Chenicals, especially PCB’s should take pride of place as a causative factor. These estrogen-mimicking chemicals have settled in places like the Arctic and are likely to be released back into the environment with the melting ice – another possible cause of human extinction.
We have known about this ever since the book “Our Stolen Future” came out in the 90’s
Humanity at risk as sperm levels among Western men plummet to record low
Unknown amount of trapped persistent organic pollutants poses threat to marine life and humans as temperatures rise