Where do waterborne diseases rank in causing human health problems?

The lack of clean water resources and sanitation facilities looms as one of the most serious environmental health problems faced today by a large fraction of the world's population, especially those living in developing regions. The onset of waterborne diseases in water is enormous and largely attributed to the fact that the World Health Organization (WHO) has estimated that 1.1 billion people globally lack basic access to drinking water resources, while 2.4 billion people have inadequate sanitation facilities, which clearly accounts for many water-related acute and chronic diseases. Some 3.4 million people, many of them young children, die each year from water-borne diseases, such as intestinal diarrhea (cholera, typhoid fever, and dysentery), caused by microbially-contaminated water supplies that are linked to deficient or non-existent sanitation and sewage disposal facilities.


Globally, water-borne diseases are the second leading cause of death in children below the age of five years, while childhood mortality rates from acute respiratory infections rank first. Around the world, water supply and sanitation facilities are rapidly deteriorating and currently are operating at a fraction of their installed capacity.

This situation is particularly serious in many urban regions of developing countries in Asia, Africa, and Latin America where the poor have very limited access to clean water supplies and sanitation facilities, which pose infectious disease risks to the population, especially among infants and young children. This situation is often more pronounced in rural areas, where the problem of water resources and inadequate sanitation facilities still largely remains to be solved.

Added to this is the rapid industrialization of many developing regions, where in the past few decades water contamination by toxic chemicals and hazardous wastes has aggravated an already serious water pollution problem. Many freshwater streams and lakes around the world have been contaminated with industrial discharges and agricultural runoffs that carry a large variety of toxic chemical substances and hazardous wastes. Many contaminated water sources contain a number of heavy metals, pesticides, and other agricultural chemicals, along with persistent organic pollutants (POPs), many of which remain in the environment for long periods of time and bioaccumulate in the food web, causing many acute and chronic diseases, ranging from severe skin and liver disorders to developmental abnormalities and human cancer. B. The Hemispheric Picture: In a report based on the Meeting of Environment Ministers of the Americas, held in Montreal, Canada on March 29 - 30, 2001, which represented 33 countries in the Western 2 Hemisphere, the environmental threats to public health from contaminated drinking water was summarized as follows:

"Although important progress has been made in recent years, approximately 90 million people in the Americas still do not have ready access to water. Many of those who do have the benefit of being connected to a water source, drink water that can make them sick."

Threats to water quality can be biological and chemical. About 300 million people in the Americas are at risk of contracting serious diseases such as cholera, typhoid fever, and viral hepatitis. Parasites such as Giardia and Cryptosporidium are also a serious threat, particularly in developing countries. Biological and chemical contaminants enter source waters mainly through the discharge of human, animal, and industrial wastes.

In Latin America and the Caribbean less than 12% of collected wastewater is treated. This means that enormous amounts of raw sewage, along with industrial effluents and run-off water contaminate the ground and surface water sources needed for public water supplies. It is estimated that a reduction in the incidence of certain bacteriological diseases of up to 80% could be achieved through effective water source protection from raw sewage. Even where most people have access to treated water, there is an ever-present risk of an outbreak of waterborne diseases or other human illnesses from direct ingestion of, or exposure to, contaminated water or the consumption of any foods so contaminated by water. In Canada, mostly in small towns and villages, many "boil water" advisories are regularly issued over concerns about the microbiological safety of the water.

The threat from waterborne disease was highlighted in the spring of 2000 when the spread of E. Coli bacteria in the drinking water supply of a small town resulted in several deaths and a large number of ill people. The disparity in the water supply is also an issue. Poor people are less likely to be connected to regular sources of water supply and often are forced to purchase highly-priced poor quality water from vendors. The high cost of water and lack of quality are generally responsible for the low level of personal hygiene and the associated spread of communicable diseases, and the high prevalence of water-related diseases. Inequities are also visible between water supply coverage in urban and rural populations.

A recent global assessment carried out by WHO-PAHO-UNICEF indicates that in most developing countries the best-served rural dweller is much worse off than the worst-served urban dweller. Insufficient and ineffective management of surface and coastal waters also has important detrimental impacts on the potential for rivers and beaches to be used for bathing, swimming, and other recreational activities. Not only does this cause 3 problems to public health, but it can also be responsible for the loss of revenue from tourism." II. Summary of Water-Related Diseases Worldwide: · Bacterial Diseases: According to WHO and the US Centers for Disease Control and Prevention (CDC), over 2 billion people, mostly living in developing countries, are at elevated risk of water-related bacterial diseases.

While there are many illnesses that may be identified in this category, the major water-related diseases include acute dehydrating diarrhea (cholera), abdominal illness (typhoid fever), acute diarrhea (dysentery), and chronic diarrhea (Brainerd diarrhea). The following is a more precise description of these culprits...

  • Cryptosporidiosis: In the past two decades, in many regions of the world, including the United States, a common water-related diarrhea disease that is increasingly been recognized as a major public health problem is cryptosporidiosis, caused by a microscopic parasite (Cryptosporidium). It is generally found in drinking water, swimming pools, and recreational streams that have been accidentally contaminated by human fecal wastes.
  • Giardia: Another increasingly common water-related diarrhea disease around the world, including the United States, is giardiasis, which is caused by a one-celled microscopic parasite (Giardia). Similar to the spread of cryptosporidium in the environment, giardia is transmitted by discharges of fecal wastes into the water, food, soil, and other surfaces, and therefore the preventative hygienic measures that are being recommended to lower the overall incidence of the former disease applies here equally well.
  • Malaria: One of the most serious vector-borne diseases in the world today is malaria. It occurs in many tropical regions of the world, such as Central and South Africa, Hispaniola, the sub-Saharan region of Africa (where the largest incidences are annually reported), the Indian subcontinent, Southeast Asia, the Middle East and Oceania. It is a water-related disease since it is caused by four subspecies of microscopic parasites (Plasmodium) carried by female Anopheles mosquitoes that breed its larvae in stagnant waters and storage reservoirs in warm climates.
  • Malarial Incidence: Each year, 300 to 500 million people contract malaria worldwide, of which 1.5 to 2.7 million people die from the disease, the overwhelming majority (90%) of them children below the age of 5 years. Since the 1970s, there has been a resurgence of malaria in different regions of the world, partially due to the rapid formation of resistant parasites to malaria-preventing drugs, such as chloroquine and other quinoline products. In addition, significant increases in the incidence of malaria in recent years have been caused by the construction of dams, intensified irrigation systems, and other water-related projects, which have become new mosquito breeding sites in many developing regions.
  • Schistosomiasis: It is estimated that 200 million people worldwide are infected with schistosomiasis, with another 2 billion people in some 74 countries are at elevated risk from this debilitating water-borne disease. Schistosomiasis (sometimes known as bilharzia) is caused by parasitic worms (Schistosoma) when human beings come into contact with certain types of snails that harbor these parasites in contaminated fresh 4 water. The main factor in the proliferation of this disease is when human fecal wastes are dumped in freshwater sources.

The problems of water pollution and drinking water contamination in the two North American countries tend to be similar in nature, since the types of industrial and municipal discharges, disposal of hazardous wastes, and agricultural runoffs are not markedly different. The chemical and biological contaminants in drinking water that have serious potential impacts on human health are numerous.

In recent years, several water-borne infectious diseases outbreaks have occurred in the United States and Canada that were caused by parasites found in contaminated rivers and lakes. These include Cryptosporidium and Giardia, which enter surface waters through improper sewage disposal and animal wastes. · The extensive chlorination in the United States and Canada to destroy pathogenic bacteria in drinking water supplies has led to an even larger problem; the formation of disinfectant by-products, such as halogenated hydrocarbons. One class of these halogen-containing organic 7 compounds -- trihalomethanes (e.g., chloroform) -- pose long-term health impacts on the general population, such as liver, kidney, central nervous system disorders and may pose an increased risk of contracting cancer.

The widespread use of the fuel additive MTBE in the United States has led to its increasing presence in many surfaces and groundwater sources in the country. While the long-term toxicity of MBTE has been documented, a drinking water standard for this pervasive contaminant has not been established as yet by the United States Environmental Protection Agency. Drinking water sources may also contain radioactive substances, such as Radium 226/228 and a variety of beta-emitting minerals found in underground aquifers. These contaminants pose cancer risks to individuals who ingest radioactive sources of drinking water over a long period. In addition, radon gas in the soil can dissolve and accumulate in groundwater posing a health risk to communities that ingest such contaminated sources of water. Radioactive radon has been shown in recent years to be a potentially cancer-causing substance.

Worldwide, dirty water will continue to be the cause of numerous diseases and rank second only to poor nutrition in causing human suffering and death. Poor nutrition, poor hygiene, and poor sanitation often go hand-in-hand with an inadequate supply of good quality water, especially in the highly-populated developing countries. Studies have estimated that there are as many as 4 billion cases of diarrhea worldwide each year due to consumption of contaminated water and that 2.2 million people die each year from diarrhea diseases. And until the quality of the water is increased, these waterborne disease conditions will likely remain.

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