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Cashins & Associates Blog

Industrial Hygiene: Methylene Chloride Review

Posted by Eileen Watkins on Wed, May, 20, 2015 @ 14:05 PM

Methylene-Chloride-Chemical-Label-LB-1592-086Methylene chloride, also known as dichloromethane, is an organic solvent which can be found in manufacturing facilities, the food industry, furniture refinishing shops, and perhaps even in your own home.  It has the potential to damage your health if you are exposed to harmful concentrations.  Do your employees handle methylene chloride?  Are they at risk of excessive exposures?  Read on to learn more.

Methylene chloride is used in the manufacturing of antibiotics and vitamins, to extract caffeine from coffee, and as a degreasing agent.  It is also an ingredient in many paint strippers and adhesive removers.  In fact, the US Department of Health and Human Services' Household Products Database reports that some paint strippers contain up to 90% methylene chloride.  This example serves as a reminder that harmful chemicals are not only found in the workplace - many times they are in our cupboards and cabinets at home.

Methylene chloride has a very low vapor pressure, which means that liquid methylene chloride readily converts to the vapor state.  Given this information, it's easy to understand that methylene chloride often enters the body by way of inhalation.  Skin absorption can also be a route of exposure, however.  Once it has entered the body, methylene chloride takes a number of different pathways through it.  For example, some methylene can be detected in exhaled air and urine.

Probably the most damaging pathway involves methylene chloride's metabolism to carbon monoxide.  We know that carbon monoxide is dangerous, but let's look at how this compound effects our bodies on a cellular level.  Blood-borne carbon monoxide molecules seek out and attach to hemoglobin, a molecule that transports oxygen through the blood and to our tissues and cells. Unfortunately, carbon monoxide has a strong affinity for hemoglobin - much higher than oxygen's affinity for hemoglobin.  This means that when carbon monoxide and oxygen compete to attach to a hemoglobin molecule, carbon monoxide is 250 times more likely to win the fight.

The hemoglobin-carbon monoxide structure is called carboxyhemoglobin.  Elevated carboxyhemoglobin levels stress the heart and can cause irregular heartbeats.  Smokers, who have higher carboxyhemoglobin levels that non-smokers (because cigarette smoke contains carbon monoxide), are more at risk of these effects.

Methylene chloride can also damage the liver and kidneys.  Like all organic solvents, it can depress the central nervous system and cause drowsiness, blurred vision, and slower reflexes.  Like some other organic solvents, it can damage the middle and/or inner ear and cause hearing loss. Skin contact with methylene chloride can cause redness and burns.  Methylene chloride can also be absorbed by the skin, enter the bloodstream, and then migrate to other organs.  Finally, OSHA and other occupational health groups have labeled methylene chloride as a "probable" or "suspect" carcinogen.  This means that some evidence suggests that exposures to this compound can increase a person's risk of cancer.

OSHA regulates workplace exposures to methylene chloride in its substance-specific standard, 29 CFR 1910.1052.  This standard specifies that employers who have methylene chloride in the workplace must monitor their workers' exposures in order to determine if they exceed the Action Level (AL) of 12.5 parts per million (ppm) or the Permissible Exposure Limit (PEL) of 25 ppm. 

It also requires all employers to train their employees on methylene chloride.  Other provisions of the standard, such as regulated areas, engineering and work practice controls, and medical surveillance are triggered when exposures reach the AL or the PEL.

Safety Managers and EHS Professionals, do your employees handle methylene chloride on the job?  If the answer is yes, have you had their methylene chloride exposures properly measured by an industrial hygienist? Are your employee's exposures under the AL and PEL?  If not, are the other OSHA requirements fully implemented?  Do your employees need to wear a respirator when they handle methylene chloride?  Are the gloves you provide to employees made of a material that has been tested for use with methylene chloride? 

Cashins can evaluate your methylene chloride use, conduct employee exposure monitoring, train your employees on safe methylene chloride handling, and help you navigate your way through OSHA's Methylene Chloride Standard. If you are using methylene chloride ensure you have a complete industrial hygiene program in place.  Click on the button below to contact us with your request! 

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