And walking along an average pavement is also technically harmful due to the aromatic hydrocarbons/benzenoates, heavy metals etc that are given off from catalitic convertors when not operating at optimum temps (eg. 400c) due to the average car run not giving them enough time to get to working temp (ever smelt a rotten egg smell in or around town when driving...that's why).
Not having a go here shrekfeet, just that not all drugs that you either buy in the shops , or are given by doctors , are always 'safe' . Some are quite the reverse...They are as safe as technology & science know at the time - that is the proviso. Asbestos was safe until our understanding of it improved. So either remove yourself from the grid entirely (however you cannot ultimately remove yourself from the effects of modern day society), trust in what you are told or judge for yourself. Scaremongering helps no-one but does panic those who choose not to check for themselves. It can be as harmful as those substances/products etc we are wanting to reduce/eliminate.
Oh and "back in the day mercury was considered safe" until science defined otherwise (mad hatters!!). What else can we use......