Apparently quite a few uninformed people, which is why Johnson & Johnson removed it from its baby shampoo:

Formaldehyde occurs naturally in common fruits and vegetables (even organic ones). “Unless people calling for removal of quaternium-15 are also keeping their children from eating apples and french fries,” Hartings says, “I think their activism might be misplaced.”

Our own bodies create formaldehyde as a normal byproduct during amino acid synthesis and overall metabolism, including breaking down antibiotics and other medications. It’s also in drinking water and the air we breathe. Homer Swei, a scientist at Johnson & Johnson, points out that 90 percent of the formaldehyde around us is naturally occurring, with 60 percent of that coming from plants and trees, yet it’s still perfectly fine to walk through the woods.

More at the link. As one quoted scientist says, it’s all about the dose, not the molecule.

Related: An unvaccinated student in the SF Bay area came down with measles. Thousands may have been exposed:

Remember: When you get vaccinated, you are not just protecting you and yours. You’re also helping protect babies too young for their shots, older people, and people with compromised immunities (for example, those who are on immunosuppressants for cancer or arthritis treatment). Herd immunity is real, and important.

People like Jenny McCarthy, Andrew Wakefield, RFK Jr., NVIC, and the AVN are wrong. Vaccines don’t cause autism, have very low risk, and have huge benefits. I hope this situation in San Francisco doesn’t turn into an outbreak because that could be very nasty indeed. We’ve seen it happen too many times before, and it’s the legacy of those people above and others who spread anti-vax nonsense.

Every year, for the past 20-years, I’ve gotten the flu shot. Haven’t gotten the flu. I’ve watched plenty of co-workers who’ve refused the vaccine come down with terrible, 7-10 day cases of it. I have no regrets . . . or sympathies.