In Diagnosis: Mercury, Dr Hightower retraces her investigation into the modern prevalence of mercury poisoning, revealing how political calculations, dubious studies, and industry lobbyists endanger our health. While mercury is a naturally occurring element, she learns there's much that is unnatural about this poison's prevalence in our seafood. Mercury is pumped into the air by coal-fired power plants and settles in our rivers and oceans, and has been dumped into our waterways by industry. It accumulates in the fish we eat, and ultimately in our own bodies. Yet government agencies and lawmakers have been slow to regulate pollution or even alert consumers.