1000 cubic meters is the recommended minimum amount per person by most hydrologists
Waterborne diseases may be controlled and even eliminated through changes in water sources, quality and human behavior.
Week 5 Mph 605 Water & Health Part I
MPH 605 Environmental Health Week 5<br />Part I: Water and Health<br />Dr. Sylvia Hood Washington, PhD ,ND S, MSE MPH<br />1<br />
Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />2<br />The Hydrologic Cycle<br />Over 97 percent of the world’s water is salty, found in the oceans and in inland seas and saltwater lakes. <br />The remaining 3 percent is freshwater but over two thirds of this is locked in the Antarctic and Arctic ice caps. <br />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. <br />Water is in a continuous motion among these locations in a so-called hydrologic cycle. <br />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. <br />
Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />5<br />Freshwater<br />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. <br />At the close of the 20th century an estimated 1.2 billion people lacked clean water, compared to about 1 billion in 1990.<br />
Water Stress in 2025<br />27% of nations will face water stress (water levels at or below 1,700 m3 per person per year)<br />Occurs when population growth is higher than expected<br />Zero per capita availability in <br />West Bank<br />Seychelles<br />Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />7<br />
Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />11<br />Agriculture and Water Scarcity<br />On a global scale, agriculture use of water represents almost 70 percent of the water withdrawal. <br /> It is estimated that 6800 gallons of water is needed to grow a day’s food for a family of four. <br />Agricultural uses of water are the greatest global contributors to water scarcity and depletion of aquifers.<br />
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Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />13<br />Climate Change and Water Availability<br />Changes to the climate such as warming global temperatures will cause :<br />increased evaporation from the oceans<br /> an increase in water vapor in the atmosphere <br />Increase in precipitation, involving more severe weather events. <br />More water vapor in the atmosphere will exacerbate the greenhouse effect :<br />precipitation may increase in some regions and <br />decrease in others shifting the water scarcity burden.<br />
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Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />17<br />Microbiological Contaminants<br /><ul><li>Biological contaminants can occur from point sources such as leaking septic systems or nonpoint sources such as runoffs from city streets.
Most but not all of biological contaminants result from human or animal wastes and therefore waste management practices play a major role in water contamination. </li></li></ul><li>Exposure Routes<br />Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />18<br />
Deposition, Storage and Bioaccumulation of Pathogens<br />Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />19<br />
Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />21<br />Waterborne Diseases<br />Vector-Borne Diseases<br /> Some of the most prevalent and deadly infectious diseases are transmitted by vector that are related to the water. <br />Pathogens<br /> While a wide range of diseases are caused by waterborne pathogens, the most common outcome from such pathogens is acute gastrointestinal infection (AGI). <br />
Water Related Diseases and Climate Changes<br /><ul><li>Waterborne Diseases are likely to become a greater problem as the climate changes and the hydrologic cycle is affected.
Runoff from heavy rainfalls or melting snow can contaminate recreational water (higher levels of bacteria) and therefore increase human illness.</li></li></ul><li>Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />23<br />
Traditional Indicator—Microbial Contamination: Coliform<br />Why? Supposedly offers the overall microbial content<br />1900s: nutrient agar plate at 37 degrees C<br />More recently enumerated in selective liquid culture media---most probable number method<br />Membrane filtration technique<br />Enzyme specific assays<br />Challenged lately because… <br />Human pathogens can survive for extended periods<br />Fate is very much organism specific<br />Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />24<br />
Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />26<br />Safe Drinking Water<br />The safety of drinking water extends from the source to the faucet.<br />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.<br />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.<br />Water Distribution: Distribution is a critical step and in many cases of water contamination and waterborne disease outbreaks has been identified as the cause. <br />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.<br />
Dr. Sylvia Hood Washington, PhD ,ND , MSE MPH<br />27<br />Chemical Contaminants: Chemical contaminants can occur from point sources or nonpoint sources.<br />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. <br />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). <br />Common nonpoint sources are agriculture, forestry, urban, mining, construction, dams, channels, land disposal, saltwater intrusion and city streets.<br />
Point Source Discharges<br />Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />28<br />Types of Discharges<br />
Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />30<br />Regulatory Framework<br />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.<br />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.<br />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.<br />
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Dr. Sylvia Hood Washington, PhD,ND, MSE MPH<br />32<br />EPA Water Contaminants<br />For detailed information go to:<br />http://www.epa.gov/safewater/contaminants/index.html<br />