Arsenic is naturally higher in some of the NWT rivers, lakes and soils because of local geology... However, through decades of gold mining operations at Giant, Con and Negus mines in Yellowknife, a toxic form of arsenic, called arsenic trioxide in the form of dust, was released into the environment. In the environment, arsenic is found in two forms: Organic (less harmful); and Inorganic (toxic). Organic arsenic is commonly found in fish and shellfish.  YKHEMP results found that local fish are safe to eat. Inorganic arsenic is commonly found in some rice and rice products, seaweed, berries, and some mushrooms. Some arsenic is found in cigarettes.