There is an obvious survival advantage to the emotion of disgust – we should fear putting unhealthy, tainted, contaminated, or poisonous substances into our bodies. Emotions, however, are a double-edged sword. They are an effective evolutionary mechanism for motivating creatures to engage in certain behavior, but they also tend to be crude and undiscriminating – inadequate to deal with our complex modern society.
A dispassionate consideration of objective scientific evidence is the optimal strategy for deciding on which foods and substances are safe to consume, but it is far easier to scare people about toxins than to reassure them with data. We see this frequently with the anti-vaccine movement, and also with anti-fluoridation attitudes. It is easy to scare people with the idea that there are “chemicals” in our drinking water.
One company, San Diego Pure Water, seems to have made such scaremongering into a marketing strategy. Their website is full of articles and videos claiming that fluoride is the “the greatest fraud that has ever been perpetrated.”