Working Safely with Methylene Chloride

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

2. 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

3. 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

4. 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.

5. 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

6. Routes of exposure • Inhalation • 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/CDC recommends that methylene chloride be regulated as a suspected carcinogen (lung and liver cancer)

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

10. 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

11. 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)

12. 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

13. 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

14. 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!)

15. 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

16. 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.

17. 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

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 Hazardous Waste Removal Request paperwork, and call EHS&RM for removal (474-5617)

20. 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

21. 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