I agree. This isn’t a rational discussion about public health, epidemiology and toxicology.
This is really a expression of fear that in today’s technological society so much of what affects us --what goes right into our bodies, even in something as simple and wholesome as a clean glass of water – is decided on by mysterious unknown people thousands of miles away for reasons that we really can’t understand. And put that way, the fear is at least a little understandable.
I think the best response is something like “It really is kind of scary that there’s invisible chemicals in our drinking water. Sure sounds bad. But based on the people I met who were majoring in Public Health, I think we don’t need to worry about their good intentions. If they say it’s helping us, I believe them.”