Fatal Exposure to Methylene Chloride Among Bathtub Refinishers

United States, 2000-2011

Debra Chester, MS; Kenneth D. Rosenman, MD; George R. Grimes, MD; Kathleen Fagan, MD; Dawn N. Castillo, MPH

Disclosures

Morbidity and Mortality Weekly Report. 2012;61(7):119-122. 

In This Article

Editorial Note

Methylene chloride is a highly volatile, colorless, toxic chemical that is widely used as a degreaser, process catalyst, and paint remover.[6] Because methylene chloride vapors are heavier than air, in the case described in this report they likely remained in the bathtub after application. To use products containing methylene chloride safely, work areas must be well-ventilated, and when levels of methylene chloride exceed exposure limits even after implementation of engineering and work practice controls, workers must use respiratory protective equipment, such as tight-fitting, full-face, supplied-air respirators.[4] OSHA's standard for methylene chloride, which was promulgated in 1997, covers all occupational exposures to the chemical (e.g., general industry, shipyard employment, and construction). The standard mandates that air monitoring, medical surveillance, hazard communication, and personal protective equipment be in place where methylene chloride is used.

Methylene chloride primarily is absorbed via inhalation, although it also is absorbed effectively by intact skin. To protect against skin absorption, butyl rubber or polyvinyl alcohol gloves must be worn; latex gloves like those used in the case described in this report will not protect against skin absorption. Methylene chloride is metabolized to formaldehyde and carbon monoxide[6,7] and is categorized as a carcinogen.[8]

COHb levels in the blood as great as 10%–12% can result from methylene chloride exposure.[2,6] COHb levels in this range can cause headache, nausea, or dizziness. Arrhythmias have been reported at COHb levels as low as 4%–6%, angina at levels as low as 3.9%, and electrocardiographic changes at levels as low as 2.0%.[6,9] In the 13 deaths analyzed in this report, the data indicate that carbon monoxide was not likely the cause of death. Because methylene chloride, like many solvents, acts as a central nervous system depressant causing narcosis at high concentrations, the decedents likely lost consciousness and died from respiratory depression. Consistent with this conclusion were the high methylene chloride blood levels at the time of autopsy found in the six persons whose methylene chloride blood levels were quantified (Table). However, because eight of the 13 decedents had cardiac disease (six with coronary artery disease and five with a cardiomyopathy or valvular disease), the arrhythmogenic effect of the methylene chloride itself or of its metabolite, carbon monoxide, might have been a contributing factor in their deaths.

Methylene chloride–based stripping products usually are applied with a paint brush or aerosol can. The products cause the bathtub coating to pucker, allowing it to be easily scraped away so that a new finish can be applied. In a small, enclosed bathroom, it is unlikely that a methylene chloride stripping agent can be used safely. Alternative methods of bathtub stripping, such as sanding, should be used. Alternative chemicals that could be used include petroleum distillates, acetate, mineral spirits, caustic paste, and acid-based formulas. However, these other methods and chemicals have their own hazards, and all employers and employees should be well aware of their risks.[10] Potential worker exposures should be evaluated to determine whether the work process is safe and to ensure that workers are protected.

The findings in this report are subject to at least three limitations. First, the number of deaths identified by OSHA likely is an underestimate because the IMIS database does not include all occupational deaths and injuries (e.g., those of self-employed workers). Second, the data examined in this report are limited to workers and do not address potential risks to consumers who have access to some of these products. Finally, additional deaths among bathtub refinishers might have been ascribed to heart disease when they were actually caused by methylene chloride.

Both OSHA and NIOSH are issuing communications regarding the risk for death from bathtub refinishing using methylene chloride strippers and the availability of safer products. The Michigan program distributed an investigation report and a hazard alert[10] after identifying bathtub refinishers in Michigan through Internet directories.

Methylene chloride also presents a risk to persons among the general public who seek to do their own bathtub refinishing. A review of the OSHA IMIS system, the Internet, and hardware stores, found 42 stripping products, 26 (62%) of which are readily available on the Internet or at local hardware stores. Many of these stripping products contain 60%–90% methylene chloride. Many Internet sites promote do-it-yourself bathtub stripping, and no state or federal restrictions exist on the use of methylene chloride stripping agents. The widespread availability of these products and their effectiveness puts both professional bathtub refinishers and do-it-yourselfers at risk. Public health agencies, worker safety agencies, manufacturers, and trade organizations should clearly communicate the extreme hazard posed by using methylene chloride–based stripping products in bathtub refinishing.

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