- Worldwide, 1.1 billion people do not have access to an improved water source* (1). Many more obtain their drinking water from improved, but microbiologically unsafe, sources.
- An estimated 2.6 billion people — half of the developing world — lack access to adequate sanitation (almost 40% of the world’s population) (2,3).
- Water-related diseases are the most common cause of illness and death among the poor of developing countries. According to the World Health Organization, 1.6 million deaths per year can be attributed to unsafe water, poor sanitation and insufficient hygiene (4).
- Worldwide, 149 countries and territories are affected by at least one neglected tropical disease (NTD) (5).
- Guinea Worm Disease (GWD) is an extremely painful parasitic infection spread through contaminated drinking water. GWD is characterized by thread-like worms slowly emerging from the human body through blisters. Infection occurs among people living in impoverished communities in remote parts of Africa that do not have safe water to drink. In 2007, over 9,500 cases of Guinea Worm Disease were reported. Most of those cases were from Sudan (61%) and Ghana (35%) (6).
- Worldwide, soil-transmitted helminths infect more than one billion people due to a lack of adequate sanitation (7).
- Trachoma is the world’s leading cause of preventable blindness and results from poor hygiene and sanitation. Approximately 41 million people suffer from active trachoma and nearly 10 million people are visually impaired or irreversibly blind as a result of trachoma (8). Trachoma infection can be prevented through increased facial cleanliness with soap and clean water, and improved sanitation.
- http://www.cdc.gov/healthywater/global/
2. Safe Water
Clean/Safe Water Drinking Water
For 100 years, public water supplies have been treated with disinfectants, such as chlorine, to reduce the risks of infectious disease from waterborne pathogens. Although water disinfection has been highly effective in reducing the incidence of certain diseases, such as cholera and typhoid, the continued occurrence of waterborne disease outbreaks demonstrates that contamination of drinking water with pathogenic bacteria, viruses, and parasites still poses a health risk when treatment is inadequate. The use of disinfectants, while reducing microbial risks, creates new potential problems as chemical by-products are formed during the treatment process. Some of these disinfection by-products (DBPs) have been shown to cause cancer and other toxic effects in experimental animals. In humans, however, the scientific evidence is inconclusive. In addition, surface water and groundwater supplies that are used as a source of drinking water may be contaminated by a variety of chemicals of potential public health concern. For example, arsenic, a naturally occurring contaminant of drinking water in some areas, has been shown to cause cancer, cardiovascular disease and other effects in exposed individuals. Research is required to obtain sufficient understanding of the health risks posed by these chemical and microbiological contaminants, and to develop a strong scientific basis for setting new drinking water standards that may be needed to protect public health. NOTE: Information on drinking water laws and regulations, publications and other resources can be found at the EPA Office of Water's website located at: www.epa.gov/ow/.
Problem (DBPs): A large number of organic and inorganic chemicals, such as trihalomethanes, haloacids, bromate and chlorate, are found in disinfected drinking water as a result of reactions between disinfectants and chemical precursors in the source water. Many of these disinfection by-products (DBPs) have been shown to cause adverse health effects at high doses in experimental animals, and epidemiology studies have suggested potential risks of cancer and adverse reproductive outcomes in human populations. EPA is currently working with the water industry and other stakeholders to determine the need for more stringent standards for DBPs found in drinking water.
Scientific Questions:
- What are the health effects of DBPs in communities served by disinfected drinking water?
- What is the toxicity of individual chemical contaminants and mixtures of DBPs at low doses?
Approach: NHEERL is supporting the establishment of scientifically sound regulatory decisions on DBPs by conducting health effects research to address key uncertainties in the risk assessment for these contaminants. This research includes epidemiology and toxicology studies across a variety of scientific disciplines for characterizing the risks associated with exposure to DBPs in drinking water. An emphasis is being placed on studies of adverse reproductive outcomes, but research will also be conducted on cancer and, to the extent necessary, neurotoxic and immunotoxic effects. Epidemiology research will emphasize an evaluation of the potential reproductive risks that may be associated with DBP exposures. Toxicology research on DBPs will include dose-response studies and research on mode of action and pharmacokinetics to provide information needed to support more biologically based risk assessments for the most important by-products. Research on DBP mixtures will address hypotheses concerning the relative risks of different complex mixtures as a function of treatment characteristics and source water quality, and the nature of possible by-product interactions at low doses.
- Our studies were the first to demonstrate that dichloroacetic acid (DCA) is a hepatocarcinogen in the rat. We also showed that DCA induces a unique rasoncogene mutation in hepatocellular carcinomas in rodents. This information may help elucidate the mechanisms by which this chemical causes liver cancer in animals, and may provide information to assist in extrapolation of the experimental data to humans.
- Our investigators found that renal tube injury caused by chloroform was present in rodents only at doses that resulted in increased tumor incidence, thereby lending support for a risk assessment approach based on a non-linear mode of action.
- We discovered a new pathway by which certain trihalomethanes (THMs) cause cancer in laboratory animals. Our findings reveal that the metabolism of THMs containing bromine produces highly reactive metabolites that damage DNA and cause gene mutations. Interestingly, this new genotoxic pathway does not appear to occur with chloroform, a THM that lacks bromine. The metabolic pathway involves the enzyme glutathione-s-transferase in rodents. Because an analogous enzyme is found in humans, a similar pathway is likely to be active in people.
- In a chronic exposure study in which rats and mice were exposed to bromate in drinking water, we found that bromate causes cancer in the male rat at 3 sites: the kidney, thyroid, and mesothelium. EPA used these results in its decision to maintain the MCLG for bromate at zero for the final Stage 1 DBP rule.
- http://www.epa.gov/NHEERL/research/drinking_water.html
3. Water and Sanitation
- Water-related diseases are the most common cause of illness and death among poor people in developing countries. According to the World Health Organization,1.6 million deaths per year can be attributed to unsafe water, poor sanitation, and lack of hygiene (1).
- An estimated 1.1 billion people do not have access to an improved water source * (2). Many more obtain their drinking water from improved but microbiologically unsafe sources.
- An estimated 2.6 billion people — half of the developing world — lack access to adequate sanitation (almost 40% of the world’s population) (3-4).
- Unsafe drinking water, inadequate availability of water for hygiene and lack of access to sanitation together contribute to about 88% of deaths from diarrheal diseases, or more than 1.5 million of the 1.9 million children younger than 5 years of age who perish from diarrhea each year, mostly in developing countries. This amounts to 18% of all the deaths of children under the age of five and means that more than 5,000 children are dying every day as a result of diarrheal diseases (13).
- Improved water sources reduce diarrhea morbidity by 21%; improved sanitation reduces diarrhea morbidity by 37.5%; and the simple act of washing hands at critical times can reduce the number of diarrhea cases by as much as 35%. Improvement of drinking-water quality, such as point-of-use disinfection, would lead to a 45% reduction of diarrhea episodes (1).
- According to the United Nations Millennium Development Goals Report, regions with the lowest coverage of "improved" sanitation in 2004 were sub-Saharan Africa (37%), Southern Asia (38%) and Eastern Asia (45%) (5).
- In 2004, more than three out of every five rural people, over 2 billion, did not have access to a basic sanitation facility (6).
- Worldwide, millions of people are infected with neglected tropical diseases (NTDs), many of which are water and/or hygiene-related, such as Guinea Worm Disease, Buruli Ulcer, Trachoma, and Schistosomiasis. These diseases are most often found in places with unsafe drinking water, poor sanitation, and insufficient hygiene practices (7-8).
- Worldwide, soil-transmitted helminths infect more than one billion people due to a lack of adequate sanitation (9).
- Guinea Worm Disease (GWD) is an extremely painful parasitic infection spread through contaminated drinking water. GWD is characterized by thread-like worms slowly emerging from the human body through blisters. Infection affects poor communities in remote parts of Africa that do not have safe water to drink. In 2007, over 9,500 cases of Guinea Worm Disease were reported. Most of those cases were from Sudan (61%) and Ghana (35%) (10).
- Trachoma is the world’s leading cause of preventable blindness and results from poor hygiene and sanitation. Approximately 41 million people suffer from active trachoma and nearly 10 million people are visually impaired or irreversibly blind as a result of trachoma (11). Trachoma infection can be prevented through increased facial cleanliness with soap and clean water, and improved sanitation.
- According to the United Nations and UNICEF, one in five girls of primary-school age are not in school, compared to one in six boys. One factor accounting for this difference is the lack of sanitation facilities for girls reaching puberty. Girls are also more likely to be responsible for collecting water for their family, making it difficult for them to attend school during school hours (5, 12). The installation of toilets and latrines may enable school children, especially menstruating girls, to further their education by remaining in the school system.
- In order to meet the
United Nations' Millennium Development Goal
(PDF, 2.31 mb, 21 pages) to halve the proportion of
people without sustainable access to improved
drinking water and basic sanitation by 2015:
- An estimated 1.1 billion people will need to gain access to an improved water source.
- An estimated 1.6 billion people will need to gain access to basic sanitation (accounting for expected population growth) (6).
- Even if the
United Nations' Millennium Development Goal
(PDF, 2.31 mb, 21 pages) for improved drinking water
and basic sanitation is reached by 2015, it will
still leave:
- An estimated 790 million people (11% of the world’s population) without access to an improved water supply.
- An estimated 1.8 billion people (25% of the world’s population) without access to adequate sanitation (6).
* An improved water source is defined as water that is supplied through a household connection, public standpipe, borehole well, protected dug well, protected spring, or rainwater collection.
1. UN Millennium Project.
Health, Dignity, and Development: What Will it Take?
Available at
http://www.unmillenniumproject.org/documents/WaterComplete-lowres.pdf.
2. World Health
Organization. Meeting the MDG Drinking Water and
Sanitation Target: A Mid-Term Assessment of Progress.
Available at
http://www.who.int/water_sanitation_health/monitoring/jmp2004/en/index.html.
3. The United Nations
Department of Economic and Social Affairs.
International Year of Sanitation: Sanitation is Vital
for Human Health. Available at
http://esa.un.org/iys/health.shtml.
4. U.S. Census Bureau.
International Programs Center: Population Clocks.
Available at
http://www.census.gov/ipc/www/.
5. The United Nations.
Millennium Development Goals Report 2007. Available at
http://www.un.org/millenniumgoals/pdf/mdg2007.pdf.
6. World Health
Organization and UNICEF. Meeting the MDG Drinking Water
and Sanitation Target: The Urban and Rural Challenge of
the Decade. Available at
http://www.who.int/water_sanitation_health/monitoring/jmpfinal.pdf.
7. World Health
Organization. Neglected Tropical Diseases, Hidden
Successes, Emerging Opportunities. Available at
http://whqlibdoc.who.int/hq/2006/WHO_CDS_NTD_2006.2_eng.pdf.
8. Hotez PJ, Molyneux DH,
Fenwick A, Ottesen E, Ehrlich Sachs S, Sachs JD.
Incorporating a rapid-impact package for neglected
tropical diseases with programs for HIV/AIDS,
tuberculosis, malaria. PLoS Med 2006;3(5):e102.
Available at
http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371%2Fjournal.pmed.0030102
.
9. World Health
Organization. Soil-Transmitted Helminths. Available at http://www.who.int/intestinal_worms/en/index.html.
10. The Carter Center.
Distribution by Country of 9,570 Cases of Dracunculiasis
Reported During 2007. Available at
http://www.cartercenter.org/resources/pdfs/health/
guinea_worm/guinea_worm_cases_country_2007.pdf.
11. International
Trachoma Initiative. What is Trachoma? Available at
http://www.trachoma.org/core/sub.php?cat=trachoma&id=trachoma.
12. UNICEF and IRC.
Water Sanitation and Hygiene Education for Schools:
Roundtable Proceedings and Framework for Action.
Available at
http://esa.un.org/iys/docs/san_lib_docs/SSHE_OxfordRoundTable.pdf.
13. UNICEF.
Progress for Children: A Report Card on Water and
Sanitation. Number 5, September 2006. Available at
http://www.unicef.org/publications/files/Progress_for_Children_No._5_-_English.pdf
(PDF, 1.2 mb, 36 pages)
