Working Safely with Methylene Chloride Environmental Health, Safety, and Risk Management University of Alaska Fairbanks September 2008

Report
Working Safely with
Methylene Chloride
Environmental Health, Safety, and
Risk Management
University of Alaska Fairbanks
September 2008
Overview
OSHA methylene chloride standard
 Properties of methylene chloride
 Routes of exposure and health effects
 Protecting yourself
 Handling and storage
 Spills and accidents
 Waste disposal

OSHA methylene chloride standard
 Found
in: 29 CFR 1910.1052
• CFR: Code of Federal Regulations
 Includes:
• Appendix A: substance safety data sheet
and technical guidelines for methylene
chloride
• Appendix B: medical surveillance for
methylene chloride
29 CFR 1910.1052

Establishes the following:
8-hour permissible exposure level (PEL) at 25
ppm
 15 min short-term exposure level (STEL) at
125 ppm
 Action level at 12.5 ppm (8 hours)

• At this exposure level, employee must undergo
medical surveillance

Specifies requirements for PPE, air
monitoring, establishment of regulated areas,
etc.
Properties of methylene chloride




Liquid: clear and colorless, with a chloroform-like
odor
Readily evaporates
Vapor density = 2.9 (air = 1)
 Vapors are heavier than air and will sink
Odor threshold estimates vary from 25 ppm to 320
ppm (and adaptation to odor can occur)
 PEL is 25 ppm over an 8 hour day, so if you can
smell it, you are already over the limit
 Methylene chloride does not have adequate
warning properties
Routes of exposure

Inhalation


Skin absorption


Occurs via contact with liquid and/or vapor
Eyes


Primary route of exposure due to high volatility
Splashes with liquid, or exposure to vapors
Ingestion (rare)

Eating or drinking without washing hands and
face after working with methylene chloride
Health effects: acute




Central nervous system depressant
Adverse effects on heart due to production of CO during
metabolism of methylene chloride
Evidence for liver toxicity (elevated liver enzymes)
Immediate symptoms may include:
 Dizziness
 Headaches
 Irritation of eyes, respiratory tract, skin, mucous
membranes
 Loss of coordination (leading to accidents and
mistakes)
 Narcosis (at high exposures)
Health effects: chronic
Clear evidence exists that methylene chloride
causes cancer in animals
 Some studies suggest that there is an
increased risk of cancer among workers who
are exposed to methylene chloride

 Other

studies show no apparent correlation
NIOSH/CDC recommends that methylene
chloride be regulated as a suspected
carcinogen (lung and liver cancer)
Protecting yourself
Engineering controls
 Personal protective equipment
 Specific lab safety practices

Engineering controls





Use all methylene chloride-containing solutions
in a properly functioning chemical fume hood
Conduct all work at least 6” inside sash
Keep sash as low as possible (even lower than
the posted maximum operating sash height)
Conduct all work in a plastic tray for spill
containment
Keep all bottles closed when not in immediate
use
Personal protective
equipment




Long pants and long-sleeve shirt or lab coat
Closed-toe shoes or rubber boots
Splash goggles
Gloves:
 2 pair are recommended
• 1st pair (next to skin): polyethylene or laminate
• 2nd pair (over 1st pair): nitrile or neoprene
• Used for puncture resistance/strength; MC
penetrates this material readily
 Polyvinyl alcohol (PVA) gloves are also suitable (do
not expose to water!)
 Change gloves frequently (immediately if contact with
MC occurs)
Specific lab safety practices







Review your protocol prior to beginning the procedure
(every time)
Inspect your PPE for cracks, holes, signs of wear
Make sure the fume hood has a current maximum sash
height sticker
Clearly label ALL bottles (stocks and wastes)
Use the smallest amount possible
Have a hardcopy of the MSDS in an easily accessible
location in the lab
Check access to functioning eye wash and safety shower
Storage of methylene
chloride
Classified as a health hazard (blue)
 Use secondary containment (polyethylene
tray) for all bottles (stocks and wastes)
 Ensure that caps are tightly sealed

If you are losing volume in your bottles over
time, then you effectively have a release to
the environment (a.k.a. a spill)
 Check bottles regularly


Store in a well-ventilated area
If something goes wrong…

Spills not involving contact with a person


Small spill (e.g. a few mL):
• Use absorbent pads to mop up the liquid
• Continue to wear your PPE while cleaning up the
spill
• Place all pads and towels in a double plastic bag
and seal. Leave in the hood.
• Notify EHS&RM (474-5617) that you have a bag of
methylene chloride cleanup materials to pickup.
If you do not feel comfortable cleaning up the spill,
call EHS&RM for help (never put yourself at risk!)
If something goes wrong…

Spills not involving contact with a person

Large spill outside the fume hood (>1L):
• Alert others in the area to evacuate the lab
• Contain the spill (with pads, vermiculite, etc.) if it is
safe to do so
• Leave the area and close the door
• Call EHS&RM at 474-5617 or 474-5413
• Tell them that you have a methylene chloride
spill, and the exact location
• Tell them where you will be so they can contact
you for more information if needed
If something goes wrong…

Spills involving skin exposure
 Immediately wash the affected areas with running water
(at least 15 minutes).
 If large areas of the body are involved, immediately get to
the emergency shower or eyewash (if eye exposure only)
• Remain in the shower for 15 minutes, removing all clothing and
contaminated items while in the shower

Be alert for signs and symptoms of exposure—dizziness,
headache, confusion
• Inhalation exposure will result from skin exposure

Immediately notify EHS&RM (474-5413), and your
supervisor of the incident. Seek medical attention.
If something goes wrong…

Spills involving eye exposure (both liquid and
vapor):
Get to eyewash
 Use eyewash for 15 minutes, holding both lids
open
 Seek medical attention

Plan ahead for your process


Anticipate steps in your process where
something could go wrong, and plan for them.
Example: You are centrifuging samples
containing methylene chloride and one of the
tubes breaks in the rotor.


What do you do? What is the hazard here?
Example: You are working with methylene
chloride and the fire alarm goes off.

What do you need to do to secure your
experiment before evacuating the building?
Waste Disposal


Collect all methylene chloride-containing wastes
in a well-labeled compatible (glass or PTFE—
Teflon®) container
 No methylene chloride (no matter how dilute)
should be put down the drain
 Clearly label container with the concentration of
methylene chloride, and a warning statement
(e.g. “health hazard: toxic”)
When the container is full, complete Hazardous
Waste Removal Request paperwork, and call
EHS&RM for removal (474-5617)
When to contact EHS&RM

Contact EHS&RM if:

You experience adverse health affects which might
be attributable to methylene chloride
You are exposed to methylene chloride via a spill
or splash
You have methylene chloride-contaminated wastes
to pick up
You have any questions or concerns

Call 474-6771, 474-5487, or 474-5617



Emergency Response
Contacts
In an emergency, call: 911
 Campus hotline: 474-7UAF (7823)
 Facilities Services: 474-7000

Emergency information is available at:
www.uaf.edu/alert
 Safety information is available at:
www.uaf.edu/safety


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