How dangerous is long-term exposure to formaldehyde?  I have been exposed to it at work for 35 years and I believe I am allergic to it.  It has gotten so bad that I have had to stay away from work for some time. - Bill, Colorado

            Formaldehyde is a very potent irritant.  Commonly it irritates the eyes, nose, throat, and sinuses, resulting in red, sore, or watery eyes; sore or dry throat; runny nose; and sinus irritation or congestion.  It can also cause neurotoxic effects such as headaches, excessive fatigue, malaise, and lethargy.  It may also cause skin rash on contact with liquids that contain it; there is also evidence that skin rashes may occur from airborne gas-phase exposures.

            While a number of cases of asthma associated with industrial exposures have been confirmed, formaldehyde-induced asthma appears to be relatively rare.  It may, however, predispose one to asthma caused by other agents.  The evidence that formaldehyde causes allergies is, at best, circumstantial and not definitive.  However, formaldehyde can react with human protein to produce protein complexes that have the potential to cause allergic reactions.

            Formaldehyde exposures cause inflammatory reactions in tissue, particularly respiratory airways in humans.  Australian studies have shown significant nitric oxide (NO) levels in the expired breath of individuals exposed to formaldehyde concentrations of 50 parts per billion (ppb).  In the 1980s, formaldehyde concentrations of 50 ppb or greater were very common in U.S. homes.  Such inflammatory responses may contribute to the development of asthmatic symptoms or respiratory infections.

            Formaldehyde exposures in the workplace have been, and continue to be, much higher than those in residential buildings.  The OSHA permissable exposure limit (PEL) is 0.75 ppm (parts per million) averaged over a full day.  This is a high exposure concentration compared to those that have been associated with adverse health effects in non-occupational environments.  The OSHA PEL was a political compromise.  The PEL had previously been 2 ppm and previous to that, 5 ppm.  Though most employers and employees believe that exposure below 0.75 ppm is safe (because 0.75 ppm is acceptable under OSHA rules), it is not.  Other standard-recommending bodies have recommended occupational exposure limits of 0.30 ppm (ACGIH) and 0.016 ppm (NIOSH).

            Studies conducted in Europe have indicated that neurotoxic symptoms such as headache and fatigue become increasingly more severe with longer exposure durations among individuals exposed occupationally.  Though some adaptation apparently occurs, high exposures for extended periods of time increase one’s risk of adverse health effects.