Presentation for a graduate level course in "Environmental Health"

1. MPH 605 Environmental Health Week 5 Part I: Water and Health Dr. Sylvia Hood Washington, PhD ,ND S, MSE MPH 1

2. Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 2 The Hydrologic Cycle Over 97 percent of the world’s water is salty, found in the oceans and in inland seas and saltwater lakes. The remaining 3 percent is freshwater but over two thirds of this is locked in the Antarctic and Arctic ice caps. The available freshwater is in rivers, lakes, atmosphere and within the ground and only makes up less than 1 percent of the world’s water. Water is in a continuous motion among these locations in a so-called hydrologic cycle. Without the continuous evaporation from the oceans, precipitation on land and runoff back to the oceans, no surface or groundwater recharge can take place and we would eventually exhaust our freshwater supplies.

3. Definitions Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 3

4. Ideal Characteristics of Drinking/Source Water Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 4

5. Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 5 Freshwater Eventhough the percentage of the population who live without access to potable water declined in the 1990s, rapid population growth meant that in terms of actual numbers, more people than before lacked clean water. At the close of the 20th century an estimated 1.2 billion people lacked clean water, compared to about 1 billion in 1990.

6. Water Scarcity Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 6

7. Water Stress in 2025 27% of nations will face water stress (water levels at or below 1,700 m3 per person per year) Occurs when population growth is higher than expected Zero per capita availability in West Bank Seychelles Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 7

8. Americans ---Profligate Water Users Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 8

9. Somalia Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 9

10. Aquifer Recharge Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 10

11. Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 11 Agriculture and Water Scarcity On a global scale, agriculture use of water represents almost 70 percent of the water withdrawal. It is estimated that 6800 gallons of water is needed to grow a day’s food for a family of four. Agricultural uses of water are the greatest global contributors to water scarcity and depletion of aquifers.

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13. Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 13 Climate Change and Water Availability Changes to the climate such as warming global temperatures will cause : increased evaporation from the oceans an increase in water vapor in the atmosphere Increase in precipitation, involving more severe weather events. More water vapor in the atmosphere will exacerbate the greenhouse effect : precipitation may increase in some regions and decrease in others shifting the water scarcity burden.

14. Human Impacts Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 14

15. Biological ContaminantsKnow pp. 509-510, Table 15.5 Bacteria Viruses Protozoa Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 15

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19. Deposition, Storage and Bioaccumulation of Pathogens Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 19

20. Environmental Transformation of Pathogens Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 20

21. Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 21 Waterborne Diseases Vector-Borne Diseases Some of the most prevalent and deadly infectious diseases are transmitted by vector that are related to the water. Pathogens While a wide range of diseases are caused by waterborne pathogens, the most common outcome from such pathogens is acute gastrointestinal infection (AGI).

24. Traditional Indicator—Microbial Contamination: Coliform Why? Supposedly offers the overall microbial content 1900s: nutrient agar plate at 37 degrees C More recently enumerated in selective liquid culture media---most probable number method Membrane filtration technique Enzyme specific assays Challenged lately because… Human pathogens can survive for extended periods Fate is very much organism specific Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 24

25. Famous Outbreaks Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 25

26. Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 26 Safe Drinking Water The safety of drinking water extends from the source to the faucet. Source Protection: To protect human health as it relates to water supply, source water must be protected through maintaining generous buffers, limiting access for recreational purposes and preventing agricultural and industrial uses. Water Treatment: Water treatment is essential for not only poor quality water sources but also for high quality source water. The steps of water treatment involve: coarse filtration, coagulation, precipitation, filtration and finally post filtration disinfection. Water Distribution: Distribution is a critical step and in many cases of water contamination and waterborne disease outbreaks has been identified as the cause. Point of Use Treatment and Bottled Water: As an alternative to tap water consumption, consumers are turning to point of use treatment or bottled water. While these are viable options, there is a compelling argument that if the money spent on these options were invested in municipal treatment and distribution many health risks could be mitigated.

27. Dr. Sylvia Hood Washington, PhD ,ND , MSE MPH 27 Chemical Contaminants: Chemical contaminants can occur from point sources or nonpoint sources. A point source is a stationary location or fixed facility from which pollutants are discharged; any single identifiable source of pollution; for example, a pipe, ditch, shop, ore pit, factory smokestack. Nonpoint sources diffuse pollution sources (that is, the pollutants do not have a single point of origin or are not introduce into a receiving stream from a specific outlet; for example, they are pollutants carried off the land by storm water). Common nonpoint sources are agriculture, forestry, urban, mining, construction, dams, channels, land disposal, saltwater intrusion and city streets.

28. Point Source Discharges Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 28 Types of Discharges

29. Nonpoint Source Discharges Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 29

30. Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 30 Regulatory Framework Safe Drinking Water Act: This act was passed in 1974 and amended in 1986 and 1996; it mandates that the EPA must regulate contaminants in drinking water that might post a risk to human health. Total Coliform Rule: Finalized in 1989 by the EPA, the Total Coliform Rule is the driving force behind drinking water safety and frequently serves as the first indication of potential contamination. The rule requires a water system to establish a regular coliform sampling plan, with sample sites that accurately represent water quality throughout the distribution system. Consumer Confidence Reports: The Amendment of 1996 to the Safe Drinking Water Act requires Consumer Confidence Reports to be provided so that Americans can make practical, knowledgeable decisions about health and their environment.

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32. Dr. Sylvia Hood Washington, PhD,ND, MSE MPH 32 EPA Water Contaminants For detailed information go to: http://www.epa.gov/safewater/contaminants/index.html