BC  Distr GENERAL  UNEP/CHW/OEWG/1/INF/8 31 March 2003

BC  Distr GENERAL  UNEP/CHW/OEWG/1/INF/8 31 March 2003

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UNEP/CHW/OEWG/1/INF/8
31 March 2003
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OPEN-ENDED WORKING GROUP OF THE BASEL
CONVENTION ON THE CONTROL OF
TRANSBOUNDARY MOVEMENTS OF
HAZARDOUS WASTES AND
THEIR DISPOSAL
First session
Geneva, 28 April to 2 May 2003
Item 5 (g) (i) of the provisional agenda
HAZARDOUS CHARACTERISTIC H11 – TOXIC (DELAYED OR CHRONIC)
Attached is the draft scoping paper on hazardous characteristic H11 as
submitted by the United States.
Draft Scoping Paper for Elaboration of
Basel Annex III Hazardous Characteristics
H-11, Toxic (Chronic or Delayed)
A Proposed Approach to the
Basel Convention Hazardous Characteristic: H-11
CHARACTERIZATION OF CHRONIC OR DELAYED TOXICITY
Prepared by the US EPA
March 28, 2003
Contents
1. Introduction 4
2. Scope & definitions 4
3. Proposed assessment strategy 6
Appendix A:
Proposed H-11 Waste Constituent Categories and De Minimis
Concentrations 8
1. Introduction
The present document discusses proposed criteria for classifying
wastes with regard to the delayed or chronic toxic hazard, H-11, under
the Basel Convention. A key goal of the Basel Convention is ensuring
protection of human health and the environment during the management
and transboundary movement of waste. The Annex III hazardous
characteristics work with the Annex VIII and IX waste lists to
accomplish this goal. In general terms, this means that people and the
ecology should be protected against potential adverse effects caused
by the generation, transport, handling and recycling or disposal of
waste. In terms of delayed or chronic toxicity, protection is to be
ensured when those adverse effects may result from very low but
prolonged exposure of people to waste, or adverse effects occurring
long after exposure has ceased. When the hazards posed by a waste are
too great, the waste is classified as Basel hazardous, and the range
of Basel controls and protections will apply.
According to the Basel Convention, Annex III, the hazard
characteristic: H11 “Toxic (Delayed or chronic)” is defined as:
“Substances or wastes which, if they are inhaled or ingested, or if
they penetrate the skin, may involve delayed or chronic effects,
including carcinogenicity.”
The delayed or chronic impact of a chemical substance, or waste,
depends on the ability of the chemical substance or waste to have a
toxic effect on people, as well as on exposure to the waste or
chemical. Exposure to people can occur during any phase of waste
management: storage, transportation, treatment, and disposal or reuse.
The recent contractor’s report (Senes, 2002) addressing the H-11
characteristic identified several aspects of developing a
classification system for chemicals with regard to chronic toxicity to
humans.
A critical aspect of the H-11 classification system is data on the
adverse health impact to people exposed to the constituents of the
waste. These data are in the form of studies on the toxic effects and
potency of waste constituent chemicals. Therefore, a successful H-11
classification system will be built first on the waste lists in
Annexes VIII and IX, and secondarily on data describing the chemical
composition of wastes, used in conjunction with chemical hazard data.
Also, as noted in the recently finalized discussion of waste
ecotoxicity, H12 under the Basel Convention (cite), classification of
wastes should be independent of local or regional conditions. The
Basel Convention aims to control transboundary movement of hazardous
wastes, and the principles for evaluation should be harmonized across
all the Annex III characteristics in order to facilitate
implementation. Site specific analysis is inappropriate for Basel H-11
classification, since Basel is applied across such a wide variety of
site conditions. Consistent consideration of exposure is necessary to
create a classification system that can be practically implemented,
and is harmonized with the principle of using intrinsic hazard of the
waste or its chemical constituents as the basis for classification.
2. Scope and Definitions
2.1 Scope of the work
The scope of the current work is to derive criteria for the hazard
characteristic: H11 Toxic (Chronic or delayed) in order to obtain a
tool for the classification of wastes with regard to their chronic
toxicity. The proposed criteria are based on parameters that are
generally accepted as indicators of chronic or delayed hazard (e.g.
carcinogenicity or organ system toxicity following long-term low level
exposure, or adverse health effects occurring some time after exposure
of any duration ceases). While classification of most wastes can be
made by referencing Annexes VIII and IX, the presence of a waste type
in Annex VIII or IX of the Basel Convention does not preclude
evaluation according to the hazard characteristics in Annex III in a
particular case. The criteria may thus be used in specific cases, for
evaluating a possible hazard of a waste indicated in these annexes, or
for evaluation of specific wastes, which are not included in Annexes
VIII or IX. The intended use of the proposed criteria is not, however,
for routine evaluation of individual wastes as the costs and time
consumption will be too large for this purpose. The daily evaluation
of individual wastes is therefore done by reference to Annexes VIII
and IX.
2.2 Definitions
It is important to have a common understanding of the definition of
the hazard characteristic: H11 Toxic (chronic or delayed) before
consensus on criteria can be achieved. The fundamental definition of
the H 11 characteristic is:
Toxic (Delayed or chronic): Substances or wastes which, if they are
inhaled or ingested, or if they penetrate the skin, may involve
delayed or chronic effects, including carcinogenicity.
This definition implies an assessment of hazard to people resulting
from long-term, low-level exposure, or adverse health effects
occurring at some point in time after exposure has stopped. The delay
in occurrence of an adverse effect associated with chemical or waste
exposure could be as short as a week or two, or as long as several
years or even decades. Long latency for the appearance of adverse
effects may make it more difficult, as a scientific matter, to
establish a causal connection between chemical exposure and adverse
health impact. However, the length of the delay is irrelevant to the
H11 classification, as long as a causal connection between the
exposure and adverse effects is scientifically established.
Carcinogenicity offers prominent examples of this. Environmental
cancers typically occur either after long term, low level exposures,
or in some case, years after exposure has ended1.
Chemicals act to cause adverse health effects in several different
ways. Acute toxicity describes a situation in which a single, usually
high-dose exposure to a chemical produces adverse health effects
immediately or very soon after the exposure. Acute toxicity occurs
when the dose exceeds the ability of the body to accommodate, excrete,
or detoxify the chemical. Below this threshold, there may be no
injury, while above it, serious injury or death may result. Also, in
any population there will be a range of individual threshold doses,
which can be identified by testing or careful evaluation of poisoning
incidents. The mode of action of chemicals in acute toxicity often
involves either severe damage to an organ or organ system (causing it
to fail), or when the chemical overwhelms a critical biochemical
pathway, resulting in death or injury to organs. Examples would be
carbon monoxide, hydrogen cyanide, or organophosphate pesticide
poisoning.
Chronic or delayed toxicity describes the situation where lower
exposures (which do not cause adverse effects observable at the time
of exposure), occur over some time period, and adverse effects develop
either during the exposure or after it ends. Many adverse effects of
chronic exposure occur only above some threshold dose level, but
others may not have thresholds for injury. Most carcinogens are
considered to not operate in a threshold mode, although this is a
topic of scientific debate. That is, at any dose level, there is some
possibility of an individual developing cancer related to the chemical
exposure. Therefore, the toxic potency of carcinogenic and
non-carcinogenic chronic toxins are expressed differently. Toxic
potency for threshold chronic effects is expressed as daily dose,
called the reference dose (RfD), in mg chemical/kg body weight-day.
Carcinogen potency is expressed as the probability of cancer
developing in a person receiving a low dose over some time period, or
risk/mg/kg body weight-day.
Assessment of two properties intrinsic to chemicals, hazard and toxic
potency, are used to create a classification system for chemicals or
wastes. Hazard assessment, or hazard identification, is commonly used
in risk management of chemical substances and closely related to
classification of hazard, e.g. a classification of wastes according to
the Basel Convention.
Hazard identification is a qualitative determination that specifies
the adverse effects the chemical can cause which would classify it as
hazardous. A substance may, for example, be hazardous because of its
potential for carcinogenicity, toxicity to a particular organ or organ
system, or an ecotoxicological property.
Toxic potency, or dose-response assessment, is a quantitative
assessment that provides information on the dose of a chemical
required to cause the toxic effect. Chemicals acting with thresholds
typically show a steep rise (sharp change in slope) in toxic response
over some narrow range of dose, that allows for the identification of
a dose at which most individuals will suffer the chemical’s adverse
effects. For non-threshold chemicals, the dose-response curve is more
smooth and uniform (constant slope), and intersects the dose-response
plot at the zero point. In creating a classification system, the
hazard assessment determines that a chemical should be in the system,
and the dose response assessment identifies the specific category
within the system (e.g., Class A, B, or C, etc.) for each chemical
warranting classification.
Carcinogenicity and chronic toxicity data are widely available in the
published literature, and a number of sources have collected key
studies on particular chemicals to develop a critical assessment of
the hazard posed2. Most data are based on testing in animals; human
epidemiological studies are available for only a few chemicals. There
is also considerable variability in the availability of toxicity data
by the three H-11 exposure routes. While data on toxicity or
carcinogenicity by oral ingestion of chemicals is available for many
chemicals of interest, data on hazards from inhalation exposure are
available for many fewer chemicals. For exposure by dermal absorption,
data are available for only a handful of chemicals. Extrapolation of
toxicity data between exposure routes is difficult to do reliably, and
in some cases adverse effects are specific to a particular route of
exposure3.
Hazard classification systems are applied to wastes4 through the use
of de minimis cut-off values corresponding to the different classes in
the system, since the degree of hazard is different for the different
chemicals and classes. Wastes being examined under the H11 system
which are found to exceed the de minimis value for their toxic
chemical constituents would be Basel H 11 hazardous. The three
exposure routes defined by H-11 to be incorporated in evaluations of
hazard are: oral ingestion, inhalation, and dermal absorption. The
highest level of chronic exposure to wastes and waste constituents by
these three exposure routes, will occur for those in direct contact
with the waste and its constituents in the course of storage,
transport, recycling or disposal. De minimis values can be developed
by considering the highest plausible exposure for these waste
management operations. Protecting the most exposed persons will also
protect all less-exposed persons. This proposed approach will
harmonize classification of wastes for H11 toxicity (chronic or
delayed) with hazard and dose-response assessment, and allow for
consistent classification of waste based on the intrinsic hazard of
the waste’s constituent chemicals.
As noted in the recently approved elaboration of the Basel H 12
(ecotoxic) characteristic, international classification systems are
used in countries with highly different environmental conditions and
technological development levels. The classification criteria proposed
are based on chemical and waste intrinsic properties, which do not
take the site-specific exposure situation or the specific
environmental conditions into consideration. This classification would
be independent of time and place and indicate the potential impact if
release or exposure should take place.
3. Proposed Assessment Strategy
The proposed strategy is based on that used in development of the
Basel H 12 (ecotoxic) characteristic. It relies on a tiered approach
with the following steps:
1. Initial assessment based on lists of hazardous and non-hazardous
wastes (i.e. Basel Convention Annexes VIII and IX).
2. Assessment based on the content of hazardous chemicals in the waste
(i.e., total concentration in the whole waste).
As with implementation of the H 12 characteristic, the first step of
the strategy to implement H 11 is to determine whether the hazardous
properties of the waste have already been evaluated according to the
Basel Convention (i.e. the waste appears in either Annex VIII or Annex
IX). If the waste does not appear on either of these lists, an
evaluation according to Step 2 is conducted. It should, however, be
noted that in any particular case, the presence of a waste on the
lists in Annexes VIII and IX does not preclude an assessment according
to Annex III.
The evaluation of the toxic (delayed or chronic) hazard in Step 2
would be made by reference to a classification table similar to the
one below. However, the current table considers only ingestion
hazards; data on inhalation and dermal exposure hazards is yet to be
considered.
There is no third step of creating new test data for purposes of H-11
implementation, due to the expense and difficulty of generating
chronic toxicity or carcinogenicity data. Basel H-11 determinations
will need to be made using the best available data. Repeated need for
chronic toxicity data on a particular chemical may support development
of such data over the long-run.
Finally, the approach taken in the H-12 characteristic elaboration can
also be used with the H-11 characteristic for assessment of wastes
containing multiple chemicals of concern.
Appendix A
Basel H-11 Waste Constituent Categories and De Minimis Concentrations
in Waste
Waste Constituent De Minimis Waste Concentration
Hazard Category (Waste is not H-11 hazardous below this value)
Category A: Unit cancer risk of greater than 1 per mg/kg-d 100 ppm
Chronic toxicity RfD less than 10-3 mg/kg-d
(Note: Arsenic, with unit cancer risk of 1.5 per mg/kg-d would fit in
Category A)
Category B: Unit cancer risk of 10-1 to 1 per mg/kg-d 1000 ppm
Chronic toxicity RfD between 10-3 and 10-2 mg/kg-d (0.10%)
Category C: Unit cancer risk of 10-2 to 10-1 per mg/kg-d 1.0%
Chronic toxicity RfD between 10-2 and 10-1 mg/kg-d
(Note: Benzene, with unit cancer risk of 5.5 x 10-2 per mg/kg/d would
fit in Category C)
Category D: Unit cancer risk less than 10-2 per mg/kg-d 10%
Chronic toxicity RfD greater than10-1 mg/kg-d
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 UNEP/CHW/OEWG/1/1
1 The occurrence of lung cancer in asbestos workers is a good example
of the latency effect.
2 These include USEPA’s IRIS data base, IARC, WHO, and others.
3 A model being developed by the US EPA may be useful for assessing
dermal hazards.
4 Wastes are mixtures of many chemical substances, some of which are
toxic and some not.
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