Dichloromethane
Dichloromethane, also known as methylene chloride, is a colorless, volatile liquid with a sweet, chloroform-like odor[1]. It is widely used as a solvent in various industries, including paint and coating removal, pharmaceuticals, metal cleaning, chemical processing, and aerosols[4]. Despite being one of the least toxic simple chlorohydrocarbons, dichloromethane poses serious health risks, particularly through inhalation, which can cause symptoms ranging from drowsiness to respiratory tract irritation and even death[2]. It is also suspected to be carcinogenic, although the degree of exposure required to cause cancer is not yet fully established[2].
Dichloromethane is produced by chlorinating methane, and its production involves a series of reactions that yield a mixture of chloromethane, dichloromethane, chloroform, and carbon tetrachloride, as well as hydrogen chloride as a byproduct. These compounds are separated through distillation. The production process is significant, with an estimated 400,000 tons produced in the US, Europe, and Japan in 1993.
The use of dichloromethane is not without risks. It can react with certain strong nucleophiles, and its high volatility makes it an inhalation hazard. It can also be absorbed through the skin, and contact can severely irritate and burn the skin and eyes, with possible eye damage[3]. Inhaling dichloromethane can irritate the nose, throat, and lungs, and higher exposure can cause headache, nausea, dizziness, and unconsciousness[3].
The Environmental Protection Agency (EPA) has evaluated the risks associated with methylene chloride and proposed a rule to prohibit its use in paint and coating removal for both consumer and commercial purposes, citing unreasonable risks to workers, consumers, and bystanders[4]. The Occupational Safety and Health Administration (OSHA) has also addressed the occupational risks associated with methylene chloride, highlighting the need for protective equipment and safe handling practices[5].
In summary, dichloromethane is a widely used solvent with significant health and environmental risks. Its production and use require careful handling and adherence to safety protocols to minimize exposure and mitigate potential harm.
Citations:
[1] https://en.wikipedia.org/wiki/Dichloromethane
[2] https://www.acs.org/molecule-of-the-week/archive/d/dichloromethane.html
[3] https://nj.gov/health/eoh/rtkweb/documents/fs/1255.pdf
[4] https://www.epa.gov/assessing-and-managing-chemicals-under-tsca/fact-sheet-methylene-chloride-or-dichloromethane-dcm-0
[5] https://www.osha.gov/methylene-chloride