Formaldehyde damage to DNA and inhibition of DNA repair in human bronchial cells.

Cultured bronchial epithelial and fibroblastic cells from humans were used to study DNA damage and toxicity caused by formaldehyde. Formaldehyde caused the formation of cross-links between DNA and proteins, caused single-strand breaks in DNA, and inhibited the resealing of single-strand breaks produced by ionizing radiation. Formaldehyde also inhibited the unscheduled DNA synthesis that occurs after exposure of cells to ultraviolet irradiation or to benzo[a]pyrene diolexpoxide but at doses substantially higher than those required to inhibit the resealing of x-ray-induced single-strand breaks. Therefore, formaldehyde could exert its mutagenic and carcinogenic effects by both damaging DNA and inhibiting DNA repair.