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Typhoid. 1880. 1900. 1920. Chlorination of Drinking Water. Uses - Disinfection. 1908 began cholera, typhoid - water borne diseases Saved millions of lives Side products now of concern. Disinfection Processes. Chlorination Chlorine Chloramine T Bleach Bromination
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Typhoid 1880 1900 1920 Chlorination of Drinking Water Uses - Disinfection • 1908 began • cholera, typhoid • - water borne diseases • Saved millions of lives • Side products now of concern
Disinfection Processes • Chlorination • Chlorine • Chloramine T • Bleach • Bromination • Iodination • Ozone • U.V. • Radiation • Silver Salts
Chlorination Process Chlorine Gas (Cl2) Chlorine Dioxide (ClO2) Bleach (sodium hypochlorite) Chloramine T (ammonia + chlorine)
Humic Substances Fulvic Acid Humic Acid Humin Light Yellow Dark Grey Black Yellow Brown Brown Black Water Components Water Color - Decaying Organic Matter - Surface Water/Some Groundwater • Treated by Chlorination
Chlorination Water Chlorination - Organic Residue Cl2+ NOM CHCl3+ THM + Other NOM = Natural Organic Material THM = CHCl3, CHBrCl2 CHBr2Cl, CHBr3 Other = di, trichloroacetic acids chlorinated ketones di, trichloroacetonitrile
THM Production THMs …... ..…... .…... …... ..…... .…... .…... …... ..…... .…... …... …... .…... .…... …... …... ..…... .…... …... ..…... .…... …... Nonvolatile Organic Carbon Trihalomethanes Haloacetic Acids Haloacetonitriles Haloketones Other (>100)
Time Table 1908 Chlorine Disinfection - U.S. 1974 THMs - Netherlands - New Orleans 1975 EPA - 80 cities THMs - Widely Present Relate to Chlorination 1977 Confirmed, Other Products Identified 1980s THM Remain Predominant Form Mean THM - 36-39 µg/l (ppb) Mean Haloacetic Acid - 17 µg/l (ppb) 1990 Reduce Excessive Chlorination Use Chloramine T
X X C H X Cl Br Cl C H H Br C Cl Br THM
THM (Chloroform) Toxicity • Chloroform • - anesthetic • - “syrups” • Liver, Kidney Toxicity • Biotrans • CHCl3 CHCl3* Macromolecules • Cancer - Animals • - lifetime exposure • - every day, high levels • - liver, kidney, lung Cancer Toxicity
THM Toxicity II THMs - Bromo Compounds CHBr3~ CHCL3 Liver Toxicity CHBr3~ ? CHCl3 Cancer Haloacetic Acids Cancer, Co-Carcinogen 60 µg/l (ppb)
Disinfection Products/Toxicity Trihalomethanes Chloroform Cancer, Human CHBrCl2 Cancer, Human CHBr2Cl Liver CHBr3 Cancer, Human Haloacetic Acids Trichloroacetic Liver Dichloroacetic Cancer, Human
THM Standard • 100 µg/l (ppb) - finished water • Reduce to 50 µg/l • In Discussion • Recheck Water Utilities • - mean 38 µg/l (same as prior) • Cost vs real health benefits • 100 µg/l 80 µg/l December 2001
THM Cancer Epidemiology I • 1997 K.P. Cantor, NCI - Epidemiology • Epidemiology Studies (1977 1997) • 1st-Ecological - Epidemiological (1977) • - Water source - surface • - Mississippi River • - Water supply characteristics • - Bladder, colon, rectal cancer • - descriptive • 2nd Case - control mortality records • - water exposure variables • - cancer bladder, colon, rectum • - brain • - strengthen hypothesis, but limits
THM Cancer Epidemiology II • 3rd - Colon, Rectal Cancers • - lack consistency, source unclear • - variations from state to state • - geographic differences in byproducts? • 3rd - Bladder Cancer • - more consistent • - all associations positive • - correlate to duration exposure • 4th - Regard results with concern • - need better link to • - by products mixture • - individual’s characteristics
THM - Birth Outcomes • Trichloroethylene - South Tucson • - birth defects • Chloroform - Birth Defects • - Schuetz • THMs • - still births • - birth defects • Probably More Important • > cancer
Risk - Cost Benefit • Chlorination/Disinfection • - water borne disease • - save million(s) of lives • Chlorination Byproducts • - link to cancer? • - can “control” quantity byproducts • Efforts/Cost to Further Reduce Byproducts • Animal Models vs Humans • - cancer site vs animals • - concentration required • Birth Effects • - concentrate efforts • - difficult to study • Extraneous Factors • - other chemicals • - diet changes