Second Hand Smoke
In each of these cases, scientists themselves have conspired with the leftists to keep the lies alive. To a varying degree. In the BPA instance, not so much. In the case of Global Warming, a lot.
The biggest disaster was the unnecessary ban on the use of DDT. As a result, malaria, which was starting to be put under control by the early 1960’s, became a serious problem again by the late 1970’s.