It is one of the most toxic substances known to man and has been used to poison kings, emperors and even prize winning racehorses. But scientists have discovered one small population of people living in a remote part of the Andes in north west Argentina who have developed some resistance to arsenic. They have found that over thousands of years the local inhabitants there have developed a genetic ability to metabolise the arsenic to reduce the impact it has on their bodies. Local women in San Antonio de los Cobres in the Andes (pictutred above) carry a genetic variant that gives them greater tolerance of the poison arsenic by helping them to metabolise the element more efficiently . Worldwide arsenic poisoning caused by contaminated water and food is thought to harm more than 137 million people. Even low levels of arsenic poisoning can cause damage to the lungs, heart, kidneys and liver, leading to cancer, heart disease and diabetes. Napoleon Bonaparte’s mysterious death has generated a host of murder conspiracy theories over the years. The Emperor was said to have died from stomach cancer. The physician who led the autopsy found evidence of a stomach ulcer but some people said it was the most convenient explanation for the British, who wanted to avoid criticism over their care of the Emperor. Napoleon's father died of stomach cancer. In 1955 the diaries of the leader's valet were published, which included the description of bed-bound Napoleon months before his death. Based on the description, scientists put forward other theories as to why he died - which included arsenic poisoning. Arsenic was used as a poison during the era because it was undetectable when administered over a long period. It was noted in a later book that Napoleon's body was found to be remarkably well preserved when moved in 1840 and arsenic is a preservative. In 2007 a toxicologist said he found mineral arsenic in napoleon's hair shafts, which supported the theory that he was murdered. The wallpaper used in the emperors bedroom on St Helena also contained high levels of arsenic compound used by British manufacturers as a dye. It has been suspected that if the wallpaper got hot it might have emitted the poisonous gas arsine, but other scientists think the poison would have had to be consumed internally - or that the leader really did die of cancer. In higher doses it can damage the immune system, trigger bleeding, convulsions and eventually coma and death. However, people living in the sparsely populated area around San Antonio de los Cobres, a village high in the Andes in the Puna region of Argentina, appear to have developed a way of dealing with the poison more effectively. For close to 11,000 years the indigenous population there, who are descended from the Atacameños people, have been drinking water contaminated with arsenic. Dr Karin Broberg, a researcher in environmental medicine at Lunds University in Sweden, and her colleagues found that some time between 7,000 and 10,000 years ago, the local populations in the region underwent some genetic changes that have given a greater resistance to arsenic. They found that the people living in the area are able to consume more than 20 times the levels that are currently considered to be a safe expsoure level. Dr Broberg told MailOnline: 'The arsenic is in the volcanic bedrock and at some places in higher concentrations. 'The arsenic has then been released into springs that are used for drinking water purposes. 'Yet the people living in this area have a relatively high arsenic exposure and a efficient and less toxic metabolism.' Dr Broberg and her colleagues, whose work is published in the journal Molecular Biology and Evolution, studied the genome of 124 Andean women living around the village of San Antonio de los Cobres. They also screened the women for their ability to metabolise arsenic by looking for levels of the mettaliod element in their urine. They pinpointed a key set of mutations in their genes that appear to have given them the ability to tolerate far high levels of arsenic exposure. They found one gene in particular - AS3MT, which is thought to play a role in arsenic metabolism - occurred in far higher frequencies compared to populations living in Columbia and Peru. The village of San Antonio de los Cobres is located in a remote part of the Andes in north west Argentina . Arsenic was commonly used as an ingredient in medicine and cosmetics but also was often used as a poison . They estimate that the increase in this gene variant occurred around 10,000 to 7,000 year ago based on high levels of arsenic found in the hair of a mummy excavated in the region. Other populations around the world are known to carry this particular AS3MT gene variant, with the highest frequencies in Peruvians, Native Americans and Vietnam. The researchers say this is an example of human adaptation to an environmental poison - something that is often seen in animals such as rats. Arsenic contamination can occur as a result of industrial activity such as gold mining but also occurs naturally. During the Elizabethan era arsenic trioxide was used to create makeup for women's faces. It was also used to make poisonous gas lewisite during the First World War, which caused its victims to blister before they died. The bedrock in the area around San Antonio de los Cobres (shown above) contains high levels of arsenic . The poison was also implicated in the causing maddness of King George III and the death of Napoleon Bonaparte. In 2008 the authorities in China also confirmed that Emperoro Guangxu, who was the second last emperor to rule the country, was poisoned with a massive dose of arsenic. King Faisal I of iraq was also found to have suffered symptoms of arsenic poisoning while in Switzerland in 1993 and South American independence leader Simon bolivar is thought to have died due to chronic arsenic poisoning. The successful race horse Phar Lap was also found to have died after a massive dose of arsenic. Dr Broberg said although the people in San Antonio de los Cobres were not consuming anything near these levels, they did have more resistance than other populations. she said: 'These levels do not result in acute toxicity but arsenic slowly damages cells and tissues and can result in later diseases. 'It is important to emphasis that the people living in this area also can get adverse effects of arsenic, as arsenic is very potent, despite having a more efficient metabolism. 'Their potential degree of tolerance is something we want to look into.'
Locals in San Antonio de los Cobres, Argentina have resistance to poison . Their water supply is contaminated with arsenic 20 times level deemed safe . Scientists at Lund University in Sweden conducted genetic tests on locals . Inhabitants were found to have genetic variation that metabolises arsenic . The villages can still be poisoned by high levels but can tolerate low levels . Arsenic poisoning is thought to harm more than 137 million people globally .