Formaldehyde
Formaldehyde is a gas with a pungent odor that is used commonly in the processing of paper, fabrics, and wood products and for the production of urea foam insulation. Low-level formaldehyde exposure has been found in stores selling clothing treated with formaldehyde-containing crease-resistant resins, in mobile homes, and in tightly enclosed rooms built with large quantities of formaldehyde-containing products used in construction materials. Formaldehyde aqueous solution (formalin) is used in varying concentrations (usually 37%) as a disinfectant and tissue fixative. Stabilized formalin may also contain 6–15% methanol.
Mechanism of toxicity
Formaldehyde causes precipitation of proteins and will cause coagulation necrosis of exposed tissue. The gas is highly water-soluble. When inhaled, it produces immediate local irritation of the upper respiratory tract and has been reported to cause spasm and edema of the larynx.
Metabolism of formaldehyde produces formic acid, which may accumulate and produce metabolic acidosis if sufficient formaldehyde was ingested.
Formaldehyde has been listed by the International Agency for Research on Cancer (IARC) as a known human carcinogen associated with nasal sinus and nasopharyngeal cancer. NIOSH also considers formaldehyde a carcinogen.
Toxic dose
Inhalation. The OSHA workplace permissible exposure limit (PEL) is 0.75 ppm (8-hour TWA). The NIOSH-recommended exposure limit (REL) is 0.016 ppm (8-hour TWA; the REL is 0.1 ppm for a 15-minute exposure). The air level considered immediately dangerous to life or health (IDLH) is 20 ppm.
Ingestion of as little as 30 mL of 37% formaldehyde solution has been reported to have caused death in an adult.
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