Formaldehyde and Other Aldehydes
Formaldehyde is widely used on campus for preserving or fixing biological cells and tissues. Formaldehyde is a suspected human carcinogen and a suspected reproductive hazard. Formalin is an aqueous solution that generally contains a 3 to 10% dilution of formaldehyde from the original 37-40% solution. Paraformaldehyde is the crystallized polymer of formaldehyde that is typically dissolved in solution for cell and tissue fixation. Typically, 3-10% formalin or paraformaldehyde solutions are used to perfuse or fix tissues.
The Occupational Safety and Health Administration (OSHA) has set the Permissible Exposure Limit (PEL) at 0.75 ppm averaged over an 8 hour work day. The action level is set at 0.5 ppm, and is the level at which action must be taken to reduce exposures. OSHA also mandates that no employee shall be exposed to formaldehyde in concentrations that exceed 2 ppm as a 15-minute Short Term Exposure Limit (STEL). The American Conference of Governmental Industrial Hygienist (ACGIH), a non-profit, non- governmental corporation recommends a more conservative exposure level of 0.3 ppm, and this is a ceiling (or never-to-be-exceeded) level.
Given the carcinogenic and sensitizing properties of formaldehyde, EHSRM recommends keeping exposures as low as possible, and strives to meet the NIOSH Recommended Exposure Level (REL) of 0.016 ppm. This generally requires working in a chemical fume hood whenever formalin or formalin-preserved specimens are handled. Often, researchers transfer specimens from formalin to ethanol or isopropanol. Once the transfer has taken place, it is usually safe to work with them outside the fume hood. Snorkels, placed within one duct diameter of the sample, may help remove nuisance vapors that can cause headaches or eye and respiratory irritation.