SIST-TP CEN/TR 15584:2008
(Main)Characterisation of sludges - Guide to risk assessment especially in relation to use and disposal of sludges
Characterisation of sludges - Guide to risk assessment especially in relation to use and disposal of sludges
The scope of this Technical Report includes sludges from treating municipal, industrial and food processing wastewaters, sludge from treating raw water to make it potable, and other residues having similar potential environmental impacts.
The purpose of this Technical Report is to discuss risk assessment in general and especially as it has been applied to sludges for an audience of specialists and non-specialists. The objective is to set risk assessment in the context of policy making and operating sludge use and disposal.
Charakterisierung von Schlämmen - Anleitung zur Risikobwertung im Besonderen im Bezug auf Nutzung und Lagerung von Schlämmen
Caractérisation des boues - Guide pour l'évaluation du risque en relation avec l'usage et le mise en décharge des boues
Le domaine d’application du présent document inclut les boues provenant du traitement des eaux usées municipales, industrielles et de l’industrie agroalimentaire, les boues provenant du traitement de l’eau brute pour la rendre potable et d’autres résidus ayant des impacts environnementaux potentiels similaires.
Le présent document a pour objectif d’examiner l’appréciation du risque en général et en particulier lorsqu’elle est appliquée aux boues, et s’adresse aussi bien aux spécialistes qu’aux profanes. Il s’agit de placer l’appréciation du risque dans un contexte politique et de traiter de l’utilisation et du rejet des boues.
Karakterizacija blata - Vodilo za oceno tveganja s poudarkom na uporabi in odlaganju blata
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TP CEN/TR 15584:2008
01-julij-2008
Karakterizacija blata - Vodilo za oceno tveganja s poudarkom na uporabi in
odlaganju blata
Characterisation of sludges - Guide to risk assessment especially in relation to use and
disposal of sludges
Charakterisierung von Schlämmen - Anleitung zur Risikobwertung im Besonderen im
Bezug auf Nutzung und Lagerung von Schlämmen
Caractérisation des boues - Guide pour l'évaluation du risque en relation avec l'usage et
le mise en décharge des boues
Ta slovenski standard je istoveten z: CEN/TR 15584:2007
ICS:
13.030.40 Naprave in oprema za Installations and equipment
odstranjevanje in obdelavo for waste disposal and
odpadkov treatment
SIST-TP CEN/TR 15584:2008 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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TECHNICAL REPORT
CEN/TR 15584
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
July 2007
ICS 13.030.40
English Version
Characterisation of sludges - Guide to risk assessment
especially in relation to use and disposal of sludges
Caractérisation des boues - Guide pour l'évaluation du Charakterisierung von Schlämmen - Anleitung zur
risque en relation avec l'usage et le mise en décharge des Risikobewertung im Besonderen im Bezug auf Nutzung und
boues Lagerung von Schlämmen
This Technical Report was approved by CEN on 3 March 2007. It has been drawn up by the Technical Committee CEN/TC 308.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 15584:2007: E
worldwide for CEN national Members.
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CEN/TR 15584:2007 (E)
Contents Page
Foreword.3
1 Summary.4
2 Scope .5
3 Normative references .5
4 Terms and definitions .5
5 Introduction.7
5.1 Hazard, Risk and Communication.9
5.2 Risk Assessment and the Precautionary Principle.9
6 Source – Pathway – Receptor .10
7 A framework for environmental risk assessment and management.12
7.1 Problem formulation.13
7.2 Key stages of environmental risk assessment.14
7.3 The social aspects of risk .14
7.4 Risk screening and prioritisation.15
7.5 Quantification and dealing with uncertainty.15
7.6 Evaluating the significance of a risk.16
7.7 Options appraisal and decision-making .17
7.8 Monitoring .17
7.9 Risk Management .18
8 Examples of published risk assessments for use and disposal of sludges .19
8.1 USEPA risk assessment for the Federal Sewage Sludge Rules, 1992.19
8.2 USEPA risk assessment of dioxin-like substances in sewage sludge use and disposal,
2002 .20
8.3 UKWIR risk assessment of pathogen transmission associated with using sewage sludge
on farmland, 2003 .21
8.4 Abstracts of published risk assessments for sludges and related subjects .21
Annex A (informative) Glossary of acronyms commonly used in risk assessment .30
Annex B (informative) Extended text on risk assessment, communication and management.32
Annex C (informative) Rio Declaration on Environment and Development .71
Annex D (informative) Fault Tree Analysis (FTA).74
Bibliography .76
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Foreword
This document (CEN/TR 15584:2007) has been prepared by Technical Committee CEN/TC 308
“Characterisation of sludges”, the secretariat of which is held by AFNOR.
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1 Summary
This report has been prepared within the framework of CEN/TC 308 on Characterization of Sludges. The
Scope includes sludges from treating municipal, industrial and food processing wastewaters, sludge from
treating raw water to make it potable, and other residues having similar potential environmental impacts.
The objectives of the report are to review the methodology of risk assessment, risk management and risk
communication especially as they have been applied to sludges. It includes references to, and reviews of,
some major risk assessments and abstracts of others that have been published.
Sludge is the inevitable residue of treating raw potable water and municipal and industrial wastewaters.
Treatment of these waters is designed to remove unwanted constituents from the water and concentrate them
into a small side-stream - “sludge”. The sludge may also contain surplus biomass cultured during biological
treatment processes. The objective of treatment is to avoid adverse impacts on the environment and human
health when the effluent is discharged into the environment or water is supplied for human consumption. The
concentration of beneficial constituents and of pollutants in (and health risks associated with) a sludge
depends on the initial quality of the wastewater or raw water, and the extent of treatment required to meet
quality standards for effluent discharge, and potable water.
Where effluent quality standards are raised, in order to reduce pollutant loads on the environment, the quantity
of sludge produced inevitably increases. To be consistent, the use or disposal of the sludge must also be
environmentally acceptable, sustainable and cost-effective. Sludge management typically represents about
half of the overall costs of wastewater treatment. Its management will become increasingly complex as
environmental standards become more stringent, and if outlets for sludge become more constrained by
legislation and public attitudes.
EU policy on waste is to promote waste avoidance, minimisation and recycling above disposal. Disposal of
sludge to sea ceased at the end of 1998. Disposal of sludges to landfill, which is currently the major outlet for
some sludges in Europe, is widely regarded as unsustainable. Sludge production cannot be avoided (although
the quantity can be reduced by treatment). The only remaining significant options are recycling or destruction
by combustion. Recycling options include use on land as an organic fertiliser or soil improver for farming, land
restoration, etc. Destruction options include combustion with or without energy recovery, gasification, and
using the sludge as a process fuel, with the ash being used or landfilled.
Many sludges and residues contain beneficial constituents and properties with positive environmental
advantages. For example, recycling phosphate and thus reducing the need to extract primary raw material
and extending the life of the planet’s reserves.
The EU has decided (CEC, 2000) that environmental policies should be proportionate to risk and non-
discriminatory. When there is sufficient information, there should be risk assessment and, when there is
insufficient information, measures should be put in place to fill the information gap and an interim
precautionary approach applied.
In popular understanding, “safe” can be interpreted as “something we don’t have to worry about”. There is a
social factor as well as the numerical factor. Some people talk of the “One-hit” model, especially for
carcinogens, which assumes that interaction of a single molecule with DNA could trigger mutation that could
replicate as cancer but if this were applied universally it would stop all activity. Doing risk assessment lets us
understand the aspects that drive the risk and therefore enables us to target the regulation – it improves the
way we regulate.
Risk assessment should inform a decision rather than support a decision that has already been taken, i.e. the
science should come first and then the politics (informed by the science). Equally the performance of risk
assessment needs to be adequately resourced (time, money, people, etc.), it needs to be transparent (i.e. the
models and assumptions should be published) and stakeholders need to be involved at the earliest stages.
The fundamental question is “risk of what to whom”. Risk communication has emerged as an essential
activity.
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In order to increase public and stakeholder confidence the views of non-expert audiences may be brought into
the risk assessment process and supporting [background] documents should be published so that the
assumptions and models are clearly visible.
There is abundant information about the fate and transport of the constituents of sewage sludges, but less
information about the other sludges. However, relatively few risk assessments have been published.
2 Scope
The Scope of this document includes sludges from treating municipal, industrial and food processing
wastewaters, sludge from treating raw water to make it potable, and other residues having similar potential
environmental impacts.
The purpose of this document is to discuss risk assessment in general and especially as it has been applied
to sludges for an audience of specialists and non-specialists. The objective is to set risk assessment in the
context of policy making and operating sludge use and disposal.
3 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
Not applicable
4 Terms and definitions
For the purposes of this report, the following terms and definitions apply:
4.1
harm
physical injury or damage to the health of people or damage to property or the environment
[ISO/IEC Guide 51]
4.2
hazard
potential source of harm
[ISO/IEC Guide 51]
4.3
risk
combination of the probability of occurrence of harm and the severity of that harm
[ISO/IEC Guide 51]
4.4
perceived risk
sum of risk and “outrage” – outrage is what makes people upset
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4.5
contaminant
substance, material or agent that is unwanted in a sludge
[CR 13455 : 1999]
4.6
pollutant
contaminant present in a sludge that due to its properties, amount or concentration causes harm
[CR 13455 : 1999]
4.7
potentially toxic element
chemical elements that have a potential to cause toxicity to humans, flora and fauna. Typically, this term
refers to “heavy metals” and others such as arsenic, selenium, boron, fluorine that exhibits a typical, dose
related, sharp toxicity curve
[CR 13455 : 1999]
4.8
user
anybody exposed to the product, including professional and non-professional (amateur) users, and general
public exposed not from a user standpoint
[CR 13455 : 1999]
4.9
intended use
use of a product, process or service in accordance with information provided by the supplier
[ISO/IEC Guide 51]
4.10
reasonably foreseeable misuse
use of a product, process or service in a way not intended by the supplier, but which may result from readily
predictable human behaviour
[ISO/IEC Guide 51]
4.11
safety
freedom from unacceptable risk
[ISO/IEC Guide 51]
4.12
protective measure
means used to reduce risk
[ISO/IEC Guide 51]
4.13
residual risk
risk remaining after protective measures have been taken
[ISO/IEC Guide 51]
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4.14
tolerable risk
risk that is accepted in a given context based on current values of society
[ISO/IEC Guide 51]
4.15
risk analysis
systematic use of available information to identify hazards to estimate the risk
[ISO/IEC Guide 51]
4.16
risk evaluation
procedure based on the risk analysis to determine whether the tolerable risk has been achieved
[ISO/IEC Guide 51]
4.17
risk assessment
overall process comprising a risk analysis and a risk evaluation
[ISO/IEC Guide 51]
4.18
Monte Carlo Analysis (MCA) or Simulation
process of repeatedly sampling from probability distributions to derive a distribution of outcomes (i.e. risks or
hazards)
5 Introduction
About 500 years ago, Paracelsus (1493-1541) wrote: "Dosis facit venenum." ("The dose makes the poison.").
The relationship between dose and response (effect) is still one of the most fundamental concepts of
toxicology (the science of poisons), but when we discuss environmental alarms and chemical health risks it is
sometimes forgotten. A logical consequence of the dose concept is that all environmental risk analysis is more
or less quantitative in nature.
Risk management is at the heart of European policy on the environment as well as other aspects of life. It is
also at the heart of many businesses. For example, risk assessment is the foundation of the insurance and
pensions industries.
In order for there to be a risk [4.3] to a receptor there must be a source of the hazard [4.2] and a pathway by
which a sufficient (harmful) dose is delivered to the receptor. In the case of the use or disposal of sludges, the
sludge could be a source of chemical or biological hazards, the receptors could be organisms living in soil or
water or on the surface of the land, and the pathway could be direct ingestion of the sludge or via air, plants or
water.
Risk assessment [4.17] is often portrayed incorrectly as being different from the precautionary principle,
indeed they are sometimes portrayed as being incompatible. The precautionary principle was first recognised
at international level in the World Charter for Nature, adopted by the UN General Assembly in 1982. It was
enshrined at the United Nations’ Conference on Environment and Development, meeting at Rio de Janeiro in
June 1992 (Annex C principle 15) this and European Commission policy (CEC, 2000) show that they are both
part of managing environmental risk.
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Risk assessment has established itself as an essential tool for the management of environmental risk and has
been widely adopted by businesses, regulators and the financial sector. However, the perception of risks by
members of the general public can differ from the quantitative assessments of risks. For example, it was
difficult to persuade people to wear seat belts in cars, not to smoke, etc. because members of the general
public’s perceptions of the risks differed from those calculated by actuaries. The realisation of this dichotomy
led to awareness that “risk communication” is also important. Table 1 gives examples of actuarial risks
associated with normal everyday activities to give some context and to put the subject into perspective.
Table 1 – Examples of risks involved in normal activities (from FWR, 2002)
Activity Risk Of Cases per million
Travel 1000 miles by air Fatal accident 3
Travel 1000 miles by car Fatal accident 20
Travel 1000 miles by motorcycle Fatal accident 400
Working 10 years in a factory Fatal accident 300
1 glass of wine per day for 10 years Cirrhosis 1000
1 cigarette per day for 10 years Heart attack or lung cancer 2500
Living 1 year at age 30 Death from all causes 1000
Living 1 year at age 55 Death from all causes 10000
Figure 1 gives a representation of the major components of the process of hazard identification, risk
assessment, risk management and risk communication. It shows examples of the types of data that are
required; if there are insufficient data the precautionary principle should be invoked, in a way that is
proportionate to the likely risk and on a time-limited basis, until the data necessary to estimate risk have been
obtained (CEC, 2000). Cultural and political values are also shown as components because, for example,
levels of risk or practices that are acceptable in one community might be unacceptable in another. It would
seem illogical to have measures for different regulated activities within the same population that give markedly
different levels of protection so there needs to be some consistency and proportionality.
A number of assumptions have to be made when assessing risk (as indicated in Figure 1). For example, when
assessing the risk of transmitting toxic chemicals from sludge, via soil to crops and then to humans it is
necessary to make assumptions about the proportion of the diet that comes from sludge treated land. It is
important to document these assumptions in order that the basis is transparent. If somebody finds the result
difficult to accept, they can then check the assumptions and models to see whether they are reasonable.
Figure 1 – The major components of the risk assessment and risk management process
(from NAS, 2002)
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5.1 Hazard, Risk and Communication
Crompton (2005) discussed the distinction of hazard and risk by the example of cyanide in a kitchen; the
hazard is always very high but the risk depends on the exposure. If the bottle is clearly labelled and locked
away in a safe the risk is small; if the bottle is unlabelled and in an unlocked kitchen cupboard the risk is much
greater; if the cyanide is in a cup of tea the risk is very high indeed.
A newspaper headline “Cyanide found in kitchen” would be accurate and scary but it does not describe the
risk. The same headline would be true if there were apples in the kitchen because apple pips contain small
(non-harmful) amounts of amygdalin that breaks down to cyanide. The dose of cyanide from apple pips is so
small that it is metabolised and is harmless, even if the coating is broken open by mastication.
5.2 Risk Assessment and the Precautionary Principle
Life is a continual process of managing and assessing risks. Take as an example crossing a road. By
experience and example we learn to estimate the density and speed of the traffic and to assess when the risk
[of being hit by a vehicle] is acceptably low to attempt to cross the road. If the traffic is so continuous and fast
that there are no breaks for the risk to be acceptable we can walk to the nearest controlled crossing, i.e.
employ risk reduction technology. However a person who is deaf and blind would not have the data required
for assessing the risk; a deaf and blind person would be wise to employ the Precautionary Principle and not
cross the road until their data gap was filled, e.g. by the assistance of a sighted person.
The authority responsible for the safety of pedestrians might decide that the risk of injury from crossing roads
was unacceptable and all roads should be fenced. Traffic control lights would still entail the risk that vehicles
might not stop; also, they disrupt traffic flow and cause delays. To eliminate the risk of pedestrian-vehicle
collision, crossing would be permitted only at monitored subways (underpasses) or bridges. Monitoring would
be in order to manage the risk of muggings. This approach is taken for motorways, autobahns, freeways and
other very high-risk roads but it would be disproportionate to apply the policy to all roads. The cost of creating
and maintaining the infrastructure and the inconvenience would be disproportionate to the risk. In practice,
the authorities responsible for road safety assess the risks from data they have collected about accidents.
The Precautionary Principle is an integral part of risk assessment. If there are sufficient data to assess the
risk with a reasonable degree of confidence, action/policy is based on the data. As with all scientific and
engineering exercises, a margin of safety will be applied. The size of this margin is related to the confidence
in the data and also to political choice. The tolerable level of risk for which the action/policy provides
protection is also a political decision; the EU has decided this should be consistent and proportionate. If
having examined the available data, they are considered to be insufficient or inconsistent, an interim and
proportionate action/policy is established and at the same time the necessary measures are put in hand to fill
that data gap so that a risk assessment is possible.
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6 Source – Pathway – Receptor
It is fundamental that in order for there to be a risk there must be a receptor and that there must be a pathway
by which the hazard is transmitted from the source to the receptor. If one of these elements in the chain is
missing there can be no risk.
When considering sludge as a source of hazards, there are several possible receptors and several possible
pathways; they are outlined in Table 2.
Table 2 – Generalised examples of possible source-pathway-receptor chains for use and disposal of
sludges
Source → Pathway → Receptor Consideration
Sludge → human Direct ingestion or via skin puncture etc.
Sludge → soil → human Direct ingestion or via skin puncture etc.
Sludge → soil → plant → human Dietary intake of plant material from sludge
treated land diluted through food retail chain
Sludge → soil → plant → animal → human Dietary intake of products from animals grazing
or fed on crops from sludge treated land
Sludge → soil → animal → human Direct ingestion of sludge treated soil by animals
and transmission to humans
Sludge → soil → airborne dust → human Respiration of dust from sludge treated land
Sludge → (soil) → air → human Respiration of dust, odour, bioaerosols and
airborne chemicals – includes incineration etc.
Sludge → soil → ground/surface water → human Contamination of drinking water sources –
includes landfill of sludges and ashes
Sludge → soil → surface water → fish → human Dietary intake of contaminated fishes
Sludge → soil → surface water → fish Toxicity to fishes from contaminated water, flora
and fauna
Sludge → soil → plant → animal Toxicity to animals eating plants growing in
sludge treated soil
Sludge → soil → animal Toxicity to direct ingestion of sludge treated soil
Sludge → soil → plant Toxicity to plants growing in sludge treated soil
Sludge → soil → soil biota Toxicity to soil organisms and impairment of soil
functions
Sludge → soil → soil biota → predator Toxicity to predators of soil organisms
When assessing risk it is essential to estimate the change [modulation] of “availability” or effective dose at
each step in a pathway crucial. In the case of sewage sludge, the amount of research has been substantial
(e.g. summarised in ICON, 2001 and Smith, 1996 and 2000). There has been less research on the other
sludges but effects could be deduced judiciously from the sewage sludge data.
Table 2 lists examples of pathways and receptors that might be considered in a risk assessment for use
and/or disposal of sludges. It is mainly concerned with chemical and biological risks. From a business or
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operational point of view, one could add the risk of legal action for not complying with regulations, for damage
to the company’s/organisation’s reputation, for creating an actionable nuisance or for accidents to employees
and others through a lack of regard to health and safety.
Individuals might be exposed to hazards via several pathways. Classically risk assessments have assessed
each pathway in turn for receptors based on a number of assumptions. Assumptions would include exposure
time, body weight, and other factors depending whether the assessment is being modelled for the average
individual in the general population, individuals that are exposed more than the average. Risk management
strategies are developed according to the pathway with the greatest risk to protect the average individual, the
highly exposed individual (HEI) or the most exposed (MEI). This is called deterministic assessment, more
recently there has been a trend to assess the probabilities of exposure to the different pathways etc. in
combination (see clause B.8.6 for a discussion of deterministic and probabilistic risk assessment).
In some cases the product(s) of transformation and breakdown on the pathway from the source to the
receptor are themselves hazards, for example the metabolites of DDT, DDE and DDD, also have toxic
effects.
DDT is a pesticide once widely used to control insects in agriculture but now banned in many countries
because of damage to wildlife, it breaks down to DDE, and DDD. They are all broken down rapidly in air by
sunlight (t = 2 days). They are strongly sorbed by soil; most DDT in soil is broken down slowly to DDE and
½
DDD by microorganisms; the half-life of DDT in soil is 2-15 years, depending on the type of soil. DDT and
DDE build up in plants and in fatty tissues of fish, birds, and other animals.
DDT is still used in some countries because it is inexpensive and very effective for controlling malaria
mosquitoes and locusts.
This is an example of balancing risks and cultural and political values. When there is risk of millions of
deaths per year because of malaria (mosquitoes) and starvation (locusts), the environmental risk from DDT
might be considered acceptable until a preferable control is available.
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7 A framework for environmental risk assessment and management
At the outset it is essential to decide and understand the purpose and context, i.e. the “risk of what to whom”.
The analysis should be systematic and logical. It should consider how the output will be used, and the cost,
social acceptability and effects of the risk management measures that will emerge.
Figure 2 shows a framework for environmental risk assessment and risk management (Anon, 2000 and
Pollard and Guy, 2001).
Figure 2 – An example of a framework for environmental risk assessment and risk management
(from Anon, 2000)
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A risk assessment framework is useful to show how the component stages relate to each other and inform the
overall decision being made. Agreeing the framework early on can avoid misunderstandings between
experts, stakeholders and the public later on. It is now agreed that it is good practice to involve stakeholders
at the earliest stage so that they agree the model rather than presenting them with completed assessment
only to find they argue about the fundamental basis.
A pragmatic approach to environmental risk assessment can transform what may sometimes appear to be an
extremely detailed, complex and resource-intensive process into a practical aid to decision-making. Figure 2
provides a framework for a tiered approach to envi
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