Experiences in Mercury Spill Clean-up at UCLA
Presented to
the American Chemical Society
April 3, 2001
Joe Raab, CIH
University of California, Los Angeles
The Mercury Haz Mat Story:“When a Good Element Goes Bad”
• Overview of mercury
• Examples of mercury spill clean-ups
• Mercury clean-up tools
• Absorbents and indicators
• Determining “how clean is clean”
• Mercury reduction steps
Mercury
• Elemental / organic / inorganic compounds.
• Liquid rather than solid at room temperature.
• Low vapor pressure (evaporates slowly) but often produces significant vapor at room temp.
• Mostly absorbed through the lungs or sometimes through damaged and broken skin.
• Usually a lack of acute symptoms, chronic affects to CNS.
• Bio-accumulates in the food chain.
Items which Contain Mercury
• Gauges, manometers barometers, and vacuum gauges,
• Blood pressure sphygmomanometers
• Mercury switches and relays
• Thermometers
• Mercury containing thermostat probes.
• Dental amalgam• Hospital equipment• Laboratory solutions• Fluorescent & high
intensity discharge (HID) lamps
Types of Mercury Spills at UCLA 1997-1999
6
1
6
8
26
0 5 10 15 20 25 30
Other
Electrical Switches
Sink Traps
Sphygs
Thermometers
Mer
cury
Sou
rce
Typ
e
Number of Incidents on UCLA Campus
Mercury Incidents at UCLA Center for Health Sciences vs. Campus
Mercury Incidents at
CHS68%
Mercury Incidents at
other locations32%
Calculating the Costs (1999 data)
• Disposal cost (assuming 80% due to haz mat events)– Disposal cost = $34.65/lb.
– 1,437 lbs.
– Total cost = $39,833
• Haz Mat Response Cost– Labor hours = 280.59
– Personnel cost = $100/hr.
– Total cost = 28, 059
Office Spill from Mercury Above-Ceiling
• The problem = trapped mercury in plumbing lines above the ceiling
• During demolition of the floor above, approx. 0.25 liters of mercury hit the tiles and contaminated the office below.
Office Spill from Mercury Above-Ceiling
Contaminated Materials:• Ceiling tiles and light fixtures
• Leased office copier
• Carpet
• files
• Etc.
+ Phase II from trapped mercury in a light fixture !!!!!
Pathology Laboratory
• B5 fixative (6.6% mercuric chloride & 2.3% sodium acetate solution)
• Was placed into aluminum container and corroded through onto the floor.
Pathology Laboratory
• Air and bulk samples revealed extensive contamination of the floor.
• Many attempts made to clean the floor until finally the decision was made to remove it.
• Additional contamination found in sinks and plumbing systems
Pathology Laboratory
• Floor was ultimately removed and drummed.
• Accomplished using trained abatement workers using jack hammers and controls similar to lead abatement.
Blood Pressure Sphygmomanometers
• Many recent incidents.
• Contamination of care giver and patient is common.
• Pressure applied results in large dispersal of a large volume of mercury.
• Very difficult clean ups.
Mercury Thermometers
• Can be well contained or dispersed.
• Drop height increases dispersion.
• Often in ovens, incubators, carts, refrigerators and other difficult areas.
• Haz Mat “Size up” steps are very important.
Mercury Clean-up Tools
• Vacuum Cleaners
• Mercury spill kits and pumps
• Absorbent sponges
• Direct Reading Instruments
• Personal Protective Equipment
Vacuum Cleaners
• Advantages:– Easy pick up of bulk materials.
– Different styles and sizes available.
• Disadvantages:– May not work on some
contamination.
– Need routine maintenance and parts replacement.
– May create vapor during clean-up.
– Expensive
Mercury Spill Kits and Hand Pumps
• Advantages:– Good for small spills and
individual drops.
– Provide access to difficult areas.
• Disadvantages:– Not efficient for large
spills.
– Requires repetitive action.
– May miss small droplets.
– Eye fatigue.
Mercury Sponges• Wetted sponge with
amalgam on one side.
• Advantages:– Best when used with small
spills to accumulate and amalgamate small droplets.
• Disadvantages:– May spread drops around.– Sometimes does not
amalgamate well.– Can be messy.– Amalgam can look like Hg.
Direct Reading Instruments: Jerome Mercury Monitor
• Direct reading instrument which deposits mercury vapor on gold film and reads concentration based on change in electrical resistance.
• LOD = 0.003 mg/m3.
Direct Reading Mercury Instruments
Advantages:• Accurate real time
monitoring of mercury vapor.
• Good for tracking down areas of contamination.
• Aids in the selection of appropriate PPE.
• Aids in identification of contaminated items.
Disadvantages:• Direct reading is not
directly comparable to PEL.
• Background may be high during clean-up.
• LOD limitations. May give a false sense of security.
• Can become saturated.
Personal Protective Equipment (PPE)
• Respirator – Typically tight fitting half
or full face with mercury vapor cartridges.
– End of Service Life Indicator.
• Protective Suit
• Booties– contamination of shoes is
common
• Gloves
Mercury Absorbents and Indicators
• Typically applied after some effort has been made to take up the bulk material.
• Many require significant application time to absorb the mercury.
• The characteristics of the contaminated surfaces will determine their success.
• Reapplication or additional agitation may be necessary.
Hg Absorb• Typically granular zinc and
citric acid.
• Acid slightly agitates and frees up the mercury to be absorbed.
• Requires additional clean-up.
• Contact with Hg contamination is important.
• Not good on porous surfaces.
Mercury Indicator Powder
• Sulfur, Silicon Dioxide, & Proprietary ingredient.
• Sprinkle over spill and wait at least 24 hours.
• Color change from dull yellow to rust.
• Very helpful in identifying problem areas of contamination.
Liquid Absorbents
• Liquid mixture containing copper sulfate, calcium chloride, potassium iodide, & sodium thiosulfate.
• Apply with sprayer, leave for 24 hours and rinse off.
• Forms mercury sulfide.
• Better on porous surfaces than solid absorbents.
Determining “How Clean is Clean?”
• Direct reading instrument mercury measurements of non-detect.
• NIOSH Method 6009 using hopcalite tubes and atomic absorption analysis – Estimated method LOD = 0.3 g
– What do you compare result to (PEL, 1/10 PEL?)
• Mercury indicator powder - no color change.
• Swipe samples.
• Hazardous waste leachate testing methods.
Mercury Reduction Steps
• Non-mercury alternatives– (i.e. Replacement of blood pressure
sphygmomanometers)
• Literature campaign• Substitute chemicals (i.e. zinc chloride fixatives)• Secondary containment for existing sources• Future mercury round-ups
Conclusions
• Mercury spills are disruptive, expensive, time consuming, etc.
• Mercury spills can be very difficult to clean, requiring a variety of tools and well trained haz mat crews.
• Always check personnel in the area of the spill for contamination on their person.
Conclusions (continued)
• Mercury absorbents and indicators can be essential after the initial clean-up to rid the area of trace material.
• Sometimes a successful clean-up requires the removal of contaminated materials (i.e. carpet).
• Consult waste managers about the disposal of contaminated materials.
Conclusions (continued)
• Determining the extent of the contamination is difficult and can require a combination of analytical methods.
• Consider long term exposures prior to “clearing” an area.
• The best method for dealing with mercury spills is to prevent them in the first place by using mercury reduction methods.