Controlling Exposure to Methylene Chloride

methylene-chloride-chemical-label-lb-1584-86Several chemicals that are commonly found in countertop fabrication shops and used by countertop installers pose a potential health risk to employees and others who are exposed, and one of the most dangerous is methylene chloride. Methylene chloride exposure in the workplace is strictly controlled by federal OSHA standards and 28 OSHA-approved state standards.

Methylene chloride is a colorless liquid with an odor similar to that of chloroform, and it is used in several industrial and commercial processes, including paint stripping, sealer stripping, resin production, metal cleaning/degreasing and adhesives manufacturing and use.

Federal Exposure Limits

The most common routes of overexposure for employees are through inhalation and skin contact. The federal action level for airborne methylene chloride is 12.5 ppm over an eight-hour time-weighted average (TWA). This means that businesses with this level of exposure are mandated to comply with controls, including exposure monitoring and medical surveillance.

The short-term exposure limit (STEL) to methylene chloride for employees is 125 ppm over 15 minutes, and the permissible exposure limit (PEL) is 25 ppm over eight hours. These limits were set in 1997, and a regularity review conducted in 2010 determined that these levels are justified in protecting the health of U.S. workers.

Remember, however, that these are the federal exposure limits. You may live in one of the 28 states that override the federal standard, and the limits in your state could be more stringent.

Dangers of Methylene Chloride

Methylene chloride has been declared a potential occupational carcinogen by OSHA, a probable human carcinogen by the U.S. Environmental Protection Agency (EPA) and a possible human carcinogen by the International Agency for Research on Cancer (IARC). It has been banned altogether from paint strippers in the European Union (EU), and it is prohibited from being used in 13 product categories in California.

From 2000 to 2016, a total of 14 people have died in the U.S. from acute overexposure to methylene chloride. Thirteen of these fatalities were bathtub refinishers, and the other worked in a paint-manufacturing facility. However, furniture strippers and anyone else coming into contact with airborne or liquid methylene chloride are susceptible to adverse health effects.

Short-term exposure to high concentrations of methylene chloride can produce the following symptoms:

  • Confusion
  • Lightheadedness
  • Dizziness
  • Nausea
  • Headache
  • Vomiting

Skin exposure to liquid methylene chloride can cause irritation, redness, swelling and burns, and it can be equally irritating to the eyes, mouth and upper digestive system. In addition, long-term exposure may produce the following adverse health effects:

  • Dry, cracked and inflamed skin
  • Liver damage
  • Central nervous system (CNS) damage
  • Aggravation of existing angina and heart conditions
  • Increased risk of cancer

Hazard Controls for Methylene Chloride

A number of controls are mandated and recommended by OSHA and other chemical-hazard experts. The first of which is communicating the hazard to employees and other employers at multi-employer worksites. Workers must be trained about the hazard and how to reduce exposure. The best course of action to take is to replace all products with methylene chloride, but if this is not possible, other measures must be taken.

Products containing methylene chloride should not be used in confined or unventilated spaces, and additional exhaust ventilation should be in place when used indoors. Simply opening windows and using household room fans are not sufficient for ventilation. Full-face, supplied-air respirators should be provided to employees in areas with high concentrations of methylene chloride, and protective gloves and clothing should be worn at all times.

Areas where methylene chloride is used must be marked as regulated areas, and restrictions should on access to these areas should be implemented. In addition, employers are required to begin an exposure-monitoring program in regulated areas in some situations.

For further information about methylene chloride, refer to OSHA Publication 3144-06R or contact the nearest state or federal OSHA office.