Water-related diseases

Arsenicosis

Drinking water rich in arsenic over a long period leads to arsenic poisoning or arsenicosis. Many waters contain some arsenic and excessive concentrations are known to naturally occur in some areas. The health effects are generally delayed and the most effective preventive measure is supply of drinking water low in arsenic concentration.

The disease and how it affects people

Arsenicosis is the effect of arsenic poisoning, usually over a long period such as from 5 to 20 years. Drinking arsenic-rich water over a long period results in various health effects including skin problems (such as colour changes on the skin, and hard patches on the palms and soles of the feet), skin cancer, cancers of the bladder, kidney and lung, and diseases of the blood vessels of the legs and feet, and possibly also diabetes, high blood pressure and reproductive disorders.

Absorption of arsenic through the skin is minimal and thus hand-washing, bathing, laundry, etc. with water containing arsenic do not pose human health risks.

In China (Province of Taiwan) exposure to arsenic via drinking-water has been shown to cause a severe disease of the blood vessels, which leads to gangrene, known as ‘black foot disease’. This disease has not been observed in other parts of the world, and it is possible that malnutrition contributes to its development. However, studies in several countries have demonstrated that arsenic causes other, less severe forms of peripheral vascular disease.

The cause

Arsenicosis is caused by the chemical arsenic. Arsenic is a toxic element that has no apparent beneficial health effects for humans.

Natural arsenic salts are present in all waters but usually in only very small amounts. Most waters in the world have natural arsenic concentrations of less than 0.01 mg/litre.

Arsenicosis is caused by exposure over a period of time to arsenic in drinking water. It may also be due to intake of arsenic via food or air. The multiple routes of exposure contribute to chronic poisoning. Arsenic contamination in water may also be due to industrial processes such as those involved in mining, metal refining, and timber treatment. Malnutrition may aggravate the effects of arsenic in blood vessels.

WHO’s Guideline Value for arsenic in drinking water is 0.01 mg /litre. This figure is limited by the ability to analyse low concentrations of arsenic in water.

Distribution

Natural arsenic contamination is a cause for concern in many countries of the world including Argentina, Bangladesh, Chile, China, India, Mexico, Thailand and the United States of America.

Scope of the Problem

Because of the delayed health effects, poor reporting, and low levels of awareness in some communities, the extent of the adverse health problems caused by arsenic in drinking-water is unclear and not well documented. As a result there is no reliable estimate of the extent of the problem worldwide. WHO is presently collecting information in order to make such an estimate.

Case reports on the situation in various countries have been compiled and the arsenic problem in Bangladesh in particular has prompted more intensive monitoring in many other countries. In Bangladesh, 27 % of shallow tube-wells have been shown to have high levels of arsenic (above 0.05mg/l). It has been estimated that 35 – 77 million of the total population of 125 million of Bangladesh are at risk of drinking contaminated water (WHO bulletin, volume 78, (9):page 1096). Approximately 1 in 100 people who drink water containing 0.05 mg arsenic per litre or more for a long period may eventually die from arsenic related cancers.

Interventions

The most important action in affected communities is the prevention of further exposure to arsenic by provision of safe drinking-water. Arsenic-rich water can be used for other purposes such as washing and laundry. In the early stages of arsenicosis, drinking arsenic-free water can reverse some of the effects. Long term solutions for prevention of arsenicosis include:

For provision of safe drinking-water:

• Deeper wells are often less likely to be contaminated.
• Rain water harvesting in areas of high rainfall such as in Bangladesh. Care must be taken that collection systems are adequate and do not present risk of infection or provide breeding sites for mosquitoes.
• Use of arsenic removal systems in households (generally for shorter periods) and before water distribution in piped systems.
• Testing of water for levels of arsenic and informing users.

In order to effectively promote the health of people the following issues should be taken into account:

• Monitoring by health workers – people need to be checked for early signs of arsenicosis – usually skin problems in areas where arsenic in known to occur.
• Health education regarding harmful effects of arsenicosis and how to avoid them.

Health Effects of Drinking Water Contaminants

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Prepared by:
Sandra A. Zaslow and Glenda M. Herman

Extension Housing Specialists

 

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Published by: North Carolina Cooperative Extension ServicePublication Number: HE-393

Last Electronic Revision: March 1996 (JWM)

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People are increasingly concerned about the safety of their drinking water. As improvements in analytical methods allow us to detect impurities at very low concentrations in water, water supplies once considered pure are found to have contaminants. We cannot expect pure water, but we want safe water.

The health effects of some contaminants in drinking water are not well understood, but the presence of contaminants does not mean that your health will be harmed. In North Carolina, drinking water is generally of high quality and free from significant contamination. Public water supplies are tested, and regulated to ensure that our water remains free from unsafe levels of contamination. Small private water supplies, including wells, are not regulated by drinking water standards, and the owner must take steps to test and treat the water as needed to avoid possible health risks.

What is in your drinking water? The only way to know is to have it tested.

Drinking water can become contaminated at the original water source, during treatment, or during distribution to the home.

 

• If your water comes from surface water (river or lake), it can be exposed to acid rain, storm water runoff, pesticide runoff, and industrial waste. This water is cleansed somewhat by exposure to sunlight, aeration, and micro-organisms in the water.
• If your water comes from groundwater (private wells and some public water supplies), it generally takes longer to become contaminated but the natural cleansing process also may take much longer. Groundwater moves slowly and is not exposed to sunlight, aeration, or aerobic (requiring oxygen) micro-organisms. Groundwater can be contaminated by disease-producing pathogens, leachate from landfills and septic systems, careless disposal of hazardous household products, agricultural chemicals, and leaking underground storage tanks.

Possible Health Effects

The levels of contaminants in drinking water are seldom high enough to cause acute (immediate) health effects. Examples of acute health effects are nausea, lung irritation, skin rash, vomiting, dizziness, and even death.

Contaminants are more likely to cause chronic health effects – effects that occur long after repeated exposure to small amounts of a chemical. Examples of chronic health effects include cancer, liver and kidney damage, disorders of the nervous system, damage to the immune system, and birth defects.

Evidence relating chronic health effects to specific drinking water contaminants is limited. In the absence of exact scientific information, scientists predict the likely adverse effects of chemicals in drinking water using human data from clinical reports and epidemiological studies, and laboratory animal studies.

Drinking Water Standards

The Safe Water Drinking Act of 1974 directed the U.S. Environmental Protection Agency (EPA) to ensure that public water systems (systems serving more than 25 people) and noncommunity water systems (hotels, campsites, restau- rants, migrant workers’ encampments, and work sites) meet minimum standards for protecting public health. Its main provisions directed the EPA to establish minimum drinking water standards to limit the amounts of various contaminants found in drinking water. Because of growing concerns about the safety of the water supply, amendments were made to strengthen this law in 1986. These amendments required the EPA to do the following:

• Develop a maximum contaminant level goal (MCLG) and a maximum contarninant level (MCL) for all regulated contaminants. MCLGs are nonenforceable health-based goals and represent the maximum level of a contaminant that is expected not to cause any adverse health effects over a lifetime. MCLs are enforceable contaminant levels. They are set as close to the MCLG as possible and are based on protecting public health within economical and technical reason.
• Increase the number of regulated contaminants to a total of 83 by June, 1989. MCLs must be set for an additional 25 contaminants every 3 years thereafter.
• Set required schedules for water systems to monitor for contaminants in drinking water.
• Identify best available technologies (BATS) for removing excess contaminants from water, based on efficiency, availability, and cost.
• Issue variances and exceptions to systems that cannot comply with MCLs despite the application of BATS, unless an “unreasonable risk” to health exists. “Unreasonable risk” has not yet been defined.
• Provide for public notification when drinking water standards are violated.
• Ban the use of lead pipes, solder, fittings, and flux in public water systems.
• Bolster enforcement of penalties for violators of drinking water standards at the state and local level.
• Provide for protection of groundwater sources.

Contaminants are regulated when they occur in drinking water supplies and are expected to threaten public health. Most levels established by the EPA allow a sufficient margin of safety, but acceptable contaminant levels vary widely among individuals and population groups. For example, high sodium levels, harmless for most people, can be dangerous for the elderly, people with high blood pressure, pregnant women, and people having difficulty in excreting sodium.

North Carolina has adopted EPA standards and the state has responsibility for enforcing drinking water standards.

Risk Assessment

Every day, you can be exposed to combinations of many toxic substances and these substances may interact.

What is in water may represent only a small part of your overall exposure to a specific contaminant. Scientists who investigate how contaminants affect human health get information in several ways. They may study how a toxic substance has affected people in a community over time. In some cases, this can show relationship between exposure to a contaminant and a health effect They may also use animal studies to collect information on the acute and chronic health effects.

Research helps scientists determine toxic doses and levels below which toxic effects are not observed. For noncancer-causing toxic substances, scientists use “acceptable daily intake” to estimate risk. The acceptable daily intake is the amount of a contaminant or toxic substance that humans can consume daily for a lifetime without any known ill effects. It includes a margin of safety. For a cancer-causing substance, no safe level has been set. Toxicity is estimated by calculating a risk estimate, or the concentration of a substance that presents the least acceptable risk. In the case of cancer-causing toxins, regulations are based on a level of risk that is acceptable, not a safe amount or concentration of a substance.

Four Groups of Contaminants

Microbial Pathogens. Pathogens in drinking water are serious health risks. Pathogens are disease-producing micro-organisms, which include bacteria (such as giardia lamblia), viruses, and parasites. They get into drinking water when the water source is contaminated by sewage and animal waste, or when wells are improperly sealed and constructed. They can cause gastroenteritis, salmonella infection, dysentery, shigellosis, hepatitis, and giardiasis (a gastrointestinal infection causing diarrhea, abdominal cramps, and gas). The presence of coliform bacteria, which is generally a harmless bacteria, may indicate other contamination to the drinking water system.

Organics. People worry the most about potentially toxic chemicals and metals in water. Only a few of the toxic organic chemicals that occur drinking water are regulated by drinking water standards. This group of contaminants includes:

• Trihalomthanes (THMs), which are formed when chlorine in treated drinking water combines with naturally occurring organic matter.
• Pesticides, including herbicides, insecticides, and fungicides.
• Volatile organic chemicals (VOCs), which include solvents, degreasers, adhesives, gasoline additives, and fuels additives. Some of the common VOCs are: benzene, trichloroethylene (TCE), styrene, toluene, and vinyl chloride. Possible chronic health effects include cancer, central nervous system disorders, liver and kidney damage, reproductive disorders, and birth defects.

Inorganics. These contaminants include toxic metals like arsenic, barium, chromium, lead, mercury, and silver. These metals can get into your drinking water from natural sources, industrial processes, and the materials used in your plumbing system. Toxic metals are regulated in public water supplies because they can cause acute poisoning, cancer, and other health effects.

Nitrate is another inorganic contaminant. The nitrate in mineral deposits, fertilizers, sewage, and animal wastes can contaminate water. Nitrate has been associated with “blue baby syndrome” in infants.

Radioactive Elements. Radon is a radioactive contaminant that results from the decay of uranium in soils and rocks. It is usually more of a health concern when it enters a home as a soil gas than when it occurs in water supplies. Radon in air is associated with lung cancer.

Summary

As people hear about the possibility of contaminants in their drinking water, they worry about potential health effects. Water supplies once considered to be pure may have various contaminants, often from natural sources. These are usually at levels below those considered to be harmful.

If you are concerned, test your water. For more information on water quality, testing, and treatment, contact the Extension Center or health department in your county or your physician.