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.