2. Health and social problems associated with arsenic

High doses of arsenic cause acute toxic effects, disrupt the cardiovascular and nervous systems and quickly lead to death. Long term ingestion of low levels of arsenic for many years produces a range of symptoms which together are known as arsenicosis, and can lead to cancers and death.

Human exposure to arsenic can take place through ingestion, inhalation or skin adsorption; however, ingestion is the predominant form of arsenic intake, and there is no significant risk from using arsenic contaminated water for washing. The inorganic forms typical in drinking water, are much more toxic than the organic ones that are present in sea food, which can be quickly discharged from the body.

The first visible symptoms of chronic arsenic ingestion are abnormal black-brown skin pigmentation known as melanosis and hardening of palms and soles known as keratosis. If arsenic intake is continued, skin de-pigmentation develops into white spots that look like raindrops ( leuko-melanosis). Palms and soles thicken and painful cracks emerge ( hyper-keratosis).

Arsenic can disrupt the vascular system leading to gangrene in the legs, (black foot disease) and a correlation has been found between hypertension and arsenic in drinking water.

The US Environmental Protection Agency (USEPA) estimates that two out of 1,000 people who drink water for many years with 50 mg/L of arsenic will get skin cancer. The International Agency for Research on cancer has also identified arsenic in drinking water as a cause of bladder and lung cancer.

How quickly symptoms develop depends on the chemical composition of the water and on nutrition. The only remedy is either to switch to arsenic-free drinking water or to remove it from the water before it is used for drinking or cooking. People affected by arsenic poisoning may also face social exclusion. Most of the affected population in Bangladesh and West Bengal live in rural areas. Some estimates say that more than 100,000 people have been identified with arsenic related symptoms, and the fear is that their number will grow exponentially in coming years.