Thimerosal is sometimes (often?) used as a preservative for vaccines. It contains a small amount of mercury, something like 25 micrograms/dose.
With respect to the considerable battery of vaccines given to infants and small chilluns, how big a deal is this?
Well, for one thing, vaccine manufacturers are trying to get away without using thimerosal.
Second, I’d be more concerned about, say, living downwind from a dirty, coal-burning power plant which continually puts small bit of mercury into the air than from a teeny bit in a vaccine, which is a very infrequent occurance.
Neither of my pediatricians have used vaccines with that preservative in years. It was all over the news a few years back, when it was tentatively linked to the explosion of autism diagnoses.
I know of some people who are strongly concerned about this, one of whom is a nurse. So you aren’t alone in your worry.
Whether those worries have any solid basis is beyond my knowledge base.
If you look carefully at the table you will see that none of the vaccines routinely given to young children has more than a trace of mercury.
Well, this study seems fairly well designed and didn’t find any effect:
Other than flu vaccines–which aren’t routinely given to children–only trace amounts of thimerosal are in children’s vaccines. Most contain none at all, and it’s been completely banned in several states (most recently California).
As far as studies go, the only ones I’m aware of are attempting to address the common nutcase idea that childhood vaccination causes autism; this is completely and routinely debunked, most recently with the MMR vaccine, look here for a casual-reader version, and here for links to all sorts of news stories on it.
I don’t know much about other supposed effects of tiny mercury amounts beyond the autism one that gets so much conspiracy-theory press. But I do know that Whooping cough, measles, and a number of other diseases which actually DO harm (even kill) children are on the rise since this scare started.
There’s more mercury in some kinds of fish than you could ever get from a vaccine. Are any parents claiming that salmon gave their kid autism?
Post hoc, ergo propter hoc
Some childhood vaccinations occur at roughly the same age that autism symptoms start to be noticable. Most kids probably don’t start eating salmon that early. (And given the level of toxins in fish, shouldn’t).
People are very, very good at seeing patterns and cause/effect relationships – even when they don’t exist.
That’s a fairly good point to make. At the EPA limit of .3 micrograms per gram of fish it would take about 3 ounces of fish to reach the same value of mercury.
The CDC says that
The brands in the chart with Thimerosal are not used in children under 12, except for the flu vaccines.
There have been other threads on this in the past, but I can’t seem to find them, right now.