Rapid Screening Assessment

Polymers Identified from Phase Two of the Domestic Substances List Inventory Update

Environment and Climate Change Canada
Health Canada
June 2016

(PDF Format - 510 KB)

Table of Contents

• Synopsis
• 1. Introduction
• 2. Approach
  • 2.1. Ecological Component
  • 2.2. Human Health Component
• 3. Screening Assessment Results
  • 3.1. Assessment Of Potential To Cause Ecological Harm
  • 3.2. Assessment Of Potential To Cause Harm To Human Health
• 4. Summary Of Uncertainties
• 5. Conclusion
• References
• Appendices
  • Appendix A: Polymers identified as requiring further assessment
  • Appendix B: Polymers identified as not meeting criteria under Section 64 of the CEPA

List of Tables

• Table 1: Parameters used in Exposure Scenario A
• Table 2: Parameters used in Exposure Scenario B

List of Figures

• Figure 1: Overview of the ecological polymer rapid screening approach
• Figure 2: Overview of ecological exposure scenarios
• Figure 3: Overview of polymer rapid screening approach - human health considerations
• Figure 4: Considerations for the determination of direct human exposure potential to polymers through direct use
• Figure 5: Summary of screening assessment results - ecological considerations

Synopsis

As part of the Chemicals Management Plan, the Government of Canada is assessing and managing, where appropriate, the potential health and ecological risks associated with certain polymers under the Canadian Environmental Protection Act, 1999 (CEPA). These polymers were identified as priorities for further action following completion of categorization in 2006. A section 71 Notice for the second phase of the Domestic Substances List Inventory Update initiative was published in the Canada Gazette, Part I in December 2012 to collect data on approximately 2700 substances including polymers. As a result of this data collection exercise, 336 polymers were identified as not being in-commerce at quantities greater than 1000 kg during the 2011 calendar year. A polymer rapid screening approach was applied to these 336 polymers It involved using conservative assumptions to identify polymers that warrant further evaluation of their potential to cause harm to either human health or the environment, and those that are expected to have a low likelihood of causing harmful ecological or human health effects.

The ecological component of the polymer rapid screening approach consisted of four main steps to identify substances that warrant further evaluation of their potential to cause harm. The first step involved identifying the substances that have similar structural characteristics to polymeric substances that have been previously subject to risk management under the New Substances Notification Regulations (NSNR) (Chemicals and Polymers). The second and third steps of the process involved identifying polymers that are likely to have water extractability greater than 2 % and determining whether these polymers contain reactive functional groups, as described under Schedule 7 items 1 and 5 of NSNR (Chemicals and Polymers), respectively. The final step involved applying different exposure scenarios using assumptions that are protective of the environment and comparing to a conservative acute ecotoxicity value for polymers.

The human health component of the polymer rapid screening approach consisted of a process to determine whether each polymer warranted further assessment from a human health perspective. A key element of the characterization of potential risk for human health was a determination of the potential for exposure to the general population. Polymers reported to be in commerce in Canada at less than or equal to 1000 kg during the 2011 calendar year are considered to warrant further assessment if there is evidence of direct exposure (e.g., exposure from products) of the general population in Canada. Polymers that posed a potential for direct exposure were also screened against a set of criteria in order to identify those likely to pose a low hazard to human health. If the potential for exposure to a polymer is not expected or the polymer is likely to pose low hazard to human health, it is concluded that that polymer is unlikely to cause harm to human health at current levels of exposure.

Conclusion

In total, 61 polymers were identified as requiring further assessment (5 identified for both ecological and human health considerations, 13 identified for human health considerations only, and 43 identified for ecological considerations only). Based on the information available, it is concluded that the 275 polymers listed in Appendix Bdo not meet any of the criteria under section 64 of CEPA, since they are not entering the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity, that constitute or may constitute a danger to the environment on which life depends, or that constitute or may constitute a danger in Canada to human life or health.

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1. Introduction

The Canadian Environmental Protection Act, 1999 (CEPA) (Canada 1999) requires the Minister of the Environment and Climate Change and the Minister of Health to conduct screening assessments of substances that have met the categorization criteria set out in the Act to determine whether these substances present or may present a risk to the environment or human health^Footnote1.

Under CEPA, screening assessments focus on information critical to determining whether a substance meets the criteria for defining a chemical as toxic as set out in section 64 of the Act, where:

"64. [...] a substance is toxic if it is entering or may enter the environment in a quantity or concentration or under conditions that

1. have or may have an immediate or long-term harmful effect on the environment or its biological diversity;
2. constitute or may constitute a danger to the environment on which life depends; or
3. constitute or may constitute a danger in Canada to human life or health."

The Government of Canada has identified 336 substances, which are polymers^Footnote2, as candidates for a polymer rapid screening assessment, a component of the approach to address priority polymers on the Domestic Substances List (DSL) (Environment Canada, Health Canada 2014). These 336 polymers were not identified as being in commerce at greater than 1000 kg during the 2011 calendar year based on information submitted pursuant to section 71 of CEPA regarding commercial activity in Canada under Phase Two of the Domestic Substances List Inventory Update (DSL UI; Canada 2014). Thirty-nine polymers from the Confidential Domestic Substances List (CDSL) were included as part of the 336 polymers in this rapid screening. The identities of these polymers have been masked in this report to prevent the release of confidential business information as required under section 88 of CEPA.

Polymers that meet the above criteria, but that have already been assessed and managed under CEPA, or are currently being addressed under other assessment activities, are not included in this report. Furthermore, assessments and conclusions pertaining to some of the polymers in this polymer rapid screening may be subsequently updated as part of future assessments.

This assessment incorporates input from other programs within Environment and Climate Change Canada and Health Canada. Additionally, the draft of this Screening Assessment was subject to a 60-day public comment period. While external comments were taken into consideration, the final content and outcome of the screening assessment remain the responsibility of Health Canada and Environment and Climate Change Canada.

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2. Approach

2.1 Ecological Component

The ecological component of the polymer rapid screening approach, as illustrated in Figure 1, consists of multiple steps that address different factors related to the potential for a substance to cause ecological harm. The approach is intended to be pragmatic, protective of the environment, and fairly rapid, largely making use of available or easily obtainable data.

Figure 1: Overview of the ecological polymer rapid screening approach

Step 1: Identification of polymers similar to those that have been previously subject to risk management under the New Substance Notification Program.

Under the New Substances Notification (NSN) Program, there are numerous polymers that are subject to risk management measures. Polymers identified in this step have similar structural and/or chemical functional group(s) to those that have been previously risk managed and may have similar ecological concerns. Professional judgement was used to derive representative structures^Footnote3 based on chemical names and available monomer information. Judgement was also used to identify polymers that are structurally similar (e.g., by comparing chemical functionality) to those that have been previously risk managed under the NSN Program. Substances identified at this step require further assessment and do not proceed to subsequent steps.

Step 2: Identification of polymers with water extractability greater than 2 % by weight.

The second step involves determining whether the polymer will likely have water extractability greater than 2 weight (wt) %. A water extractability greater than 2 wt, % indicates that the polymer may be available to aquatic organisms. The increased potential for exposure to aquatic organisms may present higher ecological risk. This is consistent with the approach taken by the NSN Program, where polymers with less than or equal to 2 wt % water extractability are assumed to have low exposure potential towards aquatic organisms and new substances notifications are not required to include experimental ecotoxicity data.

Literature, MSDS databases, the New Substances database for polymers, and other reliable sources and databases (e.g. QSAR toolbox, ECHA chemical database) were searched for available water extractability and solubility information. For polymers where no information on water extractability could be found, professional judgement based on representative structures and chemical names was used to determine whether the substance could potentially be extracted into water. For example, 1,3-butadiene, 2-methyl-, homopolymer (CAS RN 9003-31-0) does not contain functional groups that are considered to increase water solubility, thus it would be expected to have water extractability less than 2 wt %. It is recognized that polymers identified by the same CAS RN may have different number average molecular weights and variable monomer composition, which may affect the water extractability of the polymers. A polymer is considered to have water extractability greater than 2 wt % if it contains functional group(s) that could potentially increase water extractability. In addition, polymers that are formulated in water and polymers that form a stable emulsion in water are considered to have water extractability greater than 2 wt %. These polymers will be considered further in Step 3.

Step 3: Identification of polymers with reactive functional groups.

The third step in the ecological component involves identifying polymers with reactive functional groups described under Schedule 7 (items 1 and 5) of NSNR (Chemicals and Polymers) (Canada 2005). According to these items, there are molecular weight limitations in which a functional group may be considered to be of concern. However, as there are no molecular weight data available for polymers, it is assumed that all polymers will have molecular weight below the cut off [i.e., number average molecular weight (Mn) less than 10,000 Daltons (Da), with greater than 25 wt % less than 1000 Da, and greater than 10 wt % less than 500 Da]. In addition, only functional groups present in the polymer are considered. Polymers without any reactive functional groups are expected to have low ecotoxicity; and therefore, are not of ecological concern.

Information regarding possible representative structures was not available from the DSL IU survey (Canada 2012). As such, representative structures were derived from information provided for similar substances under the NSN Program, Chemical Abstract Services (CAS) name, as well as professional knowledge on possible polymerization mechanisms. It is recognized that some polymers may have more than one possible polymerization mechanism, leading to several possible structures. In addition, the complexity of a multicomponent polymeric reaction would increase uncertainty regarding the presence of reactive functional groups in polymers. For these polymers, it is assumed that reactive functional groups are present and they are considered further in Step 4.

Step 4: Generic aquatic exposure scenarios.

The last step in the polymer rapid screening for ecological consideration involves applying different environmental release scenarios to estimate environmental exposure. Two generic aquatic exposure scenarios were applied (described hereafter as scenarios A and B) to identify potential concerns near the point of discharge of a substance into the environment. These scenarios involve comparing conservative (i.e., ecologically protective) estimates of exposure in receiving waters with an effects threshold in order to evaluate whether a polymer is likely to cause harm to the local aquatic environment. Figure 2 illustrates these exposure estimation approaches.

These approaches make use of available data from phase two of the DSL IU, including whether the substance was in commerce in Canada at greater than the reporting threshold of 1000 kg in 2011, as well as data from the NSN Program. As specific quantity information was not provided, the maximum quantity based on the reporting threshold for phase two of the DSL IU was used as a conservative assumption in the generic exposure scenarios.

Experimental ecotoxicity data were not available for any of the substances included in polymer rapid screening. In addition, since polymers can have number average molecular weights that exceed the reliability limit of available modelling software, modelling of ecotoxicity was not performed. Ecotoxicity values were derived from data endpoints available for various polymer types and species from the NSN Program (more than 1000 endpoints available). Based on these data, the lowest toxicity value reported for any polymer type and species was for algae with an acute EC50 of 0.016 mg/L. This value is assumed to represent the worst case toxicity for polymers that are considered under the polymer rapid screening approach, and was identified as the Critical Toxicity Value (CTV). A Predicted No Effect Concentration (PNEC) was derived by dividing the CTV by an assessment factor.  An assessment factor of 10 was applied to the acute CTV of 0.016 mg/L to extrapolate from a severe short-term effect to long-term no-effects. Given the large number of species represented in the ecotoxicity dataset, no additional extrapolation assessment factor was applied to account for inter-/intra-species variation. Therefore, the PNEC was calculated as 1.6 x 10^-3 mg/L.

While the generic aquatic exposure scenarios (A and B) have been developed to be conservative overall, the level of conservatism generally applied to individual parameters is moderate, since it is recognized that:

• a high level of conservatism applied to each parameter can easily compound into an excessively conservative overall exposure scenario;
• it is very unlikely that each parameter would be "worst case" at the same time; and
• the interdependency of some parameters exists.

Thus, values in keeping with an overall worst case scenario have been used.

Figure 2: Overview of ecological exposure scenarios

Scenario A: Industrial point source aquatic release

Scenario A is based on release from an industrial facility that is manufacturing the substance and/or using it in the preparation of products. This scenario assumes the release of 5% of the substance from manufacturing and handling, based on conservative estimates for loss from cleaning of container residues (3%), transfer lines (1%) and process equipment (1%) (US EPA 1992). A conservative estimate of exposure [Predicted Environmental Concentration (PEC)] resulting from the release of the substance to the aquatic environment from such an industrial point source is calculated as shown in the following equation. The aquatic predicted no-effect concentration (PNEC) is derived as shown in the equation below. Parameters used in Exposure Scenario A are described in Table 1.

Quantity released (kg/day) = [(Qty)(Release)(1 – Wastewater removal rate)]/duration

Flow rate (m³/s) = River flow + Wastewater flow

PEC (mg/L) = [Quantity released / Flow rate](1000/86400)

Aquatic PNEC (mg/L) = CTV / AF

The PEC is then compared to the PNEC to determine a risk quotient (PEC / PNEC). If the risk quotient is greater than one, this indicates that the conservatively estimated concentration in water exceeds the aquatic estimated no-effect level and that there exists a potential to cause harm in the aquatic ecosystem. A value below one indicates that concentrations that may cause an effect to sensitive aquatic organisms are not reached and therefore harm to aquatic organisms is unlikely under this scenario.

Note that the wastewater treatment system (WWTS) removal efficiency for polymers varies significantly. However, removal efficiency typically depends on the Mn of the polymer as well as the charge on the polymer (Boethling and Nabholz 1997). For cationic, amphoteric and neutral polymers with Mn greater than 1000 Da, removal efficiency is typically assumed to be 90%. However, for polymers with Mn less than 1000 Da, the removal efficiency typically ranges between 50 and 90 %. For anionic polymers with Mn greater than 5000 Da, typical removal efficiency is greater than 50 %, and increases as molecular weight increases. For anionic polymers with Mn less than 5000 Da, typical removal efficiency ranges between 0 and 50 % (Boethling and Nabholz 1997). Considering that removal efficiency can vary significantly between different polymer types as well as varying Mn, a 50 % removal efficiency is assumed.

Scenario B: Down-the-drain aquatic release from consumer products

The second scenario (residential releases to wastewater) considers the release of 100% of the substance that is contained in a consumer product, from multiple point-sources (i.e., wastewater system discharges). Under this scenario, a value for the PEC from down-the-drain release of a substance contained in products is calculated, as well as a value for the aquatic PNEC, as defined in the equations below. Parameters used in Scenario B are described in Table 2 below.

Quantity released (kg/day) = [(Qty)(Release)(1 – Wastewater removal rate)(population)]/[(duration)(RPE)]

Flow rate (m³/s) = River flow + Wastewater flow

PEC (mg/L) = [Quantity released / Flow rate](1000/86400)

Aquatic PNEC (mg/L) = CTV / AF

As was the case for Scenario A, the PEC and the PNEC are combined to determine a risk quotient (PEC / PNEC).

Note that river flow distributions used in the two scenarios are different. The likelihood of harm from industrial releases (Scenario A) is dependent on the number of industrial facilities releasing to a water body. In that scenario, a distribution of the dilution capacities of receiving waters (river flow) was generated with a weighting by the number of industrial facilities releasing to the water body. The likelihood of harm from down-the-drain release of consumer products (Scenario B) is dependent on the human population that may be releasing a substance to a WWTS. In this scenario, a distribution of the ratio of population of the community to the dilution capacity of the receiving water body was generated. As a result, the parameters "population", "wastewater flow" and "river flow" are inter-connected. In this scenario, it is this ratio that is important, not the actual values of the population or flow rates.

There are two possible outcomes from Step 4:

• if the scenarios indicate a potential harmful effect to aquatic organisms, the substance is identified as requiring further assessment;
• if the scenarios indicate a low likelihood of harm to aquatic organisms, then the substance is anticipated to present low ecological concern.

2.2 Human Health Component

A key element of the characterization of potential risk to human health is determination of potential for exposure to the general population.

Given the reported quantities of candidate polymers in commerce in Canada (i.e., less than or equal to 1000 kg during the 2011 calendar year), exposure of the general population from environmental media such as air, water and soil (i.e., indirect exposure) is not expected to be significant. Release of a polymer to specific environmental media depends on factors such as location of release and the polymer's physical/chemical properties. Conservative modelling estimates using a fugacity-based model  for applicable smaller molecule chemicals (ChemCan 2003) indicate that assuming 100 % release of a substance (i.e., the maximum possible release of 1000 kg) to either air, water or soil, potential exposures would be predicted to be  less than 1 ng/kg bw/day. This finding is applicable to polymers as well since polymers are larger and commonly less available than smaller molecule chemicals; indirect exposure from environmental sources is not expected for polymers that are in commerce at low volumes.

Therefore, the process used to determine whether polymers warrant further assessment from a human health perspective within the rapid screening approach focuses initially on direct exposure and is illustrated in Figure 3.

Figure 3: Overview of polymer rapid screening approach - human health considerations

Polymers reported to be in commerce in Canada at less than or equal to 1000 kg during the 2011 calendar year were considered to result in potential exposure to the general population if there was evidence of direct exposure (e.g., exposure from use of cosmetics). Otherwise, exposure of the general population is not expected and it can be concluded that the polymer is unlikely to cause harm to health at current levels of exposure.

Depending on the use of the polymer, direct exposure to the general population may be possible. Considerations for the determination of direct exposure potential are described below and outlined in Figure 4.

Figure 4: Considerations for the determination of direct human exposure potential to polymers through direct use

The term "direct use" refers to the use of a polymer that is directly, or as part of a mixture, a product, or a manufactured item, sold to or made available to Canadians for their use.

"Direct use" does not include exposures from chemical products used by workers in an industrial setting or other workplace.

A user is considered to be anyone from the general public who has access to a product that is advertised, imported or sold in Canada^Footnote4.

To determine if a polymer is used in or present in a product used by Canadians, numerous sources of both domestic and international use and product information were consulted including, but not limited to:

Domestic

• Information from a mandatory CEPA section 71 survey under Phase Two of the DSL Inventory Update (Canada 2012)
• Health Canada's Lists of permitted food additives (2013)
• Health Canada's Natural Health Products Ingredients Database (NHPID 2015)
• Health Canada's Licensed Natural Health Products Database (LNHPD 2015)
• Health Canada's Drug Product Database (DPD 2014)
• Pest Management Regulatory Agency Product Information Database (PMRA 2014)
• Pest Management Regulatory Agency List of Formulants (PMRA 2010)
• List of Pharmaceuticals sold in Canada (2011 & 2012) (IMS 2013)
• Notifications submitted under the Cosmetic Regulations to Health Canada
• Notifications submitted under the Food and Drugs Act to Health Canada

International

• US EPA Chemical and Product Categories Database (CPCat 2014)
• Everything Added to Food in the United States Database (EAFUS 2011)
• US Food and Drug Administration's Food Additive Status List (US FDA 2013)
• US Food and Drug Administration's List of Indirect Additives used in Food Contact Substances (US FDA 2011)
• European Commission's Food Additive database (EU 2014a)
• European Commission's Food Flavourings database (EU 2014b)
• European Commission's Cosmetic Ingredient database (COSING 2014)
• Household Products Database (HPD 2014)
• Hazardous Substances Data Bank (HSDB c1993-2008)
• Danish Surveys on Chemicals in Consumer Products- various (Denmark 2014)
• Material Safety Data Sheets (MSDS)- various internet sources
• National and international assessments and databases

Based on the information identified from these resources the following considerations were used to determine potential for direct exposure:

1. Polymers for which direct exposures of the general population are not expected include, but are not limited to, polymers:
   1. used only as intermediates in the manufacturing process,
   2. used only for industrial use
   3. used only for research purposes, or
   4. used only as pesticide formulants – In situations where the only use identified for a polymer was as a formulant in a pesticide product registered under the Pest Control Products Act (PCPA), this potential for direct exposure to the general public was not considered further in this screening assessment. Polymers in pest control products registered under the PCPA have undergone an ecological and human health risk assessment by the Pest Management Regulatory Agency (PMRA) according to the intended use and labelling as part of their registration process. The polymers used as formulants were considered separately from those identified as active ingredients in registered pesticide products, as the formulants, while components of pesticide products, do not provide a function(s) that is/are unique to pesticides.
2. Polymers with potential for direct exposure to the general population include those that are present, either intentionally or unintentionally, in products or manufactured items that are commonly used by Canadians. These include, but are not limited to, polymers used in:
   • products intended for use by children, and manufactured items such as plastic or wooden toys;
   • personal care products^Footnote5;
   • commercial paints and inks;
   • commercial adhesives;
   • hobby activities or do-it-yourself products; or
   • cleaning products.
3. Information on the potential for the polymer to migrate from products was also considered, including the type of product that the polymer is present in, and the polymer's functional use in that product. For example, direct exposure would not be expected to occur for a polymer used as a flame retardant in fluorescent light bulbs as any actual dermal contact with the product is minimal and the flame retardant polymer is encapsulated within the bulb. If this information is not known for a polymer, it was assumed that the polymer may be migrating out of the final product, which may lead to direct exposure for users.

As indicated in Figure 3, polymers for which potential for direct exposure was identified were further screened against a set of criteria that are indicative of polymers likely posing a low hazard to human health. For a polymer to be considered as posing low hazard, the screening criteria include:

1. The polymer must not be classified as carcinogenic, mutagenic, toxic to reproduction (CMR).
2. The polymer must be either
   1. a low concern polyester consisting only of monomers listed in Schedule 8 of the NSNR (Chemicals and Polymers); or
   2. a polymer that contains functional groups considered to be non- reactive in biological settings.
3. The polymer can contain only the following:
   • Carbon, hydrogen, nitrogen, oxygen, silicon and sulphur;
   • Sodium, magnesium, aluminum, potassium, calcium, chlorine, bromine and iodine as the monoatomic counter-ions Na⁺, Mg²⁺, Al³⁺, K⁺, Ca²⁺, Cl^-, Br^- or I^-;
   • Fluorine, chlorine, bromine or iodine covalently bound to carbon; and
   • Less than 0.2% (by weight) of any combination of the following atomic elements: lithium, boron, phosphorus, titanium, manganese, iron, nickel, copper, zinc, tin or zirconium.
4. The polymer must not be designed, or expected, to substantially degrade, decompose or depolymerize;
5. The polymer must not be water insoluble and high molecular weight if inhalation is a potential route of exposure-in the absence of data regarding physical/chemical properties and molecular weight, it is conservatively assumed that the polymer may be high molecular weight and water insoluble;
6. The polymer must not be water absorbing and high molecular weight if inhalation is a potential route of exposure-in the absence of data regarding physical/chemical properties and molecular weight, it is conservatively assumed that the polymer may be high molecular weight and water absorbing; and
7. The polymer must not be structurally similar to those that have been previously risk managed under the NSN Program for potential health concerns.

A polymer that poses potential for direct exposure and does not meet the above criteria for low hazard is considered to require further assessment. For polymers that pose potential for direct exposure yet are considered to be likely low hazard, it is concluded that these polymers are unlikely to cause harm to human health at current levels of exposure.

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3. Screening Assessment Results

3.1 Assessment of Potential to Cause Ecological Harm

In this section, an overview of the results obtained at each step of polymer rapid screening for the substances covered under this assessment is provided. These results are summarized in Figure 5.

Figure 5: Summary of screening assessment results - ecological considerations

Step 1: Polymers similar to those that have been previously subject to risk management under the New Substances Notification Program.

Polymers that have been previously subject to risk management under the NSN Program can generally be divided into five classes including: surfactant type; cationic type; epoxy type; perfluorinated type; and siloxane type polymers. Based on comparison of name and possible structural features between low volume polymers and New Substances polymers, 48 were identified as having similar structural properties to one of the five classes of polymers identified above. Currently, these polymers may be in use at low quantities or are not in commerce; however, due to the similarities to the substances that have been subject to risk management by the NSN Program, it is concluded that they be considered further.

Step 2: Polymers with water extractability greater than 2 wt %.

Of the 288 polymers assessed in Step 2, 199 substances were identified as having water extractability potential greater than 2 wt %. These substances were further assessed in Step 3.

Step 3: Polymers with reactive functional groups

Based on comparison of reactive functional groups and polymerization potential, as well as information available from the NSN Program, 147 of the 199 substances were considered to have the potential to contain one or more reactive functional groups, as listed under Schedule 7 (item 1 and 5) of the NSNR (Chemicals and Polymers) (Canada 2005).

Step 4: Generic aquatic scenarios

In this assessment, the quantity used in the exposure scenarios was 1000 kg per year, which was the reporting threshold for polymers under Phase Two of the DSL IU (Canada 2012). Both Scenario A (industrial point source aquatic release) and B (down-the-drain release from consumer products) were considered for 147 polymers.

Based on the industrial and consumer products release scenarios described above, as well as the conservative assumption of worst case ecotoxicity described in Section 2.1, all 147 low volume substances considered in Step 4 are not considered to be of ecological concern.

Summary of results from ecological assessment

In total, 48 of the substances evaluated using the ecological polymer rapid screening approach were identified as warranting further screening assessment from an ecological perspective. A list of these substances is provided in Appendix A. The other 288 substances were identified as posing a low risk of harm to organisms or the broader integrity of the environment at current levels of exposure.

3.2 Assessment of Potential to Cause Harm to Human Health

Of the 336 polymers examined from a human health perspective, six polymers were identified as having a use pattern that may lead to potential direct exposure of the general population, but they are considered to be low hazard. Exposure to the general population was not expected for another 312 polymers. Together these 318 polymers were identified as being unlikely to cause harm to human health at current levels of exposure.

The remaining 18 polymers were identified as having the potential to result in direct exposure to the general population and do not meet the criteria for low hazard; therefore, these 18 polymers will be subject to further assessment. A list of these polymers requiring further assessment is provided in Appendix A.

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4. Summary of Uncertainties

It is recognized that conclusions resulting from the use of this polymer rapid screening approach have associated uncertainties. However, the use of a wide range of information sources (relating to both exposure potential and hazard concerns identified for a polymer), as well as the use of conservative exposure scenarios increases confidence in the overall approach that polymers identified as not requiring further assessment are unlikely to be of concern.

Uncertainties associated with the ecological assessment include the assumptions made to derive representative structures, potential presence of reactive functional groups, monomer composition, number average molecular weight, water extractability, and aquatic toxicities. It is also recognized that polymers covered under the same CAS RN may have significantly different number average molecular weights and monomer composition; and hence, a range of physical-chemical properties and hazard. However, conservative assumptions were made for these polymers based on professional judgment. In addition, a worst case toxicity based on toxicity data from the NSN Program was selected for risk quotient determination.

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5. Conclusion

In total, from both ecological and human health assessments, 61 of the 336 polymers were identified as requiring further assessment (Appendix A).

Based on the information available, it is concluded that the remaining 275 polymers (Appendix B) are not entering the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity, that constitute or may constitute a danger to the environment on which life depends, or that constitute or may constitute a danger in Canada to human life or health. It is therefore concluded that the 275 polymers listed in Appendix B do not meet any of the criteria set out in section 64 of CEPA.

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Appendices

Appendix A: Polymers identified as requiring further assessment

Table A1 Notes

[a]

The Chemical Abstracts Service Registry Number (CAS RN) is the property of the American Chemical Society and any use or redistribution, except as required in supporting regulatory requirements and/or for reports to the government when the information and the reports are required by law or administrative policy, is not permitted without the prior written permission of the American Chemical Society.

[b]

A Confidential Accession Number is given to a substance whose identity is confidential and the chemical name masked pursuant to Sections 3 to 7 of the Masked Name Regulations (Canada 1994).

[c]

Masked names are allowed by CEPA if the publication of the explicit chemical or biological name of a substance would result in the release of confidential business information.

Appendix B: Polymers identified as not meeting criteria under Section 64 of the Canadian Environmental Protection Act, 1999 (CEPA)

Table B1 Notes

[a]

The Chemical Abstracts Service Registry Number (CAS RN) is the property of the American Chemical Society and any use or redistribution, except as required in supporting regulatory requirements and/or for reports to the government when the information and the reports are required by law or administrative policy, is not permitted without the prior written permission of the American Chemical Society.

[b]

A Confidential Accession Number is given to a substance whose identity is confidential and the chemical name masked pursuant to Sections 3 to 7 of the Masked Name Regulations (Canada 1994).

[c]

Masked names are allowed by CEPA if the publication of the explicit chemical or biological name of a substance would result in the release of confidential business information.

[d]

These substances were not identified under subsection 73(1) of CEPA but were included in this assessment as they were considered as priorities based on other human health concerns.

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