For coal, a good example of how bad it is, is the recommendation that pregnant women limit tuna consumption because of its mercury content.
There is no farmed tuna, its all wild caught from the big blue oceans.
Why does tuna have mercury? Because it eats things that have mercury in them. Where did they get the mercury from? Rain. Where did the rain get it? Coal emissions! Coal has mercury and when you burn coal, it goes into the atmosphere and then, eventually, into the ocean. So much mercury has been released by coal burning that the ALL THE OCEANS are contaminated to the point where predator fish have levels in their flesh high enough to warrant health warnings.
I have tried this tack. All fish everywhere are tainted by mercury to some extent. They seem not to care.
The thing which seemed to make them shut up was doing the math showing that the total weight of just coal ash from a coal plant running for a year is comparable to the entire weight of materials for a similar capacity wind farm (which is rated for ~20 years of use). I assume similar or less for solar (numbers harder to find).
Japan had dolphin meat in their kids lunches. That didn't end well as the dolphin's are contaminated with high levels of mercury as well. I guess being right next to China, and most of their power comes from coal, and the wind generally flows from west to east did it. Some kids actually got sick from the high Mercury levels.
There is no farmed tuna, its all wild caught from the big blue oceans. Why does tuna have mercury? Because it eats things that have mercury in them. Where did they get the mercury from? Rain. Where did the rain get it? Coal emissions! Coal has mercury and when you burn coal, it goes into the atmosphere and then, eventually, into the ocean. So much mercury has been released by coal burning that the ALL THE OCEANS are contaminated to the point where predator fish have levels in their flesh high enough to warrant health warnings.