The video presentation answered a lot of questions for me. Prof Michaux sounds like a smart fella, for an Aussie. Conclusions start at about 47 minutes.
Assoc Prof Simon Michaux - The quantity of metals required to manufacture just one generation of... - YouTube
The backing for this headline is (as usual) a systematic review. Leave aside the fact that no 20-year olds were enrolled in the studies (that is the journalist's fault) and examine the review itself.
Look at the heterogeneity of the studies. Are there major differences besides the dosage of ω-3? How are those accounted for? How does the depth of analysis compare to, say, this blog post?