Screening assessment sector-specific inorganic unknown or variable composition, complex reaction products and biological materials group

Screening Assessment Sector-specific Inorganic UVCBs Group

Environment and Climate Change Canada

Health Canada

August 2018

Cat. No.: En14-330/2018E-PDF
ISBN 978-0-660-27546-8

Synopsis

Pursuant to sections 68 or 74 of the Canadian Environmental Protection Act, 1999 (CEPA), the Minister of the Environment and the Minister of Health have conducted a screening assessment of 57 substances of Unknown or Variable Composition, Complex Reaction Products and Biological Materials (UVCB), referred to collectively as the sector-specific inorganic UVCBs group. Substances in this group were identified as priorities for assessment as they met categorization criteria under subsection 73(1) of CEPA or were considered a priority on the basis of other human health concerns. The Chemical Abstracts Service Registry Numbers (CAS RN^{Footnote 1} ), Domestic Substances List (DSL) names and some common names are listed in the table below.

Abbreviations: NA, not available
^a This substance was not identified under subsection 73(1) of CEPA but was included in this assessment as it was considered a priority on the basis of other human health concerns.
^b This common name is not taken from National Chemical Inventory (NCI) (2012)

These 57 UVCBs were grouped for assessment as their commercial activity is restricted to a small number of industrial sectors and exposure is either not expected or is considered to be negligible. The approach used in this assessment focuses on the exposure characterization of the substances and includes consideration of information on commercial activity (i.e., manufacturing or import into Canada) and uses, as well as existing measures to prevent or limit exposure to the environment and consequently to the general population of Canada.

The main sectors of activity for the substances are the base metals processing, iron and steel manufacturing, aluminium smelting and automotive parts manufacturing, pulp and paper manufacturing, and cement manufacturing sectors. The potential for ecological exposure was assessed by grouping the substances among five "types" to clarify the release potential of the substances: "no longer manufactured or imported," "intermediate," "waste," "by-product" or "substances with other commercial uses in other sectors." For substances that either were no longer manufactured or imported or were intermediates, exposure was not expected as the substances were either no longer in commerce or were found to be consumed on-site (or at other facilities) as feedstock or on-site for energy recovery. For substances determined to be wastes or by-products, ecological exposure to the environment was considered negligible because they were either disposed of on-site at the facility (e.g., some wastes from the base metals processing sector), sent to a specialized hazardous waste facility or met regulation standards to confirm lack of hazardous characteristics.

This approach used information submitted by companies in response to either a voluntary survey or to Phase 2 of the DSL Inventory Update, as well as other technical information including technical reports generated for Environment and Climate Change Canada. On the basis of the information received, 38 substances were determined to be no longer manufactured or imported or intermediates, 10 were determined to be intermediates or wastes, 3 were determined to be by-products or wastes, and 5 were determined to be wastes. On the basis of the information available, the potential for exposure of the environment to these substances is considered to be either negligible or not expected. One additional substance, a sulfite liquor (CAS RN 68131-31-7), was determined to be an intermediate within the pulp and paper manufacturing sector for which ecological exposure is not expected, and according to the exposure characterization of the substance for a number of applications within other sectors, its potential for ecological exposure is negligible.

Considering all available lines of evidence presented in this screening assessment, there is low risk of harm of the environment from all 57 substances in the sector-specific inorganic UVCBs group. It is concluded that these 57 substances do not meet the criteria under paragraphs 64(a) or (b) of CEPA as 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 or that constitute or may constitute a danger to the environment on which life depends.

Given that ecological exposure was considered either negligible or not expected, general population exposure to substances through environmental media was consequently considered to be either negligible or not expected. Additionally, uses identified (beyond the pulp and paper manufacturing sector) were not considered to result in general population exposure. Accordingly risk to human health is considered to be low for all 57 substances.

On the basis of the information presented in this screening assessment, it is concluded that the 57 substances in the sector-specific inorganic UVCBs group do not meet the criteria under paragraph 64(c) of CEPA as they are not entering the environment in a quantity or concentration or under conditions that constitute or may constitute a danger in Canada to human life or health.

Therefore, it is concluded that the 57 substances in the sector-specific Inorganic UVCBs group do not meet any of the criteria set out in section 64 of CEPA.

1. Introduction

Pursuant to section 68 or 74 of the Canadian Environmental Protection Act, 1999 (CEPA) (Canada 1999), the Minister of the Environment and the Minister of Health have conducted a screening assessment of 57 substances of Unknown or Variable Composition, Complex Reaction Products and Biological Materials (UVCBs), referred to collectively as the sector-specific inorganic UVCBs group, to determine whether these substances present or may present a risk to the environment or to human health. The substances in this group were identified as priorities for assessment as they met categorization criteria under subsection 73(1) of CEPA or were considered a priority on the basis of other human health concerns (ECCC, HC [modified 2017]).

These 57 UVCBs were grouped for assessment as their commercial activity is restricted to a small number of industrial sectors, and they were anticipated to have a limited potential for exposure to humans and the environment. The approach used in this assessment focuses on the exposure characterization of the 57 substances and includes consideration of information on commercial activity (i.e., manufacturing or import into Canada) and uses, as well as existing measures to prevent or limit exposure to the environment and consequently to the general population of Canada. The substances had reported manufacturing or import quantities received through submissions of information provided in response to notices under section 71 of CEPA regarding commercial activity in Canada for the year 2011 (Canada 2012; Environment Canada 2013).

This screening assessment includes consideration of information on uses and exposure, including information submitted by stakeholders. Relevant data were identified up to July 2016. Additional data were submitted by stakeholders up to November 2016. Targeted literature searches were conducted up to June 2016. Empirical data from key studies as well as some results from models were used to reach conclusions. When available and relevant, information presented in assessments from other jurisdictions was considered.

This screening assessment was prepared by staff in the CEPA Risk Assessment Program at Health Canada and Environment and Climate Change Canada and incorporates input from other programs within these departments. The ecological assessment, on which the human health assessment is based, underwent external review and/or consultation. Comments on the technical portions relevant to the environment were received from the European Chemicals Agency (ECHA). Additionally, the draft of this screening assessment (published July 22, 2017) 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.

This screening assessment focuses on information critical to determining whether substances meet the criteria as set out in section 64 of CEPA, by examining scientific information and incorporating a weight–of-evidence approach and precaution.^{Footnote 2} This screening assessment presents the critical information and considerations on which the conclusion is based.

2. Identity of substances

The substances in this risk assessment are considered predominantly “inorganic UVCBs”. UVCB substances are derived from natural sources or complex reactions and cannot be characterized in terms of constituent chemical compounds because their composition is too complex or variable (EC, HC 2006).

Inorganic UVCB substances in the sector-specific inorganic UVCBs group contain many inorganic elements and are comparable to complex mixtures of multiple metals and metalloids. For example, according to its Domestic Substances List (DSL) definition, the substance “Solutions, precious metal hydrometallurgical” (CAS RN^{Footnote 3} 129618-37-7) may contain metal ions of palladium, platinum, gold, silver and small amounts of rhodium, ruthenium, iridium and other non-ferrous elements, such as copper, nickel, cobalt, lead, bismuth, antimony, arsenic, selenium and tellurium (NCI 2012). Because the composition of a UVCB substance is process-specific and varies between facilities within a sector of activity, representative composition information is often not available or is approximate.

The CAS RNs, DSL names, and DSL definitions for the substances in this group are presented in Appendix A (Table A-1). A list of additional chemical names (e.g., other common names) is available from the National Chemical Inventories (NCI 2012).

A total of 57 inorganic UVCB substances, distributed primarily in the base metals processing, iron and steel manufacturing, aluminium smelting and automotive parts manufacturing, pulp and paper manufacturing, and cement manufacturing sectors, were identified as remaining priorities for assessment and included in the sector-specific inorganic UVCBs group on the basis of their limited use and negligible expected release potential.

3. Approach for sector-specific inorganic UVCBs

3.1 Basis of the ecological and human health assessment approach

The assessment of sector-specific inorganic UVCBs group focuses on the exposure characterization of each substance to determine whether risks to the environment and/or to human health are anticipated. This approach was taken because:

1. the hazardous characteristics of the UVCBs are not defined given their variable and complex compositions;
2. many substances in this group are limited to a few sectors and are expected to be site-restricted or sector-restricted substances with a low potential for exposure to humans and the environment; and
3. measures exist to prevent or to limit releases of certain substances or their constituents for most sectors considered in the assessment.

Substances in this group are site-restricted^{Footnote 4} or sector-restricted, and exposure to humans and the environment is either not expected or considered negligible. Site-restricted substances are expected to remain on the facility's site, where they may be further processed or disposed of. Sector-restricted substances are those that are only used within a particular industry, but may leave a facility and be transported to other industrial facilities in the same industry, for example as feedstock in metal recovery operations, including metal recycling.

Many of these UVCBs are known hazardous substances with potential specific inorganic components, such as lead, already on Schedule 1 of CEPA, and measures (e.g., federal regulations, voluntary measures) are in place to minimize releases from facilities and to limit exposure to the environment and to humans.

The assessment approach is presented in Figure 3-1, and additional information on the exposure characterization approach is provided in Section 3.2.

3.2 Exposure approach

The exposure potential for the 57 Sector-specific Inorganic UVCB substances is determined on the basis of two main considerations:

1. the potential to be released to environmental media (i.e., the type of substance); and
2. in certain cases, the existence of measures to limit exposure to the environment and consequently to humans.

The substances are grouped by "type" to characterize their potential for exposure using several lines of evidence. This includes function codes and consumer and commercial codes information as well as North American Industry Classification System Codes (NAICS) submitted under Phase 2 of the Domestic Substances List Inventory Update (DSL IU Phase 2) (Environment Canada 2013; ECCC 2016a), literature reviews, and results from voluntary stakeholder engagement (ECCC 2016b). These codes provide information on the uses or functions of substances in an industrial or a commercial/consumer use setting and are used as a first line of evidence to classify the substance. The definitions of the codes are provided in Appendix C (Table C-1).

For the purpose of this assessment, five substance "types" were therefore defined: "no longer manufactured or imported," "intermediate," "waste," "by-product" and "substance with other commercial uses in other sectors" (Table 3-1). The commercial activity of substances determined to be "no longer manufactured or imported" was updated as a result of voluntary stakeholder engagement activities (ECCC 2016b) and their exposure potential is non-existent. Substances determined to be "intermediate" are transient (i.e., transformed into another substance) and their potential for exposure is negligible. "Intermediates" may be site-restricted process intermediates or sector-restricted substances that are sent to another site for further processing and transformed into another substance (e.g., residue sent for metal recovery). Substances determined to be "wastes" can be site-restricted (i.e., disposed of on the site of the facility) or sent to specialized facilities to be disposed of, and exposure may be negligible when considering measures that exist to limit exposure, especially when sent off-site. "By-products" is a term widely used in industry and refers to substances generated by a specific sector that may have commercial applications. Permitted uses may depend on meeting certain criteria from provincial regulations, and exposure to the substances may therefore be considered acceptable. The last type, "substances with other commercial uses in other sectors," refers to substances used in sectors other than the ones discussed in this assessment and that may require further assessment if the exposure potential is unknown.

^a. Definition from Environment Canada (2012).
^b. This definition also covers a substance manufactured at one site and transported to a second site where it is consumed, or a substance imported at one site and transported to a second site where it is consumed, as expressed in the definition of "site-limited intermediate" in the New Substances Notification Regulations (Chemicals and Polymers) (Canada 2015).

Measures that exist to limit exposure to the substances would be considered when determining the exposure potential of the substances, particularly for non-site-restricted "wastes" or "by-products." Measures in place to limit exposure to the substance during its manufacturing, processing, transportation or disposal include federal or provincial regulations and voluntary measures (e.g., codes of practice), provincial/territorial operating permit requirements, and best practices and guidelines put in place by industry.

4. Sources and uses

Information regarding the manufacture or import of a number of the inorganic UVCBs for the year 2011 was obtained through a notice issued pursuant to section 71 of CEPA, commonly referred to as Phase 2 of the DSL Inventory Update (Canada 2012). Results for these substances with regard to their quantities in commerce and uses (Environment Canada 2013) are presented in section 4.1 and 4.2, respectively.

4.1 Sources

Survey results indicate the 57 inorganic UVCBs included in the approach were generally manufactured^{Footnote 5} or imported into Canada in 2011 in large quantities (Environment Canada 2013). Quantities varied between ranges of 10–100 t and 1 000 000–10 000 000 t for manufacturing and between ranges of 0.01–0.1 t and 1 000–10 000 t for import into Canada (Table B-1, Appendix B). Only 9 substances were manufactured in quantities lower than 100 t.

Substances were distributed almost exclusively in the base metals processing, iron and steel manufacturing, aluminium smelting and automotive parts manufacturing, pulp and paper manufacturing, and cement manufacturing sectors, with next to no overlap between these sectors. Two substances, "zinc, dross" (CAS RN 69011-50-3) and "lead, dross" (CAS RN 69029-52-3), were manufactured by companies from both the base metals processing and iron and steel manufacturing sectors. Another substance, "aluminum dross" (CAS RN 69011-71-8), was manufactured by companies associated with both the aluminium smelting and automotive parts manufacturing sectors.

Relatively small quantities (i.e., 0.1–1 t up to 10–100 t) of "slags, ferrous metal, blast furnace" (CAS RN 65996-69-2), "sulfite liquors and cooking liquors, green" (CAS RN 68131-30-6) and "sulfite liquors and cooking liquors, spent alkali-treated" (CAS RN 68131-31-7) were imported by five companies involved in other sectors of activity.

Results from voluntary information gathering conducted with stakeholders for the years 2014 to 2016 determined that one company was no longer manufacturing the substance "matte, copper" (CAS RN 67711-91-5) in 2014 and that the substance "sulfite liquors and cooking liquors, green" (CAS RN 68131-30-6) was no longer imported into Canada in 2015 (ECCC 2016b).

4.2 Uses

"Function codes" (UXXX) and "consumer and commercial codes" (CXXX) provide information on the uses or functions of substances in an industrial or a commercial/consumer use setting. Results for the 57 substances show that multiple codes were often provided for the same substance, but companies predominantly provided the codes U015 "Intermediates" and U999 "Other" or C206 "Metal materials not otherwise covered in this table" or C999 "Other" for substances within the five main sectors (Environment Canada 2013, ECCC 2016a, ECCC 2016b). The list of codes and their definitions are provided in Appendix C (Table C-1), and detailed results for each substance within each sector are provided in Appendix D (Tables D-1 to D-5). Codes identified as confidential business information (CBI) are masked to protect confidentiality.

5. Potential to cause ecological harm

5.1 Ecological exposure assessment

The exposure assessment of the 57 Inorganic UVCB substances is discussed by sector in sections 5.1.1 to 5.1.6. The aluminium smelting and automotive parts manufacturing sectors are discussed together (5.1.3) and the exposure assessment of substances with other commercial uses in other sectors is discussed in section 5.1.6. A summary of the exposure characterization is presented in section 5.1.7.

5.1.1 Base metals processing

The base metals processing sector includes smelting and refining facilities that produce precious and base metals from ores or scrap and process wastes through pyrometallurgical, hydrometallurgical and vapo-metallurgical processes (Environment Canada 2006). Base metals include copper, lead, nickel and zinc, and depending on the origin of the ore or scrap metal and its residual metals content, various metals such as gold, silver, indium, germanium, cadmium, bismuth and selenium may be recovered as co-products (Environment Canada 2006).

The sector uses or produces substantial quantities of a number of complex inorganic substances as a result of its manufacturing processes and pollution control devices (e.g., cyclones). A total of 45 substances were confirmed to be manufactured or imported into Canada by this sector in 2011, including two substances that are also manufactured by the iron and steel sector. Whether substances may be recovered or disposed of varies from facility to facility depending on a number of technical, environmental and economic factors (Environment Canada 2006). On the basis of the analysis of function codes and relevant consumer and commercial codes submitted by industry, these 45 substances were determined to be intermediates or wastes (Table D-1).

A total of 34 substances were determined to be "intermediates" on the basis of the function code for "Intermediate" (U015), "Other" (U999), "Plating agents and surface treating agents" (U023) and, when relevant, the consumer and commercial code "Other" (C999) submitted by industry. These substances were either further processed on-site or sent to recycling for metal recovery (Environment Canada 2013, ECCC 2016b). The substance "matte, copper" (CAS RN 67711-91-5) was determined to be no longer manufactured in 2014 by one company that submitted the function code U999 in 2011 (Environment Canada 2013, ECCC 2016b).

Seven substances with the function codes U015 and U999/C999 or just U999/C999 were determined to be either "intermediate" or "waste." Facilities situated upstream in base metals processing are usually equipped with large smelting furnaces where residues produced at various steps of the manufacturing process may be re-introduced to recover valuable metals and may effectively be considered "intermediates." For example, substances that are often considered wastes such as "slags, precious metal recovery lead refining" (CAS RN 69029-85-2) and "slags, lead smelting, zinc reduced" (CAS RN 175448-53-0) are re-introduced in the furnace of one smelting facility for metal recovery (Environment Canada 2002) and are therefore "intermediates" at that particular facility. Downstream facilities such as metal refineries that produced higher purity metals may not "recycle" the substances on-site and may have declared sending the substances to metal recyclers for metal recovery or to other facilities for disposal, depending on market value (Environment Canada 2013).

Four substances with the code U999 and consisting of slags and other residues were determined to be "wastes," with the exception of the substance "slags, lead smelting" (CAS RN 69029-84-1), which had the code U015 submitted by a company that responded to the DSL IU Phase 2 survey (Environment Canada 2013). These substances are disposed of if their valuable metal content is too low to warrant further recovery or too high to pass a leachate test allowing other uses (e.g., construction materials) (Hatch 2004). The substances are generally stored on-site (Environment Canada 2002; Environment Canada 2013), and leachate from the disposal areas is collected and treated (Hatch 2004) as required by federal and provincial regulations.

5.1.2 Iron and steel manufacturing

The iron and steel manufacturing sector is comprised of integrated mills and mini-mills. Integrated mills process iron ore to produce iron in blast furnaces (BFs) using metallurgical coke and then transform iron to steel in basic oxygen furnaces (BOFs). Non-integrated mills (or "mini-mills") melt scrap steel or direct-reduced iron (DRI) in electric arc furnaces (EAFs) to form new steel products. EAFs are also used to produce carbon and alloy steels (US EPA 1995a).

This sector uses or produces substantial quantities of a number of complex inorganic substances as a result of its manufacturing processes and pollution control devices. A total of seven substances were reported to be manufactured in Canada in 2011 by this sector. On the basis of the analysis of function codes and consumer and commercial codes submitted by companies, the seven substances were determined to be intermediates, by-products or wastes in the iron and steel sector (Table D-2). Two of the substances, "zinc, dross" (CAS RN 69011-50-3) and "lead, dross" (CAS RN 69029-52-3), are also manufactured by the base metals processing sector, where they were also determined to be intermediates (section 5.1.1). Small quantities from 1000 to 10 000 kg of "slags, ferrous metal, blast furnace" (CAS RN 65996-69-2) imported into Canada in 2011 by companies from other sectors of activity, are discussed in section 5.1.6.

Four substances were produced at a limited number of facilities in the iron and steel manufacturing sector were determined to be intermediates (Environment Canada 2013). Indeed, these four substances are further processed at specialized recycling facilities to recover valuable metals such as zinc, lead or tin.

The substances "slags, ferrous metal, blast furnace" (CAS RN 65996-69-2), "slags, ferrous metal, blast furnace, desulfurizing" (CAS RN 125408-74-4) and "slags, steelmaking" (CAS RN 65996-71-6) are by-products, produced at various steps of the processing of iron ore to manufacture iron and steel (Environment Canada 2001; US EPA 1995a). Steel slags are incidentally produced by all 15 primary steelmaking facilities in Canada. Iron and steel slags are considered a commodity (USGS 2016) and are used mainly for construction and environmental applications because they are generally alkaline and contain lower concentrations of many trace elements as compared to non-ferrous slags (Piatak et al 2015). According to a review of the Canadian iron and steel sector by Environmental Health Strategies (EHS) (2013), slags are generally processed on-site or by specialized industries and sold for other uses in accordance with provincial regulations (e.g., need to pass a leachate test). Blast furnace slags are processed on-site or by a contractor. They can be water-cooled or pelletized and are sold for use as construction material mainly in the cement industry (Environment Canada 2001; EHS 2013). Basic oxygen furnace slags are broken into pieces and residual steel is recovered magnetically before the slag is finally crushed and screened (Environment Canada 2001). Approximately two-thirds of basic oxygen furnace slags were recycled off-site for use as aggregate in parking lots or road shoulders or for use in hot mix asphalt and in the cement industry, while the remaining portion is stockpiled on-site of the facilities (EHS 2013). Electric arc furnace slags generated by mini-mills were processed by a contractor and sold for use in the cement or road construction industries (EHS 2013).

5.1.3 Aluminium smelting and automotive parts manufacturing

The aluminium smelting sector in Canada comprises facilities that produce aluminium and alumina from mined ore. The ore is refined into alumina by the Bayer process, while the reduction of alumina to primary aluminium is done via electrolysis using the Hall-Heroult process (US EPA 1998).

The sector uses or produces substantial quantities of a number of complex inorganic substances as a result of its manufacturing processes. A total of three substances were reported to be manufactured or imported into Canada by this sector in 2011 (Environment Canada 2013). The substance "aluminum dross" (CAS RN 69011-71-8) was also reported to be manufactured by one automotive parts manufacturing company, which identified it as being an intermediate (i.e., function code U015). Voluntary stakeholder engagement on the substance determined that it is a waste recycled off-site to recover valuable aluminium (ECCC 2016b). On the basis of the analysis of function codes and consumer and commercial codes submitted by companies, the three substances were determined to be intermediates or wastes in the aluminium smelting sector (Table D-3).

"Aluminum, dross" (CAS RN 69011-71-8) contains predominantly aluminium oxide and may be sent to external recycling for the recovery of aluminium or disposed of in landfills (Environment Canada 2013; Sanexen Environmental Services 2013).

The substances "aluminum, manufg. cathodes, carbon" (CAS RN 69011-72-9) and "waste solids, aluminum oxide electrolysis cathodic" (CAS RN 96690-57-2) are closely linked. The first is an integral part of the electrolytic process to produce aluminium metal and is imported in Canada for use in aluminium metal manufacturing. In the Hall-Heroult process, electrolytic reduction of alumina occurs in shallow rectangular cells, or "pots," consisting of insulated steel shells lined with carbon which serves as the cathode (US EPA 1998). The pots, including the steel shell lined with refractory materials insulation and the layer of carbon, need to be refurbished every 5 to 8 years (Sanexen Environmental Services 2013) because cathodes become saturated with contaminants. The substance "waste solids, aluminum oxide electrolysis cathodic" (CAS RN 96690-57-2) corresponds to the used pots (including the cathode), which are commonly named "spent pot liners" (SPLs). This waste is considered hazardous as it may contain sodium cyanide (NaCN) among other components and may be explosive if exposed to water (Øye 1994). It must therefore be managed appropriately. In Canada, SPLs can be sent to specific treatment facilities (e.g., one exists in Quebec) for processing or disposed of in designated landfill and disposal areas (Sanexen Environmental Services 2013). The substance "aluminum, manufg. cathodes, carbon" (CAS RN 69011-72-9) may be classified as an intermediate that becomes an integral part of "waste solids, aluminum oxide electrolysis cathodic" (CAS RN 96690-57-2) once it needs to be replaced.

Aluminium dross and spent pot liners are two of several types of waste from the aluminium smelting industry identified by the National Pollutant Release Inventory (NPRI) as transferred off-site for disposal or recycling (Environment Canada 2015a).

5.1.4 Pulp and paper manufacturing

The pulp and paper manufacturing sector includes facilities that manufacture pulp or paper products, which is generally accomplished via three major processing steps: pulping, bleaching and paper product production.

The sector uses or produces substantial quantities of a number of complex inorganic substances as a result of its manufacturing processes. A total of three substances were reported to be manufactured in Canada by this sector (Environment Canada 2013). On the basis of the analysis of function codes and consumer and commercial codes, the three substances were determined to be intermediates in the pulp and paper sector (Table D-4).

The three substances are spent liquors from chemical pulping processes. The main objective of the pulping process is to separate cellulose fibre from lignin to free fibres for papermaking (EC, HC 1991). The two main types of pulping process are mechanical and chemical. As summarized in the assessment report of effluents from pulp mills using bleaching (EC, HC 1991), chemical pulping uses a mixture of chemicals to separate the cellulose fibres from the lignin, and two major chemical processes exist: Kraft and sulfite pulping.

Kraft pulping is carried out in an alkaline medium and releases fibres by dissolving lignin in a caustic (or alkaline) solution of sodium hydroxide and sodium sulfide. This solution is commonly referred to as "white liquor" and dissolves the lignin that binds the cellulose fibres together (US EPA 1995b). Spent cooking liquor and pulp wash water are combined and concentrated to form "black liquor" (US EPA 1995b) and may correspond to the UVCB substance "sulfite liquors and cooking liquors, spent" (CAS RN 66071-92-9), which can be fired in a recovery furnace. The combustion of organics (e.g., lignin) dissolved in the black liquor provide heat for generating steam or electricity and for converting sodium sulfate to sodium sulfide (US EPA 1995b). The inorganic chemicals present in the black liquor collect as a molten smelt at the bottom of the furnace. This smelt is then dissolved in water to form "green liquor," corresponding to "sulfite liquors and cooking liquors, green" (CAS RN 68131-30-6), which may then be transferred to a causticizing tank where quicklime (calcium oxide) is added to convert the solution back to white liquor, which may correspond to "sulfite liquors and cooking liquors, spent, alkali-treated" (CAS RN 68131-31-7), for return to the digester system (US EPA 1995b).

The sulfite process is similar to the kraft process but is carried out under acidic conditions and solubilizes lignin through sulfonation using a solution of sulfur dioxide and alkaline oxides, such as sodium, magnesium, ammonium, or calcium (EC, HC 1991). Chemical recovery in calcium base systems found mostly in older mills is not practical and the spent liquor is usually discharged or incinerated (US EPA 1995b). In ammonium base operations, heat can be recovered by combusting the spent liquor, but the ammonium base is thereby consumed (US EPA 1995b). In sodium or magnesium base operations, the heat, sulfur and base may all be feasibly recovered (US EPA 1995b). In the acid sulfite process, the spent liquor is referred to as "red liquor" and corresponds to the UVCB substance "sulfite liquors and cooking liquors, spent" (CAS RN 66071-92-9) as described by CAS. If recovered, the spent liquor is sprayed into a furnace and burned to produce steam, which is then used to operate the digesters, or evaporators or to generate electricity (US EPA 1995b). When sodium-based liquor is burnt, the inorganic compounds are recovered as a molten smelt containing sodium sulfide and sodium carbonate. This smelt can be further processed to absorb sulfur dioxide from the flue gas and sulfur burner or may be sold to a kraft mill as raw material for producing "green liquor" (US EPA 1995b) corresponding to "sulfite liquors and cooking liquors, green" (CAS RN 68131-30-6).

In a limited number of Canadian facilities, sulfite liquors are intermediates for the manufacturing of a variety of other substances, such as lignosulfonates, high purity cellulose, rosins or fatty acids, or vanillin (Adams 1988; Environment Canada 2015b; Magdzinski 2006; Mikkola et al 2016). These manufactured substances may be used as feedstock in a wide variety of industrial or commercial applications such as food products, pharmaceuticals and explosives, coatings (i.e., cellulose), inks and adhesives (i.e., rosin), paints and corrosion inhibitors (i.e., fatty acids), as surfactants and dispersants in textile dyes, cement concrete, wax and asphalt emulsions or transformed into carbon black (i.e., lignin and lignosulfonates) (Magdzinski 2006).

In the pulp and paper manufacturing sector, all three substances are considered intermediates manufactured by chemical pulping sulfite mills (Environment Canada 2013) that may be transformed to recover energy or to produce other substances.

5.1.5 Cement manufacturing

Portland cement consists of a mixture of hydraulic cement minerals, calcium silicates, aluminates and aluminoferrites, and calcium sulfates (US EPA 1995c). The manufacturing of Portland cement may be summarily described by the following steps: raw materials acquisition and handling, kiln feed preparation, pyroprocessing, and finished cement grinding (US EPA 1995c). The main part of Portland cement manufacturing is the pyroprocessing system where the raw mix is transformed into clinkers in rotary kilns through a variety of chemical reactions and physical processes at temperatures of up to 1510°C (US EPA 1995c).

The substance "flue dust, portland cement" (CAS RN 68475-76-3) is defined as "a complex combination of finely divided inorganic particles separated from the exit gases formed during the manufacture of Portland cement, and consists of uncalcined raw materials along with partially calcined materials" (NCI 2012). The substance corresponds to the particulate materials (PM) that are captured from the smokestack. The largest source of PM at cement plants is the pyro-processing system, which includes the kiln and clinker cooler exhaust stacks (US EPA 1995c). Flue dust is incidentally manufactured at all 16 cement manufacturing facilities in Canada. The dust from the smokestack may be recycled into the kiln or landfilled at an approved facility (US EPA 1995c).

The substance was reported to be manufactured in Canada in 2011 by fewer than four cement manufacturing companies (ECCC 2016a). The substance was attributed the function code U999 and is identified as a waste produced during cement production that is recycled back into the process (ECCC 2016a). On the basis of this information, the substance "flue dust, portland cement" (CAS RN 68475-76-3) is determined to be either an intermediate if recycled within the process or a waste (Table D-5).

5.1.6 Other sectors of activity

Three substances, primarily linked to iron and steel manufacturing or pulp and paper manufacturing, were also imported into Canada in 2011 by four or fewer companies involved in other sectors of activities: "slags, ferrous metal, blast furnace" (CAS RN 65996-69-2), "sulfite liquors and cooking liquors, green" (CAS RN 68131-30-6) and "sulfite liquors and cooking liquors, spent alkali-treated" (CAS RN 68131-31-7) (Table D-6) (Environment Canada 2013). When considering upper range limits, these import quantities are 10 000- to more than 1 000 000-fold smaller than the quantities manufactured by the iron and steel or pulp and paper manufacturing sectors (Table B-1).

Slags from blast furnace may be used as supplementary cementitious materials in concrete, mortars (NRMCA 2012) or cement-based waterproofing sealants (BASF 2012). To be used as cementitious materials, the composition of the blast furnace slags must meet certain sulfate chemical composition standards from ASTM C989 (ASTM International 2016). Additionally, cement is used to stabilize and solidify hazardous waste, as contaminants are immobilized within the solid concrete matrix (Ucaroglu and Talinli 2012) and possibly transformed. Therefore, considering the relatively small quantity in commerce and the fact that the product must meet certain chemical quality standards for it to be used and that it may be immobilized or transformed, the exposure potential from this use is anticipated to be negligible.

The substance "sulfite liquors and cooking liquors, green" (CAS RN 68131-30-6) may be used in paints and coatings (Environment Canada 2013). However, additional information received from stakeholders determined that the substance was no longer imported in 2015 (ECCC 2016b), indicating that the exposure potential for this substance is non-existent.

The largest use of "sulfite liquors and cooking liquors, spent alkali-treated" (CAS RN 68131-31-7) reported by importers (on the basis of quantities) is as a dust control binding agent to control fugitive emissions from storage piles and haul roads (Environment Canada 2013; ECCC 2016b). Additional information received from stakeholders for the year 2015 indicate that the substance was used exclusively by industries within the metal mining, base metals smelting or petroleum refining sectors (ECCC 2016b), and may be considered site-restricted. Sulfite liquors have been used directly for dust control in rural towns located near paper mills (WTIC 1997), but paper mills prefer other methods to reuse or to recycle liquors because they may be highly acidic, very sticky and foul-smelling (WTIC 1997). Therefore, sulfite liquors might be further processed to isolate value-added products before being used as dust control binding agents. Lignosulphonate salts, which may be derived from sulfite liquors (Section 5.1.4), are identified as the main active ingredient of many dust control binding agents (Adams 1998; Rayonier Advanced Materials 2017; US ACE 2013). They are isolated from spent sulfite liquors by a variety of physical and chemical processes (e.g., precipitation or membrane processes) (Fatehi and Chen 2016; Sjostrom 2013). The additional processing steps could indicate that the substances used in dust control binding agents actually correspond to lignosulphonate salts registered under a different CAS RN. A total of six lignin derivatives, including lignosulfonic acid (CAS RN 8062-15-5), lignosulfonic acid, sodium salt (CAS RN 8061-51-6), lignosulfonic acid, calcium salt (CAS RN 8061-52-7) and lignosulfonic acid, ammonium salt (CAS RN 8061-53-8), all of which are known ingredients of dust control binding agents, were recently found to not meet the criteria set out in section 64 of CEPA as a result of the second phase of Polymer Rapid Screening (ECCC, HC 2017). Therefore, considering the site-restricted nature of the use of the substance as dust control binding agents, the fact that lignosulphonates are of low environmental concern and the uncertainty of whether the substance "sulfite liquors and cooking liquors, spent alkali-treated" (CAS RN 68131-31-7) is actually used for this use, exposure to the substance is considered low and of low concern to the environment.

The substance was also reported to be used as a plasticizer in 2011, but additional information received from stakeholders in 2016 determined that this use was now discontinued (ECCC 2016b). Other minor uses of the substance include its use as a concrete admixture, corrosion inhibitor, and anti-scaling agent (Environment Canada 2013) and potential for exposure is anticipated to be negligible. The substance would be immobilized within the concrete matrix and possibly transformed as a result of its use as a concrete admixture, while exposure from its use as a corrosion inhibitor and anti-scaling agent would be negligible because of the small quantities in commerce for this use (i.e., less than 1000 kg).

5.1.7 Summary of the ecological exposure assessment

The exposure characterization of 57 inorganic UVCB substances primarily imported and manufactured by the base metals processing, iron and steel manufacturing, aluminium smelting and automotive parts manufacturing, pulp and paper manufacturing, and cement manufacturing sectors as well as a small number of other sectors was conducted (section 5.1.1 to 5.1.6).

Results for the main industrial sectors indicate that 38 substances were determined to be no longer manufactured or imported or intermediates, 10 were determined to be intermediates or wastes depending on the company, 3 substances were determined to be by-products or waste, 5 substances were determined to be wastes only, and 1 substance was determined to be an intermediate within the pulp and paper manufacturing sector. An exposure characterization of this last substance for a number of applications within other sectors determined that its potential for exposure to the environment is negligible. On the basis of the information available, the potential for exposure of these substances to the environment is considered either negligible or not expected.

Therefore, on the basis of the information available, the potential for exposure of the 57 inorganic UVCB substances to the environment is either negligible or not expected.

5.2 Characterization of ecological risk

On the basis of information obtained from multiple sources (regulatory survey, voluntary industry submissions, an in-depth literature review, and a search of material safety data sheets) the likelihood of exposure to the inorganics UVCBs included in this assessment and the potential for ecological harm are considered to be low.

Substances that are no longer manufactured or imported have a non-existent exposure potential. Substances that are intermediates (either site-restricted or sector restricted) are consumed on-site or further processed at other facilities where they are transient, indicating that they transformed into different substances. Additionally, measures (including provincial/territorial operating permit requirements and best practices and guidelines put in place by industry) exist to minimize releases from facilities during processing or transport. Disposal of wastes is also governed by such measures, and the substances are either disposed of on-site or sent to specialized facilities for disposal. The use of substances that have commercial applications as by-products must meet certain standards specified by operating permits or existing regulations or the uses identified have negligible exposure potential (e.g., immobilization of the substance in solid matrices or site-restricted uses).

Therefore, environmental exposure to the 57 substances is expected to be negligible, and harm to the environment is not expected. It is therefore concluded that the 57 inorganic UVCBs 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, or that constitute or may constitute a danger to the environment on which life depends.

6. Potential to cause harm to human health

Information obtained from the DSL IU Phase 2 survey, voluntary industry submissions, material safety data sheets and consumer product databases were searched to investigate the potential for exposure to consumers from products. On the basis of this search, exposure from products available to consumers is not expected.

Given that ecological exposure was considered either negligible or not expected, general population exposure to substances through environmental media was consequently considered to be either negligible or not expected. Additionally, uses identified (beyond the pulp and paper manufacturing sector in Table D-6) were not considered to result in exposure to the general population.

Accordingly, risk to human health is considered to be low for all 57 substances.

7. Assessment of uncertainties

Substances determined to be by-products may only be used if specific environmental criteria are met, and substances determined in this report to be intermediates or wastes are not expected to be released into the environment. Monitoring data for specific substances in the Canadian environment were not identified in order to systematically verify these assumptions. However, it is unclear whether analytical protocols exist to monitor these kinds of complex substances, and if releases were to occur, these are not anticipated to be in the original chemical form to which a CAS RN is attributed.

Because many potential individual components of these inorganic UVCBs are listed on Schedule 1, List of Toxic Substances, under CEPA, releases of these substances are already regulated at the federal or provincial levels. Additionally, releases of many individual components of the UVCB substances are reportable to the NPRI or to federal, provincial, and/or territorial monitoring and surveillance programs, and environmental monitoring data may be consulted when available in the context of other moiety assessments.

8. Conclusion

Considering all available lines of evidence presented in this screening assessment, there is low risk of harm to the environment from the sector-specific inorganic UVCBs group. It is concluded that the 57 substances in the sector-specific inorganic UVCBs group do not meet the criteria under paragraphs 64(a) or (b) of CEPA as 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 or that constitute or may constitute a danger to the environment on which life depends.

On the basis of the information presented in this screening assessment, it is concluded that the 57 substances in the sector-specific inorganic UVCBs group do not meet the criteria under paragraph 64(c) of CEPA as they are not entering the environment in a quantity or concentration or under conditions that constitute or may constitute a danger in Canada to human life or health.

Therefore, it is concluded that the 57 substances in the sector-specific inorganic UVCBs group do not meet any of the criteria set out in section 64 of CEPA.

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Appendices

Appendix A. Substance identity information

Appendix B. Quantities in commerce in Canada in 2011

^a Values reflect quantities reported in response to a survey conducted under section 71 of CEPA (Environment Canada 2013). See survey for specific inclusions and exclusions (Schedules 2 and 3).

^b SHI: responses provide voluntarily through the Stakeholder Interest form (SHI)

^c Manufacturing and import quantities are reported in ranges to mask Confidential Business Information.

Appendix C. Substances use pattern in 2011

CBI: Confidential Business Information.

Appendix D. Function codes and exposure potential types of the sector-specific inorganic UVCBs group

CBI: Confidential Business Information