Where is arsenic a problem?
The following is a list of countries that have identified areas of high arsenic in their water resources. Some are naturally occurring in groundwater, some come from geothermal sources (such as hot springs) and some are affected by mining.
Countries that are not listed may have problems that have either not yet been recognized, or have not been reported in the literature that I have read.
The magnitude of the problem in Bangladesh brought this issue to worldwide attention. According to some estimates, arsenic in drinking water will cause 200,000 – 270,000 deaths from cancer in that country alone.
Let’s look at the situation in Bangladesh. About 30,000,000 people are estimated to be consuming arsenic contaminated drinking water (>50 ppb or mg/L) in that country. This is a huge public health disaster. Way bigger than any other environmental catastrophe. And worst of all, it happened because people were trying to make the water safer to drink there.
Many people in developing nations die every year due to illnesses spread by water. Diseases like cholera, typhoid, diarrhea and many others kill millions of people each year. To decrease the incidence of disease in Bangladesh about 30 years ago, aid agencies, and later private companies, started replacing shallow dug wells that were contaminated with surface water (and bacteria from fecal material) with deeper bedrock wells. Unfortunately, due to the geological formations in the area, the wells in many regions had high arsenic levels. It was not until the 1990s that the medical problems there were finally linked to the water.
Taiwan is another area that has been very hard-hit by arsenic poisoning through drinking water.
The following map from the USGS shows areas in the United States where groundwater samples had high arsenic levels. You can see that in Maine some samples were very high. Where there are no symbols, there is no information, so the problem may be even bigger than it seems based on this map.