Chlorination of Drinking Water Uses - Disinfection 1908 began  cholera, typhoid - water borne diseases Saved millions of lives Side products now of concern Typhoid

Disinfection Processes Chlorination Chlorine Chloramine T Bleach Bromination Iodination Ozone U.V. Radiation Silver Salts

Chlorination Process Chlorine Gas (Cl 2 ) Chlorine Dioxide (ClO 2 ) Bleach (sodium hypochlorite) Chloramine T (ammonia + chlorine)

Water Components Water Color - Decaying Organic Matter - Surface Water/Some Groundwater Fulvic AcidHumic AcidHumin Light YellowDark GreyBlack Yellow BrownBrown Black Humic Substances Treated by Chlorination

Chlorination Water Chlorination - Organic Residue Cl 2 + NOM  CHCl 3 + THM + Other NOM = Natural Organic Material THM = CHCl 3, CHBrCl 2 CHBr 2 Cl, CHBr 3 Other =di, trichloroacetic acids chlorinated ketones di, trichloroacetonitrile

THM Production THMs Trihalomethanes Haloacetic Acids Haloacetonitriles Haloketones Other (>100) Nonvolatile Organic Carbon ….... …..... …... …..... …... ….... …..... …... ….... …..... …... ….... …..... …... …...

Time Table 1908Chlorine Disinfection - U.S. 1974THMs -Netherlands -New Orleans 1975EPA - 80 cities THMs - Widely Present Relate to Chlorination 1977Confirmed, Other Products Identified 1980sTHM Remain Predominant Form Mean THM µg/l (ppb) Mean Haloacetic Acid - 17 µg/l (ppb) 1990Reduce Excessive Chlorination Use Chloramine T

THM X X C X H Cl CH C H Br

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

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 ChloroformCancer, Human CHBrCl 2 Cancer, Human CHBr 2 ClLiver CHBr 3 Cancer, Human Haloacetic Acids TrichloroaceticLiver DichloroaceticCancer, 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