What is Formaldehyde, does lash adhesive usually contain Formaldehyde, and is it dangerous?
Formaldehyde is not an ingredient in any eyelash extension adhesive on the market. You can confirm this for yourself by checking the Material Safety Data Sheet (MSDS) for each chemical product supplied by the manufacturer.
It is, however, formed as a byproduct of the decomposition of other materials in the adhesive. This includes those adhesives labeled "Formaldehyde Free".
Doug Schoon (Cosmetic Scientist) recently held a live Facebook Q&A regarding eyelash extensions. During which, he stated that for formaldehyde to be harmful in humans, it must be breathed in high volume for a long period of time. Exposure to the tiny amount of formaldehyde produced during the application of eyelash extensions is negligible, and not harmful to your health.
Everything on the planet has a safe and unsafe level of exposure. Too much water can kill you! (google water intoxication). To this end, cyanoacrylate, its ingredients and byproducts are only dangerous upon overexposure, if no precautions are taken.
What precautions should you be taking?
It is always recommended to keep cyanoacrylate out of your breathing space, work in a well-ventilated area, wear a mask rated for VOC's and use source-capture ventilation if possible. Fully cure leftover adhesive by dropping water on it, and dispose in a metal pedal bin with lid.
If you'd like to see the full live Q&A with Doug Schoon, we've included the video below.