Not sure what you are asking….
You posted an advisory from Berkley. Do you have anything more, or is that all Google turned up?
While I think formaldehyde is a very poor choice, the science on that particular study is very, very weak. While it is possible to form the chemical in question under specific conditions, all of the tests combining dilute HCl and formaldahyde suggest that the carcinogenicity can be accounted for by formadahyde and is probably due to due to the formaldahyde alone. So they the alarm re. boat heads is probably unfounded.
- It will be dilute.
- You won't be exposed because you flushed the head many times before adding acid, I hope.
- You should not be using formaldahyde.
- HCl can be damaging to the head, so I wouldn't use that either. Raritan and others make good products based on phosphoric acid.
But yes, NO FORMALDAHYDE should be preached far and wide.