Formaldehyde is toxic to proteins, so bacteria will not be produced in it....... preservation is very convenient. The toxin, simply put, is carcinogenic, other are trivial ... ... electrophilic substances are carcinogenic (do not ask me what is an electrophilic substance ...... headache) ...... acute toxicity, leading to the denaturation of proteins will affect a series of roles of ... anyway, where are harmful ... but it seems that the human body can break down formaldehyde, do not need to worry about long-term damage (in addition to increasing the chances of cancer)......