d) Arsenic is now recognized to be one of the world’s greatest environmental hazards, threatening the lives of several hundred million people.
b) Naturally occurring arsenic leaches into water from surrounding rocks and once in the water supply it is both toxic and carcinogenic to anyone drinking it.
c) It is colourless and odourless and consequently people use it instead of more obviously polluted surface water.
a) Natural arsenic pollution affects 21 countries across the world sometimes reaching a concentration more than ten times the WHO guidelines.
