1. Working Safely with Methylene Chloride
Environmental, Health, Safety, and Risk Management
University of Alaska Fairbanks
May 2013

2. Overview Methylene Chloride Standard Properties of Methylene Chloride
Routes of Exposure and Health Effects
Protecting Yourself
Handling and Storage
Spills and Accidents
Plan Ahead
Waste Disposal

3. Methylene Chloride Standard
OSHA (Occupational Safety and Health Administration) 29 CFR
(Code of Federal Regulations)
It’s the law!
Includes:
Appendix A: substance safety data sheet and technical guidelines for methylene chloride
Appendix B: medical surveillance for methylene chloride

4. Methylene Chloride Standard (cont.)
Establishes the following:
8-hour Permissible Exposure Level (PEL) at 25 ppm (parts per million)
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 (personal protective equipment), air monitoring, establishment of regulated areas, etc.

5. Properties of Methylene Chloride
Liquid: clear and colorless, with a chloroform-like odor (pleasant, sweet)
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
Another common name for methylene chloride is dichloromethane

6. Routes of Exposure Inhalation Skin absorption Eyes Ingestion (rare)
Primary route of exposure due to high volatility
Skin absorption
Occurs via contact with liquid and/or vapor
Eyes
Splashes with liquid, or exposure to vapors
Ingestion (rare)
Eating or drinking without washing hands and face after working with methylene chloride

7. 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)

8. 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 (National Institute for Occupational Safety and Health)/CDC (Center for Disease Control) recommends that methylene chloride be regulated as a suspected carcinogen (lung and liver cancer). For more information, visit:

9. Protecting Yourself Engineering controls Personal protective equipment
Specific lab safety practices

10. Protecting Yourself: engineering controls
Use all methylene chloride-containing solutions in a properly functioning chemical fume hood
Make sure the fume hood has a current maximum sash height sticker (tested by EHSRM within the last year)
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

11. Protecting Yourself: personal protective equipment
Long pants and long-sleeve shirt
Chemical resistant lab coat (NOT the standard cotton-poly ones) or chemical resistant apron
Closed-toe shoes or rubber boots
Splash goggles
Gloves:
2 pair are recommended
1st pair (next to skin): laminate (SilverShield)
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 methylene chloride occurs)

12. Protecting Yourself: specific lab safety practices
Review your protocol prior to beginning the procedure (every time)
Inspect your PPE for cracks, holes, signs of wear
Clearly label ALL bottles (stocks and wastes)
Use the smallest amount possible
Have a hardcopy of the SDS in an easily accessible location in the lab
Make sure pathways to functioning emergency eye wash and shower are free of obstacles
Check to make sure that emergency equipment has been tested on a regular (weekly) basis

13. Storage of Methylene Chloride
Classified as a health hazard (color coded 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

14. Spills and Accidents: 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 EHSRM ( ) that you have a bag of methylene chloride cleanup materials to pickup (see slide #19)
If you do not feel comfortable cleaning up the spill, call EHSRM for help (never put yourself at risk!)

15. Spills and Accidents: 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 EHSRM at or
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

16. Spills and Accidents: 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 EHSRM ( ), and your supervisor of the incident. Seek medical attention.

17. Spills and Accidents: 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
Immediately notify EHSRM ( ), and your supervisor of the incident

18. 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?

19. 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 online Hazardous Waste Pickup Request. Don’t know how? Contact EHSRM at or visit the EHSRM Website:

20. When to contact EHSRM Contact EHSRM 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 , , or

21. Emergency Response Contacts
In an emergency, call: 911
Dispatch (Fire & Police):
Campus hotline: 474-7UAF (7823)
Facilities Services:
Emergency information is available at:
Safety information is available at: