Arsenic is a threat in many parts of the world. It represents a problem in the drinking water supply because it is toxic at low levels and is a known carcinogenic agent. It is increasingly proven that high levels of arsenic in the drinking water supply can aggravate human health.
Arsenic-contaminated groundwater threatens the health of millions of people worldwide. The problem occurred in arsenic-rich rocks in river basins that filter potable water that is pumped to the surface through millions of tubular wells.
Elevated levels of arsenic in drinking water have reached the point at which the World Health Organization describes arsenic contamination of water as one of the most serious poisonings. An FAO report shows that arsenic in groundwater may be an even more insidious threat. An important review of studies from different parts of the world. The report concludes that people can be exposed to arsenic not only by drinking water but also indirectly by food crops irrigated with contaminated groundwater.
Arsenic may penetrate the water supply from natural deposits in the land or industrial and agricultural pollution. It is generally believed that natural arsenic dissolves in some rock formations when groundwater levels decline significantly. Some industries worldwide discharge thousands of pounds of arsenic into the environment each year. Once released, arsenic stays in the environment for an extended period. Arsenic is removed from the air through rain, snow, and progressive compaction. Once on land or in surface water, arsenic may slowly enter groundwater.
High levels of arsenic in private wells can arise from certain arsenic-containing fertilizers used in the past or from industrial waste. This may also indicate poor good construction or excessive use of chemical fertilizers or herbicides in the past.
As a member of the nitrogen family, arsenic is a highly toxic, odorless, insipid semi-metal found naturally in rocks and soil. It can be combined with other elements to form organic and inorganic arsenic compounds, which are typically more toxic and more common in water.
The World Health Organization says that consuming drinking water containing arsenic at a rate of more than 10 micrograms/liter for a long period can lead to arsenic poisoning which is a chronic condition that leads to kidney or bladder cancer.
Arsenic is responsible for kidney cancer. One possibility, say the researchers, is that kidney cancer, by decreasing the ability of the kidneys to filter out body waste, leads to increased levels of arsenic in the urine.
Generally, higher levels of arsenic in urine are associated with an increased risk of kidney cancer. But the relationship seems to be stronger among people who have impaired kidney function.
It is suggested that exposure to arsenic may cause high blood pressure or kidney disease in certain individuals, which in turn causes kidney cancer. However, impaired renal function may allow higher concentrations of arsenic to accumulate in the urine.
Arsenic is a known cause of bladder cancer, a link that relies heavily on the observations of highly exposed individuals. A large population-based case-control study indicates an increased risk of bladder cancer in people exposed to low-to-moderate levels of arsenic through drinking water. The association was strongest among heavy water users who relied on shallow dugouts that were prevalent during the years of use of arsenic-based pesticides.