Fatal Exposure to Methylene Chloride
Among Bathtub Refinishers — United States, 2000–2011
Weekly
February 24, 2012 / 61(07);119-122
In 2010, the Michigan
Fatality Assessment and Control Evaluation program
conducted an investigation into the death of a bathtub
refinisher who used a methylene chloride–based paint
stripping product marketed for use in aircraft
maintenance. The program identified two earlier, similar
deaths in Michigan. Program staff members notified CDC's
National Institute for Occupational Safety and Health (NIOSH),
which in turn notified the Occupational Safety and
Health Administration (OSHA). In addition to the three
deaths, OSHA identified 10 other bathtub refinisher
fatalities associated with methylene chloride stripping
agents that had been investigated in nine states during
2000–2011. Each death occurred in a residential bathroom
with inadequate ventilation. Protective equipment,
including a respirator, either was not used or was
inadequate to protect against methylene chloride vapor,
which has been recognized as potentially fatal to
furniture strippers and factory workers (1,2) but
has not been reported previously as a cause of death
among bathtub refinishers. Worker safety agencies,
public health agencies, methylene chloride–based
stripper manufacturers, and trade organizations should
communicate the extreme hazards of using methylene
chloride–based stripping products in bathtub refinishing
to employers, workers, and consumers. Employers should
strongly consider alternative methods of bathtub
stripping and always ensure worker safety protections
that reduce the risk for health hazards to acceptable
levels. Employers choosing to use methylene
chloride–based stripping products must comply with
OSHA's standard to limit methylene chloride exposures to
safe levels.
The Michigan program is one
of nine state Fatality Assessment and Control Evaluation
programs funded by NIOSH to identify work-related injury
deaths, conduct investigations to identify contributory
factors, and develop recommendations for preventing
deaths in similar situations. The findings of these
investigations and subsequent recommendations are
summarized in narrative reports broadly disseminated to
employer and worker groups and posted at the NIOSH
Fatality Assessment and Control Evaluation website.*
OSHA Investigation
OSHA and OSHA-approved State
Occupational Safety and Health Plans†
conduct investigations of worker deaths and enforce
compliance with worker safety and health regulations. A
review of the Integrated Management Information System
(IMIS), a database for federal and state OSHA
investigations, identified 12 methylene chloride–related
deaths associated with professional bathtub refinishing
operations during 2000–2011. One of the three deaths
identified by the Michigan program was not in IMIS
because the decedent was self-employed and therefore
outside OSHA's enforcement jurisdiction. The ages of the
13 decedents ranged from 23 to 57 years (median = 39
years) (Table). Twelve were male.
Ten different products were
associated with the 13 deaths. Six of the products were
marketed for use in the aircraft industry, the rest for
use on wood, metal, glass, and masonry. None of the
product labels mentioned bathtub refinishing. The
percentage of methylene chloride in the products ranged
from 60% to 100%.
Toxicology tests from
specimens collected at autopsy indicated methylene
chloride blood levels ranging from 18 to 223 mg/L in the
six decedents for whom values were recorded; a level of
<2 mg/L is expected in a person working within the OSHA
allowable air standard for exposure to methylene
chloride fumes (3). Among the five decedents
whose carboxyhemoglobin (COHb) levels were tested,
levels ranged from absent to mildly elevated (range:
zero to 5%) (Table), indicating that
carbon monoxide was unlikely to have been the primary
cause of death (although the durations of exposure to
methylene chloride and receipt of oxygen during
resuscitation efforts, two factors that can affect COHb
levels, were not known).
Analysis of IMIS data
regarding deaths from methylene chloride showed an
increase in cases involving bathtub refinishing since
2000. During 1976–1999, only two (8%) of all methylene
chloride deaths investigated by OSHA were linked to
bathtub refinishing. Since 2000, 13 (75%) of the
methylene chloride deaths investigated by OSHA occurred
during bathtub refinishing. Following is an illustrative
case report.
Case Report
In March 2010, the co-owner
of a Michigan-based bathtub refinishing company, aged 52
years, was refinishing a bathtub in an apartment
bathroom that was approximately 5 feet by 8 feet (1.5
meters by 2.4 meters) with an 8-foot (2.4-meter)
ceiling. He was using an aircraft paint stripper product
that contained 60%–100% methylene chloride. The bathroom
ceiling had a 50 cubic feet per minute (1.4 cubic meters
per minute) ventilation fan; however, the fan was off.
The man wore latex gloves and did not wear respiratory
protection or use engineering controls (e.g., a local
exhaust ventilation system) to vent the methylene
chloride vapor.
Approximately 90 minutes
after the man began working on the tub, he did not
answer a call to his cellular telephone. An apartment
maintenance man entered the apartment to look for the
man and found him behind the closed bathroom door,
unresponsive, and slumped over the tub. The maintenance
man telephoned 911 and then a second maintenance man.
The two maintenance men pulled the man off of the tub.
The second maintenance man, a certified emergency
medical technician, began cardiopulmonary resuscitation.
When emergency responders arrived an estimated 2 minutes
later, they moved the victim to another part of the
apartment and continued resuscitation before
transporting him to a local hospital. The man was
declared dead at the hospital.
The decedent had a history
of hyperlipidemia, and his autopsy revealed mild
coronary atherosclerosis and mucus plugging of bronchi
and bronchioles. His blood methylene chloride level at
autopsy was 50 mg/L. All other toxicology test results
from the autopsy, including COHb, were reported as
negative. The death certificate listed the cause of
death as "sudden cardiorespiratory arrest due to or as a
consequence of inhalation of toxic fumes."
Based on the size of the
bathroom, size of the tub, and an estimate that 6 fluid
ounces (177 mL) of methylene chloride-based stripper was
used during a typical job, exposure levels were
estimated for both the tub and bathroom environments.
The concentration of methylene chloride vapor was
estimated at 92,949 to 154,916 parts per million (ppm)
in the bathtub and 5,099 to 8,499 in the bathroom. The
man's estimated time-weighted average exposure to
methylene chloride, based on 1 hour of exposure, was 637
to 1,062 ppm in the bathroom and 11,618 to 19,364 ppm in
the tub, many times greater than OSHA's short-term
exposure limit of 125 ppm, 8-hour permissible exposure
limit of 25 ppm, and the NIOSH immediately dangerous to
life and health level of 2,300 ppm (4,5).§
Reported by
Debra Chester, MS,
Kenneth D. Rosenman, MD, Div of Occupational and
Environmental Medicine, Michigan State Univ. George R.
Grimes, MD, Uniformed Svcs Univ of the Health Sciences,
Bethesda, Maryland. Kathleen Fagan, MD, Occupational
Safety and Health Admin. Dawn N. Castillo, MPH, Div of
Safety Research, National Institute for Occupational
Safety and Health, CDC. Corresponding
contributor: Kenneth D. Rosenman,
rosenman@msu.edu,
517-353-1846.
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.
What is already known
on this topic?
Methylene chloride is a
volatile, toxic, organic solvent used in cleaning
and paint stripping and shown to be potentially
fatal to furniture strippers and factory workers
unless used in strict compliance with safety
precautions.
What is added by this
report?
Methylene chloride–based
paint stripping agents used in bathtub refinishing
have caused at least 13 deaths in the United States
since 2000 among professional bathtub refinishers.
Because of inadequate ventilation, safe use of a
methylene chloride stripping agent in a small
bathroom is unlikely.
What are the
implications for public health practice?
Worker safety agencies,
public health agencies, manufacturers of methylene
chloride containing products, and trade
organizations should clearly communicate to
employers, workers, and the general public the
extreme hazards of using methylene chloride–based
stripping products in bathtub refinishing. Safer
methods of bathtub stripping should be recommended.
Use of trade names and commercial sources is
for identification only and does not imply
endorsement by the U.S. Department of Health and
Human Services.
References to non-CDC sites on the Internet are
provided as a service to MMWR readers and do
not constitute or imply endorsement of these
organizations or their programs by CDC or the U.S.
Department of Health and Human Services. CDC is not
responsible for the content of pages found at these
sites. URL addresses listed in MMWR were
current as of the date of publication
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