SECTION 9: Chemical Waste Disposal
EHS coordinates disposal of chemical waste from University operations.
The cost of waste disposal is borne by EHS, rather than the individual
laboratories, in part to eliminate the incentive not to use this procedure
for disposing of chemical waste.
This procedure applies to any chemical substances generated from University
operations (including laboratories, administrative units, and physical
plant operations) that are classified as hazardous based on the criteria
described below. This procedure does not apply to the disposal of biohazardous
or radioactive wastes. Contact EHS for more information about disposal
of these materials.
The Waste Disposal section of the
EHS web page contains more detailed information.
Classification of Waste as Hazardous (top)
Waste is considered hazardous if:
- It is on either of two lists of specific chemical substances developed
by the Federal Environmental Protection
Agency (EPA). Most commonly used organic solvents (e.g. acetone,
methanol, toluene, xylene, methylene chloride etc.) are included.
For a detailed listing contact Environmental Health & Safety.
- It is on a list of nonspecific sources that includes a broad range
of spent halogenated and non-halogenated solvents.
- It is on a list of specific sources that includes primarily industrial
- It exhibits any of the following characteristics as defined by
the EPA (abbreviated definitions):
Ignitable: a liquid with a flash point less than
60 degrees Centigrade; not a liquid and capable under normal conditions
of causing fire through friction, absorption of moisture or spontaneous
chemical changes; an ignitable compressed gas; or an oxidizer.
Corrosive: aqueous and has a pH less than or equal
to 2 or greater than or equal to 12.5 OR a liquid that corrodes
steel at a rate greater than 0.250 inches per year at 55 degrees
Reactive: normally unstable; reacts violently
with water; forms potentially explosive mixtures with water; generates
toxic gases, vapors or fumes when mixed with water; cyanide or sulfide
wastes that generate toxic gases, vapors or fumes at pH conditions
between 2 and 12.5; capable of detonation or explosive decomposition
if subjected to strong initiation or under standard temperature
and pressure; OR classified as a Department of Transportation explosive.
Toxicity Characteristic: an extract of the waste is found
to contain certain metals, pesticides or selected organics above
specified levels OR otherwise capable of causing environmental or
health damage if improperly disposed (this is a judgment you must
make based upon your knowledge of the material from the MSDS.
Packaging Chemical Wastes (top)
Materials that are to be disposed of as hazardous waste should be placed
in sealable containers. Waste disposal cost is based on volume, not
weight, therefore, whenever possible, containers should be filled, leaving
a headspace for expansion of the contents. Often the original container
is perfectly acceptable. If you routinely generate significant quantities
of compatible solvents, bulking of waste in five-gallon carboys provided
by EHS may be practical.
container should not react with the waste being stored (e.g. no hydrofluoric
acid in glass). Similar wastes may be mixed if they are compatible (e.g.
Wastes from incompatible hazard classes should not be mixed
(e.g., flammables with oxidizers). Certain metals also cause disposal
problems when mixed with flammable liquids or other organic liquids
(see Special Problems). Containers must be kept closed
except during actual transfers. Do not leave a hazardous waste
container with a funnel in it.
Chemical containers that have been emptied should be triple-rinsed
and air-dried in a ventilated area. Once this has been accomplished,
the container can be disposed of as regular recyclable trash. If the
original contents were highly toxic the container should be rinsed first
with an appropriate solvent and the washings disposed of as hazardous
waste. More specific information about disposal of empty chemical containers
can be found on the EHS web
Labeling of Waste Containers (top)
Waste containers must be labeled with the words HAZARDOUS
WASTE along with the names of the principal chemical constituents
and the approximate
percentage. Waste container labels can be obtained by contacting Environmental
Health and Safety at x8-5294. Use of these labels is preferred, but
not mandatory, unless the waste will be placed in storage before disposal.
If you choose not to use the standard labels, the container still must
bear the words HAZARDOUS WASTE and the chemical
contents. Label the collection container as soon as accumulation begins.
Do not list reactants, only products. For
example, if a cyanide was used in a reaction but all of the material
was oxidized to a cyanate before disposal, do not list cyanide on the
label. Use chemical names not symbols, structural diagrams or product
Labeling should be accurate and legible and should include the name
of the generator, the name of the Lab Group or PI, and an extension
where someone who is knowledgeable about that specific waste can be
reached on the day of the pickup in case
questions arise during packaging for disposal.
Disposal Procedure (top)
Chemical Waste Pickups are generally scheduled for the last Thursday
of the month through the academic year. A notice of the pickup is distributed
to Departmental Chemical Hygiene Officers, Department Safety Managers
and other interested persons approximately one week in advance via the
Waste Paper. Contact EHS at 8-5294 if you would like to receive this
Pickups take place at four Main Campus locations:
Lewis Thomas Laboratory loading dock – for Molecular Biology,
EEB and Geosciences
E-Quad (loading dock) – for SEAS and PMI
Frick loading dock – for Chemistry, Psychology and Visual Arts
Jadwin Room 124 – for Physics only
Specific arrangements for getting material to the pickup site are the
responsibility of the individual departments. Refer questions of this
nature to your Departmental Safety Manager or Chemical Hygiene Officer.
Generally, wastes must be at the pickup site by 9 AM the day of the
pickup to be included.
Special Wastes (top)
Thallium, Beryllium, and Osmium pose special
disposal problems - especially when in combination with other wastes.
If you will be generating wastes containing these elements please contact
EHS before you begin.
Metallic mercury is considered a recyclable,
rather than hazardous waste. If you generate mercury waste or have mercury
debris from a spill or equipment breakage, contact EHS to arrange a
Ethidium Bromide usually does not need to
be disposed as hazardous waste. Electrophoresis gels containing trace
amounts of ethidium bromide (less than 0.1%) may be placed in regular
laboratory trash. Gels containing more than 0.1% (usually dark pink
or red color) should be placed in the medical waste boxes. Ethidium
bromide solutions may be neutralized and disposed down the drain. Neutralization
procedures are outlined on the EHS web page (www.princeton.edu/~ehs/etbr.html).
Used Oil: Used oil is not disposed of as
part of the Hazardous Waste program, with the following exceptions:
- Vacuum Pump Oil
- Cutting Oils
- PCB Contaminated Oil
- Oil mixed with hazardous wastes
EHS does not coordinate or pay for used oil disposal. For more information,
see the EHS web page.
Silica gel, molecular sieves and dessicants
are not considered hazardous waste unless they are grossly contaminated.
Uranium and thorium compounds, such as uranyl
acetate, uranyl nitrate, uranyl formate, uranium oxide, thorium nitrate
and thorium oxide, are considered radioactive waste, rather than chemical
waste. See the Waste Disposal web page for more information.
Chemical wastes that are combined with radioisotopes
are considered mixed waste. Contact the Radiation
Safety Officer at 8-5294 before generating this type of waste. Mixed
waste is difficult to dispose and should be minimized to the extent
Do not bring wastes to the pickup site that are not properly identified.
The disposal company can not legally transport or dispose of them. Arrangements
for chemical analysis of unknowns can be
made through EHS. Costs associated with improper management of hazardous
waste (e.g. characterization of unknowns, special handling of peroxidizable
compounds etc.) are charged back to the generator department.
Sharp Implement Disposal (top)
Many individuals on campus have occasional or routine need to dispose
of sharp implements or “sharps”, such as razor blades or
other cutting blades, broken glass, glass slides, syringes, or other
items that can easily puncture the skin. It is important that these
types of sharp implements not be placed directly
into trash receptacles with other general trash
or in the paper-recycling receptacle
in order to prevent injury to those who must handle the general trash
and recyclables coming from the offices, labs and shops.
Sharp implements must be placed in a puncture-resistant container,
such as rigid plastic or corrugated cardboard. For example, an occasional
razor blade that needs disposal could be placed in a disposable plastic
container with a screw-top lid or could be wrapped in a piece of corrugated
cardboard and secured with packaging tape. For sharps that are routinely
generated, a sealable box or container should be used.
General Recommendations (top)
- Don’t purchase more of a chemical than you expect to use in
the foreseeable future. The costs of disposal often exceed the purchase
cost by a considerable margin.
- Scale down experiments to a practical minimum to reduce the total
amount of waste generated.
- Consistent with safe practice, bulk compatible waste in containers
up to five gallons in capacity to reduce disposal costs (consult with
- Keep all chemical containers clearly and unambiguously labeled.
- Keep all containers of waste sealed except during filling. Do not
leave funnels in containers.
- Dispose of your wastes at the completion of a project - don’t
abandon them for someone else to deal with later.
Waste Minimization and Pollution Prevention (top)
Waste minimization is a national policy and the responsibility of each
person who generate hazardous waste. Princeton University is committed
to managing operations in an environmentally sensitive and responsible
manner. Everyone must do his or her part in minimizing hazardous waste
General principles for waste minimization, in order of priority, are:
- Elimination - any modification that results
in the elimination of waste generation.
- Substitution - replacement of hazardous
substances with less hazardous materials.
- Scale Reduction - a reduction of the
amount of hazardous materials used in a procedure.
- Recycling - the reuse of waste materials
either back into the same process or into a different process.
- Reclamation - any process that allows
materials to be used again after some sort of purification, such as
- Treatment - an additional step added
to an experimental or analytical procedure to reduce or eliminate
the toxicity of the waste.
Contact EHS for consultation on ways to reduce waste in your operations.
Report any successful waste minimization projects to EHS in order to
share these practices with other labs. See the Waste Disposal section
of the EHS web page for more information.