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

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Presentation on theme: "Working Safely with Methylene Chloride Environmental Health, Safety, and Risk Management University of Alaska Fairbanks September 2008."— Presentation transcript:

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 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 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 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)

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 ( ) 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 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 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 ( ), 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 ( )

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 , , or

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


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