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  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

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 • 1 st pair (next to skin): polyethylene or laminate • 2 nd pair (over 1 st 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