By Ken Roy
Posted on 2023-09-15
A chemical hygiene officer (CHO) for a high school science department decided to inspect a chemistry laboratory, preparation room, and chemical storeroom after one of its chemistry teachers retired at the end of the school year in June. In one of the corrosive chemical cabinets in the chemical storeroom, a large undated bottle of picric acid (IUPAC name 2,4,6-trinitrophenol) was found with crystals growing around the metal cap. Picric acid is in the family of nitroaromatic explosives as trinitrotoluene (TNT) and can be used as a bio-stain for collagen fibers. It forms shock-sensitive explosive salts with metals (such as lead) and is too unwieldy for most usual applications.
The CHO remembered that several years ago, bomb squads were sent to several high schools in the Midwest to remove this potentially dangerous explosive. Concerned about the serious chemical hazard and health/safety risk the picric acid presented, the CHO contacted the local fire marshal and state bomb squad to safely and promptly have the bottle of picric acid removed from the school grounds.
This scenario is unfortunately not uncommon. Biological and chemical waste is highly regulated by local, state, and federal laws and therefore must be disposed of in a safer way. The Occupational Safety and Health Administration (OSHA) designed specific components in the Occupational Exposure to Hazardous Chemicals in Laboratories Standard (the Laboratory Standard) 29 CFR 1910.1450, and the Hazard Communication Standard 29 CFR 1910.1200, to help prevent or reduce hazardous waste accidents by requiring the development and use of biological/chemical waste management programs. The Resource Conservation and Recovery Act (RCRA), enacted in 1976, is the federal law that requires all institutions to have guidelines to reduce the amount of hazardous materials, and in conjunction with the Environmental Protective Agency (EPA), to promote methods to protect human health and the environment.
The picric acid should never have been stored because there could have been potentially disastrous consequences for employees and students. Whether these hazardous chemicals are expired, not used any longer, or just present an unacceptable potential hazard and risk—through shared responsibility of the administration, faculty, staff, and CHO—the hazardous materials must be removed and discarded using appropriate legal safety standards and better professional safety practices.
This blog post aims to raise academic laboratory educators’ levels of awareness of general recommendations for developing biological/chemical waste management with an emphasis on disposing of potentially hazardous laboratory biologicals and chemicals. By EPA definition, biological/chemical waste management is the collection, treatment, and disposal of waste material that can cause harm to human health or the environment.
The first activity that must be completed to prepare for hazardous waste management disposal is to determine what hazardous wastes are present and the manner of which they are to be disposed. The following is a recommended action plan for removal and disposal of hazardous waste.
Generally, biological and/or chemical hazard disposal protocol requirements include the following.
Do not combine incompatible or unknown chemicals in one container. By combining two or more incompatible or unknown types of biologicals or chemical materials, toxic vapors can develop, or a dangerous reaction such as a fire or explosion can happen. The Chemical Hygiene Plan and/or Hazard Communication Plan should include a policy in which no biologicals or chemicals are to be combined when in use or when preparing them for disposal. Liquid waste should also be secured in leakproof containers. Check the SDS for any other storage rules, such as ventilation requirements or the maximum level storage containers should be filled to allow for vapor expansion.
OSHA requires that chemical manufacturers provide SDSs for every hazardous chemical. SDSs, formerly known as Material Safety Data Sheets, are standardized documents that contain health and safety data about specific chemicals. They typically contain information such as
Once biological and/or chemical waste is found, ensure it is properly identified. All waste containers must include labels that identify the waste. Never use abbreviations; spell out the name of the substance completely.
Appropriate storage and disposal matters for these reasons.
3. Landfills can leak organic liquids and heavy metals into groundwater.
4. Worksite chemical hazards/risks can result in employee injuries.
Many potential types of biological and chemical hazardous waste are commonly found in academic instructional sites (laboratories and classrooms) and related locations (chemical storerooms and preparation rooms). Referencing the SDS section 11 will classify the toxicological information. Included are examples of the more common potential hazards.
(Aqueous alcohol solutions <24% ABV* exempt)
– Oral rat LD:50 <5,000 mg/kg
– Fish LC:50 < 10 mg/L
– Inhalation rat LC:50 <200 mg/L
– Dermal rabbit LD:50 <20,000 mg/kg
*ABV = Alcohol by volume; LD = Lethal Dose; LC = Lethal Concentration
In addition, some household products commonly used also may be hazardous, including but not limited to these.
In addition, recycling and other special wastes may be found in science, technology education/engineering, Career and Technical Education (CTE), and STEM labs, including these.
The following list will help you prepare for a safer waste disposal activity (Section 13 of the SDS).
– Safe from damage
– Doesn’t impede work
– Readily and unimpeded access
– Secure when instructional or related space is unattended
2. Waste Containers
– Impervious to intended contents
– Tight-fitting cap/lid
– Labeled upon first addition of waste
– Clean exterior
– Kept in a secondary waste container in case of accidental leakage
3. Waste Compatibility
– Combine only wastes that are compatible with other constituents.
– Leave at least one inch of headspace in containers.
– Do not place solid objects in narrow-mouthed vessels.
– Do not place wastes that may cause overpressure in tightly sealed containers.
– Do not combine mercury-bearing wastes with any other waste.
4. Removing Waste From Instructional Space/Related Work Areas
The type of potentially hazardous biological or chemical waste found will determine how and when the waste can be disposed. Flinn Scientific has great resources on biological and chemical disposal procedures. Some examples include the following.
1. General trash
– Sugars, agars, gums, amino acids, and inert solids such as talc, and dry resins and filter media
– Dry wipes, bench papers and mats, empty containers, unbroken glassware, pipette tips, and weighing papers and dry resins and filter media
2. Drain disposal
– Aqueous solutions containing buffers and salts (less than 10% by weight)
– Neutralized inorganic acids and bases (pH 5–9)
– Flowable aqueous gels, nutrient broths and agars
– Spent formalin solutions
– Used neutral pH cleaning solutions and “dishwater” from glassware cleaning
– Some specimen preservation solutions not including formaldehyde.
– The following inorganic salt cations have low levels of toxicity: Al, Bi, Ca, Fe, Li, Mg, K, Sc, and Na.
– The following inorganic salt anions have low levels of toxicity: halides, carbonates, hydroxides, sulfates, and phosphates.
As part of a biological/chemical waste management program, an annual hazardous waste disposal should be required in instances when a dangerous waste is located. In that case, it is critical to have it removed immediately to help prevent a potentially serious safety incident, including harm to employees, students, and the facility. When in doubt, contact your school’s department of environment health and safety and/or CHO or district representative. Equally important and a legal requirement/better professional safety practice is the ongoing training of all employees annually dealing with instructional site biological and chemical use, storage, and disposal.
Safety Blog Acknowledgement
NSTA Chief Safety Blogger Dr. Ken Roy wishes to sincerely thank Brian C. Duffy, Ph.D., a nationally recognized Wayne Community College (Goldsboro, North Carolina) chemistry instructor, NSTA Research in Science Education Committee member, and former NSTA Safety Advisory Board Chair, for his professional review of this commentary.
Submit questions regarding safety to Ken Roy at email@example.com. Follow Ken Roy on Twitter: @drroysafersci.