November 1993

Disposal of Acrylamide Gels

There has been much discussion lately about the ultimate fate of acrylamide gels. These gels must be disposed of as a hazardous material.

Acrylamide gels are used in electrophoresis, separating proteins on the gel. Often hazardous substances such as ethidium bromide are used in coordination with these gels. When the experiment is complete, the gel cannot be thrown out as regular trash but must be considered a hazardous waste.

At CWRU, we follow a policy that demands that if there is even a chance that something is a toxic or hazardous material, it must be disposed of in an environmentally sound way. Since these gels are potentially hazardous because they are used in conjunction with toxic materials, we cannot allow researchers to dispose of them in any other way.

Acrylamide itself is a regulated substance, and there is always the possibility of not all of it polymerizing. Furthermore, the gel itself, because it is a gel and not a solid, cannot be picked up as solid waste.

Dispose of acrylamide gels by placing them in a glass container marked "hazardous waste." The corresponding paperwork should also be completed and in place. Do not throw these away as normal trash.

The "Hazards" of Chemicals

Injuries from chemicals can happen four basic ways:

  • by force (such as an explosion)
  • by poisoning
  • by destruction of tissue (such as acid burning the skin)
  • by displacement of air breathed in.

Because the ways in which chemicals can harm the body are varied, it is important to know how to recognize whether a chemical is potentially harmful and in what form.

Whether or not exposure to a chemical is harmful depends on three factors: the dose (how much), the duration and frequency (how long and how often) and the route (how exposure occurs). A change in any one of these three factors can change the effect of the chemical in the person exposed.


As a general rule, the larger the dose, the more quickly an injury occurs. As the dose increases, the severity of the injury increases. The MSDS for a chemical lists the Permissible Exposure Limit (PEL) and the Threshold Value Limit (TVL)--the amount of the chemical to which one can be exposed with no harm--but this applies only to inhalation at the point of exposure.

Duration and frequency:

The duration and frequency of exposure will also affect the severity of an injury. Chemicals with acute toxicity cause injury very soon after a single exposure. Other chemicals have chronic toxicity--they cause harm only after repeated exposure.


Exposure is also affected by the ways or routes in which chemicals enter the body. The most obvious route of entry is through the mouth and nose. Breathing in harmful dusts, mists, gases or vapors provides the most direct way for chemicals to enter the blood and usually causes harmful effects faster than any other route. Eyes offer another route of entry, and since eyes, nose and mouth are connected by open passages, any chemical that gets in your eyes can be swallowed or inhaled.

Effect of Exposure

The effect of exposure to a hazardous chemical can be either local (at the site of the exposure) or systemic (inside the body).

Local reactions usually result from a single exposure and may result from minor irritation to severe tissue damage. Sometimes a local reaction doesn't occur until after repeated exposure, such as an allergic skin rash. Splashing or spilling a chemical can result in local reactions in the eyes and skin and may cause pain, itching, or tissue damage. Swallowing a harmful chemical can cause local reactions in the mouth, esophagus, stomach, and intestines. These kinds of reactions are serious an may lead to long-term illness or even death. Breathing in harmful gases, mists, dusts, or fumes can burn.

Compressed gases are unique in that they have the potential to be exposed simultaneously to both mechanical and chemical hazards. If the gas is flammable, fire or explosion is possible under certain conditions. Additional hazards can arise from the toxicity or reactivity of the gas. And since so much potential energy is created through the compression of the gas, a cylinder can be a potential rocket.


Thus, careful procedures are necessary for handling and storing compressed gas cylinders. Here are some tips to reduce their potential hazard.

Cylinder Handling

  • always use a cylinder hand truck for transport.
  • the cylinder cap should always be firmly in place when the cylinder is moved.
  • cylinders should be chained or otherwise secured in an upright position at all times.
  • do not drop cylinders or permit them to fall against each other.
  • leave valve caps on cylinders until secured and ready for use.
  • all valves should be closed when not in use.
  • use the proper regulator for the particular gas.
  • always consider cylinders to be full and handle accordingly.
  • cylinders of non-liquefied gases should be considered empty while a little positive pressure (approx. 25 psig) still remains in order to prevent suck-back and contamination.
  • cylinders containing liquefied gases should never be completely emptied in order to prevent suck-back and contamination.
  • the contents of cylinders must be identified with decals, stencils, glued or wired-on tags, or other markings on the cylinders. Color codes alone or tags hung around the necks of the cylinders are not acceptable. Cylinders lacking proper identification must not be accepted from vendors.
  • employees must not attempt to repair cylinders or cylinder valves or to force stuck or frozen cylinder valves.
  • empty cylinders must be marked "EMPTY" or "MT" with grease pencils. Generally, this marking should be on a large piece of adhesive or masking tape stuck on the cylinder rather than on the cylinder itself. However, some cylinders have tags wired to the valve that identify their contents; in this case, the bottom half of this tag may be torn off to indicate an empty cylinder. In all cases, empty cylinders must be easily identified so as not to be confused or stored with full cylinders.
  • demurrage charges continue until cylinders are returned to the supplier; therefore, empty cylinders should be returned promptly. Furthermore, very old cylinders can form shock-sensitive peroxides, another reason to return cylinders as soon as they are empty.

Cylinder Storage

  • store cylinders in a fire-resistant, cool, dry, and adequately ventilated area.
  • the storage area should not contain any sources of ignition.
  • storage area temperature should not exceed 100 degrees Fahrenheit.
  • the floor should be level and designed to protect cylinders from dampness.
  • cylinders should be protected from weather extremes and direct sunlight.
  • store gases supporting combustion at least 25 feet from fuel gases, preferably in another storage area.

All researchers should know the characteristics of the gases he or she uses: toxicity, flammability, compatibility with materials and other gases.

The information for the above article was taken from pages 27-28 of the CWRU Chemical Safety Manual. Please look here for further information on the safe use of compressed gas, or call the DOES office at x2907.

Holiday Fire Safety

With the holidays approaching, residence hall staff needs to be more aware of the increased fire hazards in the dorms-decorations and electrical lighting are only a few of the items that can spark disaster. Staff should be able to quickly recognize potential dangers and take corrective action. Here are some safety measures to keep in mind:

  1. Decorations must be flame-proofed or made of non-flammable material.
  2. If decorating a live tree be sure to:
    • use a fresh evergreen that has been treated with a flame retardant;
    • equip it with a tree stand that can hold water at the base of the tree, and keep it full at all times;
    • remove the tree from the residence hall prior to closing for Christmas break.
    No electrical equipment or devices are permitted on or under trees; only indirect lighting may be used. Nor are candles or open flames allowed on, under, or within 10 feet of the tree.
  3. If using a metal tree, do not place electrical lights or other electrical objects on them.
  4. Decoration materials must not be exposed to light bulbs, heaters, or other heat or flames.
  5. Gift wrappings should be removed from the residence hall soon after gifts are unwrapped. These wrapping materials must not be placed in corridors or storage areas.
  6. Decorations covering large surface areas-doors, walls, or ceilings-are not permitted.
  7. Door decorations must not overlap the top, bottom, or sides of doors.
  8. All Christmas decorations must be removed from the residence hall before Christmas break.

Disposal of Radioactive Liquids

Disposing of radioactive liquids requires some special procedures not applicable to solid wastes. When readying liquids for disposal, keep in mind that:

  1. Radioactive liquids ready for disposal must have a pH between 5 and 9. Please test to make sure that the liquid's pH is within these limits; if it is not, neutralize it before you call the Radiation Safety Office for disposal.
  2. The Disposal Listing for Radioactive Material (Liquid) needs to be very specifically filled out. The names and amounts of the chemicals in the liquid should be identified on this sheet. And remember, fill out one sheet per container.

You must also account for liquid radioactive waste on the Radiation Waste Disposal Form. For data entry purposes, we use only the Waste Disposal Form-the Liquid Waste Form remains with the container for segregation in processing.

Seven Rules of Biosafety

  1. Do not mouth pipette.
  2. Manipulate infectious fluids carefully to avoid spills and the production of aerosols and droplets.
  3. Restrict the use of needles and syringes to those procedures for which there are no alternatives; use needles, syringes, and other "sharps" carefully to avoid self-inoculation; dispose of sharps in leak- and puncture-resistant containers.
  4. Use protective laboratory coats and gloves.
  5. Wash hands following all laboratory activities, following the removal of gloves, and immediately after contact with infectious materials.
  6. Decontaminate work surfaces before and after use and immediately after spills.
  7. Do not eat, drink, store food, or smoke in the laboratory.

Incident in Smith Building

We hear often in the lab about the importance of compatibility-which gloves are compatible with which chemicals, which chemicals might react with each other, or how chemicals should be stored on the shelf. But the incident in Smith Building a few weeks ago serves as a reminder that the issue of chemical storage compatibility extends also to the containers in which chemicals are stored.

In Smith Building, a solvent mixture of methyl isobutyl ketone and acetic acid was being stored in a container made of polyethylene. The solvent in this case acted as a "stress-cracking agent" in reaction with the container and caused it to crack from the inside to the outside. Over a period of months, the integrity of the container weakened and eventually the sides collapsed.

Nalgene, the company from which the container was bought, said that polyethlyene should not be used to store an MIBK-acetic acid mixture because after only 6-9 months this sort of cracking will occur. Instead, a type 316 stainless steel container should be used.

If you are not storing a chemical or solvent in its original container, be sure to check its compatibility with the new container's material. Though the incident at Smith was a singular example, this sort of problem can occur with many chemicals and solvents if they are not properly stored.

A chemical's MSDS, or Material Safety Data Sheets, contains information about that chemical's compatibility, as well as a wealth of other information on its safe usage. Each laboratory should have a MSDS copy either on disk or in hard copy for each chemical used in that lab, and all employees of the lab should know the location of the MSDS holdings.

Please call DOES (x2907) if you require any MSDS copies or if you have questions concerning chemical compatibility or storage in your lab.