Methylene Chloride

Methylene Chloride is used as a solvent in many of ECU’s research laboratories. It is also used in the formulation of paint strippers, pharmaceuticals, degreasers and film.

As of April 1997, Methylene Chloride use is regulated by a revised OSHA Standard: 29 CFR 1910.1052
Synonyms: CH2 CL2, dichloromethane, Aerothene MM

CAS Number: 75-09-2

Appearance/Odor: Colorless, volatile liquid with a chloroform-like odor. Odor threshold 160 to 230 ppm.

Chronic Exposure: Human Carcinogen

Provisions of the Standard

Permissible Exposure Limits: No employee may be exposed to airborne concentrations in excess of 25 ppm as an 8-hour time weighted average (TWA). Short term exposure limit (STEL) is established at 125 ppm during a 15-minute sampling period. At 12.5 ppm TWA, the employer must establish regulated use areas, exposure monitoring procedures, and medical surveillance protocols.

Standard Requirements

Exposure monitoring must be conducted for representative individuals performing tasks most likely to result in exposure.

If an exposure is identified, monitoring must be continued until the exposure is engineered out.

  • Personal Protective Equipment will be used to protect personnel until air monitoring results show no exposure above the permissible exposure limits.

Regulated areas must be established wherever an employee’s exposure to airborne concentrations of MC exceeds or can reasonably be expected to exceed either the 8-hour TWA PEL or the STEL. The employer shall limit access to regulated areas to authorized persons.

Medical Surveillance is required for all individuals who are:

  • Required to wear respirators (Respirator physical)
  • Exposed above the action level for 30 days or more each year
  • Exposed at or above the 8-hour TWA for 10 or more days per year

See the full text at 29 CFR 1910.1052

Most laboratory use of Methylene Chloride should occur in an operating chemical fume hood. This will usually reduce personal exposure to the chemical below these levels.

If Methylene Chloride is used, contact EH&S to have exposure monitoring conducted.