Disposal of empty reagent bottles can be one of the more confusing gray areas in laboratory compliance, and there are both regulatory requirements to follow as well as best practices that can be helpful in keeping the lab orderly, reducing odors, and avoiding chemical exposures.
Federal EPA hazardous waste regulations under the Resource Conservation and Recovery Act [40 CFR 261.7(b)] define an empty container as one which has been emptied “using the practices commonly employed to remove materials from that type of container, e.g., pouring, pumping, and aspirating” and which contains one inch or less of residue or 3% or less of the total container capacity (like many regulations, these are written more with large industrial scale drums in mind than lab-scale containers).
The exception to this empty container rule is that any container which held a material on the EPA’s “P-list” of acutely hazardous wastes (either in pure powdered form or in solution as the sole or active ingredient) must be treated as a hazardous waste, and cannot be rinsed or otherwise cleaned for disposal. Relatively few common lab reagents fall into this category; several that do are sodium azide, sodium cyanide, and potassium cyanide. The P-list is found in 40 CFR 261.33.
Many laboratories collect empty containers for disposal in boxes or bins that are open to room air, so for some hazardous chemicals that are not P-listed, it may be recommended to go beyond the EPA empty container requirements and rinse the empty container to more completely remove any remaining residues that can cause odors and potential airborne exposures. Since empty bottles are often permitted to be disposed of as standard trash or for recycling, rinsing also minimizes the overall amount of hazardous residue leaving the facility.
When triple rinsing empty reagent bottles, the rinsate should be collected and added to a compatible hazardous waste stream rather than being sink disposed, since many chemical residues are prohibited from being discharged to the wastewater, and keeping wastewater free of all chemicals is best practice. The waste label should account for any rinsate being added to the waste. For some chemicals that are not water-soluble, another appropriate solvent such as ethanol or isopropanol may be used, followed by a water rinse.
Defacing the bottle label is usually the final step in preparing an empty bottle for disposal. Defacing should be done attentively, with the chemical name as well as any hazard symbols fully defaced with a bold dark marker so that there is no possible ambiguity about the bottle’s contents. Some labs also use “EMPTY” labels to further indicate that bottles are clean for disposal. If the bottles are being sent out with a waste vendor, they may require that the caps be removed as well as the label being defaced.
One more practice to be avoided is leaving empty chemical bottles uncapped in chemical fume hoods to “air out.” Environmental regulatory inspectors view this as prohibited airborne release/disposal of hazardous waste, and are likely to cite violators when they observe it.
This Blog was written by Chris Neal, Quality, Research, and Training Specialist
