It's also important to clarify that the lead exposure of previous generations didn't doom humanity or anything. Part of the reason these issues take so long to address is the considerable uncertainty of how small changes in the human environment interact with our very concept of self. This is a tricky question to get good answers to, but we've gotten answers before, and are likely to get good answers again.
This is a pretty good first step into the issue by a reasonable person, but basically, we know that almost all plastics function as endocrine disruptors and it turns out you probably don't want anything in your body disrupted accidentally. It's not clear whether there exists a safe amount of plastics, but it's very likely we're over it, and when you see continual decline of average sperm counts, this is probably the best guess why. It's also plausibly related to the current obesity epidemic, which has impacted both men and women substantially.
There's a pretty salient public health crisis at the moment, but public health is an important, continual process. Let's not forget to keep learning, or underestimate the importance of public health.