by multiplying and dividing, respectively, the guideline value by 10.

3 Table A2.4 values for chemicals from agricultural activities that are of health significance in drinking-water value a Non-pesticides (mg l 1 ) Remarks Nitrate (as NO 3 ) 50 Short-term exposure Nitrite (as NO 2 ) 3 Short-term exposure 0.2 (P) Long-term exposure Pesticides used value a in agriculture (mgl 1 ) Remarks Appendix Alachlor 20 b Aldicarb 10 Applies to aldicarb sulfoxide and aldicarb sulfone Aldrin and dieldrin 0.03 For combined aldrin plus dieldrin Atrazine 2 Carbofuran 7 Chlordane 0.2 Chlorotoluron 30 Cyanazine 0.6 2,4-D 30 Applies to free acid (2,4-dichlorophenoxyacetic acid) 2,4-DB 90 1,2-Dibromo-3-chloropropane 1 b 1,2-Dibromoethane 0.4 b (P) 1,2-Dichloropropane (1,2-DCP) 40 (P) 1,3-Dichloropropene 20 b Dichlorprop 100 Dimethoate 6 Endrin 0.6 Fenoprop 9 Isoproturon 9 Lindane 2 MCPA 2 Mecoprop 10 Methoxychlor 20 Metolachlor 10 Molinate 6 Pendimethalin 20 Simazine 2 2,4,5-T 9 Terbuthylazine 7 Trifluralin 20 limited. b For substances that are considered to be carcinogenic, the guideline value is the concentration in drinking-water associated with an upper-bound excess lifetime cancer risk of 10 5 (one additional cancer per of the population ingesting drinking-water containing the substance at the guideline value for 70 years). Concentrations associated with estimated upper-bound excess lifetime cancer risks of 10 4 and 10 6 can be calculated by multiplying and dividing, respectively, the guideline value by 10.

4 466 Water Wells and Boreholes Table A2.5 values for chemicals used in water treatment or materials in contact with drinking-water that are of health significance in drinking-water Disinfectants value a (mg l 1 ) Remarks Chlorine 5 (C) For effective disinfection, there should be a residual concentration of free chlorine of 0:5 mgl 1 after at least 30 min contact time at ph <8.0 Monochloramine 3 Disinfection by-products value a (mgl 1 ) Remarks Bromate 10 b (A,T) Bromodichloromethane 60 b Bromoform 100 Chloral hydrate 10 (P) (trichloroacetaldehyde) Chlorate 700 (D) Chlorite 700 (D) Chloroform 200 Cyanogen chloride 70 For cyanide as total cyanogenic compounds Dibromoacetonitrile 70 Dibromochloromethane 100 Dichloroacetate 50 (T,D) Dichloroacetonitrile 20 (P) Formaldehyde 900 Monochloroacetate 20 Trichloroacetate 200 Trichlorophenol, 2,4,6-200 b (C) Trihalomethanes The sum of the ratio of the concentration of each to its respective guideline value should not exceed 1 Contaminants from treatment chemicals value a (mgl 1 ) Remarks Acrylamide 0.5 b Epichlorohydrin 0.4 (P) Contaminants from pipes and fittings value a (mgl 1 ) Remarks Antimony 20 Benzo[a]pyrene 0.7 b Copper 2000 Staining of laundry and sanitary ware may occur below guideline value Lead 10 Nickel 20 (P) Vinyl chloride 0.3 b limited; A, provisional guideline value because calculated guideline value is below the practical quantification level; T, provisional guideline value because calculated guideline value is below the level that can be achieved through practical treatment methods, source control, etc.; D, provisional guideline value because disinfection is likely to result in the guideline value being exceeded; C, concentrations of the substance at or below the health-based guideline value may affect the appearance, taste or odour of the water, causing consumer complaints. b For substances that are considered to be carcinogenic, the guideline value is the concentration in drinking-water associated with an upper-bound excess lifetime cancer risk of 10 5 (one additional cancer per of the population ingesting drinking-water containing the substance at the guideline value for 70 years). Concentrations associated with estimated upper-bound excess lifetime cancer risks of 10 4 and 10 6 can be calculated by multiplying and dividing, respectively, the guideline value by 10.

5 Table A2.6 values for pesticides used in water for public health purposes that are of health significance in drinking-water Pesticides used in water for public health purposes a value (mgl 1 ) Chlorpyrifos 30 DDT and metabolites 1 Pyriproxyfen 300 From World Health Organization (2004), reproduced by permission of the World Health Organization. a Only pyriproxyfen is recommended by WHOPES for addition to water for public health purposes. Appendix Table A2.7 values for cyanotoxins that are of health significance in drinking-water value a (mgl 1 ) Remarks For total microcystin-lr Microcystin-LR 1 (P) (free plus cell-bound) From World Health Organization (2004), reproduced by permission of the World Health Organization. a P, provisional guideline value, as there is evidence of a hazard, but the available information on health effects is limited. Table A2.8 Guidance levels for radionuclides in drinking-water Guidance Guidance Guidance level level level Radionuclides (Bq l 1 ) a Radionuclides (Bq l 1 ) a Radionuclides (Bq l 1 ) a 3 H Be C Na P P S Cl Ca Ca Sc Sc Sc V Cr Mn Mn Mn Fe Fe Mo Mo Tc Tc m Tc Tc Ru Ru Ru Rh Pd Ag m Ag Ag Cd Cd m Cd In m In Sn La Ce Ce Ce Ce Pr Nd Pm Pm Sm Sm Eu Eu Eu Gd Tb Er Tm Yb Ta 100 (Continued )

6 468 Water Wells and Boreholes Table A2.8 (Continued ) Guidance Guidance Guidance level level level Radionuclides (Bq l 1 ) a Radionuclides (Bq l 1 ) a Radionuclides (Bq l 1 ) a 56 Co Co Co Co Ni Ni Zn Ge As As As As Se Br Rb Sr Sr Sr Y Y Zr Zr m Nb Nb Nb Ra b Ra Ra b Ra b Th b Th b Th Th b Th b Th b Th b Pa Pa b Pa U U U U U b Sn Sb Sb Sb m Te Te m Te Te m Te Te m Te Te I I I I Cs Cs Cs Cs Cs Cs Cs Ba Ba U b U b U U b,c Np Np Pu Pu Pu Pu Pu Pu Pu Pu Am Am m Am Am W W Re Os Os Os Ir Ir Pt m Pt Au Au Hg Hg Tl Tl Tl Tl Pb Bi Bi Bi b Pb b Po b Ra b Cm Cm Cm Cm Cm Cm Cm Bk Cf Cf Cf Cf Cf Cf Cf Cf Es Es m Es 100 a Guidance levels are rounded according to averaging the log scale values (to 10 n if the calculated value was below 3 10 n and above 3 10 n 1 ). b Natural radionuclides. c The provisional guideline value for uranium in drinking-water is 15 mgl 1 based on its chemical toxicity for the kidney.