May 1995

Annual Fire Drills

The annual practice fire drills begin in May and will run throughout the year. The Department of Occupational and Environmental Safety (DOES) asks that all occupants of buildings cooperate during this time.

Department coordinators for each building, who will help with preplanning within their departments, are contacted by DOES prior to the drill to arrange a suitable time. The tentative schedule for 1995 is as follows:

May: Millis, Morley, Biology, Adelbert.

June: Rockefeller/Strosacker, Smith, Bingham, Baker, Crawford, Tomlinson.

July: Kent Hale Smith, White, Glennan, Yost, Pardee, BRB.

August: Eldred, Emerson Gym, Adelbert Gym, Quail, Wickenden.

September: Medical School (East, West, and Tower), Nursing School, Dental School, Fribley Commons, Leutner Commons, Sears Library.

October: Enterprise Hall, Thwing Center, Dively, Mather House, Mather Memorial, Mather Dance.

November: MSASS, Guilford House, Hayden, Freiberger Library, Gund (Law School), Wade Commons.

It is important that the coordinators inform employees in their departments of basic procedures to follow (Evacuation Plan) during a drill and/or emergency.

Individuals who may have difficulty evacuating an area during an emergency or who may have difficulty hearing or seeing an emergency alarm need to have an approved evacuation plan for emergency drills and for actual emergencies. Each individual with a disability (whether temporary or permanent) that could affect communication or mobility must also take the time to become familiar with the existing alarm systems and exits in the buildings s/he frequents. The department's coordinator will assist those who may have difficulty with an evacuation by helping that individual make necessary special arrangements. Please participate and cooperate when there is a drill or actual event in your building. If you need more information contact your department coordinator or the DOES at x2907.

Alternatives to Liquid Scintillation Counting: Using a GM Probe

Liquid scintillation counting is the most common method of counting wipes or smears for beta-emitting isotopes. However, an alternative exists that is cheaper and reduces the amount of waste: using a GM probe.

Liquid scintillation counting is popular because it is highly efficient, especially for low energy beta emitters. However, there are drawbacks as well: there is a high cost for both the vials and the fluid, it creates a large quantity of waste, and it takes time. Using a GM probe to count wipe tests may be the answer to these problems.

How it Works

A wipe or smear test condenses loose contamination over a large area to a small area. If the minimal detectable activity of the probe for that specific isotope is less than the Action Level for removable contamination, then these wipes may be counted with the GM probe. These results must be recorded.

The benefits of using a probe to count the results of a wipe are clear: most importantly, you do not have to buy scintillation fluid or vials, saving money and eliminating the corresponding waste materials. It also saves a lot of time that could then be devoted to research.

Is it Right For You?

Counting with a GM probe has its conditions. It cannot be used to count tritium, 125I, 51Cr, or 22Na. It works well on 14C, 32P, 35S, and 45Ca. Also, the minimal detectable activity must be less than the Action Level for removable contamination. The procedure for calculating this is as follows:

  1. Assume that all count rates below twice background are "indistinguishable from background."
  2. Divide the background count rate by a decimal (not percentage) efficiency. This yields a minimal activity that must be present to be detected.
  3. This minimal detectable activity must be less than the Action Level for removable contamination (see the Radiation Safety Manual appendices for all MDAs). If it is, then wipes may be assayed using a GM probe.

Though this alternative counting method may not be used by everyone, we encourage researchers to see if it is viable procedure for their labs. It is just as efficient and generates many benefits. Please call the Radiation Safety Office (x2906) if you have any questions or want additional information.

Clean-up of Radioactive Contamination

Over the past few weeks there have been several radioactive spills that have not been contained before the contamination spread. Here are some reminders on the proper procedure in the case of a spill and how to effectively contain it and clean it up. Any spill, no matter how minor, must be reported to the Department of Occupational and Environmental Safety (386-2906).

During Experiments

  • Monitor often during experiments so any contamination in unexpected or outlying areas is caught before it is inadvertently spread.
  • This is especially true of hands and feet. Since it is mostly through walking or touching other objects that contamination is spread, it is vital that hands and feet be clean.
  • For the same reason, survey the floor during and after experiments. In looking at the recent spills, it was clear that walking had distributed contamination throughout the lab. The floor should be monitored regularly during monthly or post-experiment surveys.
  • Leave gloves and foot covers at the experiment area or discard them immediately in the proper container.

Wear the Proper Protection

Wearing the proper protective clothing is vital to spill containment and worker safety. Take the following precautions:

  • Mark clearly the area in which the spill occurred.
  • Don't walk or allow others to walk in the contaminated area.
  • Have spare shoes or booties handy so a potentially contaminated pair can be left near the area and another clean pair is available to wear.
  • After a spill, do not walk around in high traffic areas such as hallways or restrooms. Shoes should be surveyed every time the area of the spill is left.
  • Better yet, wear foot-covers to decrease the chances of radiation getting on your shoes; this will limit the potential of spreading the spill by walking.
  • Wear a lab coat when working with radiation.

Spill Clean-up

When a spill occurs, follow these procedures:

  • Absorb any aqueous material first with a tissue or towel.
  • DO NOT wet the area with detergent or "rad-con" and water. Adding water to a spill, even with the detergent in it, will only spread the area of contamination. Concentrate on keeping the spill as contained as possible.
  • After all of the aqueous medium has been absorbed, wet the area with "rad-con" and water.
  • Clean until no radioactive material can be lifted off the surface; then measure to see if levels are too high and if shielding is needed to lower levels to background. Always mark a radioactive spot with tape, listing the isotope, activity, and date.

Radioactive Waste Pick-Ups: A Review

  • Have waste bags and forms filled out and ready for pick-up before you call our office since waste pick-ups start as early as 9:00 am. If the waste is not ready when a technician arrives, the pick-up date will be rescheduled.
  • The name of the Primary Investigator (not the lab's technician) should be at the top of the Radioactive Waste Disposal Form. The form should also be signed by the PI; however, a technician may sign the PI's name along with his or her own initials. An account number must be written on the form for waste tracking purposes. We do not charge for radioactive waste pick-ups.
  • A separate Liquid Waste Disposal Form should be filled out for each bottle of liquid waste. Write down the chemical constituents of the waste, the pH of the liquid, and the chemical form of the isotope. The waste will not be picked up if the above information is not on the form.
  • Liquid waste will no longer be accepted in glass bottles. Use recyclable plastic containers instead.
  • Liquid waste that is found to contain plastic pipette tips or other small items will be returned to the lab so they can be removed, and another pick-up will be scheduled.
  • Replacement supplies can be obtained by calling the RSOF at x2906. If you plan on scheduling a pick-up and need supplies, the technician on pick-ups by prior arrangement can drop them off to the lab during the pick-up route.
  • Please do not let waste accumulate in the lab. We would prefer you call us more often if you find that you are generating large amounts of waste.

Any questions about waste packaging, supplies, or filling out forms can be directed to Karen Janiga at Radiation Safety (x2906).

Ordering Waste Containers

Producers of chemical or hazardous waste materials must supply their own containers to hold their waste for disposal. Safety Services can no longer supply these containers.

In the past, we have in certain cases supplied 55-gallon drums to researchers. However, all researchers must now supply their own drums or containers. Make sure that the container is compatible with the chemical waste it will hold; for example, do not dispose of corrosives in a metal drum.

Call Safety Services if you would like to know what kind of drum or container is needed to hold certain wastes or if you need information on ordering containers (x2907).

Waste Minimization Techniques

Minimizing waste in the laboratory is important for both economic and environmental reasons. The cost of disposing chemicals and other hazardous wastes has drastically increased, with some sites no longer even accepting certain wastes (such as those containing mercury). The need to minimize radioactive wastes is perhaps even more vital since there are no available sites for disposal.

But just as important is our campus' pledge to be as environmentally sound as possible. One of the most effective ways to do this is to reduce the amount of waste being created: less waste to dispose of means less waste in circulation that can potentially damage our environment.


For chemicals more than radioactive materials it is possible to create less waste before the experiment even starts. Examine your methods and materials before you begin:

  • Purchase only what is needed. Do not order larger quantities to take advantage of unit cost savings--disposal costs down the road for the unused portion of the chemical greatly exceeds the initial savings. CWRU's new chemical store sells chemicals in smaller quantities to provide this sort of convenience.
  • Pre-weigh chemicals for undergraduate teaching labs. This will reduce spills and other wastes generated by students weighing their own materials as well as increase laboratory productivity.
  • Substitute less hazardous chemicals in experiments to reduce the cost of the disposal of hazardous chemicals. For example, use alcohol instead of benzene; use sodium hypochlorite instead of sodium dichromate.
  • Use alcohol or digital thermometers instead of mercury thermometers, which break easily and are extremely expensive to clean up and dispose of.

There are also many post-experiment techniques available that allow you to reduce the amount of waste leaving your lab:

  • When cleaning with solvents, use spent solvent for the initial cleaning and use fresh solvent only for the final rinse.
  • DOES now has a still that can recycle many would-be waste solvents to near-pure form. Call our department (x2907) to see if your department creates such reusable waste.
  • Destroy wastes as part of the last step of the experiment if possible, provided the result is not a regulated material (call Safety Services to confirm). Such end-procedure neutralization techniques include oxidation reduction or precipitation and filtration of solids.
  • Label all containers, new or temporary, with the proper information, even if the solutions they contain are innocuous. Disposing of an "unknown" waste, which is what materials in unlabeled containers often become, requires time-consuming and costly analysis. In addition, unknowns are dangerous in that they may explode or cause adverse reactions at any time.

Radioactive Materials

  • Buy at least two reusable containers for liquid waste. Single-use containers such as milk jugs or tissue culture flasks must be thrown out as solid radioactive waste, adding to the overall waste stream. This can be prevented by using reusable containers, which we return to researchers as quickly as possible.
  • Survey gloves, booties, and footcovers after experiments to determine whether or not they are contaminated. If they are not, throw them out as regular or biohazardous waste, not as radioactive waste.
  • The same is true for bench paper; just because an experiment using radiation was performed upon it does not automatically make it radioactive as well. Survey the paper and cut out the contaminated sections, throwing the rest away as regular or biohazardous waste.
  • Use spill trays whenever possible so if a spill does occur it is completely contained. These trays are available with non-porous covers to make clean up even easier.
  • Be careful to separate your waste by isotope since their half-lives are different. We segregate waste into drums based on isotope, and when a drum is decayed it can be removed from our storage site, giving us more room for new waste. However, if there is tritium in 32P waste, for example, we must leave the waste until the tritium can be disposed--ten years--even though the bulk of the waste, the 32P, has already fully decayed.
  • Be careful to separate regulated chemical waste from non-regulated waste. One splash of regulated material in a gallon of non-regulated material means the whole gallon has become regulated waste and must be disposed of as such after all the radiation has decayed.
  • Use practices that will prevent the spread of contamination: wear booties or footcovers; remove or meter your gloves before doing anything else (such as using the telephone or the water fountain).
  • Frequently survey your areas (bench, equipment, floors) during experiments to catch any contamination before it spreads.