Genotoxicity of 1,1-dichloroethane

Area of Science:

• Toxicology
• Biochemistry
• Carcinogenesis

Background:

• 1,1-Dichloroethane (1,1-DCE) is a chemical compound with potential toxicological implications.
• Understanding its interaction with biological molecules is crucial for risk assessment.

Purpose of the Study:

• To investigate the in vivo and in vitro covalent binding of 1,1-dichloroethane to macromolecules.
• To identify the metabolic pathways and enzymes involved in 1,1-DCE binding.
• To assess the role of glutathione (GSH) in the detoxification of 1,1-DCE.

Main Methods:

• In vivo intraperitoneal injection of 1,1-DCE in rats and mice.
• In vitro incubation of 1,1-DCE with organ microsomes and cytosolic fractions.
• Analysis of covalent binding to nucleic acids and proteins.
• Assessment of enzyme induction/inhibition effects.

Main Results:

• 1,1-DCE showed covalent binding to macromolecules in vivo, with a Covalent Binding Index typical of weak carcinogens.
• Liver P-450-dependent microsomal mixed function oxidase system was the primary mediator of in vitro binding to nucleic acids and proteins.
• Lung microsomes showed weak efficiency, while kidney and stomach microsomes were ineffective.
• Phenobarbitone pretreatment enhanced binding, whereas 2-diethylaminoethyl-2,2-diphenyl valerate suppressed it.
• Cytosolic enzymes did not catalyze binding.
• Glutathione (GSH) addition decreased or suppressed binding, suggesting a detoxificant role.

Conclusions:

• 1,1-Dichloroethane exhibits weak carcinogenic potential due to its covalent binding to macromolecules.
• Hepatic microsomal enzymes are key players in 1,1-DCE activation and binding.
• Glutathione plays a significant role in detoxifying 1,1-dichloroethane, similar to other chlorinated compounds.