As another commenter pointed out, plasticizers are not plastics. It's disingenuous to link health issues with plasticizers to microplastics. Additionally, we should not extrapolate concerns with BPA plastics releasing chemicals when placed under specific stressors (e.g. heat) to all plastics in the environment. There have been no studies I'm aware of that link microplastics to endocrine disruption. Even the first article you linked specifically states that the primary concern with microplastics is likely a physical (not chemical) one.

The slowdown in population growth has been a topic of world leaders for quite some time. This isn't a topic of interest because world leaders are somehow concerned about the cause (e.g. chemicals in the environment). In fact, the cause is well known and due to fairly straight forward anthropologic factors. As quality of life improves, population growth declines. This happens in nature as well. Populations under stress tend to reproduce more. World leaders are interested in modeling/understanding this as it has macroeconomic effects (e.g. Japan's decade long struggles with stock market decline). This is also why the US and the west in general has went so heavy on quantitative easing for the past decade. They are trying to stave off deflation. Unfortunately, COVID and the associated supply shocks caused that plan to go off the rails a bit...

Finally, I'm not sure what climate change policy has to do with any of this.