ABC of Safety in the Biological Sciences
WASTE DISPOSAL PROCEDURES
GENERAL WASTE MANAGEMENT - HAZARDOUS WASTE
The following regulations are similar to or the same as those which apply in the United States of America, the United Kingdom and Australia and are endorsed by the World Health Organisation. They can be used as a general guide for the disposal of laboratory wastes.133 134
Transport of Dangerous Goods (Wastes) by Road or Rail
Transport of dangerous goods is covered by legislation in many countries. In general terms wastes considered hazardous are those which are poisonous, corrosive or present a risk of fire or explosion and are therefore a danger to people or the environment. It is the responsibility of the waste producer to ensure that the waste is fully and correctly defined and classified (TABLE 14).
The potential risk to health and the
environment is perhaps greatest when hazardous wastes are
transported. There is a need for all of those involved, from the
producer to the final disposer, to be aware of the type of material
being handled and its associated hazards. Substances considered to
be hazardous are as follows:
acids and acidic solutions
alkali metals and alkaline earth metals
alkalis and alkaline solutions
antimony and antimony compounds and solutions
arsenic and arsenic compounds and solutions
barium compounds and solutions
beryllium compounds and solutions
boron and boron compounds
cadmium and cadmium compounds and solutions
carcinogens, teratogens and mutagens
chromium compounds and solutions
copper compounds and solutions
cyanides or cyanide solutions and cyanide complexes
heterocyclic organic compounds containing oxygen, nitrogen or sulphur
hydrocarbons and their oxygen, nitrogen and sulphur compounds (excluding oils)
infectious waste being:
Waste generated in small amounts does not warrant disposal through specialised commercial systems. However, these substances still carry a risk and generally should not be discharged to sewer nor disposed of by mixing with non-hazardous waste. Disposal of this waste is the responsibility of the waste producer. There are various procedures which can be instituted to ensure safe and proper disposal, although reducing the amount of hazardous waste generated should not be overlooked. The procedures include:
- chemical name
- method of packaging and the condition of the container
- technical data on the chemical, including detail of potential hazards
Cyanide wastes should be oxidised to cyanate in alkali solution after which it can be disposed of either:
Oxidising and Reducing Agents
Small quantities of the waste should be reduced or oxidised as appropriate to the substance and can be discharged to sewer. Large quantities should be stored and removed by a licensed waste contractor.
Chemicals which react violently with water or ignite on exposure to air must be converted to a non-reactive state before discharge to sewer (permission from local Authorities may be required).
Metallic mercury should be recycled. Mercury compounds should be converted to mercuric sulphide and stored. Seek advice on removal from local Authorities.
Heavy Metal Compounds
If possible, reduce the residue to the solid phase. The material may then be disposed of by encasing and removal to an approved landfill.
All effort should be made to recover and recycle beryllium compounds.
Halogenated Organic Compounds
All effort should be made to recover halogenated solvents. If this is not practical in the laboratory environment commercial redistillation should be considered.
All effort should be made to recover hydrocarbon solvents. For most laboratories this will require commercial redistillation. Failing recovery, waste flammable solvents should be segregated before burning in a high temperature incinerator equipped with an afterburner and scrubber. They should never be discharged to sewer.
Biological material should be sterilised by autoclaving or burned in a high temperature incinerator.
Medical waste is defined as consisting of the following:
Medical waste, excluding discarded needles, needle syringe combinations and any other sharp surgical instruments must be contained for storage and disposal in clearly labelled bags which are impervious to moisture and have a strength sufficient to preclude ripping, tearing or bursting under normal conditions of handling. The bags must be securely tied so as to prevent leakage or expulsion of solid or liquid wastes during storage, handling or transport.
Discarded needles, needle syringe combinations and any other sharp surgical instruments must be contained for disposal in rigid puncture proof containers which are taped closed, tightly lidded or locked. The lid must not open if the container falls or is dropped.
The quantity and variety of waste generated by medical procedures constitutes a significant disposal problem and because of the hazardous and possible infective nature should be transported in accordance with the following conditions:
Human tissue not requiring legal burial is best disposed of by high temperature incineration. Blood and other body fluids should be autoclaved before disposal. After autoclaving, disposal, in many countries, is allowed in the normal sewerage system subject to local Council or Government approval.
Guidelines for the Storage, Transport and Disposal of Infectious Waste
Infectious waste is defined as waste arising from medical, nursing, dental, veterinary, pathology, pharmaceutical or similar practice, investigation, treatment, care, teaching and research which by virtue of its infectious content may prove a hazard or give offence unless previously rendered safe and inoffensive.
Infectious waste should include the following categories:
The disposal of sharps should not incorporate cutting, bending or any other manipulation that could generate aerosols or splatter contaminated material. They should be disposed of at the site of use into a suitable container which has the following features:
High temperature incineration is the preferred means of disposal. This destroys pathogenic organisms and is effective in rendering the majority of toxic substances harmless. Alternatively material may be autoclaved then disposed of in a domestic landfill dump. However, special autoclave bags which are capable of withstanding the temperature and pressure are required. Autoclaving may produce problems due to the sheer bulk of waste material and compaction. As well with large amounts of material, steam penetration at the required temperature does not always occur resulting in material that is still infective.
Because the range of chemicals is too diverse there are no general guidelines for their disposal. Each chemical should be addressed on an individual basis and disposed of according to the specifications of the chemical manufacturers, distributors and local authorities.
Disposal of chemical waste into the sewerage system should be actively discouraged. Not only is there potential for environmental damage but also some chemicals will erode the sewerage system whilst others may cause an explosion, either acting alone or in combination with other chemicals.
Cytotoxic waste is any material which is, or may be, contaminated with a cytotoxic drug during the preparation, transport or administration of the cytotoxic drug. These substances are highly toxic and the only effective method of disposal is high temperature incineration. However the decomposition temperature for some cytotoxic compounds has not been accurately determined and recommendations for disposal may need to be sought from the manufacturer or relevant statutory authorities.
If the waste consists of a mixture of cytotoxic drugs and other materials it must also be incinerated at high temperature. Human waste contaminated with low concentrations of cytotoxic drugs, such as urine or faeces, may be disposed of in the sewerage system provided that it is suitably diluted and washed away with large amounts of water. Local authorities may need to be consulted.
Storage and transportation of cytotoxic waste should be in a bag or container of adequate quality to ensure that it does not split or break during handling. The waste bag should not react with the cytotoxic material which it contains and it should be purple in colour whilst also bearing the internationally recognised cytotoxic symbol.
Radioactive waste is any material which is, or may be, contaminated with a radioactive isotope. Such waste can be produced during radioimmunoassay, nuclear medical techniques, some bacteriological procedures and research and can be in the form of solid, liquid or gas.
The handling, storage and disposal of radioactive waste must comply with local legal requirements. If such local requirements do not exist the overriding principle is that all persons who handle the material should have minimal exposure (see Table ionising radiation).
A Radiation Safety Officer should be designated and be responsible for all radiation safety matters including the safe handling, storage and disposal of this material.
Waste radioactive material should be stored in a bag or container that is coloured red and which bears the black, internationally recognised symbol for radioactivity. The bag or container must be of adequate quality to ensure that it does not split or break. The bag or container should not react with the waste radioactive material. Radioactive waste should never be mixed with non-radioactive waste nor should waste emitting different types of radiation be mixed.
Short lived isotopes should be stored (refrigerated) for several half lives before being disposed of to sewer (liquid waste) or to the normal garbage disposal system (solid waste). Biologically active waste must be disinfected before disposal.
Long lived isotopes should be disposed of as soon as possible by waste contractor.
All waste storage areas should be monitored for radioactivity on a regular basis.
Eyes: irrigate with running tap water from an eye wash facility followed by a wash in normal saline.
Skin: brush lightly with soap and running water. If this fails apply titanium dioxide paste and wash off with soap and running water. If this fails try washing with EDTA soap.
As a final procedure immerse in saturated potassium permanganate solution - allow to dry then remove the permanganate stain with 5% sodium bisulphate solution.
Ingested: Wash the mouth several times with hydrogen peroxide solution (5 ml of a 10 volume solution in 250 ml of water). If sallowed induce vomiting.
WASTE TO SEWER
The nature and levels of the components and characteristics of liquid waste which can be legally disposed of to the sewerage system vary considerably and local authorities or other government instrumentalities should be consulted. In general terms permission to discharge is based on the final effluent meeting certain pre-determined standards. The deliberate dilution of waste discharges to achieve compliance with the prescribed limits is normally prohibited.