melamine-formaldehyde resins, which are used as adhesives in the production of particle board, fiber board, and plywood. Formaldehyde is also used in the manufacture of plastics, insulation, fertilizers, fungicides, biocides, corrosion inhibitors, embalming fluids, disinfectants, and household cleaners, and it is used in the textile industry in the production of permanent press and fire-retardant fabrics.

Formaldehyde occurs naturally in the environment and is emitted from vegetation, forest fires, and animal wastes (ATSDR 1999). It is a natural component of fruits and other foods and is an essential intermediate in human metabolism (IARC 1995; ATSDR 1999). Although naturally occurring, formaldehyde also enters the environment from many anthropogenic sources. In fact, combustion sources, such as power plants, incinerators, refineries, wood stoves, kerosene heaters, and cigarettes, are typically the largest contributors of formaldehyde emitted to the environment (ATSDR 1999). Other sources of formaldehyde emissions include motor vehicles, construction materials, textiles, paper, and cosmetics.

Formaldehyde has been monitored in both ambient and indoor air; concentrations are typically higher in indoor air (ATSDR 1999). Ambient measurements in urban and rural areas in the United States indicate a range