Chlorination of Drinking Water Uses Disinfection Typhoid 1880

Chlorination of Drinking Water Uses - Disinfection Typhoid 1880 1900 1920 • 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 (Cl 2) Chlorine Dioxide (Cl. O 2) Bleach (sodium hypochlorite) Chloramine T (ammonia + chlorine)

Water Components Water Color - Decaying Organic Matter - Surface Water/Some Groundwater Humic Substances Fulvic Acid Humic Acid Light Yellow Dark Grey Yellow Brown Black • Treated by Chlorination Humin Black

Chlorination Water Chlorination - Organic Residue Cl 2 + NOM CHCl 3 + THM + Other NOM = Natural Organic Material THM = CHCl 3, CHBr. Cl 2 CHBr 2 Cl, CHBr 3 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 1980 s 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

THM X X C H X Cl Cl C Cl Br H Br C Br H

THM (Chloroform) Toxicity • Chloroform - anesthetic - “syrups” • Liver, Kidney Toxicity Cancer Biotrans CHCl 3* Macromolecules Cancer - Animals Toxicity - lifetime exposure - every day, high levels - liver, kidney, lung

THM Toxicity II THMs - Bromo Compounds CHBr 3 ~ CHCL 3 Liver Toxicity CHBr 3 ~ ? CHCl 3 Cancer Haloacetic Acids Cancer, Co-Carcinogen 60 µg/l (ppb)

Disinfection Products/Toxicity Trihalomethanes Chloroform CHBr. Cl 2 CHBr 2 Cl CHBr 3 Cancer, Human Liver Cancer, Human Haloacetic Acids Trichloroacetic Dichloroacetic Liver 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) • 1 st-Ecological - Epidemiological (1977) - Water source - surface - Mississippi River - Water supply characteristics - Bladder, colon, rectal cancer - descriptive • 2 nd Case - control mortality records - water exposure variables - cancer bladder, colon, rectum - brain - strengthen hypothesis, but limits

THM Cancer Epidemiology II • 3 rd - Colon, Rectal Cancers - lack consistency, source unclear - variations from state to state - geographic differences in byproducts? • 3 rd - Bladder Cancer - more consistent - all associations positive - correlate to duration exposure • 4 th - 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