> Opposition to DDT was focused by the 1962 publication of Rachel Carson's book Silent Spring. It talked about environmental impacts that correlated with the widespread use of DDT in agriculture in the United States, and it questioned the logic of broadcasting potentially dangerous chemicals into the environment with little prior investigation of their environmental and health effects. The book cited claims that DDT and other pesticides caused cancer and that their agricultural use was a threat to wildlife, particularly birds. Although Carson never directly called for an outright ban on the use of DDT, its publication was a seminal event for the environmental movement and resulted in a large public outcry that eventually led, in 1972, to a ban on DDT's agricultural use in the United States. https://en.wikipedia.org/wiki/DDT#History
By the way, you can get Silent Spring for free on https://www.fadedpage.com/showbook.php?pid=20151002 – and it is still very much worth reading; eloquent and poetic while still being factual, informative and balanced. The producers of DDT and other poisons started a smear-campaign after the publication, but it only lead to a Streisand-effect. See also this little clip from her single TV interview: https://www.youtube.com/watch?v=8nriVjC0H8I
You can go back to the 70's.
There was a fascinating amount of experimentation in education when I grew up in the 70's. I went to two rather interesting "experimental" schools — one public, one private. But regardless, there was a Zeitgeist in the 70's both of danger (over-population, pollution) but also of optimism — that we could change course as a society if we wanted.
As an anecdote, I remember a fascinating visitor when I was in elementary school. A man showed up in our class with a fascinating machine that was described as a "computer"! (This was perhaps 1973 or so — it may well have been an analog computer.) The thing was upright and perhaps the size of a Pachinko machine. He explained that you could set some dials to represent perhaps human growth, energy use ... something like that. I mean, I was quite young so I think a lot of it flew over my head — perhaps his audience was generally an older age. In any event it was supposed to calculate ... something ... maybe how many years before we ran our of food or fissile fuel or space on the planet....
Afterword: Sadly, speaking of Zeitgeist, it seems something happened around the close of President Carter's term and when Reagan's presidency began. The Metric System they had taught us in elementary school was out the window. Ha ha, even national markers in the U.S. that had added Metric to the Imperial(?) units would dropped the metric units....