In defence of thimerosal

Mercury treaty debate: Should thimerosal be banned as a vaccine preservative? - Slate Magazine

A detailed and interesting explanation here as to why the mercury compound thimersol should be allowed to remain in vaccines.

Other forms of problematic mercury are not so harmless, however:

Estimating its global impact is difficult, but in some populations almost 2 percent of children are born with mental retardation caused by mercury poisoning.

This all reminds me:  the 1980 science fiction novel Timescape by Gregory Benford, which I only partially read since I don't care for Benford's inability to write likeable characters, starts with a near future "mercury hunt" in the sewers under some university town.  If I recall correctly, it was an extrapolation that mercury for scientific use was becoming in shorter supply and much more expensive, and hence these scavenging trips through drains and sewers would be viable in the future.  If I am remembering it right, that was one (amongst many) predictions in the book that failed to pass.   [If you want to guarantee a science fiction book with a short shelf life, set it about the near future and make lots of detailed predictions about what will go wrong.]