symptom related to formaldehyde exposure. However, when compared to control groups, the frequency of symptoms did not exceed the controls except for wheezing, difficult breathing, and a burning skin sensation. Controlled studies have suggested that tolerance to formaldehyde's odor and irritating effects can occur over a prolonged exposure. See also Phenol formaldehyde resin References External links Urea formaldehyde (Plastics Historical Society) History of urea-formaldehyde: Chapter 1 of: Carl Meyer, Urea-Formaldehyde Resins (Reading, Massachusetts: Addison-Wesley, 1979) Urea-Formaldehyde Foam Insulation(Canada Mortgage and Housing Corporation) Indoor Air Quality: Formaldehyde(US Environmental Protection Agency) Formaldehyde.... its safe use in foundries (UK Health and Safety Executive) (United States Environmental Protection Agency) (Environmental and Occupational Health Assessment Program|Connecticut Department of Public Health) (Consumer Product Safety Commission|Consumer Product Safety Commission) (Forest Products Laboratory: USDA Forest Service) [Dunky, M., "Urea-formaldehyde (UF) adhesive resins for wood," International Journal of Adhesion and Adhesives, 1998. (18:2).] (Encyclopædia Britannica) (PropEx.com) (U.S. Dept. of Labor, Occupational Safety and Health Administration (OSHA)) Polyamides Synthetic resins Plastics Thermosetting plastics