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