There is a common pro-vaccination argument that attempts to equate the amount of formaldehyde injected into the body when receiving a vaccine, with the amount of formaldehyde ingested into the GI tract when eating a pear.
Here is a classic example:
A 200g pear contains up to 12,000 μg of formaldehyde naturally.
Vaccines contain up to 100 μg, or 0.83% of the formaldehyde in a pear.
i.e. A pear contains 120 times more formaldehyde than a vaccine.
I loathe this argument mainly as a non-sequitur factoid, but also because it is often parroted without references in a hypocritical argument to tell people not to believe everything they are told.
For example, it is not hard to find (repeated) examples of similar claims with different numbers:
there’s 600 times more formaldehyde in a pear than a vaccine.
Put another way, the amount contained within a vaccine is more than 50 times less than what is in a pear.
I found this image on a Mothering.com forum
The difference is subtle, but notice it is 600 times as much (a factor of 5 increase), and the level of blue has changed by maybe 10%.
Vaxplanations repeat the 120 times claim, but I give them credit for also addressing the ingestion versus injection difference.
Gizmodo says a 220 g pear contains 8,600 to 13,200 µg of formaldehyde, putting the original 12,000 µg for a 200 g pear at the upper end.
This forum commenter seems to have lost a percentage sign:
A typical vaccine may contain up to 100 ug, or 0.83 of the formaldehyde available in a typical pear.
So what is the real ratio of formaldehyde between a typical pear and a typical vaccine? 50:1, 120:1, 600:1, 1:0.83 or a different number?