March 1994

Formaldehyde and Air Monitoring

Since 1992, the year that new OSHA formaldehyde standards went into effect, much emphasis has been placed on monitoring the levels of formaldehyde to which researchers may be exposed. The Department of Occupational and Environmental Safety (DOES) has a formaldehyde monitoring program in place to ensure safe limits are established in the laboratory.

The OSHA standard applies to formaldehyde gas and all mixtures or solutions composed of greater that 0.1% formaldehyde. It also applies to all materials capable of releasing formaldehyde into the air at concentrations reaching or exceeding 0.1ppm.

The limits set in 1992 are as follows: the Permissible Exposure Limit (PEL) is 0.75ppm/8hr. average. The Short Term Exposure Limit (STEL-the peak exposure acceptable in one fifteen minute period) is 2.0ppm, and the Action Limit (the level at which precautionary action must be taken) is 0.5ppm/8hr. average. It is important to realize that the odor threshold of formaldehyde for most people is 0.8-1.0ppm. This means that formaldehyde levels may exceed the PEL even though you do not smell anything-odor is not a reliable indicator of compliance with OSHA limits.

Researchers who use formaldehyde without a fume hood (even if only occasionally) should have filled out a questionnaire last year stating this information. Based on the information given-how often you use formaldehyde, under what conditions-one of our safety technicians will ascertain if and when monitoring is needed. If it is, the technician will contact you to set up a date.

Air monitoring takes place for the length of the procedure or 8 hours, whichever comes first. If OSHA limits are not exceeded, no further monitoring will be necessary for another year unless a change in personnel, process, control measures, or equipment occurs. Contact DOES under these circumstances to set up a monitoring session.

If, during air monitoring, OSHA limits are exceeded, action must be taken. If the PEL or STEL is exceeded, the process must stop until proper engineering controls and personal protective equipment (PPE) are put in place. If the Action Limit is exceeded, the engineering controls in place (a fume hood, for example) must be checked and adjusted. The process itself, unlike with PEL or STEL limits, does not necessarily have to be changed. Air monitoring will continue until results from two consecutive sampling periods taken at least 7 days apart show that safety levels are being met.

Labeling of formaldehyde is stringent. All materials capable of releasing formaldehyde must be identified and labeled. If the solution contains 0.1% formaldehyde or if it is capable of releasing 0.1ppm formaldehyde, a label must be in place saying: "DANGER: Contains Formaldehyde: Irritant and Potential Cancer Hazard" (available from our office). In addition, a written communication program for exposure should be placed in each lab.

Specific training in formaldehyde is required by the standard for all employees working with or having the potential of being exposed to formaldehyde. Formaldehyde training is included in the OSHA Lab Standard Training sessions offered by DOES. Call us (x2907) if you need to set up a monitoring session.

Sorting Out Laboratory Waste

Decreasing landfill space and new landfill laws makes waste disposal a tricky business, especially for producers like CWRU: diverse types of waste and lots of it. Waste generated at CWRU-from "sharps" to notebook paper-must be carefully segregated in order to ensure disposal in an environmentally sound way.

Basically, there are two avenues for waste disposal: contaminated or biohazardous waste, disposed of in red biohazardous containers, either in rigid boxes if it is "sharp" or bags if not, and uncontaminated lab waste, to be disposed of in black bags. A fuller explanation of what goes where in the world of waste is given below.


hypodermic needles, syringes, scalpels, cannulas, microscope slides, coverslips, broken glass, razor blades, and all pipettes.

All sharps must be disposed of in puncture-proof containers. Contaminated sharps must be disposed of in a red, rigid, plastic SHARPS container. All discarded hypodermic needles, syringes, cannulas and scalpels, whether or not they are contaminated, must also be disposed of in a red, rigid, plastic SHARPS container.

All other perceived sharps that are not contaminated-microscope slides, coverslips, broken glass, pipettes, or any other item which may cause a puncture wound or cut-may be disposed of in a puncture-proof cardboard box. This box must clearly be labeled "SHARPS" so that everyone is aware of the contents.

For pick-up of non-radioactive sharps call the Biohazard Pick-up line (x6906) before 4:00 for an evening pick-up. For pick-up of radioactive sharps, call the Radiation Safety Office (x2906).


all non-sharp infectious waste such as plastic petri plates; plastic tissue culture vessels containing media, cultures and stocks of infectious agents; devices used to transfer, inoculate or mix such agents; and paper or cloth material contaminated with these agents.

All waste of this sort must be sterilized prior to disposal. Each researcher is responsible for treating waste as close to the point and time of waste generation as possible.

Biohazardous waste must be autoclaved in red bags labeled with the international biohazard symbol. After sterilization is complete, mark "Sterilized" on the bag and tag it with the Investigator's name and the date of sterilization. These bags must remain in the lab for pick-up.

Call the Biohazard Pick-up line (x6906) before 4:00 for an evening pick-up.


all other laboratory waste that has not been contaminated by radioactive, chemical or infectious agents such as petri plates, paper cloths, gloves, tubing, non-sharp lab wastes, empty chemical containers, as well as "ordinary trash" like packaging materials (such as empty Fisher pipette containers) and cardboard.

This waste should be disposed of in black bags and can go out as general trash to be picked up by the custodial staff.

Recyclable goods such as paper and glass, cans and plastics should be disposed of in specially marked green or blue bins.

Previously, ordinary trash had to be placed in separate clear bags. Now this is no longer necessary-ALL general uncontaminated laboratory waste can be disposed of together in black bags. Questions concerning proper disposal should be addressed immediately- call the Department of Occupational and Environmental Safety (x2907) with any specific needs or problems. It is vital that waste at its source-in the lab-be properly prepared for disposal.

Picric Acid: A Serious Explosive

Picric acid solutions are frequently used in campus research and clinical procedures for making tissue fixatives, organic synthesis, and some protein work. In solution, picric acid is relatively safe. When picric acid is dry, however, it becomes a shock-sensitive, unstable compound with more explosive force than dynamite. Extreme care should therefore be taken when handling potentially dangerous picric acid. Keep the following guidelines in mind:

  1. Never let picric acid crystallize and never open a source of picric acid that you suspect is dehydrated. Just the friction from unscrewing a cap is enough to detonate picrate crystals in the cap threads.
  2. Never heat picric acid to or near dryness. Its shock-sensitive properties increase with heating and it will spontaneously explode.
  3. Picric acid will form highly explosive picrate salts upon mixture with lead or zinc metals and nitric acid.
  4. If you find an old container of dry picric acid with a metal cap, do not touch it! Metal picrate salts may form as the acid corrodes the metal cap over time, and some metal picrate salts are even more shock-sensitive than the acid form. Removal and disposal of such containers is a job for the bomb squad, literally.
  5. When ordering picric acid, purchase solutions instead of the wetted paste whenever possible.
  6. Finally, picric acid is a toxic compound and should be handled with gloves.

Picric acid in its shock-sensitive condition looks and acts like dry sand; its dangerous explosive properties are evident only in its dehydrated crystalline form. Picric acid should contain at least 15% water by weight; if you suspect a container of picric acid is too dry, call the Department of Occupational and Environmental Safety (x2907) and we will come inspect it. Please do not try to dispose, hydrate, or otherwise take care of it yourself.

Disposal of Radioactive Waste in the Sanitary Sewer

All laboratories are permitted to dispose trace quantities of radioactive materials down the sanitary sewers provided that the radioactive solution is not classified as a regulated waste by the EPA. Prior sewer disposal criteria by the NRC demanded that radioactive material be "soluble" and "readily dispersible," and that the disposed material met all other Federal, State, and local sewer disposal criteria.

With the enactment of new NRC regulations (effective Jan. 1, 1994) the definition for " sewer disposable materials" has been changed. The radioactive material constituent must be soluble or be a readily dispersible biological material. In addition, the regulations restrict sewer concentrations based on the chemical form of radioisotope.

Since January 1993, in anticipation of these changes, the Radiation Safety Office has required that researchers list the chemical form of the isotopes in aqueous solutions we pick up for decay in storage. For those labs that dispose of radioactive materials down the sanitary sewer, the sewer disposal waste logs should include the chemical form of the isotope (i.e. dATP) in addition to the date, isotope, and activity of the disposal.

In most labs on campus, the radioactive material being disposed down sanitary sewers is already dissolved in aqueous solutions or incorporated into tissue culture cells, meeting the criteria of the new regulation. Therefore, besides having to record the chemical form of the radiolabeled compound, the Radiation Safety Office does not anticipate any major changes to the sewer disposal habits of labs based on the new ruling.

A notice containing details and a sample disposal log will be mailed to radioactive materials users in the near future.

Vial Control

The Radiation Safety Office has observed ongoing problems with scintillation vials during waste pickup. Below are some guidelines to proper vial disposal to prevent leakage and to ensure safety for all involved.

  • Use only the appropriate bag for disposing vials--the bags we give out for dry waste are inappropriate for disposing vials.
  • Vials should be double bagged to control leakage.
  • Vial bags should not be overfilled--use a number of small bags rather than one overfilled bag.
  • They should not contain anything but vials--no gloves, paper, pipette tips, tissue trays, etc.
  • Scintillation fluid does not need to be separated from the vial itself before disposal; the entire vial (cocktail included) can simply be thrown away.

Leaking vial bags will NOT be picked up by Radiation Safety technicians. A contamination hazard is present for all involved, and we will not risk the massive cross contamination that can occur in these situations. The Radiation Safety Office has small, thick-walled vial bags available for free. If you need some, call us at x2906.