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Arsenic can be exposed to the human body through inhalation, ingestion and dermal absorption. Inhalation takes place through respiration whereas ingestion occurs by the digestion of contaminated water and food. This latest is the primary route of exposure. Dermal absorption takes place due to the direct contact of arsenic compounds with the skin. Whatever the sources and modes of exposure, the total impact depends upon the duration of absorption, excretion and thereby retention in the body, the arsenic substance in question, the concentration, and furthermore the chemical nature of the intake process.

Arsenic is not a physiological constituent of human body and no firm evidence is found to show that arsenic in any form is essential to the human body. Some animal studies suggest according to [USEPA: Technologies and Costs for Removal of Arsenic from Drinking Water, Report, Dec. 2000.] that Arsenic compounds in low concentration may be an essential nutrient for some animals. Arsenic compounds have formerly been used as a medical treatment of maladies like Leukaemia, Syphilis and Psoriasis, but most not with any profound effect. Cf. Appendix 5: Cures, Medical, and Industrial Usage of Arsenic, page 64. Today almost all medical usages have been replaces by other modern drugs. The United States Environmental Protection Agency (USEPA) has classified arsenic as a human carcinogen.

The symptoms of the adverse health effects can be divided up into the acute health effects and the chronic effects. The former are those that occur directly after a brief exposure of high concentrations. The chronic effects occur gradually over time, and develop after a long term exposure of low levels of arsenic concentrations. Such effects are often difficult to obtain an overview over, in order to e.g. calculate the cost for the population in Nepal, since a variety of other diseases disturbs the health picture of the individual. NEWAH is in the process of combining statistical data of cancer incidents with high concentrations of total Arsenic intakes in the affected district of Nepal. [Kim R. Adamsen: Calculation Cancer Incidents, Internal spreadsheet and notes, 2001.]

In 0, page 56, the acute effects found in the literature is listed, similarly Appendix 4:, page 61, lists the chronic effects. The medical cures after high Arsenic intakes, the former medical usages and the industrial usages are listed in Appendix 5:, page 64.

Acute Levels

Different severe adverse health effects have been reported in the literature. The acute poisoning of arsenic involves effects on the central nervous system, leading to coma and for doses from 60 to 180 mg, for an adult human being, to death. It can cause gastrointestinal and cardiac damage and can affect the respiratory tract, the skin of the body, and numerous other severe health problems as reported in 0

Arsine gas, which usually is not the problem talking about drinking water, except when using certain measuring methods, is even more poisonous than solid As compounds, with a threshold limit value of 50 ppb. 20 – 50 ppb of arsenic gas inhaled for 30 minutes is lethal. Inorganic arsenic compounds are also extremely toxic. USEPA has established a reference dose of 0.3 mg/kg/d for inorganic arsenic compounds.

Health Effects of Chronic Contamination

Chronic doses can cause vascular disorders, such as black - foot disease. Epidemiological studies in Chile and Taiwan have linked arsenic with skin and lung cancer. Sodium arsenate and arsenite have shown several tetratogenic potentials in different mammalian species. Various manifestations, such as hyperpigmentation, keratoses, and lung cancer have been observed where high occupational exposure to arsenic has occurred. Cf. Appendix 4:, page 61, for a throughout list.

When arsenic compounds are introduced into the body, it will to some extend accumulate until an injurious state is reached. Supposing these arsenic compounds are not expelled, it can easily be calculated that it takes 60.000 / 50 = 3.3 years to reach a deadly concentration, if an adult drinks 1 litre of water containing a 50 µg/l level of arsenic compounds. However this calculation is only shown here in order to indicate and give an idea of the minimum number of years to reach a deadly dose. Arsenic compounds are expelled through e.g. urine and faeces. The amount expelled given a certain dose have not been measured in Nepal, however the concentration in fingernails and hair is being measured for the time being by the leading scientific laboratory in Nepal: Environmental and Public Health Organisation (Enpho). The chronic poisoning of arsenic compounds can therefore be considered as a slow killer, and it is difficult to compare the health effects to e.g. more acute microbiological contaminations. No direct data is available for the long term arsenic effects on the Nepali population to date. [Kim R. Adamsen: The Arsenic Concentration Impact on the Nepali Population, Internal NEWAH rapport, 2001.] NEWAH is working on this in a co-operation with the Tribuwan University, Kathmandu. ?? Is it there the professor is ?

After the graduate build up in tissues, organs, hair and nails the first symptoms are different sorts of skin disorders, leading to dark spots, particularly on the extremities. Later the skin problems become worse, and leads to open sores all over the body. ?? Put in picture of cancer on leg by E. Wilson. Severe disorders, such as gangrene, melanoma, black tongue, nausea, vomiting, stomach pain, partial paralysis, and blindness can also in time occur.

The chemical is also believed to cause several types of cancer in the internal organs. USEPA has classified inorganic arsenic compounds as a class A carcinogen. Prolonged exposure to arsenic is believed to cause tumours in the bladder, kidney, liver and lungs, and depending on the dose these adverse effects do not manifest in the exposed individual until after several years of exposure. See Appendix 4: Pathological Picture of Chronic effects of A, page 61 for a throughout list of maladies. [Kim R. Adamsen: Medical Effects of Arsenic Ingestion, Internal note, 2002.]

Compared to Bangladesh and India, which are known to have high arsenic concentrations in the groundwater the Nepali incidence rates of liver cancer, lung cancer, melanoma of skin, bladder cancer, and kidney cancer are all higher, giving reason to believe, that the arsenic problem in Nepal is severe. This is naturally not a “proof”, since the mentioned cancer types can originate from other sources. Lung cancer e.g. also comes from smoking.

NEWAH regards the chronic arsenic issue with outmost seriousness, and is certainly not happy to have been able to provide over 6000 wells to unsuspecting villagers, with the possibility of these supplies having such serious health effects.

Taken from the report "The Arsenic Contamination of the Drinking Water in Nepal" by Anil Pokhrel, head of technical section of NEWAH & Kim Rud Adamsen, hydrology adviser of NEWAH

Download the whole report in MSWord format.