I just found this in a cursory google search.
However, this chemical also occurs naturally in the environment. As a metabolic intermediate, formaldehyde is present at low levels in most living organisms. Formaldehyde can be found naturally in food up to the levels of 300 to 400 mg/kg, including fruits and vegetables (e.g. pear, apple, green onion), meats, fish (e.g., Bombay-duck, cod fish), crustacean and dried mushroom, etc ( Appendix).
Jenny, formaldahyde occurs naturally in the blood in much higher levels than is in vaccines. I wouldn't inject myself with goat cheese, either, but when I eat it the various components that its broken up into DO enter my blood in some amount. When you eat a pear, some amount of formaldahyde ends up in your blood. It makes no difference whether it came from food or a vaccine, it ends up in the same place.
What is different is the percentage that ends up there. A much smaller percentage of what you eat ends up in your blood before being excreted, a higher percentage (up to 100%) of what is in a vaccine does. Generally this distinction is negated because the amounts we consume are many many times greater than the amount contained in a vaccine.