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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
ppm15 min short-term exposure level (STEL) at
125 ppmAction 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 limitMethylene chloride does not have adequate
warning properties
Routes of exposure
InhalationPrimary route of exposure due to high volatility
Skin absorptionOccurs via contact with liquid and/or vapor
EyesSplashes 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 chlorideOther 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 eyewashUse eyewash for 15 minutes, holding both lids
openSeek 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®) containerNo methylene chloride (no matter how dilute)
should be put down the drainClearly 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 chlorideYou are exposed to methylene chloride via a spill
or splashYou have methylene chloride-contaminated wastes
to pick upYou 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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