Aldehyde-Induced Cytotoxicity in Cultured Human Bronchial Epithelial Cells

Effects of the tobacco smoke related aldehydes, i.e. acetaldehyde, formaldehyde and acrolein, have been investigated in cultured human bronchial epithelial cells. When survival is measured as loss of colony-forming efficiency, acrolein is 200–fold and 5000–fold more toxic than formaldehyde and acetaldehyde, respectively. At cytotoxic concentrations, the cellular content of free thiols is markedly depleted by acrolein, whereas formaldehyde and acetaldehyde only slightly decrease thiols. These aldehydes cause many other pathobiological effects in human cells that relate to the initiation and promotion phases of carcinogenesis, including: DNA damage, mutation, inhibition of DNA repair, and squamous differentiation. Interpretation of the importance of these cytopathic effects in carcinogenesis has to be based on accurate determinations of aldehyde-induced cytotoxicity.