Ground Water Rule Epidemiology

1. Ground Water Rule Epidemiology

2. Presentation Outline • Evolution of the Ground Water Rule • Public Health Aspects of the Ground Water Rule • Microbial Contaminants in Ground Water • Health Effects of Microbial Contaminants • Waterborne Disease Outbreaks • Introduction to Walkerton E. coli:0157 Outbreak

3. Evolution of the Ground Water Rule • Traditionally, ground water has been considered safe to drink without treatment. • However, studies conducted by various groups indicate that ground water can be vulnerable to contamination by viruses and bacteria. • Many of these pathogens are the result of fecal contamination.

4. The Ground Water Rule • The GWR was first proposed in May 2000 in response to the 1996 Amendments to the Safe Drinking Water Act. • The purpose of the rule is to provide for increased protection against microbial pathogens in GW. • The final rule was published in the Federal Register and was effective January 8, 2007. The compliance date is December 1, 2009. • DEC has received a 2-year extension and the current deadline to adopt the rule is 2010.

5. Public Health Hazard • EPA estimates that there are approximately 185,000 illnesses each year due to contaminated GW. • The GWR is expected to reduce the number of waterborne viral illnesses by nearly 42,000 cases. • Many ground water systems currently do not disinfect or otherwise treat their drinking water. • The capacity of soil and aquifer materials to attenuate pathogens depends on many different factors.

6. Microbial Contaminants in Ground Water • Waterborne pathogens are commonly transmitted by the fecal-oral route. • Over 120 types of harmful enteric viruses are excreted in human feces. • Most waterborne disease outbreaks associated with ground water sources are thought to be caused by viruses.

7. Pathogenic Bacteria • Waterborne Pathogenic Bacteria • Legionella • Mycobacterium avium • Shigella • Helicobacter pylori • Vibrio cholerae • Samonella typhi • Salmonella typhimurium • Yersinia • Campylobacter • Escherichia coli (E. coli 0157) • Arcobacter butzleri

8. Pathogenic Viruses • Enteroviruses • Coxsackieviruses • Echoviruses • Poliovirus • Enterovirus 70&71 • Hepatitis A virus • Hepatitis E virus • Adenovirus • Rotavirus • Norovirus • Astrovirus • Sapovirus

9. Other Pathogens • Cryptosporidium • Giardia • Entamoeba hystolytica • Eimeria • Naegleria fowleri • Fungi • Mold • Filamentous bacteria

10. Pathogen Movement and Persistence • Most pathogens from fecal matter remain either near the surface or near the point of origin in the case of an underground source. • Rapid pathogen transport can occur in aquifers that have large pores, like gravel dominated aquifers or those in fractured bedrock. • Pathogen survival depends on a number of factors. • In most cases, only a small portion of the original pathogen density will reach the well intake.

11. Fecal Contamination of GW • Most contamination comes from failed septic systems and leaking sewer lines. • Other sources include cross connections and surface discharge. • Over 1 trillion gallons of septic tank waste is released to the subsurface every year.

12. Health Effects • Waterborne pathogens commonly travel the fecal-oral route of transmission. • Most common health effects are gastro-intestinal, including vomiting and diarrhea. • Some chronic health effects are caused by waterborne pathogens.

13. Fecal Contamination Indicators • E. coli • Total Coliform • Enterococci • Fecal Streptoccoci • Bacillus subtilis • Clostridium perfringens • Bacteriophage • Coliphage

14. Waterborne Disease Outbreaks • The CDC maintains a database of information on waterborne disease outbreaks in the US. • CDC defines a waterborne disease outbreak as occurring when at least two people experience a similar illness after ingesting a specific drinking water. • The US National Research Council suggests that the number of identified and reported outbreaks represents a small percentage of actual outbreaks. • There is also the issue of endemic waterborne disease.

15. Sources of Waterborne Disease Outbreaks in Community GW Systems (1991-2000)

16. Sources of Waterborne Disease Outbreaks in Non-Community GW Systems (1991-2000)

17. Etiology of Waterborne Outbreaks in Community Ground Water Systems (1991-2000)

18. Etiology of Waterborne Outbreaks in Non-Community Ground Water Systems (1991-2000)

19. PWS Waterborne Disease Outbreaks Associated with On-Site Wastewater Systems

20. PWS Waterborne Disease Outbreaks Associated with Wastewater Collection Systems

21. PWS Waterborne Disease Outbreaks Associated with Ground Water Storage or Distribution Systems

22. Outbreak of Waterborne Gastroenteritis in Walkerton , Ontario – May – June, 2000 • In May and June, 2000, a waterborne disease outbreak occurred in Walkerton, Ontario (population -5000). • The outbreak was caused by E. coli 0157:H7 and Campylobacter spp. • Approximately 1346 people became sick with bloody diarrhea and severe abdominal cramps. • 65 patients were sick enough to be admitted to hospital; 27 patients developed hemolytic uremic syndrome; 6 people died as a result of the outbreak. Source: The Investigative Report of the Walkerton Outbreak of Waterborne Gastroenteritis, Oct. 2000

23. Walkerton Water System • The town of Walkerton received most of its public drinking water from three wells – Wells 5, 6 & 7 • Well 5 was 45 feet deep and was constructed in 1978. • It was located less than 240 feet from a farm where cow manure was routinely spread on the fields. • Well 6 was 215 feet deep and was constructed in 1982 and had a history of nitrate contamination from nearby fertilizer use. • Well 7 was 225 feet deep and was the main source of the town’s drinking water. It was constructed in 1987.

24. Well 5 • Well 5 was classified as Ground Water Under the Direct Influence of Surface Water in 1980. • It was required to have continuous chlorination. • Chlorine levels were not being monitored properly at the time of the outbreak. • Samples taken from the well on May 23 by the Public Health Service were positive for total coliform and E. coli. • Subsequent DNA testing of these samples confirmed the presence of E. coli 0157.

25. Events Leading to the Outbreak • Unusually heavy rains, including flooding • A shallow well subject to surface water contamination • Well located directly adjacent to a cattle farm • Cattle herd infected with E. coli and Campylobacter • Lack of adequate chlorination • Lack of adequate monitoring of daily chlorine residuals

26. Aftermath of the Outbreak • Economic costs estimated at between $64 and $155 million dollars. • Six people died as a result of the outbreak. • Many people who were infected have lingering health problems. • Criminal charges were brought against Stan and Frank Koebel – operator and manager for Walkerton PUC. • Stan Koebel received a sentence of 1 year in jail for public endangerment and falsification of data. • Frank Koebel received a sentence of 9 months of house arrest for the same offenses.

27. Summary • The Ground Water Rule was promulgated to address microbial contaminants in public water systems that use ground water as a source. • The majority of waterborne disease outbreaks in the United States are associated with ground water. • The Ground Water Rule will reduce the risk of waterborne disease outbreaks associated with ground water sources.

28. Questions