doeHealth Care Waste & Toxics Reduction Tips

for small and medium size health care facilities


In general, surgical instruments and medications that enter an already sterile part of the body (such as the blood, or beneath the skin) must have a high sterility assurance level. Examples of such instruments include scalpels, hypodermic needles and artificial pacemakers.

Sterilization can be achieved through application of heat, chemicals, irradiation, high pressure or filtration.  This fact sheet will discuss chemical sterilization and the on-site treatment of spent sterilizer solutions.  

On-site treatment can provide a cost-effective way to eliminate the perpetual liability and cost associated with dangerous waste disposal.
Dangerous waste generators may treat their own waste on-site without a dangerous waste treatment permit if they meet certain requirements. 

Chemical Sterilants

Chemical sterilants are designed to kill a broad spectrum of organisms by exposing them to high concentrations of reactive chemicals.  This means that all the common chemical gas sterilants are toxic.  Adequate measures must be taken to protect workers using these materials and many used sterilants designate as dangerous waste.  Common sterilants that designate as dangerous waste include:

Treatment by generator (TBG) involves deactivation of the active ingredients in the sterilants.  Deactivation might then allow discharging the material to a wastewater treatment plant via sanitary sewer.  Keep in mind:


Basic process to neutralize or deactivate glutaraldehyde and OPA.  sterile

  • Place expired disinfectant inside fume hood.
  • Add the recommended amount of neutralizing product for the type and amount of expired disinfectant. Stir gently.  Wait for the designated amount of time per product instructions.
  • test pH  (Many neutralization products turn treated waste a dark color. An electrode pH meter may be preferable to colorimetric test strips.)
  • Dispose of neutralized solution per local wastewater treatment authority requirements.


Products to Use:

Products available to neutralize or deactivate glutaraldehyde and OPA.  

  • Kem-Safe™
  • Aldex®
  • Glut-FREE®
  • Glute-Out®
  • Formalex®
  • Glut-Neut
  • Hyde-Out®


Ethylene Oxide: Ethylene oxide is a known carcinogen.  It designates as dangerous waste and must always be handled as such.

Glutaraldehyde and Ortho-Phthalaldehyde (OPA):  There are several commercially available products (see box 4) for the purpose of neutralizing glutaraldehyde and OPA (ANSI/AAMI, 1996), including powders, solutions, and salts.   These convert glutaraldehyde and OPA into a non-toxic, pH-neutral compound in a short timeframe.    The common neutralizing agent for these is glycine. In case of a glutaraldehyde or OPA spill, it may be suitable to use one of the following:  ammonia, ammonium carbonate powder, dibasic ammonium phosphate, or sodium bisulfite.  Please note, however, that these other neutralizers may be more hazardous than glycine and may designate as dangerous waste.  Please see Box 3 for specific neutralization steps. 

Hydrogen Peroxide solutions, Peracetic Acid solutions or solutions containing both:   These solutions are not characterized as dangerous waste and therefore do not need to be managed as such.   They are an inhalation hazard and a dermal irritant and both are corrosive.

Disposal of Treated Solutions: Check with your local Publicly Owned Treatment Works (POTW) to determine if glutaraldehyde or OPA solutions can be disposed of in the sanitary sewer system, and if so, at what concentration.  Do not discard glutaraldehyde or OPA solutions (including neutralized solutions) into septic systems. Unlike a wastewater treatment plant, septic systems don’t allow for further dilution.  The solution can be harmful for the bacteria that make the septic system work.

Recordkeeping: A treatment by generator (TBG) activity is considered a separate activity from the production or cleaning process originally generating the dangerous waste. Therefore, dangerous waste generated from a TBG activity is also counted toward the generator’s status.   Since solutions containing aldehydes designate as dangerous wastes prior to neutralization, they must be counted and recorded as dangerous waste prior to the TBG activity.  Once the solutions are neutralized and directly discharged into the POTW system in compliance with the domestic sewage exclusion (WAC 173-303-071(3)(a)) they are not required to be counted a second time.  Written logs must be kept of all dangerous waste treated on site, including the date of treatment and the amount of each dangerous waste treated.   Keep records be for a minimum of five years (see sample).

Additional Resources

For an excellent technical information memorandum on treat-by-generator rules, click here.

If you do not know your generator status you may find quick information here.

For assistance designating your wastes, click here.

For help determining how to count dangerous waste under the regulations, click here.

The complete regulations can be found here.

For a list of water and sewer districts in the state of Washington click here.



This information is brought to you by the Washington Department of Ecology/Toxics Reduction Unit with assistance from the Pacific Northwest Pollution Prevention Resource Center (PPRC) . June 2010