Lead Contamination in Drinking Water

1. Lead Contamination in Drinking Water Tim Alba Stephanie Chan Deb Dryer Jason Faulkenberry Dan Ferguson Emily Levin Miyoko Sasakura November 6, 2009

2. Sources of lead Water infiltration through lead contaminated soil Lead pipes or pipes containing lead (banned in the 1930’s) Lead solder (banned in 1986) Brass fixtures

3. Solubility Conditions Long stagnation times High temperatures Freshly exposed plumbing Low pH Low alkalinity Soft water

4. Water Soluble forms of Lead • Cerussite (PbCO3) • Hydrocerussite (Pb3(OH)2(CO3)2) (hydrated form of lead)

5. Health Effects of Lead • Natural element in the Earth’s crust • In US surface and ground water, lead levels range between 5 and 30 ug/L • Xenobiotic to the human body • Lead can mimic zinc, iron, and calcium • Normal Humans levels (1999 – 2002): • 1.9 ug/dL for children 1 – 5 years • 1.5 ug/dL for adults 20 – 59 years • d/L = deciliter = 100 mL • For the general population: • The most common source of environmental exposure is ingestion of contaminated water. • Lead in drinking water accounts for 14-20% of lead exposure

6. Health Effects of Lead • Ingested lead is absorbed by the gut and delivered throughout the body via the circulation system • Adults absorb 3 – 10% • Children absorb 40 -50% • Lead has a ½ life of 27 days in blood and 30 years in bone • The main storage site for lead: • Bones (main storage site) • Blood • Soft tissue • Lead can cross the blood-brain barrier, the placenta, and can be present in breast milk • Lead is toxic to the hematopoietc stem cells, the renal system, the reproductive system, the cardiovascular system, and the peripheral and central nervous systems.

7. Health Effects of Lead • The CDCs blood lead level threshold for lead poisoning: • Children: > 10 ug/dL • Adults: > 40 ug/dL • Symptoms of lead poisoning: • Abdominal pain • Joint pain • Myalgia • Anemia • Fatigue • Headache • Sleep disturbance • Irritability • Malaise • Symptoms are generally non-specific • Those exposed may be asymptomatic until blood lead levels are extremely high There is currently no effective way to remove lead from the blood under 30 ug/dL

8. Health Effects of Lead Children are the main concern with environmental exposure of lead from drinking water Several studies have shown that blood lead levels < 5 ug/dL are associated with: • Delinquent behavior • Deficits in IQ • Learning Disabilities • Anti-social behavior • Higher drop-out rates

9. Health Effects of Lead • A recent study (2003) showed that the relationship between the amount of lead exposure and IQ deficit is not linear • The initial dose in young children does the most damage • Another study associated childhood lead exposure with region specific reductions in adult grey matter volume • Anterior cingulate cortex: • Executive function • Mood regulation • Decision making

10. Lead and Copper Rule • Lead and Copper Rule (LCR) established in 1991 • Rule applies to Community Water Systems (CWSs) and Non-Transient, Non-Community Water Systems (NTNCWSs) • Monitoring at customer taps rather than at entry point of distribution system • Maximum Contaminant Level Goal (MCLG)=0mg/L • Action Level (AL)=0.015mg/L • Based upon 90th%-ile level of collected tap water samples—no more than 10% of samples collected from specific tap can be above AL

11. Monitoring Number of sample sites dependent upon distribution system size Can reduce the number of times sampling conducted by decreased occurrence of action level exceedance

12. Action Level • Upon exceedance of AL • Implement Water Quality Parameter (WQP) monitoring • Corrosion Control Treatment (CCT) • Source water monitoring/treatment • Public education • Repeated exceedance of AL • Lead Service Line Replacement (LSLR)

13. Treatment • pH and alkalinity control lead solubility • minimum lead release is at pH 9.8 and alkalinity of 28 mg/L • by adjusting the pH to greater than 9, plumosolvency is greatly reduced in alkalinities ranging from 10-80 mg/L • lead leaching was found to be very sensitive to alkalinities less than 50 mg/L • lead release was found to be insensitive to pH at alkalinities greater than 100 mg/L

14. Treatment, continued • pH and alkalinity are easily adjusted by addition of: • lime (CaO) • slaked lime (Ca(OH)2) • caustics (NaOH, KOH) • soda ash (Na2CO3)

15. Control • Corrosion Control • Lead service lines • Lead-Tin Solder • Anodic polarization predominates • Brass (1 – 7% lead) • First flush predominates • Natural Organic Matter • Pb2+ - NOM complexes and surface microcrystals

16. Control, continued • Disinfection processes • Many treatment processes switching from Free Chlorine to Chloramines to avoid “known” DBPs • Controversial due to production of “unknown” DBPs • Chloramine residual produces a lower ORP, and hydrocerrucite controls the solid phase, which releases more lead • Free chlorine has a higher ORP, a PbO2 controlling solid phase, and therefore less lead release than chloramines • ORP is a function of pH

17. Mitigation Corrosion Inhibitors Passivated Pipes Avoid coupling of dissimilar metals Avoid grounding household electrical system to the plumbing system Replace pipes with Medium Density Polyethylene (MDPE) Fluoride control

18. Reduction in blood lead levels, 1988-2002 “Blood Lead Levels --- United States, 1992—2002.” MMWR: Morbidity and Morality Weekly Report 27 May 2005, 54(20): 513-516

19. Large water utilities: LCR in 1991 with AL at 15ppb U.S. EPA 2005b, “Comparison of lead action level exceedances between 1992/93 and 2000/04.” Available: http://www.epa.gov/ogwdw000/lcrmr/pdfs/Comparison of Lead Action Levels.pdf [Accessed 3 Nov 2009]

20. Percent of Medium &Large Water Systems over Action Level (>15ppb) U.S. EPA 2005c,“January 2005 Summary of Lead Action Level.” Available: http://www.epa.gov/ogwdw000/lcrmr/pdfs/summary_lcmr_sdwisfed_data.pdf [Accessed 3 Nov 2009]

21. Case Study (DCWASA)1/2 District of Columbia Water and Sewer Authority (DCWASA) 500,000 customers , 135 million gallons/day to 130,000 locations Nov2002 switched to chloramines 90% of 6,170 HH >15ppb (LAL) Peak with 90% of HH >59ppb (2004)

22. Case Study (DCWASA)2/2 DCWASA, EPA and DOH take immediate action 2004 Optimal Corrosion Control Treatment (OCCT) study suggests chloramines are to blame Released of previously stable lead from services lines and other materials Added orthophosphate a passivating agent

23. Case Study (Philadelphia Schools) 2001 study evaluated drinking water lvls in 292 public schools 124(42.5%) lvls not exceed action lvl (20ppb) 28.7% lvls from 20-50 ppb 11.6% lvls from 50-100ppb 17.1% lvls of 100ppb or more Source: service connectors, lead goosenecks, lead joints or other materials containing lead

24. Conclusions • Lead pipes have been used for plumbing systems since Ancient Rome • Lead pipes are likely to remain in use for many years • Not feasible to replace all currently installed lead materials • Expensive, impractical • Pipes and fixtures beyond service connection responsibility of the homeowner

25. Traditionally lead is controlled through management of water quality • Co-compliance with increasingly stringent EPA regulations can cause unforseen corrosion problems

26. Questions?