Every generation has some product/ingredient that they didn’t know was dangerous at the time: tobacco, lead, asbestos, etc. What is that item for this generation?
Automobiles. Especially in the USA they are causing a public health crisis, environmental crisis, qualify of life crisis. I grew up loving them and they have uses but I'm fully convinced in the future they should be a luxury used for specific tasks or trips rather than the only form of transportation available.