Chapter 2.1 Definitions and classifications
Notes on this chapter
This chapter examines an important element of a hazardous waste management system:
that of a legal definition. The definition is needed to ensure control over waste transport,
treatment and disposal, as well as ensuring that appropriate management options are
selected for a particular waste.
The chapter describes some common systems and conventions concerning waste
classification that are in use around the world, and helps to set the backdrop to many of
the chapters which follow. It also sets out the lack of consistent definitions.
The purpose of this chapter is to encourage the adoption of consistent and clear hazardous
waste definitions in order to facilitate the development of hazardous waste management
strategies which are robust and which limit evasion, as well as allowing for new waste
types to be included as they arise.
Overheads in this chapter highlight some of the major sources of definitions, and the
inconsistencies, but the trainer should encourage the adoption of the Basel Convention
definitions to promote international consistency.
The topic of definitions may appear to be dry and academic, but its importance cannot be
stressed too strongly. Trainers are encouraged to try to enliven the material in this chapter
with practical examples, perhaps involving waste practitioners or representatives from
industry sectors, to help their students understand the practical realities.
Further options for training exercises can be found in some of the UNEP manuals, for
example.
List of slides
Title slide
Slide 2 General definition
Slide 3 Why definition is difficult
Slide 4 Examples of hazardous waste definitions: Basel Convention
Slide 5 Examples of hazardous waste definitions: UNEP
Slide 6 Examples of hazardous waste definitions: USA
Slide 7 Examples of hazardous waste definitions: European Waste Catalogue
Slide 8 The objective of definitions
Slide 9 Different methods of classification
Slide 10 Methods of waste classification: by origin
Slide 11 Example of waste classification by origin: Basel
Slide 12 Methods of waste classification: by hazardous characteristics
Slide 13 Hazardous characteristics: Toxicity
Slide 14 Hazardous characteristics: Corrosivity
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Slide 15 Hazardous characteristics: Ignitability
Slide 16 Hazardous characteristics: Reactivity
Slide 17 Hazardous characteristics: Eco-toxicity
Slide 18 Methods of waste classification: by chemical, biological and physical properties
Slide 19 Relative composition of hazardous waste types by region
Slide 20 Exclusions from control systems
Slide 21 Summary
Background notes
1Both for practical handling reasons and to be able to implement regulatory
requirements, it is necessary to introduce a simple system of classification of waste types
and sources. Various handling requirements, restrictions, fee structures and other
conditions are commonly based on the position in such a schedule or list a waste material
finds itself.
2 Classification can be based on one or more of a number of waste attributes. It may be
based on the source or origin, irrespective of what the waste actually contains.
Classification based on chemical, physical or biological properties of the waste is more
rigorous but requires detailed testing of the material in order to identify it. If the objective
is to calculate the size of treatment facilities, a classification based on treatability by one
of several common means may be used. Often, for practical reasons, all these criteria may
be combined.
3 It is extremely difficult to define a hazardous waste with any precision. While most
countries have defined what they consider to be ‘hazardous waste’, those definitions
differ in their detail, and while there are similarities, there are also many inconsistencies.
4 Even the terminology differs: some countries use the term ‘hazardous waste’ while in
others the terms ‘chemical’, ‘special’, ‘poisonous’, toxic’ or ‘difficult’ are used to
describe such wastes.
5 The importance attached to a legal definition of hazardous waste depends both on its
purpose and the use that will be made of it. Therefore a range of definitions is possible.
The need for a clear-cut definition is greatest if national policy requires that hazardous
waste be treated and disposed of separately from non-hazardous waste.
Criteria for defining hazardous wastes
6 Most countries use a definition for hazardous wastes based on three criteria:
 lists of particular types of wastes which are defined as hazardous
 lists of industrial processes from which the waste is defined as hazardous
These two are absolutes, and do not require testing.
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
In addition, often countries use lists of substances, the presence of which is
indicative of potential hazard and which require testing
7 In some cases meeting one or more of these criteria is judged to provide a sufficient
definition. In other cases, further reference is made to particular concentration levels or to
other criteria.
8 In general terms, any wastes or materials which pose a threat to human health and/or
the environment are deemed to be hazardous. Typically this covers chemical and oil byproducts which have no useful purpose and which pose a threat when improperly
disposed of.
9 The variety and quantity of hazardous wastes being generated are continuing to
increase, in part as a result of the range and diversity of industrial processes. This
requires a classification system flexible enough to accept new wastes.
Sources of further information
Dean, RB & Wilson, DC (Editors) (1990) Adapting hazardous waste management to the
needs of developing countries, Waste Management & Research Vol 8 No 2 March 1990
ISSN 0734-242X
ISWA (1999) International perspectives in hazardous waste management, ISWA
Working Group on Hazardous Waste ISBN 87-90402-08-1
ISWA (2000) National Hazardous Waste Management Profiles from ISWA member
countries, ISWA Working Group on Hazardous Waste ISBN 87-90402-13-8
UNEP (1991) Hazardous waste policies and strategies – a training manual, Technical
report No 10 UNEP Industry & Environment Programme Activity Centre &
Environmental Education & Training Unit, Paris ISBN 92-807-1311-6
Web sites
United Nations Environment Programme, Division of Technology, Industry and
Economics www.uneptie.org
The Basel Convention www.basel.int
European Waste Catalogue www.europa.eu.int/comm/environment/impel/wastelst.htm
Handouts
1. European Waste Catalogue
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