Well, an hour of research is NOT going to go wasted, I'm going to paste it here where it's more likely to be seen. I went out of my way to make sure to use sites that had nothing whatsoever to do with immunizations. Only found to be harmful in large quantities. I searched on all of the search engines, nothing. It is used to add permanent-press qualities to clothing and draperies, is found in glues and adhesives.
Cigarette smoke introduces formaldehyde into an environment.
It is in some home insulation, and is found in higher concentration in newer homes, as it dissipates over time. It is also used in fingernail hardeners. The association with Alzheimer's is the result of a lifetime of accumulation. Alzheimer's patients today were not vaccinated as children. I looked high and low on unbiased sites and could find nothing more about this compound.