Thanks for the context, very interesting. When did you get those shots as a child (ie what year, if you don't mind), and do you have any sense of which ones might have been the cause?
My parents followed the usual schedule. I was born in 1986. I'm not sure what the schedule was exactly back then, but I had several shots under the age of 5, a few more leading up to age 10, and a few more up until my last shot in 2016. Iirc the majority of them before 2001 included thimerosal as a preservative. I don't think any one shot was a specific cause, and rather it was a cumulative thing. I do know that the MMR shot does not contain thimerosal.
This FDA Q&A is a good read, although obviously biased against my perspective:
The FDA does acknowledge that kids in my generation were exposed to mercury slightly exceeding the established safety limit for oral exposure, but makes no mention as to how it is not appropriate to use an oral limit when the exposure is through injection. Toxicologists know that the exposure route makes all the difference in how toxic a substance is, and it is specifically written into environmental regulations like RCRA. For example, ingested substances are first directed straight to the liver through the portal vein for detoxification before being spread to the rest of the body. Injected substances bypass this defense mechanism. No exposure limits have ever been developed for injection, because the laws are all written for pollution, and people obviously do not inject pollution into themselves. (I was an environmental engineer for several years.)
That FDA Q&A also discusses how there was a lot of concern expressed by healthcare professionals regarding thimerosal, and that's why it was (mostly) removed, but they stress that it was just to be safe, and they have no reason to believe that it's dangerous. To be honest, it sounds like covering-their-ass double-speak to me, and reminds me of how polluting companies handle their coverups. The reality is that these things are so difficult to prove one way or the other, and the liability and denial issues are immense. No one wants to admit to themselves or others that they accidentally poisoned someone. Not just for financial reasons but for their own psychological well-being.
