Long before its ill-fated and inevitably short-lived use in make-up, arsenic has been recognised as a deadly poison. Widely labelled the King of Poisons, it is fatal when consumed even in relatively low quantities, and prolonged exposure results in a host of serious health complications. Affecting as many as 150 million people worldwide, these conditions, including cancers and keratosis, are clearly demonstrated in places arsenic is present as an environmental contaminant. The ‘Styrian Arsenic eaters’ were a community in which prolonged consumption of low levels of arsenic lead to many of them developing a tolerance to the metalloid. However, the recent discovery of tolerant Andean tribes are the first examples of human genetic resistance not only to arsenic, but to any toxic chemical.
The drinking water of these people living in the Argentinian Andes Mountains was found to contain up to twenty times the Environmental Protection Agency’s maximum contaminant level (0.01ppm), a standard set to avoid the implications of chronic exposure. A study by a team of researchers led by Dr Karin Broberg from Sweden’s Karolina Institute, identified variations in several genes, notably mutations in AS3MT, following a screen of 124 of these Andean women. The AS3MT gene has a key role in arsenic metabolism, and these adaptations are believed to be responsible for their tolerance of such high concentrations by increasing the efficiency at which the consumed arsenic is broken down. Occurring over no short period of time, the improved chance of survival that these mutations provided are thought to have become prevalent in these populations over the last 10’000 years.
There is currently no cure to arsenic poisoning. What is especially promising is the genetic aspect of this discovery, opening a new avenue in terms of scientific research, possibly in the lines of gene therapy, for the treatment of the millions being affected and at risk from arsenic pollution.