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Disinfection Byproducts in Drinking Water and Human Health

Disinfection Byproducts in Drinking Water and Human Health

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Disinfection Byproducts in Drinking Water and Human Health

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  1. Disinfection Byproducts in Drinking Water and Human Health Dave Reckhow University of Massachusetts - Amherst 2009 GRC on Water Disinfection By-Products

  2. Outline • DBP Discovery • Complementary approaches • What’s new? • Iodo compounds • N-DBPS • Reactivity of Specific Nitrogenous Constituents • Amino Acids • Amines, Purines& Pyrimidines • Others • What next? Focus on reactions with free chlorine, including comments on other disinfectants Initial products & End products

  3. 2007 John #1: Dr. John Snow 1813-1858 • Cholera • First emerged in early 1800s • 1852-1860: The third cholera pandemic • Snow showed the role of water in disease transmission • London’s Broad Street pump (Broadwick St) • Miasma theory was discredited, but it took decades to fully put it to rest

  4. Soho, Westminster Picadilly Circus

  5. John #2: Dr. John L. Leal • Jersey City’s Boonton Reservoir • Leal experimented with chlorine,its effectiveness and production • George Johnson & George Fuller worked with Leal and designed the system (1908) 1858-1914 “Full-scale and continuous implementation of disinfection for the first time in Jersey City, NJ ignited a disinfection revolution in the United States that reverberated around the world” M.J. McGuire, JAWWA 98(3)123

  6. Leal on chlorine • “the practical application of the use of bleach (chlorine) for the disinfection of water supplies seems to me to be a great advance in the science of water purification. It is so cheap, so easy and quick of application, so certain in its results, and so safe, that it seems to me to cover a broader field than does any other system of water purification yet used.” • John L. Leal, 1909

  7. Chlorination • 1-2 punch of filtration & chlorination Greenberg, 1980, Water Chlorination, Env. Impact & Health Eff., Vol 3, pg.3, Ann Arbor Sci. US Death Rates for Typhoid Fever Melosi, 2000, The Sanitary City, John Hopkins Press

  8. John #3: Johannes J. Rook • Short Biography • Education • PhD in Biochemistry: 1949 • Work experience • Technological Univ., Delft (~‘49-’54) • Laboratory for Microbiology • Lundbeck Pharmaceuticals in Copenhagen, (~’55-?) • Noury Citric acid Factory (in Holland) • Amstel Brewery • Rotterdam Water Works by 1963, chief chemist (1964-1984). • 1984-1986; Visiting Researcher at Lyonnaise des Eaux, Le Pecq. • Early Research • 1955, Microbiological Deterioration of Vulcanized Rubber • Applied Micro. • 1964, secured funds for a GC at Rotterdam • Carlo Erba with gas sample loop

  9. John Rook & DBPs • Major Contributions • Brought headspace analysis from the beer industry to drinking water • T&O problems • Found trihalomethanes (THMs) in finished water • Carcinogens !?! • Published in Dutch journal H2O, Aug 19, 1972 issue • Deduced that they were formed as byproducts of chlorination • Proposed chemical pathways Rook, 1974, Water Treat. & Exam., 23:234

  10. Oxidized NOM • and inorganic chloride • Aldehydes • Chlorinated Organics • TOX • THMs • HAAs The THMs Reactions with Disinfectants: Chlorine The Precursors! HOCl + natural organics (NOM)

  11. The Haloacetic Acids HAA6 only 11 • HAA5 & HAA6 include the two monohaloacetic acids (MCAA & MBAA) plus • One of the trihaloacetic acids: • And 2 or 3 of thedihaloacetic acids

  12. Haloacetonitriles 12 • Others that are commonly measured, but not regulated include the: • Dihalo-acetonitriles • Trihaloacetonitriles

  13. Halopropanones 13 • As well as the: • dihalopropanones • trihalopropanones

  14. Nitrosamines Trihalomethanes Haloacetic Acids Dist. Sys. Cl2 Coagulant Cl2 NH3 Settling Filtration DBPs: Formation in Plant Dave Reckhow, UMass-Amherst

  15. Epidemiology is not supported by Toxicology of known DBPs Epidemiology • Bladder Cancer • DBPs linked to 9,300 US cases every year • Other Cancers • Rectal, colon • Reproductive & developmental effects • Neural tube defects • Miscarriages & Low birth weight • Cleft palate • Other • Kidney & spleen disorders • Immune system problems, neurotoxic effects 137,000 at risk in US?

  16. National Distribution • 241,000,000 people in US are served by PWSs that apply a disinfectant High THMs are levels of at least 80 ppb over a 3 month average Gray et al., 2001 [Consider the Source, Environmental Working Group report]

  17. Hunting for the bad DBPs • Observational/empirical • Multifaceted analysis of treated waters • Companion toxicity testing • Deductive/theoretical • Postulate DBPs from known NOM substructures • Exploit Structure-toxicity models Proven Approach but Labor intensive Fewer Constraints but High Risk Also allows us to probe NOM contributions to regulated DBPs

  18. Stuart Krasner Susan Richardson THMs, THAAs The DBP Iceberg DHAAs ICR Compounds 50 MWDSC DBPs ~700 Known DBPs HalogenatedCompounds Non-halogenatedCompounds

  19. GAC Adsorption Microcoulometric Cell Pyrolysis Oven Total Organic Halogen • Standard Methods; USEPA Method #1650 • Activated Carbon Adsorption & Pyrolysis & Microcoulometric Detection of halide • Extended Method for TOCl, TOBr, TOI • Trap gases & ion chromatography • (e.g., Hua & Reckhow, 2008)

  20. The TOX Pie

  21. TOX Distribution of Newport News Water Hua & Reckhow, 2007

  22. MW Distribution of Unknown TOX Substantial overestimation of MW due to charge effects Hua & Reckhow, 2007

  23. Chlorine & Ozone produce iodate Cambridge MA Water, DOC: 4.2 mg/L, I: 200 mg/L Hua & Reckhow, 2007

  24. Iodinated TOX (TOI) Cambridge MA Water, DOC: 4.2 mg/L, I: 200 mg/L TOI : NH2Cl > ClO2 > Cl2 > O3 Hua & Reckhow, 2007

  25. Regulated DBP as surrogates • EPA’s ICR Database

  26. Organic Chloramines • Stable N-chloroaldimine from amino acids • Pathway favored at lower pHs • Half-life of 35-60 hrs @pH 7-8 Boning Liu PhD student Conyers & Scully, 1993 [ES&T 27:261]

  27. Median C/N ratio (15) TOX pie revised Organic Chloramines

  28. Source: Who is really responsible? or

  29. Watershed Origins Lake Algae Aquifer Sediment & Gravel in Lake Bed

  30. Darleen Bryan’s study Leaching Experiments White Oak White Pine Red Maple

  31. Algae as THM Precursors • From: Plummer & Edzwald, 2001 • [ES&T:35:3661] Scenedesmus quadricauda ~25% from EOM Cyclotella sp. Algae pH 7, 20-24ºC, chlorine excess

  32. Regulated DBP as surrogates • EPA’s ICR Database

  33. Watershed Origins Upper Soil Horizon Lower Soil Horizon Litter Layer Lake Algae Aquifer Sediment & Gravel in Lake Bed 33

  34. Plant biopolymers • Cellulose • Lignin • Phenyl-propane units • Cross-linked • Radical polymerization • Ill defined structure • Hemicellulose • Terpeniods • Proteins

  35. Lignin Monomers • Aromatic structures • from CuO degradation • Syringyl • Vanillyl • Cinnamyl

  36. 4-hydroxy benzenes • Among the most reactive structures tested

  37. Oven method: Hedges and Ertel (1982) 1g CuO, 25-100 mg FAS, 7 mLNaOH 170 oC in oven for 3 hours Microwave method: Goni (1998) 500 mg CuO, 50 mg FAS, 15 ml 2N NaOH 150 oC in microwave for 90 min Alkali CuO oxidation Method

  38. Mining the literature to postulate “new” DBPs • Chlorination of p-hydroxybenzoic acid based on Larson and Rockwell (1979). “A” represents electrophilic aromatic substitution, “B” is oxidative decarboxylation Haloquinones are likely intermediates

  39. PAHA II • Fill in missing steps by analogy • Halohydroxy-dienoic acids • TCAA

  40. Nitrogenous Biopolymers • Why focus on these? • Nitrogenous organics are generally quite reactive • N-DBP formation can be enhanced by chloramination • Some evidence that they are major contributors to adverse human health effects of DBPs • Relatively little is known about N-DBPs • Key suspects • Amino Acids & Proteins • Nucleic Acids, Pyrimidines & Purines • Others (e.g., porphyrins)

  41. Organic Nitrogen Abundance • Ratio to carbon • Redrawn from Westerhoff & Mash, 2002

  42. N-DBPs we know about: end products • Certain to come from N-organics when using free chlorine • Major types: • Cyanogen Halides • Haloacetonitriles • Halonitromethanes CNCl & CNBr Special focus on these compounds because of large data set 9 species

  43. Occurrence • DHANs are typically 10% of THM level • Krasner et al., 2002 [WQTC] • 12 plant survey • ICR (mean for all) • HAN4: 2.7 µg/L • CP: <0.5 µg/L • CNCl: 2.1 µg/L

  44. Genotoxicity • Work of Michael Plewa

  45. Quantitative Structure-Toxicity Models • Lowest Observed Adverse Effect Level • AWWARF report by Bull et al., 2007

  46. DHAN • Chemical Degradation in Distribution Systems • Accelerated by chlorine and base

  47. Proposed Rate Law for DCAN • Hydrolysis and oxidation k1 = 1.78 x10-7 ±0.35 x10-7 (s-1)k2 = 3.42 ±0.31 (M-1s-1)k3 = 1.30 x 10-1 ±0.08 x 10-1 (M-1s-1)

  48. DCAN half-life based on pH & HOCl • At 20 C • From Reckhow, Platt, MacNeill & McClellan, 2001 • Aqua 50:1:1-13 • Degradation in DS observed to increase with increasing pH • ICR data: Obolensky & Frey, 2002

  49. DCAD • Formed from degradation of DCAN • Readily halogenated • Only exists as N-Cl-DCAD?

  50. DCAD Stability Stable