Presentation on theme: "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."— Presentation transcript:
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
Mercury Incidents at UCLA Center for Health Sciences vs. Campus
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/m 3.
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.