Splinters Under the Fingernails

I keep trying to boil down the mercury debate to palatable doses, like an alchemist would with calomel.  I think I'm learning how to debate the PRO-VAXX camp’s position that “low levels of poisoning from Thimerosal couldn’t possibly poison anyone.”  Using this logic, let’s substitute wood for mercury. 
“The only way an individual couldn't function is if they have been hit over the head by a wood 4’x4’, and since splinters are so small, they couldn’t possibly affect a person's state of mind, even if they’ve been shoved underneath their fingernails.”