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Substance
Profile for The Challenge
1,4-Benzenediol (Hydroquinone) CAS No. 123-31-9 The Canadian Environmental Protection Act, 1999 (CEPA 1999) required the Minister of Health and Minister of the Environment to categorize the approximately 23 000 substances on the Domestic Substances List (DSL). Categorization involved identifying those substances on the DSL that are a) considered to be persistent (P) and/or bioaccumulative (B), based on criteria set out in the Persistence and Bioaccumulation Regulations (Government of Canada, 2000), and “inherently toxic” (iT) to humans or other organisms, or b) that present, to individuals in Canada, the greatest potential for exposure (GPE). Further to this activity, the Act requires the Minister of the Environment and the Minister of Health to conduct screening assessments of substances that meet the categorization criteria. A screening assessment involves a scientific evaluation of available information for a substance to determine whether the substance meets the criteria set out in section 64 of CEPA 1999. Based on the results of a screening assessment, the Ministers can propose taking no further action with respect to the substance, adding the substance to the Priority Substances List (PSL) for further assessment or recommending the addition of the substance to the List of Toxic Substances in Schedule 1 of CEPA 1999 and, where applicable, the implementation of virtual elimination of releases to the environment. A number of substances have been identified by the Ministers as high priorities for action based on the information obtained through the categorization process. This includes substances:
Based on a consideration of the ecological and/or human health concerns associated with these substances, and the requirement under section 76.1 of CEPA 1999 for the Ministers to apply a weight of evidence approach and the precautionary principle when conducting and interpreting the results of an assessment, sufficient data are currently available to consider these substances as meeting the criteria under Section 64 of CEPA 1999. As such, the Ministers have issued a Challenge to industry and other interested stakeholders through publication in Canada Gazette Part I December 9, 2006 to submit, within the timelines stated in the Challenge section of this document, below, specific information that may be used to develop and benchmark best practices for risk management and product stewardship. The substance hydroquinone was identified as a high priority for action as it was determined to have a high potential for exposure to individuals in Canada (GPE or IPE), and is considered to present a high hazard to human health. The technical human health and ecological information that formed the basis for concern associated with this substance is contained in Appendices I and II, respectively. Substance Identity
Based on information submitted by the 19 companies that notified this substance to the Domestic Substances List, 1,250 tonnes of hydroquinone were in commerce in 1986 for a variety of uses from a wide range of sectors, including (but not limited to) the categories of adhesive/binder/sealant; antioxidant/corrosion inhibitor/scavenger; formulation component; fragrance/deodorizer agent; paint/coating additives; photosensitive agent /UV absorber; pigment, dye and printing ink; and water or waste treatment chemical. Other potential uses of hydroquinone in Canada include use as a chemical intermediate in the synthesis of the following types of chemicals: antioxidants and antiozonants used in rubber processing, antioxidants used in industrial fats, oils and foods, stabilizers for monomers, stabilizers for paints, varnishes, motor oils and fuels. It is used in photographic development including black and white film, x-rays and lithography. It has been reported as a component of adhesives and casting compounds. It may be used as a corrosion inhibitor in boilers and cooling towers. Hydroquinone is a depigmenting agent used in skin lightening creams applied topically, and in the treatment of hypermelanosis. It is used in hair dyes. THE CHALLENGE
Respecting direction under section 76.1 of CEPA 1999, information obtained during conduct of categorization is sufficient to conclude that criteria under Section 64 of CEPA 1999 are met for this substance in that it “may enter the environment in a quantity or concentration or under conditions that constitute or may constitute a danger in Canada to human life or health”. As such, the Ministers are prepared to recommend to the Governor in Council that this substance be added to the List of Toxic Substances in Schedule 1 of CEPA 1999 with the intent of initiating the development of risk management measures taking into account socio-economic considerations. The measures will be subject to review in light of new scientific information, including monitoring and ongoing assessment activities. Section 71 Notice Information needed for improved decision-making with regard to risk assessment and management of this substance is being gathered using section 71 of CEPA 1999. This notice applies to any person who, during the 2006 calendar year, manufactured or imported a total quantity greater than 100 kilograms of the substance, whether alone, in a mixture, in a product or in a manufactured item. The 2006 information mandated through the notice relates to, among other things, quantity of the substance imported, manufactured or used, types of uses of the substance, and releases of the substance to the environment. Copies of the section 71 notice and guidance on how to comply with it are available from the Government of Canada Chemicals Portal (www.chemicalsubstanceschimiques.gc.ca/en/index.html), or from the contact provided below. Responses to the section 71 notice must be received at the address provided below by June 5, 2007. Opportunity to Submit Additional Information on Current Uses and Existing Control Measures to Inform the Risk Management Approach for this Substance The Ministers of Health and Environment are inviting the submission of additional information that is deemed beneficial by interested stakeholders, relating to the extent and nature of the management/stewardship of substances listed under the Challenge. Organizations that may be interested in submitting additional information in response to this invitation include those that manufacture, import, export or use this substance whether alone, in a mixture, in a product or in a manufactured item. Additional information is being invited in the following areas:
A questionnaire is available which provides a detailed template as an example for the submission of this information. Guidance on how to respond to the challenge questionnaire is also available. Interested stakeholders are invited to provide available additional information, recognizing that not all questions in the questionnaire may be relevant to a particular substance, use, or industrial sector. Copies of the questionnaire and associated guidance are available from the Government of Canada Chemicals Portal (www.chemicalsubstanceschimiques.gc.ca/en/index.html), or from the contact provided below. Responses to the questionnaire should be received at the address provided below by June 5, 2007. Request for Documents and Submission of Information Documents and instructions may be requested from the following contact. Information in response to the above Challenge must be submitted to this address.
DSL Surveys Coordinator Appendix
I Introduction Under the Canadian Environmental Protection Act, 1999 (CEPA, 1999), Health Canada undertook to categorize all substances on the Domestic Substances List (DSL) to identify those representing the greatest potential for human exposure (GPE) and those among a subset of substances considered persistent (P) and/or bioaccumulative (B) that are also considered to be “inherently toxic” to humans. In order to efficiently identify substances that represent the highest priorities for screening assessment from a human health perspective, Health Canada developed and applied a Simple Exposure Tool (SimET) to the DSL to identify those substances that meet the criteria for GPE, Intermediate Potential for Exposure (IPE) or Low Potential for Exposure (LPE), and a Simple Hazard Tool (SimHaz) to identify those substances that pose a high or a low hazard. Hydroquinone is considered to meet the criteria for GPE under SimET and for high hazard under SimHaz. This document summarizes the currently available information used to support the inclusion of this substance in the Challenge. Exposure Information from Health Related Components of DSL Categorization As mentioned above, SimET was developed and used to identify substances on the DSL considered to represent GPE. This approach was based on three lines of evidence: 1) the quantity in commerce in Canada, 2) the number of companies involved in commercial activities in Canada (i.e., number of notifiers), and 3) the consideration by experts of the potential for human exposure based on various use codes. The proposed approach was released for public comment in November 2003 and also enabled designation of substances as presenting an Intermediate (IPE) or Lowest Potential for Exposure (LPE), based on criteria for quantity and nature of use (Health Canada, 2003). Results of the Application of SimET Hydroquinone has been determined to be GPE based on a consideration of the DSL nomination information listed below. Nomination Information for DSL Quantity in Commerce The quantity reported to be manufactured, imported or in commerce in Canada during the calendar year 1986 was 1,250,000 kg. Number of Notifiers The number of notifiers for the calendar years 1984-1986 was 19. Use Codes and Description The following DSL use codes have been identified for the substance:
Potential Uses in Canada The additional information below on potential uses of hydroquinone was identified through searches of the available scientific and technical literature. Potential uses of hydroquinone in Canada include use as a chemical intermediate in the synthesis of the following types of chemicals: antioxidants and antiozonants used in rubber processing, antioxidants used in industrial fats, oils and foods, stabilizers for monomers, stabilizers for paints, varnishes, motor oils and fuels. It is used in photographic development including black and white film, x-rays and lithography. (OECD, 2002) It has been reported as a component of adhesives and casting compounds. (Spin Database, 2006) It may be used as a corrosion inhibitor in boilers and cooling towers. Hydroquinone is a depigmenting agent used in skin lightening creams applied topically, and in the treatment of hypermelanosis. It is used in hair dyes. (OECD, 2002) Hazard Information from Health Related Components of DSL Categorization Simple Hazard Tool (SimHaz) SimHaz is a tool that has been used to identify, among all of the approximately 23 000 substances on the DSL, those considered to present either high or low hazard to human health based on formalized weight of evidence criteria and/or peer review/consensus of experts. This tool has been developed through extensive compilation of hazard classifications of Health Canada and other agencies and consideration of their robustness based on availability of transparent documentation of both process and criteria (Health Canada, 2005). Results of the Application of SimHaz Hydroquinone is considered to be a potentially high hazard substance based on its classification for carcinogenicity and for genotoxicity by the European Commission (1997, 1998); ESIS, 2006. The European Commission has classified hydroquinone as Category 3 for carcinogenicity (Causes concerns for humans owing to possible carcinogenic effects) and as Category 3 for genotoxicity (Causes concerns for humans owing to possible mutagenic effects) (European Commission, 1997; European Commission, 1998; ESIS, 2006). Uncertainties SimET and SimHaz have been developed as robust tools for effectively identifying substances from the DSL considered to be human health related priorities for further consideration. It is recognized that they do not include a number of elements normally considered in a human health risk assessment such as a comprehensive characterization of exposure and hazard, a comparison of exposure metrics to hazard metrics and a detailed analysis of uncertainties. However, as a result of the combination of the severe hazard properties of these substances and their high potential for exposure to humans, evaluation of whether there is a need for preventative and protective actions is required. References European Commission. 1997 . Draft Summary Record Commission Working Group on the Classification and Labelling of Dangerous Substances. Meeting at ECB Ispra, 16-18 July 1997. European Commission Directorate General JRC. Joint Research Centre. Environment Institute. European Chemicals Bureau. ECBI/32/97 – Rev. 1. http://ecb.jrc.it/classification-labelling/MEETINGS/public.htm European Commission. 1998. Hydroquinone. Commission Directive 98/98/EC
of 15 December 1998. Annex 1A. Official Journal of the European Communities
30.12.1998. ESIS. 2006. CAS No. 123-31-9. Hydroquinone. ESIS Version 4.50. European Chemical Substance Information System. http://ecb.jrc.it/esis/ Health Canada 2003. Proposal for Priority Setting for Existing Substances on the Domestic Substances List under the Canadian Environmental Protection Act, 1999: Greatest Potential for Human Exposure. . http://www.hc-sc.gc.ca/ewh-semt/alt_formats/hecs-sesc/pdf/pubs/contaminants/existsub/exposure/greatest_potential_human_exposure-risque_exposition_humaine_e.pdf Health Canada 2005. Proposed Integrated Framework for the Health-Related Components of Categorization of the Domestic Substances List under CEPA 1999. http://www.hc-sc.gc.ca/ewh-semt/alt_formats/hecs-sesc/pdf/contaminants/existsub/framework-int-cadre_e.pdf OECD 2002. OECD SIDS Initial Assessment Profile on 1,4-Benzenediol (Hydroquinone). Organisation for Economic Co-operation and Development. http://cs3-hq.oecd.org/scripts/hpv/index.asp Scorecard. 2006. Scorecard Chemical Profile for Hydroquinone CAS No. 123-31-9. http://www.scorecard.org/chemical-profiles/uses.tcl?edf_substance_id=123%2d31%2d9 Spin Database. 2006. 1,4-Benzenediol. Spin Database Substances in preparation in Nordic countries. http://www.spin2000.net/FMPro?-db=spinstof.fp5&-op=eq&pid=123319&-max=1&-find=&-Format=spin/spinCategory.html&-lay=spincatuse . US EPA. 2000. Hazard Summary for Hydroquinone. Technology Transfer Network Air Toxics Website. United States Environmental Protection Agency. http://www.epa.gov/ttn/atw/hlthef/hydroqui.html Appendix
II Introduction The information in this document will form the basis of a screening assessment under section 74 of CEPA, 1999. Data relevant to an ecological screening assessment were identified in original literature, review documents, commercial and government databases prior to December 2005. Properties and characteristics may also have been estimated using Quantitative Structure Activity Relationship (QSAR) models. Physical and Chemical Properties Tables 1a and 1b contain experimental and modelled physical-chemical properties of hydroquinone which are relevant to its environmental fate. Table 1a. Experimental physical-chemical properties for hydroquinone
Table 1b. Modelled physico-chemical properties for hydroquinone
Manufacture, Importation, and Uses Refer to Appendix I. Release, Fate and Presence in the Environment Releases Refer to Appendix I. Fate Aquatic fate The estimated log Koc value of 2.64 (Table 1b) indicates that adsorption of hydroquinone to sediment and suspended organic matter will not be important. Volatilization from water surface to the atmosphere, based upon an experimental (3.8 ×10-11 atm · m3/mole) and estimated (8.1×10-11 and 5.8×10-11 atm · m3/mol) Henry's Law constant, will be too low to be environmentally important. Thus, if released to water, hydroquinone is expected to mainly remain in water, which can be illustrated by the results of Level III Fugacity modelling (Table 2). Table 2. Results of the Level III fugacity modelling (EPIWIN V3.12) for hydroquinone
Terrestrial fate Based on an estimated log Koc value of 2.64 (Table 1b), hydroquinone should have moderate sorption to soil and, therefore, moderate mobility in this environmental compartment. Volatilization of this chemical from moist soil surfaces is not expected to occur to any significant extent, given the experimental (3.8 ×10-11 atm · m3/mole) and estimated (8.1×10-11 and 5.8×10-11 atm · m3/mol) Henry's Law constants. The potential for volatilization of hydroquinone from dry soil surfaces is low, based upon experimental (1.91 ×10-5 mmHg) and estimated (1.64 ×10-5 mm Hg) values of vapour pressure (Tables 1a and 1b). Thus, if released to soil, hydroquinone is expected to remain in soil and, to a lesser degree, partition into water, which can be illustrated by the results of Level III Fugacity modelling (Table 2). Atmospheric fate If released to the atmosphere, hydroquinone is expected to undergo direct photochemical degradation (Table 3a). Hydroquinone may also be removed from the atmosphere by wet deposition processes (HSDB), considering very high water solubility of this chemical (Tables 1a and 1b). Presence in the Environment No monitoring data relating to the presence of this substance in environmental media (air, water, soil, sediment) have yet been identified. Evaluation of P, B and iT Properties Environmental Persistence The estimated atmospheric-oxidation half-life for hydroquinone is ~0.5 days, assuming an average atmospheric hydroxyl radical concentration of 1.5×106 molecule/cm3 (Table 3b). Therefore, in air, hydroquinone seems to be rapidly oxidized. This compound is not expected to react appreciably, with other photo-oxidative species in the atmosphere such as O3. However, photolysis of hydroquinone in air may occur. Experimental data show that when hydroquinone, adsorbed on silica gel, was exposed to ultraviolet light (290 nm) for 17 h, approximately 57% of the hydroquinone was mineralized (Freitag et al., 1985). Therefore, it is expected that reactions with hydroxyl radicals will be the most important fate processes in the atmosphere for hydroquinone, while photo-mineralization can also occur. Table 3a. Experimental persistence values for hydroquinone
Table 3b. Modelled persistence values for hydroquinone
The empirical biodegradation data (Chemicals Inspection and Testing Institute, 1992) show 70% biodegradation over 28 days in a ready-biodegradation test for hydroquinone (Table 3a). This indicates that its half-life in water is less than 182 days (6 months). For estimating degradation in water, QSAR modeling was used (Table 3b). Based on these results, the estimated timeframe for biodegradation indicates that hydroquinone can be considered as not persistent in water. This substance is not expected to hydrolyse in water. To extrapolate half-life in water to half-lives in soils and sediments, Boethling’s extrapolation factors can be used (t1/2 water : t1/2 soil : t1/2 sediment = 1: 1: 4, BIOWIN v4.01). Using these factors, it may be concluded that propylene oxide is not expected to be persistent in soil and sediments. Therefore, the empirical and modelled data demonstrate that hydroquinone does not meet the persistence criteria (half-lives in soil and water ≥182 days, in sediments ≥365 days, in air ≥2 days) as set out in the Persistence and Bioaccumulation Regulations (Government of Canada, 2000). Potential for Bioaccumulation Experimental and modelled log Kow values of 0.59 and 1.03, respectively (Tables 1a and 1b) indicate that hydroquinone does not have the potential to bioaccumulate in aquatic organisms. Experimental BCF values for this substance in green algae and fish are reported to be 35-65 L/kg (Table 4a). Importantly, QSAR-derived bioaccumulation and bioconcentration values agree very well with the experimental results (Tables 4a and 4b). The middle-trophic-level modified GOBAS BAF model produced a BAF of 1 L/kg, indicating that substance hydroquinone does not have the potential to bioaccumulate in the fish. The three BCF models provide a weight-of-evidence to support a low bioconcentration potential of this substance (BCF=1-19 L/kg). Table 4a. Experimental bioaccumulation results for hydroquinone
Table 4b. Predicted bioaccumulation values for hydroquinone
Therefore, both experimental and modelled data indicate that the substance hydroquinone does not meet the bioaccumulation criteria (BCF/BAF≥5000) as set out in the Persistence and Bioaccumulation Regulations (Government of Canada, 2000). Ecological Effects In the Aquatic Compartment Experimental ecotoxicological data provide evidence that hydroquinone causes harm to aquatic organisms at relatively low concentrations (Table 5). For fish and water flea, acute LC50/EC50 values are below 1 mg/L, while some results are even lower than 0.1 mg/L (For example, the pivotal value used to determine inherent toxicity to aquatic organisms in categorization was an LC50=0.044 mg/L). At the same time, for some less sensitive organisms such as green algae and brine shrimp, experimental ecotoxicity values are higher (17-31 mg/L). Although modelled predictions for aquatic toxicity were performed for this substance, given the numerous experimental data available, they are not presented here. Table 5. Experimental aquatic toxicity values for hydroquinone
Therefore, according to the most of the experimental data, acute LC50/EC50 values are below 1 mg/L, which indicates that hydroquinone is expected to pose a high (acute or immediate) hazard to aquatic organisms. In Other Media No effects studies for non-aquatic non-mammalian organisms were found for this compound. Potential to Cause Ecological Harm Based on the available information, hydroquinone does not persist in the environment and is not bioaccumulative, based on criteria efined in the Persistence and Bioaccumulation Regulations (Government of Canada, 2000). Information on concentrations of hydroquinone in the environment has not been identified at this time. However, the experimental ecotoxicological data indicate that hydroquinone can cause harm to aquatic organisms at relatively low concentrations in the water. It is, therefore, expected to pose a high hazard for organisms exposed to the chemical in water. Information on potential impacts in other environmental compartments has not been identified. References
AOPWIN v1.91. 2000.
U.S. Environmental Protection Agency. Arnot, J.A. and Gobas, F.A.P.C. 2003. A Generic QSAR for Assessing the Bioaccumulation Potential of Organic Chemicals in Aquatic Food Webs. QSAR Comb. Sci. 22(3): 337-345. BCFWIN 2000. Version 2.15. U.S. Environmental Protection Agency. http://www.epa.gov/oppt/exposure/pubs/episuite.htm BIOWIN 2000. Version 4.02. U.S. Environmental Protection Agency. http://www.epa.gov/oppt/exposure/pubs/episuite.htm CEPA 1999. Canadian Environmental Protection Act, 1999. 1999, c. 33. C-15.31. [Assented to September 14th, 1999]. http://laws.justice.gc.ca/en/C-15.31/text.html . Chemicals Inspection and Testing Institute. 1992. Biodegradation and Bioaccumulation Data of Existing Chemicals Based on the CSCL Japan. Japan Chemical Industry Ecology - Toxicology and Information Center. ISBN 4-89074-101-1. EPIWIN 2000. Version 3.12 U.S. Environmental Protection Agency. http://www.epa.gov/oppt/exposure/pubs/episuite.htm ECOTOX database (http://cfpub.epa.gov/ecotox/) Environment Canada. 2003. Guidance Manual for the Categorization of Organic and Inorganic Substances on Canada’s Domestic Substances List. Existing Substances Branch, Environment Canada. Gatineau, Canada, 124 p. Freitag D., Ballhorn L., Geyer H., and Korte, F. 1985. Environmental hazard profile of organic chemicals. Chemosphere, 14: 1589-1616. Granger F. S. and J. M. Nelson. 1921. Oxidation and reduction of hydroquinone and quinine from the standpoint of electromotive force measurements. J. Am. Chem. Soc., 43(7): 1401 – 1415. Government of Canada. 2000. Persistence and Bioaccumulation Regulations (SOR/2000-107). Canada Gazette, v. 134. Available at http://www.ec.gc.ca/CEPARegistry/regulations/detailReg.cfm?intReg=35 (accessed August, 2006). Hansch, C., A. Leo, and D. Hoekman. 1995. Exploring QSAR: Hydrophobic, Electronic, and Steric Constants. American Chemical Society, Washington, DC, USA.
HENRYWIN. 2000. Version 3.10. U.S.
Environmental Protection Agency. HSDB – Hazardous Substances Data Bank (http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?HSDB )
Jones, A.H.J. 1960. Sublimation Pressure Data for Organic Compounds. J.
Chem. Eng. Data. 5:196-200.
MPBPWIN
2000. Version 1.41. U.S. Environmental Protection Agency. OASIS Forecast. 2004. Version 1.14. Laboratory of Mathematical Chemistry, University "Prof. Assen Zlatarov". Bourgas, Bulgaria (http://omega.btu.bg/?section=software&swid=10 )
PCKOCWIN. 2000. Version 1.66. U.S. Environmental Protection Agency.
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PHYSPROP Database, 2003 (http://www.syrres.com/esc/physdemo.htm)
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2000. v1.41. U.S. Environmental Protection Agency. 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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