1,1-Dichloroethane

Abstract

The greatest source of exposure to 1,1-dichloroethane is inhalation of the compound in contaminated air, especially near source areas. Other potential sources of exposure are from eating contaminated food, skin contact, breathing contaminated air, or drinking contaminated water. 1,1-Dichloroethane affects the function of the central nervous system (CNS). This compound was used as an anesthetic in the past but current use is as an intermediate in chemical synthesis. 1,1-Dichloroethane is a colorless, oily liquid with a chloroform-like odor. It has been identified as a hazardous waste site chemical; therefore, it has been included in the US Environmental Protection Agency's National Priorities List. Acute (short-term) inhalation exposure to high levels of ethylidene dichloride in humans results in CNS depression and a cardiostimulating effect resulting in cardiac arrhythmias. Studies in animals have reported effects on the kidney. Upon exposure, this chemical leaves body via breath or is broken down into other chemicals and leaves the body via breath or urine. Presence of 1,1-dichloroethane in the environment is mainly related to its production, storage, consumption, transport, and disposal when it is used as a chemical intermediate, solvent, finish remover, and degreaser. It reaches the environment from biodegradation of 1,1,1-trichloroethane or when vaporized from surface waters and soils. Occupational exposure to 1,1-dichloroethane may occur via inhalation or dermal contact at workplaces where it is produced or used. A few animal studies have examined the toxicity and carcinogenicity of 1,1-dichloroethane but have failed to conclusively identify the critical targets of toxicity. Nonneoplastic effects of 1,1-dichloroethane are limited to renal toxicity in cats, maternal and fetal toxicity in rats, and alterations in body weight gain. A significant positive dose-related trend was observed for the incidence of hemangiosarcomas and mammary adenocarcinomas in female rats, hepatocellular carcinomas in male mice, and endometrial stromal polyps in female mice. Two states (California and New Jersey) have set standards for drinking water: 5 and 50 μg l−1, respectively. 1,1-Dichloroethane is classified as a possible human carcinogen (Category C) based on no human data and limited evidence of carcinogenicity in two animal species (rats and mice).