Glutaraldehyde is an aldehyde organic compound that has a particularly high affinity for proteins, reacting specifically with amine, amide, and thiol groups. Glutaraldehyde is more expensive but less toxic than formaldehyde, and it is used in countries where the use of formaldehyde is restricted. Studies show that 19% formaldehyde is approximately 40 times more toxic than 2.5% glutaraldehyde, at all times of exposure. However, when the data is calculated as molar concentrations, little difference in cytotoxicity between the two agents was observed.