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Frequently
Asked Questions and
What is an existing substance? An existing substance is a substance that has been or is currently used in Canada as a commercial substance or product, or released as a single substance, an effluent, a mixture or a contaminant into the Canadian environment. This includes substances appearing on the Domestic Substances List. What is the Domestic Substances List (DSL)? The Domestic Substances List (DSL) includes substances that were, between January 1, 1984, and December 31, 1986: 1) in Canadian commerce, or Substances on the DSL are also referred to as “existing” substances. There are approximately 23,000 substances on the DSL. The types of substances on the DSL include, organic chemicals (which make up half of the DSL substances), polymers, inorganic substances, products of biotechnology, and substances that are of “Unknown or Variable Composition, complex reaction products, or Biological materials” (referred as UVCBs). Although “new substances” are also included on the DSL, only those substances which have not or will not be evaluated as a new substance will be examined under the DSL Categorization and Screening exercise; otherwise these “new substances” are subject to the New Substances Notification Regulations (NSNR) of CEPA 1999. What is “Categorization and Screening” of substances the DSL? CEPA 1999 requires that all substances on the DSL that have not been subject to notification and assessment as new substances be categorized by September 2006. The first phase of this program, categorization, involves the systematic identification of substances on the DSL that should be subject to screening level risk assessment. For this purpose, categorization is looking for substances that: 1. are “inherently Toxic”, and display either of the characteristics
of persistence (take a long time to break down) or bioaccumulation (collect
in living organisms and end up in the food chain), or The screening level risk assessment involves a more in-depth analysis of a substance to determine whether the substance is “toxic” or capable of becoming “toxic” as defined in CEPA 1999. This determination of toxic consists of integrating the assessment of known or potential exposure of a substance with known or potential adverse effects on the environment. The screening level risk assessment may result in one of the following outcomes:
What is the definition of CEPA "toxic"? According to Section 64 of the Canadian Environmental Protection Act (CEPA 1999), a substance is "toxic" if it is entering or may enter the environment in a quantity or concentration or under conditions that:
a. have or may have an immediate or long-term harmful effect on the environment
or its biological diversity; What do P, B, and iT stand for? P stands for Persistent, B stands for Bioaccumulative, and iT stands for “inherently Toxic”. What is Persistence? Environmental persistence refers to the length of time a substance resides in the environment. A common measure of a substance’s persistence is its half-life — i.e., the time required for the concentration of a substance to diminish to half of its original value in a particular environmental medium of interest. A substance is considered persistent if its transformation half-life satisfies this criterion in any one environmental medium or if it is subject to long-range transport. Only degradation through chemical, biochemical, and photochemical processes is considered. In other words, degradation refers to the breakdown of the substance rather than its removal from a given media by physical transport processes. In the case of air, a substance may be considered as persistent in air if it is shown to be subject to atmospheric transport to remote regions, such as the Arctic. What is Bioaccumulation? Bioaccumulation is a general term describing a process by which substances
are accumulated by organisms directly from the surrounding media and through
consumption of food containing the substances. Bioconcentration is a process
by which there is a net accumulation of a substance directly from water into
aquatic organisms resulting from simultaneous uptake (e.g., gills or epithelial
tissue) and elimination (CCME 1987). In the categorization process, bioaccumulation
factors (BAF) are preferred over bioconcentration factors (BCF); in the absence
of BAF or BCF data, the octanol–water partition coefficient (log Kow)
shall be used. What is inherently Toxic to non-human organisms? The term “inherently Toxic” has been proposed and used under CEPA
1999 to distinguish from the word “toxic,” which is defined under
section 64. “Inherently Toxic” refers to the hazard a substance
presents to the environment or human health, which can be represented by the
toxic effect caused by the substance — i.e., the toxicity found in a study
or predicted due solely to the test substance, or the effect that has not been
masked or mitigated by some factor or parameter. What are the Environment Canada criteria for Categorization for P,B,iT? The P and B criteria are in accordance with the Persistence and Bioaccumulation Regulations (CEPA 1999). The criteria for iT to non-human organisms for Environment Canada are outlined in the Guidance Manual for the Categorization of Organic and Inorganic Substances on Canada’s Domestic Substances List. The criteria for P, B, and iT are as follows:
Substances that have the potential to be transported to remote areas of the globe are considered persistent, and the relevant evidence for long-range transport (LRT) will be taken into consideration in determining the persistence of substances.
Bioaccumulation factor (BAF) refers to the ratio of the concentration of a substance in an organism to the concentration in water, based on uptake directly from the surrounding medium and food. Bioconcentration factor (BCF) refers to the ratio of the concentration of a substance in an organism to the concentration in water, based only on uptake directly from the surrounding medium. The octanol-water partition co-efficient refers to the ratio of distribution of a substance in octanol compared to that in water.
LC50 represents the concentration of a substance in water causing death in 50% of the experimental organisms in the water. EC50 represents the concentration of a substance in water inducing toxic effects on 50% of the experimental organisms. NOEC, the non-observed-effect concentration, refers to the highest concentration of a substance at which there is no adverse effect observed in a toxicological study. Health Canada is responsible for the development of criteria for “inherently Toxic” to humans. For more information, please visit the website of Health Canada at http://www.hc-sc.gc.ca/ewh-semt/contaminants/existsub/index_e.html. What happens when a substance is CEPA "toxic"? For substances that are determined to be "toxic" under CEPA and are added to the List of Toxic Substances in Schedule 1 of the Act, Environment Canada and Health Canada will propose at least one instrument to establish preventive or control actions for managing the substance and thereby reduce or eliminate its release into the environment. These instruments and tools may be used to control any aspect of the substance's life cycle - from the design and development stage to its manufacture, use, storage, transport and ultimate disposal. For those substances deemed persistent and bioaccumulative and which result primarily from human activity, virtual elimination of their release to the environment is the objective. What is "virtual elimination"? Under CEPA 1999, virtual elimination means, in respect of a toxic substance released into the environment, the ultimate reduction of the quantity or concentration of the substance in the release below concentrations that can accurately be measured using sensitive but routine sampling and analytical methods. Virtual elimination is usually achieved through a series of progressive release limits set by regulations and, when appropriate, other risk management measures. The virtual elimination of toxic substances, which are persistent, bioaccumulative, result mainly from human activity and are not naturally occurring radionuclides or naturally occurring inorganic substances, is also at the core of Canada’s Toxic Substances Management Policy, a leading-edge policy among industrialized countries. By putting the virtual elimination elements of the policy into CEPA 1999, Canada is moving ahead of other countries in dealing with these toxic substances. More information on the Toxic Substances Management Policy can be found on the Environment Canada website at http://www.ec.gc.ca/toxics/TSMP/. What are the categorization colour groups? The colour groups are used to identify priorities for filling data gaps. The colours used are: Yellow, Purple, Blue, Green, White, Red and Orange (see Table 2, below). Table 1. Description of Categorization Groups (according to colour assignment)
1 REACH: Registration, Evaluation and Authorisation of Chemicals legislation as proposed by the European Union http://europa.eu.int/comm/enterprise/reach/index.htm For detailed descriptions of colour groups assigned for organics, inorganics, and organic metal salts, please refer to the corresponding fact sheets. How are the values calculated for P, B, and iT? Generally the data selection process involves a search of the scientific literature and databases for quality experimental data for each of P, B, and iT. If acceptable data is not found, QSARs or models are used to estimate the Persistence, Bioaccumulation and aquatic Toxicity of substances based on structure and physical-chemical properties. There are a number of models available for each of P, B, and aquatic iT, and the resulting predictions are weighted to produce a result. If reliable QSAR predictions are not available for a substance, professional judgement is used to provide a qualitative assessment of the substance. What are QSARs? A quantitative structure-activity relationship (QSAR) is a quantitative relationship between a biological activity (e.g. toxicity) and one or more descriptors that are used to predict the activity. For example, for many chemicals, there is a relationship between octanol-water partition coefficient (Kow) and aquatic toxicity. Kow is therefore used to estimate this endpoint. How are QSARs used in the Categorization? QSARs are used only when valid quality experimental data were not found during searches of available databases and the scientific literature. They are used to provide predictions of P, B, and aquatic iT. What will happen to the chemicals that have received categorization decisions? If a substance meets the Categorization criteria through to a final Categorization decision, it will proceed to Risk Assessment – a tiered approach to assess the potential adverse effects of a substance in the environment. The inclusion of a substance on this list does not mean that action will be taken to restrict its use or to ban it. What if there is a substance on this list that may have been incorrectly categorized? Environment Canada is providing the opportunity for individuals and interested parties to submit data. Guidance for this data submission is outlined in the fact sheet Submitting Experimental Data to the Existing Substances Program, as well as available via the website of Environment Canada, at http://www.ec.gc.ca/substances/ese/eng/dsl/cat_index.cfm. What chemicals are on Canada’s DSL? A complete listing of all of the substances on Canada’s DSL (identified by both their chemical names and their CAS (Chemical Abstracts Service) registry numbers, can be found in the spreadsheet entitled: Index of DSL Substances. Reference CCME (Canadian Council of Ministers of the Environment). 1987. Canadian Water
Quality Guidelines. Appendix I. Glossary, Symbols and Abbreviations (updated
periodically) Disclaimer: Although care has been taken to ensure that the information found on this website accurately reflects the requirements prescribed in the Canadian Environmental Protection Act (1999), you are advised that, should any inconsistencies be found, the legal documents, printed in the Canada Gazette, will prevail. |
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