1. Chapter 2.1 Definition and classification
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2. General definition A hazardous waste has the potential to
cause an unacceptable risk to:
PUBLIC HEALTH
THE ENVIRONMENT
Slide 2 Classification and definition
A coherent classification system for wastes is at the basis of many handling operations, is essential to ensure safe procedures, and is also the basis of effective control regulations.
Internationally agreed criteria and listings have been adopted by more and more countries as this simplifies exchange of information, technical assistance and trade in by-products and in wastes (where these may be legally traded).
In order to manage hazardous wastes in an environmentally sound manner, some controls must be put in place in relation to its generation, handling, storage, collection, transportation and final disposal. But in order to impose such controls, it is first necessary to understand and identify what is or could be a hazardous waste.
Hazardous wastes may arise in a number of different forms: liquids, solids, gases, or sludges. They may be by-products of manufacturing processes or simply discarded products. The hazard associated with a waste depends on its composition, its physical form and its physical and chemical properties.
In its simplest form, the definition of a hazardous waste is one that has the potential to cause harm to public health and to the environment. However, such a definition is too imprecise for use in a regulatory framework.
It is important to stress that waste classifications are related to, but generally independent of, the classification systems used for industrial chemicals. This can cause the waste generator confusion, and waste managers need to know both systems and have access to both sets of data.
Discussion point: Trainers could encourage trainees to spend a short time devising their own definition of hazardous wastes, to demonstrate the difficulty of the process.
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3. Why definition is difficult
The hazard associated with a waste depends on:
HAZARDOUS WASTE
PHYSICAL FORM
PHYSICAL PROPERTIES
CHEMICAL PROPERTIES
COMPOSITION
Slide 3 Why definition is difficult
Hazardous waste is difficult to define. Its definition may be based on its composition; its physical form; its chemical, biological or physical properties; or alternatively on the waste stream in which it arises.
Each country has its own interpretation of what constitutes hazardous waste, as well as using various terms to refer to it, such as ‘chemical’, ‘special’, ‘poisonous’, ‘toxic’ or ‘difficult’.
Worldwide there is no standard definition of hazardous wastes, and a number of different approaches are taken to the problem of defining it. When the Global Waste Survey - the first attempt to gain a worldwide picture of hazardous wastes - was conducted in 1992 it found that there were ‘almost as many definitions as countries’.
Today definitions differ according to their differing objectives. In some countries, such as the USA and Germany, wastes which cannot be disposed of with municipal solid wastes are separately classified. In other countries, such as Denmark, the objective of the definition is to ensure the most appropriate treatment. Other ways of defining hazardous wastes might include one based on its recycling potential.
In developing economies, there is often an inadequate identification of the waste streams which arise – not simply of hazardous wastes – and this can lead to an increase in pollution of the environment as well as increased risks to human health. However difficult, waste classification is an important early step in developing a waste management system.
BIOLOGICAL PROPERTIES
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4. Examples of hazardous waste definitions: Basel Convention
45 categories of wastes that are presumed to be hazardous.
PLUS …...
These categories of waste need to exhibit one or more hazardous characteristics:
flammable, oxidising, poisonous, infectious, corrosive, ecotoxic
Slide 4 Examples of hazardous waste definitions: Basel Convention
According to the Basel Convention there are 45 categories of wastes that are presumed to be hazardous.
18 are waste streams (eg clinical wastes, mineral oils, PCBs) (Y1-Y18)
27 are wastes having clearly identified constituents (eg mercury, lead, asbestos, organic cyanides, solvents) (Y19-Y45)
In addition, these categories of waste need to exhibit one or more hazardous characteristics (flammable, oxidising, poisonous, infectious, corrosive, ecotoxic)
(See also Chapter 3.2 Transboundary movement control)
In the context of the Basel Convention, the international effort to establish a cross-referenced list of hazardous wastes as a first step towards harmonisation of definitions aims to:
ensure effective international controls over transfrontier shipments of hazardous waste
distinguish between hazardous waste and materials destined for recycling, and ensure proper control over the latter while not creating an unnecessary disincentive to recycling
The Basel Convention and OECD Decision on the transfrontier shipment of waste prohibits the shipment of hazardous waste destined for final disposal to non-OECD countries. This is to prevent the dumping of hazardous waste in developing countries. Parties to the Basel Convention incorporate the requirements into their own national legislation. The treatment of wastes for recovery operations will depend on the listing of the wastes in question, with some largely excluded from the regulations while others are subject to a prior notification requirement or will require prior authorisation.
The Basel Convention has recently published two new lists, the first of wastes which are definitely considered to be hazardous (Annex A) and those which are definitely not considered hazardous (Annex B). In either case, no further testing is required.  
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5. Examples of hazardous waste definitions: UNEP
Wastes other than radioactive wastes which,
by reason of their chemical activity or toxic, explosive, corrosive or other characteristics cause danger or are likely to cause danger to health or the environment
Slide 5 Examples of hazardous waste definitions: UNEP
The UNEP definition of hazardous waste is based on the UN Transport of Dangerous Goods Code. This is a classification system for hazardous materials which does not have regard to the origin of the waste, nor to the fact that wastes are often a complex mixture of unspecified composition rather than pure substances.
Such a classification is useful for improving aspects of handling, transport and storage safety. (See also Chapter 5.2 Waste Transport)
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6. Examples of hazardous waste definitions: USA
UNDER US EPA REGULATIONS:
1 The waste is listed in EPA regulations
2 The waste is tested and meets one of the four characteristics established by EPA:
Ignitable
Corrosive
Reactive
Toxic
3 The waste is declared hazardous by the generator
Slide 6 Examples of hazardous waste definitions: USA
In the USA, the Environmental Protection Agency (EPA) regulations have three ways of defining hazardous wastes:
· The waste is included in the list of defined hazardous wastes
· The waste is tested and found to have ignitable, corrosive, reactive or toxic characteristics
· The waste generator declares it hazardous
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7. Examples of hazardous waste definitions: European Waste Catalogue
A core list of 850 types of waste
Of these, around 420 are classified as hazardous wastes
These are divided into 19 main categories
Slide 7 Examples of hazardous waste definitions: European Waste Catalogue
Many of the definitions of hazardous waste are descriptive of the waste. For an effective regulatory control system a definitive list of wastes, or a waste catalogue, is useful.
In the European Union, waste legislation was substantially revised by the adoption of Directive 91/156/EEC on waste, and Directive 91/689/EEC on hazardous waste. These provided a legal framework for waste management and disposal, and more rigorous definitions of hazardous waste.
Initially an exhaustive list of hazardous wastes was to have provided the legally binding definition of hazardous waste. This proved difficult to compile and implementation of the Directive was postponed from December 1993 until July 1995 to allow completion of a list. In December 1994 EU environmental ministers approved a core list of wastes – the European Waste Catalogue.
In 2001 the catalogue was expanded, and it now contains 420 types of hazardous waste divided into 19 main categories.
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8. The objective of definitions
Why define wastes?
To decide whether or not that waste should be controlled - this is important for the generator as well as the regulator
Why create a list?
Clear and simple
No need for testing
Slide 8 The objective of definitions
It is important to remember that the purpose of a waste definition is to decide whether or not that waste should be controlled.
Producing a list of wastes which are automatically considered hazardous is a simple approach which has particular benefits in developing economies where facilities for testing and analysis are scarce or simply do not exist.
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9. Different methods of classification
Lists eg Basel Convention Annex I, Basel List A, EU European Waste Catalogue, US EPA list
Origin eg processes, Basel Convention Annex II
Hazardous characteristics eg toxicity, reactivity, Basel Convention Annex III
Chemical and physical properties eg inorganic, organic, oily, sludges
Need to match classification to objectives
No method will suit all cases
Slide 9 Different methods of classification
Having started by looking at some of the most widely-used list-based methods of defining wastes (such as Basel and US EPA) this slide summarises the four different ways in which a definition may be achieved. As has been stated, the use of lists to define hazardous wastes has the advantage of being simple and of minimising the need for testing. Alternatively, waste definitions may be based on the characteristics of the waste, its chemical or physical properties, or on the waste stream within which it arose.
The type of waste classification system chosen depends in part on the management objectives:
· If the objective is to build disposal facilities then a classification based on treatability is appropriate
· If the objective is to ensure safe transport, then the UN hazard classification may be most useful
· If the objective is to implement a waste minimisation programme, a system based on process origin or waste stream may be best
· If the objective is to separate hazardous waste from other waste, a list is appropriate
Any hazardous waste classification system should be flexible enough to ensure that any new wastes which arise do not evade control.
For developing economies, the best starting point for definition of hazardous waste may be the Basel Convention lists A & B together with Annexes I, II and III. (See handouts)
However, it should be noted that each classification system has its particular application, and none is perfect for all uses. Accordingly it may sometimes be necessary to work with different classification systems in order to solve specific problems.
The next 7 slides look at these other methods of defining hazardous wastes.
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10. Methods of waste classification: by origin
Waste streams eg Basel Convention
Miscellaneous or ubiquitous wastes eg
contaminated soils
dusts
redundant pesticides from agriculture
hospital wastes
Slide 10 Methods of waste classification: by origin
Hazardous wastes can be classified by the waste stream in which they arise, or they can be defined as ubiquitous or miscellaneous wastes.
Using the process origin as a means of identifying wastes has limitations, as it is not possible to have a precise idea of their composition and hence the hazards they pose. Using the generic chemical group to list hazardous wastes provides more information about their properties, hazards and possible disposal options than relying on their process origin, but offers less information about their sources.
For this reason, different classification systems may be needed for different purposes, as has been stated.
The Basel Convention lists different generating processes (see next slide).
Broad groups of ubiquitous or miscellaneous wastes are not easy to identify, because they arise from a wide range of different waste streams. Examples of these diverse miscellaneous wastes include:
· contaminated soils
· dusts and fibres collected from manufacturing processes
· oils from transportation
· redundant pesticides from agriculture
· hospital wastes
· mercury from fluorescent lamps and batteries
· lead from recycling of motor vehicle batteries
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11. Example of waste classification by origin: Basel
The Basel Convention’s List of Hazardous Waste Categories (Y1-Y18) identifies wastes from specific processes
eg Y1 Clinical wastes
Y6 Wastes from the production and use of organic solvents
Y18 Residues from industrial waste disposal operations
Slide 11 Example of waste classification by origin: Basel
The Basel Convention identifies two main categories of wastes needing control, one of which is based on the waste stream or specific process which generated the waste, as the examples on the slide show.
One advantage of the Basel Convention’s waste streams listing, which lists different generating processes, is to make it possible to define a hazardous waste without having to undertake testing procedures. As has already been stated, for developing economies this may often be an important factor, given limited laboratory facilities.
(This and the other Basel Convention categories are covered in detail in Chapter 2.1 Definitions and classifications. More information on the Basel Convention in Chapter 3.2 Transboundary movement control)
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12. Methods of waste classification: by hazardous characteristics
Main characteristics:
Toxic
Corrosive
UN Committee on the Transport of Dangerous Goods by Road or Rail (ADR) lists waste characteristics. These have been adopted by Basel Convention - Annex III gives 13 characteristics, based on ADR rules, including:
Explosive
Flammable
Toxic and eco-toxic
Represented as codes H1-H13
Ignitable
Reactive
Slide 12 Methods of waste classification: by hazardous characteristics
The hazardous characteristics or properties of a waste can be used to classify it.
The four main groups of hazardous waste properties are:
· Toxic and eco-toxic
· Corrosive
· Ignitable
· Reactive
The UN Committee on the Transport of Dangerous Goods by Road or Rail (ADR) lists hazardous waste characteristics. Each hazard characteristic in the UN system is given a symbol which identifies it visually on a package. Based on this ADR list, the Basel Convention Annex III (see handouts) describes and codifies 13 characteristics eg explosive, flammable, toxic.
The next slides give some brief examples of these characteristics.
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13. Hazardous characteristics: Toxicity
Toxic wastes are harmful or fatal when ingested, inhaled or absorbed through the skin
Examples:
Spent cyanide solutions
Waste pesticides
Slide 13 Toxicity
Toxic wastes are harmful when ingested, inhaled or absorbed through the skin.
Toxic wastes disposed of on land may result in contaminated leachate. The leaching of toxic compounds or elements from landfills into groundwater is one of the most common ways in which the general population can be exposed to the chemicals found in industrial wastes.
In the US, the EPA has devised a toxicity characteristic leaching procedure (TCLP) test to identify wastes likely to leach hazardous concentrations of toxic constituents. Using the test on a waste sample creates a liquid similar to the liquid the US EPA would expect to find in the ground near a landfill containing the same waste.
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14. Hazardous characteristics: Corrosivity
Acids or alkalis that are capable of dissolving human flesh and corroding metal such as storage tanks and drums
Examples:
acids from metals cleaning processes eg ferric chloride from printed circuit board manufacture
liquor from steel manufacture
Slide 14 Corrosivity
Corrosive wastes are acid or alkaline and can readily corrode or dissolve flesh, metal or other materials. They are also one of the most common hazardous waste streams. Wastes with a high or low pH can react dangerously with other wastes or cause toxic contaminants to migrate from certain wastes.
Examples of corrosive wastes include acids from metals cleaning processes (eg ferric chloride from printed circuit board manufacture) and liquor from steel manufacture.
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15. Hazardous characteristics: Ignitability
Ignitable wastes:
can create fires under certain conditions
or are spontaneously combustible
Examples:
Waste oils
Used solvents
Organic cleaning materials
Paint wastes
Slide 15 Ignitability
Ignitable wastes are those which readily catch fire and sustain combustion. These could cause a fire during transport or storage of the waste, or after disposal.
Examples of ignitable wastes include waste oils, solvents, paints and cleaning materials. Many aerosol cans use butane as a propellant
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16. Hazardous characteristics: Reactivity
Reactive wastes are unstable under ‘normal conditions’
They can cause:
explosions
toxic fumes
gases or vapours
Examples:
Peroxide solutions
Hypochlorite solutions or solids
Slide 16 Reactivity
Reactive wastes will readily explode or undergo violent reactions. Reactivity is an important characteristic of hazardous wastes because unstable wastes can pose a problem at any stage of the waste management life cycle.
Examples of reactive wastes include discarded munitions and explosives.
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17. Hazardous characteristics: Eco-toxicity
Eco-toxic wastes are harmful or fatal to other species or to the ecological integrity of their habitats
Examples:
Heavy metals
Detergents
Oils
Soluble salts
Slide 17 Hazardous characteristics: Eco-toxicity
Animal and plant species can be much more sensitive to certain chemical substances or to conditions of pH than mammals (including humans). Some chemicals interfere with respiratory processes in fish or insects; they may mimic or interfere with hormone-driven processes; or be otherwise species-specific. Many lower species lack the detoxification processes that the mammalian liver provides to guard against harm.
The high sensitivity of some fish like trout to toxins at levels far lower than human drinking water standards illustrates the importance of regarding eco-toxicity as an important separate issue. By implication, human toxicity standrads are not always appropriate when considering ecological problems.
As well as the risk of eco-toxicity, waste may upset the normal ecological conditions - such as pH, salinity - and may result in ecological damage if they persist. Some substances such as oils and detergents that barely affect humans can nevertheless interfere with other species’ life processes including reproduction.
Issues of bio-magnification along the food chain are just as important for other species as they are for human toxicity.
Despite the importance of the above conderations, criteria, measurements and standards for exo-toxicity are not well developed, and are thus frequently discounted by regulators or waste operators.
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18. Methods of waste classification: by chemical, biological and physical properties
Inorganic wastes eg acids, alkalis, heavy metals, cyanides, wastewaters from electroplating
Organic wastes eg pesticides, halogenated and non-halogenated solvents, PCBs
Oily wastes eg lubricating oils, hydraulic fluids, contaminted fuel oils
Sludges eg from metal working, painting, wastewater treatment
Slide 18 Chemical, biological and physical properties
As was shown on slide 9, the different ways of classifying hazardous wastes include:
· Lists
· Origin
· Hazardous characteristics
· Chemical, biological and physical properties
Using a classification based on chemical and physical properties, there are four main waste groups:
· Inorganic wastes - which include acids and alkalis, heavy metals, cyanides, wastewater from electroplating, dusts from steel manufacture and smelters, asbestos
· Organic wastes – which include pesticides, halogenated and non-halogenated solvents, and PCBs
· Oily wastes – which include lubricating oils, hydraulic fluids, contaminated fuel oils
· Sludges – which include those from painting operations, metal working and wastewater treatment
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19. Relative composition of hazardous waste types by region
Slide 19 Relative composition of hazardous waste types by region
The slide shows the relative proportion of hazardous waste types in selected countries in 1995, using the classification system shown on the previous slide.
Variations in the breakdown of waste types reflect the different industrial sectors dominant in each region at the time. In the Middle East and Africa, large quantities of miscellaneous wastes and sludges, plus organic and oily wastes arose as a result of mining, the petroleum industry and the metallurgical sector. In the Asia pacific region the miscellaneous sludges came mainly from metallurgical and metal working, while in Eastern Europe those waste types came from manufacturing and wastewater treatment.
The high proportion of inorganic wastes in three of the four pie charts relate to acids and alkalis, often associated with secondary industries such as metal finishing, electronics and manufacturing.
In general, a high proportion of hazardous wastes in developing economies are liquids and sludges.
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Source: INTERNATIONAL MARITIME ORGANISATION Global waste survey, final report 1995

20. Exclusions from control systems
Some wastes may be excluded from the legal definition of hazardous wastes, and thus not subject to controls. These vary, but may include:
Hazardous waste from households - outside the controls in many countries
Small quantity generators - often placed outside the system, at least initially
Aqueous effluents discharged to sewer or treated on-site - controlled separately from hazardous wastes in most countries
Sewage sludge - excluded in some countries
Mining wastes - often excluded
Agricultural waste - often excluded
Nuclear waste - always excluded
Slide 20 Exclusions
Irrespective of the classification method, there are some kinds of hazardous wastes which have often been excluded from the hazardous waste control system in developed countries, perhaps because quantities are small or because the political or practical difficulties are too great. The legal definition is a matter of policy and expediency rather than science: the common exclusion of mine wastes is because of the sheer scale of the problem and not because such wastes are any less hazardous than those from other sources.
The slide lists some of the typical exclusions.
While hazardous waste from households is outside the normal controls in many countries, several western European countries have already established separate collection systems for this fraction. Further countries with well-developed treatment and disposal systems, including good infrastructure, are considering initiatives to collect hazardous wastes from households and bring them into the control system.
Small quantity generators may be placed outside the system in the short term, while the infrastructure is being developed and large generators are brought under control.
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21. Chapter 2.1 Summary
This chapter sets out the need for definitions, and why definition is difficult
It provides examples of definitions: Basel Convention, UNEP, USEPA, European Waste Catalogue
It gives the objective of definitions
It describes classification methods: by origin, by hazardous characteristics, by chemical, biological and physical properties
It covers exclusions from definitions
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