It is one of the most toxic substances known to man and has been used to poison kings, emperors and even prize winning racehorses. 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. 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. 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.