It is far easier to put toxic thoughts in the general public mind than it is to put chemical at toxic level that would spread as far and persist as long.
Whenever there's a physically toxic effect due to a chemical compound in the population, an investigation is immediate. Regulations are verified, enforcement is increased, and the public safety is restored.
Whenever there's a mentally toxic effect due to propaganda against (a chemical for example), the general public tends to disregard previously attained scientifically knowledge, overlook numerous supporting facts as to the actual benign nature of the issue, and the fear and bias spreads and persist.
When we rely on "experts advice" how can we tell who is a genuine interest-free trust-worthy expert? It is hard. I faced such situations myself in the past, and am sure they will come again in the future.
But here's the decisive concept: numbers and relevance.
I already posted in the past on how it is easy to present a chemical as toxic, even though it may be a vitamin without which we surely will die. For the most part, amounts are a crucial piece of information we need to know in order to assess whether something is dangerous or not.
Jow Schwarcz said it clearly and elegantly just yesterday: http://blogs.nature.com/soapboxscience/2013/05/29/the-presence-of-a-chemical-is-not-the-same-as-presence-of-risk/