Chemical Measurements in Chemical Measurements in Drinking Water: Their Use in Drinking Water: Their Use in

Monitoring Disinfection and its Monitoring Disinfection and its ConsequencesConsequences

Kusum Perera, Ph.D.Kusum Perera, Ph.D.

ObjectivesObjectives

Overview of water disinfectionOverview of water disinfection

Importance of disinfectant (chlorine) dose Importance of disinfectant (chlorine) dose measurementsmeasurements

Disinfectant By-Product (DBPs) formationDisinfectant By-Product (DBPs) formation

DBP measurement and mitigationDBP measurement and mitigation

Alternative disinfectants and other DBPsAlternative disinfectants and other DBPs

Water Disinfection by ChlorinationWater Disinfection by Chlorination

Water chlorination was a major advancement in Water chlorination was a major advancement in public health protectionpublic health protectionBy the 1920s water systems in most major By the 1920s water systems in most major cities in the USA were chlorinating their DW cities in the USA were chlorinating their DW supplysupply1940s and 1950s saw major advancements in 1940s and 1950s saw major advancements in chromatographic techniques to separate, chromatographic techniques to separate, identify and quantify chemicalsidentify and quantify chemicalsFirst chemicals resulting from disinfectant First chemicals resulting from disinfectant treatment were isolated in the 1970s, called treatment were isolated in the 1970s, called Disinfection By Products - DBPsDisinfection By Products - DBPs

Analysis of DBPsAnalysis of DBPs

Samples collected in a 40 mL vial and kept cold Samples collected in a 40 mL vial and kept cold – analysis within 14 days– analysis within 14 days

An inert gas is purged through the sample and An inert gas is purged through the sample and the volatilizing gases are trapped on to an the volatilizing gases are trapped on to an adsorbent medium – XAD resinadsorbent medium – XAD resin

The resin is heated and the emanating gases The resin is heated and the emanating gases are injected into the separating columnare injected into the separating column

The separated gases are detected, identified The separated gases are detected, identified and quantifiedand quantified

NOM + Chlorine

DBP Formation

Dichlorobromomethane

BromoformDibromochloromethane

Chloroform

Trihaloacetic Acids

X = Br, Cl

EPA Method 524.2 ChromatogramEPA Method 524.2 Chromatogram

USGS recently published a study on the occurrence of the 15 most USGS recently published a study on the occurrence of the 15 most prevalent volatiles in US groundwater using this methodprevalent volatiles in US groundwater using this method

- Separation of Chemical from Matrix- Detection & Identification- Pecision & Accuracy - Quantification- Limit of Detection/Quantification- MCL - Measurement & Enforceability

- Occurrence- Health and Illness in Populations- Exposure and Disease Outcomes- Application of Statistical Methods to the Design and Analysis of Studies- Risk Management Strategies

- Animal Studies on Chemical- Human Exposure Data- Fill gaps in knowledge base- Develop LD50 and ED50

- Health Effects based MCLGs- Contaminant Control Strategies- Availability of Treatment Techniques- Cost of Treatment Techniques - MCLs based on all of above

Health Effects Health Risks

Risk MitigationLitigation/Refinement

Chemistry Epidemiology and Biostatistics

Toxicology

Rules and Regulations

Relationships of Public Health Sciences

Biostatistics and Epidemiology THMsBiostatistics and Epidemiology THMs

Occurrence - Base on NORS (National Organics Occurrence - Base on NORS (National Organics Reconnaissance Survey, 1975), ~75% TTHMs is from Reconnaissance Survey, 1975), ~75% TTHMs is from chloroform. In some case, chloroform was found at 300 ppb. chloroform. In some case, chloroform was found at 300 ppb.

Risk Assessment - Base on National Academy of Sciences’ Risk Assessment - Base on National Academy of Sciences’ report (1977), cancer risk = 3.4x10report (1977), cancer risk = 3.4x10-6 -6 / ppb (chloroform) at / ppb (chloroform) at upper 95% confidence limits, assuming 70 year daily upper 95% confidence limits, assuming 70 year daily consumption of water at 2 L/day.consumption of water at 2 L/day.

Risk Reduction - Chloroform reduction from 300 ppb to 100 Risk Reduction - Chloroform reduction from 300 ppb to 100 ppb, about 2500 cancer cases would been avoided in a ppb, about 2500 cancer cases would been avoided in a population of 250 million people annually.population of 250 million people annually.

Source: NAS, 1977, “Drinking Water and Health”, Washington, D.C.

Regulating ChemicalsRegulating Chemicals

Maximum Contaminant Level Goals - MCLGsMaximum Contaminant Level Goals - MCLGs

Considers only health effects (NOT the limits of detection Considers only health effects (NOT the limits of detection and treatment technology)and treatment technology)

- Non-Carcinogen: - Non-Carcinogen: NOAEL (no-observed-adverse-effect level)NOAEL (no-observed-adverse-effect level)

- Carcinogen & Public Health Risk Microbes: - Carcinogen & Public Health Risk Microbes: ZeroZero

Maximum Contaminant Level - MCLsMaximum Contaminant Level - MCLs

MCL set as close to MCLGs as feasible, consider best MCL set as close to MCLGs as feasible, consider best available analytical technology, treatment techniques, cost available analytical technology, treatment techniques, cost and benefit.and benefit.

USEPAUSEPA

Trihalomethanes (THM) Rule - 1979Trihalomethanes (THM) Rule - 1979

Public health risk exists from exposure to TTHMs in Public health risk exists from exposure to TTHMs in drinking water, the potential for the risk need to be drinking water, the potential for the risk need to be reduced as much as is technologically and reduced as much as is technologically and economically feasible without increasing the risk of economically feasible without increasing the risk of micro-biological contaminations.micro-biological contaminations.

Basis of the THM Rule:Basis of the THM Rule:-- TTHMs first regulated at 100ug/L - based on TTHMs first regulated at 100ug/L - based on

cancer deaths preventedcancer deaths prevented-- Methods to reduce formation; NOM reduction Methods to reduce formation; NOM reduction in in source water and alternative disinfectantssource water and alternative disinfectants-- Availability of removal technologyAvailability of removal technology-- Cost considerationsCost considerations

Summary of C.t values (mg/L.min) for 99% inactivation at 5°C

OrganismOrganism DisinfectantDisinfectant

Free ChlorineFree ChlorinepH 6 to 7pH 6 to 7

ChloramineChloraminepH 8 to 9pH 8 to 9

Chlorine DioxideChlorine DioxidepH 6 to 7pH 6 to 7

OzoneOzonepH 6 to 7pH 6 to 7

E. E. colicoliPolio virus 1Polio virus 1RotavirusRotavirusBacteriophage fBacteriophage f

22

G. G. lamblialamblia cysts cystsG. G. murismuris cysts cystsC. C. ParvumParvum

0.034-0.050.034-0.051.1-2.51.1-2.50.01-0.050.01-0.050.08-0.180.08-0.1847->15047->15030-63030-63072007200bb

95-18095-180768-3740768-37403806-64763806-6476------72007200cc

0.4-0.750.4-0.750.2-6.70.2-6.70.2-2.10.2-2.1----7.2-18.57.2-18.57878bb

0.020.020.1-0.20.1-0.20.006-0.060.006-0.06--0.5-0.60.5-0.61.8-2.01.8-2.0aa

5-105-10cc

a Values for 99.9% inactivation at pH 6-9, b 99% inactivation at pH7 and 25°C, c 90% inactivation at pH7 and 25°CWHO Report, (Clark et al, 1993)

What is an effective disinfectant dose for pathogen inactivation in What is an effective disinfectant dose for pathogen inactivation in water?water?

Depends on …. The type of pathogen, pathogen load, turbidity, Depends on …. The type of pathogen, pathogen load, turbidity, pH and temperaturepH and temperature

Control of THMsControl of THMs

Reduce NOM prior to treatmentReduce NOM prior to treatment– Enhanced coagulation, pH controlEnhanced coagulation, pH control

Control chlorination dose or use Control chlorination dose or use alternative disinfectantsalternative disinfectants– Minimize effective doseMinimize effective dose– Chlorine dioxide, UV, etc.Chlorine dioxide, UV, etc.

Removal THMsRemoval THMs– GAC, Synthetic resinsGAC, Synthetic resins

Advancements in Analytical TechnologyAdvancements in Analytical Technology

THMs have high vapor pressure and less THMs have high vapor pressure and less soluble in water - P&T GCsoluble in water - P&T GC

Semivolatiles have lower vapor pressure Semivolatiles have lower vapor pressure but easily extracted from water - GC/MSbut easily extracted from water - GC/MS

Polar, non-volatiles difficult to pull out of Polar, non-volatiles difficult to pull out of water - LC/MSwater - LC/MS

Mass spectrometry gives selectivityMass spectrometry gives selectivity

Last count – over 700s DBPs!Last count – over 700s DBPs!

Some Chlorine DBPsSome Chlorine DBPs

Trihalomethanes (THMs)Trihalomethanes (THMs)

Chlorinated Acetic AcidsChlorinated Acetic Acids

Halogenated AcetonitrilesHalogenated Acetonitriles

Chloral hydrate (trichloroacetaldehyde)Chloral hydrate (trichloroacetaldehyde)

ChlorophenolsChlorophenols

MX (3-chloro-dichlomethyl-5-hydroxy-2(5H)-MX (3-chloro-dichlomethyl-5-hydroxy-2(5H)-

furanone)furanone)

D/DBP Rule Implementation USEPAD/DBP Rule Implementation USEPA

StageStage TTHM StandardTTHM Standard HAA StandardHAA Standard

THM RuleTHM Rule 100 µg/L100 µg/L NoneNone

Stage 1Stage 1 80 µg/L80 µg/L 60 µg/L60 µg/L

Proposed Stage 2Proposed Stage 2 40 µg/L40 µg/L 30 µg/L30 µg/L

Transition from THM rule to D/DBP rule:Transition from THM rule to D/DBP rule:• 1979 to 19941979 to 1994• Advances in analytical techniques, new tox and epi Advances in analytical techniques, new tox and epi data, risk management data, risk management• Discovery of other DBPs – Haloacetic AcidsDiscovery of other DBPs – Haloacetic Acids• D/DBP rule stage 1 – 1999 and stage 2 - 2006D/DBP rule stage 1 – 1999 and stage 2 - 2006

Disinfection’s Public Health EffectDisinfection’s Public Health Effect

ProcedureProcedure Before ImplementationBefore Implementation After ImplementationAfter Implementation

Drinking water Drinking water disinfectiondisinfection

Mortality rate from Mortality rate from typhoid:typhoid:

58 per 100,00058 per 100,000

Mortality rate from typhoid:Mortality rate from typhoid:

0.67 per 100,0000.67 per 100,000

Stage 1 D/DBP Stage 1 D/DBP rulerule

About 5000 cases of bladder cancer caused by DBPs. About 5000 cases of bladder cancer caused by DBPs. More than 2000 cases can be avoided because of More than 2000 cases can be avoided because of stage 1 rule.stage 1 rule.

Cost: additional $1.00 / household•year for >95% Cost: additional $1.00 / household•year for >95% peoplepeople

Stage 2 D/DBP Stage 2 D/DBP rulerule

From stage 1 to stage 2, about 500 cases of bladder From stage 1 to stage 2, about 500 cases of bladder cancer can be avoided annually.cancer can be avoided annually.

Cost: additional $0.62 / household•yearCost: additional $0.62 / household•year

Source: US EPA

EIC of LC/MS for Haloacetic acids by Electrospray IonizationApplied Biosystems API 4000

DisinfectantDisinfectant & Disinfection Byproducts& Disinfection Byproducts

ChlorineChlorine Trihalomethanes, Halo Acetic Trihalomethanes, Halo Acetic Acids, Halogenated Acetonitriles, Acids, Halogenated Acetonitriles, Chloral hydrate, Chlorophenols, MX Chloral hydrate, Chlorophenols, MX

ChloraminesChloramines Same as above but at lower level, Same as above but at lower level, Cyanogen Chloride, Nitrosamines (e.g. Cyanogen Chloride, Nitrosamines (e.g. NDMANDMA))

Chlorine DioxideChlorine Dioxide Chlorite, Chlorate, ChlorideChlorite, Chlorate, Chloride

OzoneOzone Formaldehyde, Aldehydes, Hydrogen Formaldehyde, Aldehydes, Hydrogen Peroxide, Bromomethanes, BromatePeroxide, Bromomethanes, Bromate

ConclusionsConclusionsDrinking water disinfection is an essential component in Drinking water disinfection is an essential component in the protection of public health. However, the type of DBPs the protection of public health. However, the type of DBPs formed is dependent on the water quality and disinfectant formed is dependent on the water quality and disinfectant used.used.Disinfection generates DBPs that can be measured Disinfection generates DBPs that can be measured reliably. Studies on Health effects and risks associated reliably. Studies on Health effects and risks associated with DBPs follow. Strategies for risk mitigation are sought with DBPs follow. Strategies for risk mitigation are sought out. Proposed legislation addresses the problem and out. Proposed legislation addresses the problem and provides an opportunity for public comment.provides an opportunity for public comment.In the US, THM rule and the accompanying regulations is In the US, THM rule and the accompanying regulations is the first legislation to address the issue of risks associated the first legislation to address the issue of risks associated with DBPs. Under the rule, water systems are required to with DBPs. Under the rule, water systems are required to monitor for DBPs to ensure control public exposure DBPs.monitor for DBPs to ensure control public exposure DBPs.Alternative disinfectants leads to other DBPs and the Alternative disinfectants leads to other DBPs and the ongoing public health challenge is to address the ongoing public health challenge is to address the emerging concernsemerging concerns