Hello, Thank you for your contact to healthcare magic. I understand your health concern, if I am your doctor I suggest you that formaline won t stay in our body system for prolong period. It will be detoxified by the liver in a day or so depending on the concentration on the body. There are some studies which shows that formaldehyde is potential carcinogen. Prolonged exposure should be avoided for future malignancy. I will be happy to answer all your future concern. Thank you, Dr Arun Tank Infectious disease specialist. Wish you a best health at health care magic.