Appendices of the Screening Assessment

Aromatic Azo and Benzidine-based Substance Grouping
Certain Azo Solvent Dyes

Environment and Climate Change Canada
Health Canada
May 2016

Table of Contents

• Appendix A: Structural Identity of Azo Solvent Dyes and Analogues
• Appendix B: Physical and Chemical Properties of the Azo Solvent Dyes and Analogues
• Appendix C: Empirical and Modelled Data for Degradation of the Azo Solvent Dyes
• Appendix D: Empirical Data for the Aquatic Toxicity of Azo Solvent Dyes and Analogues
• Appendix E: Critical Body Burden Approach for the Azo Solvent Dyes
• Appendix F: Ecological Exposure Calculations for Azo Solvent Dyes
• Appendix G: Estimated Exposures from Use of Products
• Appendix H: Benchmark Dose Calculations for Solvent Yellow 77, Sudan I and o-Anisidine
• Appendix I: Azo Solvent Dyes with Effects of Concern
• Back to the Screening Assesmment

Appendix A: Structural Identity of Azo Solvent Dyes and Analogues

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Appendix B: Physical and Chemical Properties of the Azo Solvent Dyes and Analogues

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Appendix C: Empirical and Modelled Data for Degradation of the Azo Solvent Dyes

Table C-2: Summary of modelled data for degradation of the 15 monoazo solvent dyes^{Footnote Appendix C Table C2 [a]}

Table C-3: Summary of modelled data for degradation of the seven disazo solvent dyes^{Footnote Appendix C Table C3 [a]}

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Appendix D: Empirical Data for the Aquatic Toxicity of Azo Dyes and Analogues

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Appendix E: Critical Body Burden Approach for the Azo Solvent Dyes

In terms of aquatic toxicity, the critical body burden (CBB) concept shows that an aquatic organism that takes up a chemical from water may accumulate this chemical until a certain critical body burden has been attained, causing the mortality of the organism. McCarty (1986, 1987a, b, 1990), McCarty and Mackay (1993), McCarty et al. (1985, 1991) and Van Hoogen and Opperhuizen (1988) have shown that internal concentrations of halogenated organic chemicals in fish causing death are fairly constant: about 2–8 mmol/kg.

Sijm and Hermens (2000) indicated that McCarty (1987a, b) and McCarty et al. (1991) have mathematically explained this as follows. The fairly constant internal effect concentration or lethal body burden (LBB) is the result of the bioconcentration factor (BCF), which increases with K_ow, and the external effect concentration (LC₅₀), which decreases with K_ow:

LBB = LC₅₀ × BCF

Therefore:

log LBB ≈ log (LC₅₀) + log (BCF) ≈ (–log K_ow + b1) + (log K_ow + b2) ≈ b1 + b2 ≈ constant

where b1 and b2 are constants.

Having analyzed the literature data, Sijm and Hermens (2000) emphasized that for narcotic (e.g., polychlorinated benzenes and biphenyls) and polar-narcotic compounds (e.g., chlorinated phenols and anilines), sufficient information is available to study this assumption. The authors came to the conclusion that for different organisms, the lethal body burdens for polar narcotics vary by approximately two orders of magnitude, and thus again show a significant reduction in the variation of the ecotoxicological effect concentrations, compared with the more than five orders of magnitude differences that are found in external effect concentrations for this type of mechanism of action.

While applying a CBB approach for the Azo Solvent Dyes, the following assumptions have been made: 1) for the CBB calculations for Solvent Yellow 1 and Solvent Red 24, the lipid concentration of the fish in the BCF tests is 5%; 2) Disperse Red 167, Disperse Yellow 163 and Disperse Orange 73 are suitable Azo Solvent Dye analogues, as there are limited BCF studies on solvent dyes; 3) the dyes are not reactive or specifically acting reactive chemicals, i.e., they provoke toxicity only through non-specific mechanisms (i.e., narcotic mode of action); 4) there are no dye–dispersant (or dye–solvent) interactions; 5) the purity of dye is very high; 6) for lethal effects, once the aquatic organism has reached the lethal body burden, it dies; and 8) the average acute CBB threshold is 5 mmol/kg.

Critical Body Burden (CBB) and External Effect Concentration (EEC) Calculations

Since CBB = LC₅₀ × BCF (see above), the expected external acute effect concentration (LC₅₀) can be back-calculated as:

LC₅₀ (mmol/L) = CBB (mmol/kg) / BCF (L/kg)

For Solvent Yellow 1, definitive experimental whole-body BCF data are available (see Table 5-2): 37.3 L/kg at 6 μg/L and less than 31.6 L/kg at 0.6 μg/L. Therefore, the average whole-body BCF is 34.45 L/kg.

However, the BCF in fish is usually normalized for the 5% lipid content of the organism:

BCF_L = BCF_wb-ww / L_f × 5%

where BCF_L is the lipid-normalized bioconcentration factor, BCF_wb-ww is the whole-body BCF (wet weight basis), L_f is the lipid content (fraction) in the organism and 5% is the generally accepted lipid level for lipid-normalized BCF.

If so, applying a lipid level in fish of 5%, the lipid-normalized BCF is:

BCFL = [34.45 (L/kg) / 0.05] × 0.05 ≈ 34.45 L/kg

Therefore, using the average acute CBB threshold of 5 mmol/kg, the external effect concentration can be calculated as:

Acute LC₅₀ = CBB (mmol/kg) / BCF (L/kg) = 5 (mmol/kg) / 34.45 (L/kg) = 0.145 mmol/L

Considering that the molecular weight of Solvent Yellow 1 is ~197.24 g/mol (or 197.24 mg/mmol), the external acute effect concentration, expressed in mg/L, is:

0.145 mmol/L × 197.24 mg/mmol = 28.6 mg/L

Similarly, external acute effect concentrations can be calculated for other solvent dyes as well as disperse dye analogues. The results are presented in Table 6-3.

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Appendix F: Ecological Exposure Calculations for Azo Solvent Dyes

The predicted environmental concentrations (PECs) were estimated in water, sediment and soil for the two formulation scenarios identified. Sites were identified for each scenario according to the responses to an information request from Environment Canada and Health Canada (2013 emails from importing companies to Environment Canada; unreferenced). These two scenarios include:

1. formulation of adhesives;
2. formulation of lawn and garden care products;

Estimates for Aquatic PECs

The aquatic PEC was estimated based on a number of parameters: the annual quantity of the Azo Solvent Dyes used, the number of annual operation days involved with these solvent dyes, emission factor to wastewater, removal by wastewater treatment systems, wastewater flow and receiving water dilution. The approach used in the calculations was to determine the concentration of the Azo Solvent Dyes near the wastewater treatment system’s effluent discharge point based on the wastewater flow and receiving water dilution.

The annual use quantity of the Azo Solvent Dyes at a facility was reported to be between 100 and 1000 kg for the formulation of adhesives and between 10 and 100 kg for the formulation of lawn and garden products (2013 email from company to Environment Canada; unreferenced). The actual annual use quantities of the Azo Solvent Dyes were used to determine the respective aquatic PECs.

The number of annual operation days relevant to these solvent dyes was unknown for the formulation of adhesives or lawn and garden products. The European Commission Joint Research Centre (ECJRC 2003) provided estimated numbers of annual formulation days based on annual use quantities. The estimated numbers of days for an annual use quantity between 10 and 1000 kg for the industry categories applicable to the formulation scenarios are given below:

• 1 day/year at an annual use quantity between 10 and 500 kg;
• 2 days/year at an annual use quantity between 500 and 1000 kg.

These estimates were used to convert an annual use quantity to a daily use quantity for the formulation of adhesives or lawn and garden products. For a hypothetical annual use quantity of 100 kg, the daily use quantity of the Azo Solvent Dyes was estimated by dividing the annual use quantity by an applicable number of annual operation days:

Daily use quantity of Azo Solvent Dyes (for formulation of adhesives or lawn and garden products)

= Annual use quantity / Number of annual operation days
= 100 kg/year / 1 day/year
= 100 kg/day

The emission factor to wastewater for the formulation of adhesives or lawn and garden products was unknown. It was estimated using the guidance from the ECJRC (2003). The estimated emission factor was 2% when a substance’s annual quantity was below 1 000 000 kg. This 2% estimate was used for the formulation of adhesives or lawn and garden products.

Emission factor to wastewater (for formulation of adhesives or lawn and garden products) = 2%

The daily release quantity of the Azo Solvent Dyes to wastewater from a formulation site was estimated by multiplying the daily use quantity by the emission factor to wastewater.

It was not known whether on-site industrial wastewater treatment was used at sites for the formulation of adhesives and lawn and garden products. In the absence of this information, it was conservatively assumed that there was no on-site wastewater treatment.

The daily release quantity of the Azo Solvent Dyes to the sewer system from the formulation of adhesives or lawn and garden products was simply equal to the daily release quantity to wastewater, because no on-site wastewater treatment was assumed.

Daily release quantity of Azo Solvent Dyes to sewer system (for formulation of adhesives or lawn and garden products)
= Daily release quantity of Azo Solvent Dyes to wastewater (for formulation of adhesives or lawn and garden products)

The concentration of the Azo Solvent Dyes in wastewater influent depends upon the flow of a local wastewater treatment system.

The removal efficiencies of the local wastewater treatment systems at the sites were estimated by models. The treatment systems used at these sites were all secondary, and their removal efficiencies were estimated by ASTreat (2006). The five solvent dyes identified in commerce from a survey issued pursuant to section 71 of CEPA 1999 (Canada 2006; Environment Canada 2006) and the DSL Inventory Update survey (Canada 2009; Environment Canada 2009) were non-volatile and were assumed not to biodegrade through wastewater treatment, due to a lack of biodegradation data. The removal efficiencies estimated were therefore a result of sludge removal only. The estimate, given below, was specific to the Azo Solvent Dyes used at each site:

Removal = 88.6% for formulation of adhesives or lawn and garden products
The concentration of the Azo Solvent Dyes in wastewater effluent was estimated from the concentration of solvent dyes in wastewater influent and an applicable off-site local wastewater treatment removal efficiency.

The aquatic PEC was estimated by dividing the effluent concentration by an appropriate dilution factor of the receiving water. Since the aquatic PEC is determined near the discharge point, the receiving water dilution selected should be applicable to this requirement. The full dilution potential of a river is considered appropriate if it is between 1 and 10. Otherwise, the 10-fold dilution is used for both large rivers and still waters.

The aquatic PEC results for the two formulation scenarios were 0.40 µg/L and 0.46 µg/L.

Estimates for Sediment PECs

An equilibrium sediment–water partition approach described by the European Chemicals Agency (ECHA 2010) was used to estimate the concentration of the solvent dyes in sediment. This approach assumes that the concentration in bottom sediment is in equilibrium with the concentration in the overlying water. At equilibrium, the PEC in bottom sediment can linearly correlate with the concentration in the aqueous phase of the overlying water as follows:

Sediment PEC = K_swC_w

where:

K _sw:

sediment–water partition coefficient (L/kg)

C _w:

chemical concentration in aqueous phase (mg/L)

The sediment–water partition coefficient (K_sw, L/kg) can be estimated from the organic carbon (OC) fraction of sediment (F_oc, kg OC/kg), the sorptive capacity of sediment’s OC (A_oc, L/kg OC) and a substance’s octanol–water partition coefficient (K_ow, unitless) (Gobas 2010):

K_sw = F_ocA_ocK_ow

The sediment PEC can then be calculated from the equation:

Sediment PEC = F_ocA_ocK_owCw

The concentration in the aqueous phase (C_w, mg/L) can be estimated from the aquatic PEC (mg/L). There are three distinct phases in the water column: aqueous, particulate suspended sediment and dissolved suspended sediment (Gobas 2007). Accordingly, the total concentration in the water column or the aquatic PEC (mg/L) can be expressed as a sum of the concentrations in the aqueous phase (C_w, mg/L), particulate suspended sediment (C_ps, mg/L) and dissolved suspended sediment (C_ds, mg/L):

Aquatic PEC = C_w + C_ps + C_ds

When the OC phase in particulate or dissolved suspended sediment is the phase of sorption for a substance, the above equation can be converted to an expression for estimating the ratio of the aquatic PEC (mg/L) to the concentration in the aqueous phase (C_w, mg/L) (Gobas 2007):

Aquatic PEC/C_w = 1 + (X_psF_pocA_poc + X_dsF_docA_doc)K_ow

where:

X _ps:

content of particulate suspended sediment in water column (kg/L)

F _poc:

OC fraction of particulate suspended sediment (kg OC/kg)

A _poc:

sorptive capacity of particulate OC relative to octanol (L/kg OC)

X _ds:

content of dissolved suspended sediment in water column (kg/L)

F _doc:

OC fraction of dissolved suspended sediment (kg OC/kg)

A _doc:

sorptive capacity of dissolved OC relative to octanol (L/kg OC)

K _ow:

octanol–water partition coefficient (unitless)

In Canada, the middle level for the content of particulate suspended sediment in the water column (X_ps) was 47 mg/L (i.e., 50^th percentile; Environment Canada 2013). This value was used in the derivation of the sediment PECs.

X_ps = 47 mg/L = 4.7 × 10⁻⁵ kg/L

According to Gobas (2010), the OC fraction of particulate suspended sediment varied from 0.1 to 0.2 kg/kg sediment. The lower end of this range was used in order to derive conservative sediment PECs.

F_poc = 0.1 kg OC/kg

Karickhoff (1981) proposed a value of 0.41 L/kg OC for the sorptive capacity of sediment’s OC based on a set of 17 sediment and soil samples and various hydrophobic non-polar organic compounds. This value was used for the sorptive capacity of particulate OC (Apoc).

A_poc = 0.41 L/kg OC

In Canada, the dissolved OC content in the water column averaged 2.7 mg OC/L (Environment Canada 2013). This value was used in the derivation of the sediment PECs. Note that this OC content equals the product of the content of dissolved suspended sediment, X_ds (mg/L), and the OC fraction of dissolved suspended sediment, F_doc (kg OC/kg).

X_dsF_doc = 2.7 mg OC/L = 2.7 × 10⁻⁶ kg OC/L

Gobas (2007) provided an estimate of 0.08 L/kg OC for the sorptive capacity of dissolved OC. This estimate was used.

A_doc = 0.08 L/kg OC

The octanol–water partition coefficient (K_ow) exhibits a significant influence on the sediment PEC. According to the following two equations, described previously:

Sediment PEC = F_ocA_ocK_owC_w

Aquatic PEC/Cw = 1 + (X_psFp_ocA_poc + X_dsF_docA_doc)K_ow

the dependence of the sediment PEC on K_ow is given as:

Sediment PEC = Aquatic PEC × F_ocA_oc / (1 / K_ow + X_psF_pocA_poc + X_dsF_docA_doc)

This dependence reveals that the sediment PEC approaches zero for water-soluble substances with low K_ow and approaches a maximum constant concentration for highly hydrophobic substances with high K_ow. In other words, the sediment PEC increases with K_ow. The log K_ow values for the five Azo Solvent Dyes found in commerce were in the range of 3.6–6.1. The higher-end value of this range was used to derive conservative sediment PECs.

log K_ow = 6.1, or K_ow = 1 258 925

The ratio of the aquatic PEC to the concentration in the aqueous phase (C_w) was calculated as:

Aquatic PEC/Cw = 1 + (X_psF_pocA_poc + X_dsF_docA_doc)K_ow
= 1 + [(4.7 × 10⁻⁵ kg/L × 0.1 kg OC/kg × 0.41 L/kg OC) + (2.7 × 10⁻⁶ kg OC/L × 0.08 L/kg OC) × 1 258 925]
= 1 + (2.14 × 10⁻⁶) × 1 258 925
= 1 + 2.69 = 3.69

As an example, if the aquatic PEC at a site is estimated as 10.8 µg/L, the concentration in the aqueous phase (C_w) at this site is then calculated from the ratio of the aquatic PEC to C_w:

C_w = Aquatic PEC/3.69 = 10.8 µg/L / 3.69 = 2.93 µg/L

Gobas (2010) suggested a default value of 0.01–0.03 kg OC/kg for the OC fraction of bottom sediment in rivers. The higher end of this range was selected as a standard for the sediment PECs derived.

F_oc = 0.03 kg OC/kg

As for particulate suspended sediment, the sorptive capacity of bottom sediment’s OC was taken as 0.41 L/kg OC based on the work from Karickhoff (1981).

A_oc = 0.41 L/kg OC

The sediment PEC at the site can then be estimated from the above values as:

Sediment PEC = F_ocA_ocK_owC_w

= 0.03 kg OC/kg × 0.41 L/kg OC × 1 258 925 × 2.93 µg/L
= 15 485 L/kg × 2.93 µg/L
= 45 370 µg/kg
= 45.4 mg/kg

The sediment PECs were estimated according to the above method to be 1.66 mg/kg and 1.94 mg/kg.

Estimates for Soil PECs

An approach described by the European Chemicals Agency (ECHA 2010) was used to estimate PECs in soil resulting from the land application of sewage biosolids. This approach employed the quantity of biosolids accumulated within the top 20 cm layer (ploughing depth) of soil over 10 consecutive years as the basis for soil PECs. One underlying assumption of the approach was that substances were subject to no loss due to degradation, volatilization, leaching or soil runoff upon their entry into soil via biosolids land application. This assumption therefore yielded conservative soil PECs.

When the above conservative approach was applied to the Azo Solvent Dyes, the concentration of the Azo Solvent Dyes in biosolids was first estimated at a site. The data required for this estimate included the daily quantity of the Azo Solvent Dyes released to the sewer system at a site, the sludge removal efficiency of the related local wastewater treatment system, the per capita sludge production rate and the population served by the wastewater treatment system.

The daily quantity of the Azo Solvent Dyes released to the sewer system was estimated in the aquatic PEC calculations.

The removal efficiencies of the local wastewater treatment systems at sites were estimated by models. The treatment systems used at sites were all secondary, and their removal efficiencies were estimated by ASTreat (2006). The five Azo Solvent Dyes identified in commerce from a survey issued pursuant to section 71 of ECPA 1999 (Canada 2006; Environment Canada 2006) and the DSL Inventory Update survey (Canada 2009; Environment Canada 2009) were non-volatile and were assumed not to biodegrade through wastewater treatment, due to a lack of biodegradation data. The removal efficiencies estimated were therefore a result of sludge sorption only. These estimates ranged from 26.2% to 88.6%, and the higher-end value of 88.6% was used in order to derive conservative soil PECs.

Off-site local wastewater treatment removal = 88.6%

The daily quantity of the Azo Solvent Dyes sorbed to sludge was estimated by multiplying the daily release quantity by the removal:
= Daily release quantity of Azo Solvent Dyes to sewer system (kg/day) × Off-site local wastewater treatment removal (kg/day)

The per capita sludge production rate depends upon the type of wastewater treatment. This rate was reported to be 0.080 kg/day per person for primary sludge and 0.115 kg/day per person for secondary sludge (Droste 1997). In other words, the per capita sludge production rate was 0.195 kg/day per person from secondary systems (primary sludge rate at 0.080 kg/day per person + secondary sludge rate at 0.115 kg/day per person). The higher rate from secondary systems was mainly attributed to the biomass production during biological treatment.

Per capita sludge production rate from secondary systems = 0.195 kg/day per person

As an approximation, the daily quantity of biosolids produced from a wastewater treatment system was assumed to equal the daily quantity of sludge produced. This daily quantity was calculated by multiplying the sludge production rate by the population served by the wastewater treatment system:

Daily quantity of biosolids produced from a secondary system
= Per capita sludge production rate from a secondary system (kg/day per person) × Population served by the system (number of persons)
The concentration of the Azo Solvent Dyes in biosolids was obtained by dividing the daily quantity of the Azo Solvent Dyes sorbed to sludge by the daily quantity of biosolids produced from a wastewater treatment system.

Concentration of Azo Solvent Dyes in biosolids
= Daily quantity of Azo Solvent Dyes sorbed to sludge (kg/day) ÷ Daily quantity of biosolids produced from a secondary system (kg/day)
= g/kg

The annual quantity of the Azo Solvent Dyes entering soil via biosolids land application is a function of not only the concentration of the solvent dyes in biosolids, but also the biosolids application rate. In Canada, the use of biosolids is regulated by the provinces and territories. The rate at which biosolids are land applied can therefore vary between different provinces and territories, and are summarized below for four provinces.

The annual quantity of the Azo Solvent Dyes entering soil via biosolids land application was calculated by multiplying the concentration of the Azo Solvent Dyes in biosolids by the maximum annual application rate found from the four provinces shown above.

Annual quantity of Azo Solvent Dyes entering soil
= Concentration of Azo Solvent Dyes in biosolids (g/kg) × Maximum biosolids annual application rate (8.3 t/ha per year)
= g/m2 per year

According to the approach described by the European Chemicals Agency (ECHA 2010), a period of 10 consecutive years was used to determine the quantity of the Azo Solvent Dyes accumulated over this period.

Quantity of Azo Solvent Dyes accumulated in soil over 10 years
= Annual quantity of Azo Solvent Dyes entering soil (g/m2 per year) × 10 years
= g/m2

To derive the concentration of the Azo Solvent Dyes in soil, the quantity of soil within the top 20 cm or 0.20 m layer, as per the European Chemicals Agency (ECHA 2010), was estimated from a dry soil density of 1200 kg/m³ (Williams 1999):

Quantity of soil = Soil depth × Soil density
= 0.20 m × 1200 kg/m³
= 240 kg/m²

The soil PEC at a site was then estimated by dividing the quantity of the Azo Solvent Dyes accumulated in soil over 10 years by the quantity of soil:

Soil PEC for Azo Solvent Dyes
= Quantity of Azo Solvent Dyes accumulated in soil over 10 years (g/m2) / Quantity of soil (240 kg/m2)

The soil PECs for all the sites were estimated according to the above method to be 0.31 mg/kg and 0.59 mg/kg.

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Appendix G: Estimated Exposures from Use of Products

Dermal and Oral Exposure from Textiles

Direct and prolonged skin contact with clothing may lead to dermal exposure to azo dyes. As a conservative approach, an upper-bounding exposure estimate to Solvent Yellow 77 based on full body coverage from wearing clothing is presented. It is assumed to account for exposures from multiple pieces of apparel that cover the entire surface area of the body. As Solvent Yellow 77 is relatively water soluble, the effect of laundering is expected to significantly reduce any dye that is not fixed to the textile fibre, thereby reducing the exposure after the initial washes. This effect was not factored into the estimated exposures; this adds to the conservatism of the estimates.

Estimated Daily Exposure via Dermal Route from Textile Apparel

= (SA × AW × SCF × C × M × UF × F × P) / BW

Oral Exposure from Mouthing of Textile Objects by Infants

Oral exposure to Solvent Yellow 77 is estimated based on a scenario assuming that the infant is mouthing a textile object (e.g., blanket, textile toy) that may release Solvent Yellow 77. Conservatism is built in exposure factors described below.

Estimated Daily Exposure via Oral Route from Mouthing Textile Object

= (SA × AW × C × M × F × P) / BW

Exposure Factors

SA:

Total surface area (dermal) = 18 200 cm ² (adult), 3020 cm2 (infant) (Health Canada1995)
Total surface area (oral: textile object mouthed) = 20 cm ² (Zeilmaker et al. 1999)

AW:

Area weight of textile = 20 mg/cm ² (US EPA 2012a)
The area weight of textiles can vary greatly depending on the type of material. An area weight of 20 mg/cm ² for cotton textiles is recommended by the US EPA in “Standard Operating Procedures for Residential Pesticide Exposure Assessment” (US EPA 2012a).

SCF:

Skin contact factor = 1
Based on a conservative estimate that the 100% of the full body coverage of clothing being in direct contact with the skin (i.e., SCF = 1).

C:

Concentration in textile = 0.01 (unitless) (BfR 2007)
Based on the default model developed by the “Textiles” Working Group established at the German Federal Institute for Risk Assessment (BfR 2007), assuming that a standard textile garment of 100 g/m ² is dyed with 1% active dye ingredient.

M:

Migration fraction = 0.0005 (BfR 2007)
The migration of azo dyes from textiles varies considerably depending on the type of fibre, the type of dye used, the dye load, dyeing technology and colour intensity and after treatment. The dermal exposure from textiles is partly dictated by the amount of dye that migrates from textile material onto human skin (ETAD 1983b). The “Textiles” Working Group (BfR 2007) uses a peak initial migration of 0.5% to estimate exposure to dyes from newly bought unwashed garments. The migration rate after 28 hours of simulated wash and wear cycles was observed to be less than one-tenth of the value measured for the first migration. The migration fraction of 0.0005 which is one-tenth of the peak initial migration (0.5%) is used to reflect exposure after the intial washes. It is assumed that the sweat migration rate is similar to the salivary migration rate; this is consistent with observations of leaching behaviours of dyes from textiles reported by Zeilmaker et al. (1999).

UF:

Dermal uptake fraction = 0.216 (Feldmann and Maibach 1970) 21.6% based on an in vivo dermal absorption study on Solvent Yellow 2.

F:

Exposure frequency = 1×/day

P:

Probability that Solvent Yellow 77 is present in textile = 10%.
In the RIVM risk assessment of azo dyes and aromatic amines from garments and footwear (Zeilmaker et al. 1999), the authors derived a chance of 8% for the appearance of carcinogenic azo dyes and aromatic amines in garments based on four European studies. Presumably, there would be a higher prevalence in the use of non-EU22 amines and their dyes, compared to EU22 amines and related dyes, since the former are not prohibited. Solvent Yellow 77 does not derive from EU22 amines; the prevalence of this dye is not clear because there is relatively limited product testing and monitoring on non-EU22 amines and associated dyes. Based on data available (Danish EPA 1998; Kawakami 2012; Health Canada 2013), the prevalence of certain non-EU22 amines was found to range from 0% to 23.7% (aniline). Since several dyes can derive from a given aromatic amine, the prevalence of an associated dye would be lower. Given the conservatism used in other parameters in this exposure scenario (e.g. full body coverage), the probability that Solvent Yellow 77 is present in a textile is assumed to be 10% in this Screening Assessment based on professional judgement. This is considered reasonable since the chances of an individual’s outfit containing Solvent Yellow 77 every day are low.

BW:

Body weight = 70.9 kg for adult, 7.5 kg for infant (Health Canada 1998)

Estimated Daily Exposures to Solvent Yellow 77 from Textiles via the Dermal Route

• Baby Sleeper: 8.7×10⁻⁴ mg/kg-bw per day
• Personal Apparel: 5.5×10⁻⁴ mg/kg-bw per day

Estimated Daily Exposure to Solvent Yellow 77 via Oral Route for Infants

• 2.7 × 10-5 mg/kg-bw per da

Dermal Exposure to Solvent Yellow 77 from Leather Products

Direct skin contact with articles of leather can result in dermal exposure to dyes used in leather dyeing. A number of leather products were considered in this exposure scenario, including those listed in the Danish EPA Annex XV Report on the proposed restriction of chromium in leather as leather articles (Danish EPA 2012). Of all the leather products considered, the potential drivers for exposure are presented below; furniture, apparel (e.g., jackets, trousers and gloves), footwear (e.g., shoes and boots) and toys where it is assumed that prolonged contact with the infant’s hands can occur when playing with the toy. The presented exposure estimates below are considered upper-bounding based on conservative assumptions as well as not taking into account of a final application of a polyurethane sealant coating which would further reduce the consumer’s dermal exposure to the leather dye.

Estimated Dermal Exposure to Solvent Yellow 77 from Leather Products

= (SA × AW × SCF × C × M × U) / BW

Exposure Factors

SA:

Surface area of skin contact (Health Canada 1995; Therapeutic Guidelines Ltd. 2008).
- Shoes: 1275 cm ² (adult feet)
- Boots: 4185 cm ² (adult legs and feet)
- Gloves: 455 cm ² (adult hands and forearms)
- Jackets and coats: 8920 cm ² (adult trunk and arms)
- Trousers: 5820 cm ² (adult lower body)
- Furniture: 5005 cm ² (adult back, glutes and back of thighs)
- Toys: 92.5 cm ² (infant palms)

AW:

Area weight of leather = 0.15 g/cm2 (Danish EPA 2012)
Based on the typical weight of 1 cm2 leather (of 1 mm thickness) being 0.15 g, as in the leather shoe exposure scenario in the Danish EPA Annex XV Report on the proposed restriction of chromium in leather.

SCF:

Skin contact factor = [(SA _direct × 1) + (SA _indirect × 0.1)]/ (SA _total)
Based on a conservative assumptions and a weighted approach where SCF is assumed to be 1 when the entire leather product is in direct contact with the skin and SCF is assumd to be 0.1 when the leather product is in indirect contact with the skin (e.g., shielding due to interior lining) (Zeilmaker et al. 1999). When a portion of the leather article is in direct contact and the remaining portion is in indirect contact, a weighted SCF is calculated based on surface areas (SA) of direct and indirect contact.
- Shoes: 1
- Boots: 0.1
- Gloves: 0.1
- Jackets and coats: 0.19
- Trousers: 0.19
- Furniture: 0.1
- Toys: 1

C:

Concentration in material = 0.02 (unitless weight fraction) (Øllgaard et al. 1998)

M:

Migration rate = 0.1% (derived from 39% over 365 days ; Zeilmaker et al. 1999)
The dermal exposure to dyes from leather is partly dictated by the amount of dye that migrates from leather material onto human skin. Zeilmaker et al. (1999) measured the experimental leaching of azo dyes from leather footwear material to be 15% and 39%. The leaching was determined by extracting from 1 g of unwashed material from the upper side of a newly bought leather shoe with 100 mL sweat stimulant (extraction conditions: 16 hours at 37°C while shaking). These extraction conditions are expected to overestimate migration of dyes from sweat. In estimating exposure to dyes from leather articles, it is assumed 39% of the dye content may leach over 1 year and is available for dermal exposure, which would be equivalent to 0.1% leaching over one day.

UF:

Dermal uptake fraction = 0.216 (Feldmann and Maibach 1970)
21.6% based on an in vivo dermal absorption study on Solvent Yellow 2.

BW:

Body weight = 70.9 kg (adult), 7.5 kg (infant) (Health Canada 1998)
Exposure Estimates from Leather Products for Solvent Yellow 77
- Shoes: 1.2×10 ⁻² mg/kg-bw
- Boots: 4.1×10 ⁻³ mg/kg-bw
- Gloves: 4.4×10 ⁻⁴ mg/kg-bw
- Jackets and coats: 1.7×10 ⁻² mg/kg-bw
- Trousers: 1.1×10 ⁻² mg/kg-bw
- Furniture: 4.9×10 ⁻³ mg/kg-bw
- Toys: 8.5×10 ⁻³ mg/kg-bw

Dermal exposure estimate to Solvent Orange 3 via use of shoe polish

Exposure estimate to Solvent Orange 3 via the use of shoe polish cream considering the potential subsequent exposure as described in the RIVM Cleaning Products Fact Sheet (RIVM 2006b).

Exposure frequency: 26/year (RIVM 2006b)
Product amount: 0.10 g/application (RIVM 2006b)
Adult body weight (20–59 years): 70.9 kg (Health Canada 1998)
Concentration: 1.5% w/w (based on two shoe polish products at concentrations of 0–1% and 1.5%; HPDB 2012).
Dermal absorption: 100% (default)

Estimated Per Event Dermal Exposure to Solvent Orange 3 = 0.021 mg/kg-bws

Incidental dermal and oral exposure estimates to Sudan I from ballpoint pen ink

This scenario covers both dermal and incidental oral exposure from hand-to-mouth activity by a toddler. The Art and Creative Materials Institute, Duke University, Durham, North Carolina, reported the assumption that a child will absorb 25 cm of ink line daily either through dermal or incidental oral exposure (2009 personal communication from Art and Creative Materials Institute to Existing Substances Risk Assessment Bureau, Health Canada; unreferenced). A default ink laydown rate of 100μg/cm (90th percentile level ink laydown of writing instruments; 2009 personal communication from Art and Creative Materials Institute to Existing Substances Risk Assessment Bureau, Health Canada; unreferenced) was used. Typically, the weight fraction of colourants in inks ranges from 1% to 5% (Scott and Moore 2000). In an in vitro study by Collier et al. (1993), 26% of applied Sudan I (5 µg/cm2 in acetone) was absorbed by human skin within 24 hours; this percentage includes Sudan I in the skin sample (after homogenization) and in the receptor fluid and is expected to overestimate the dermal absorption of Sudan I in this scenario, since the contact is likely to occur over a shorter period. Overall, the resulting exposure estimate is expected to be upper bounding.

Estimated Upper-bounding Per Event Exposure via Dermal Route

=(Daily ink line ×Ink laydown rate ×Conc ×Dermal Abs)/BW

Daily ink line: 25 cm
Ink laydown rate: 100 μg/cm
Concentration (Conc): 1–5% w/w (Scott and Moore 2000)
Dermal absorption fraction (Dermal Abs): 26% (Collier et al. 1993)
Body weight (BW): 15.5 kg

Estimated Per Event Dermal Exposure = 2.1 × 10-3 mg/kg-bw

Estimated Per Event Oral Exposure = 8.1 × 10-3 mg/kg-bw

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Appendix H: Benchmark Dose Calculations for Solvent Yellow 77 and Sudan I

Solvent Yellow 77: The lowest calculated BMDL₁₀ for Sudan Yellow 77 is 51.29 mg/kg-bw per day for liver tumours in male rats, one of three tumour sites for this dye. The corresponding BMD₁₀ is 78.38 mg/kg-bw per day. This BMDL₁₀ is selected for subsequent risk characterization.

Sudan I: The lowest calculated BMDL₁₀ for Sudan I is 5.54 mg/kg-bw per day for liver tumours in male rats, one of the four tumour endpoints for this dye. The corresponding BMD₁₀ is 9.31 mg/kg-bw per day. This BMDL₁₀ is selected for subsequent risk characterization.

Benchmark Dose Calculations for Solvent Yellow 77 (CAS RN 2832-40-8)

Table H-2: Incidences of malignant tumours in rats or mice exposed to Solvent Yellow 77 in feeding diets (NTP 1982a)

Benchmark Dose Calculations for Sudan I (CAS RN 842-07-9)

Table H-4: Incidences of tumours in F344 rats exposed to Sudan I in feeding diets (NTP 1982b)

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Appendix I: Azo Solvent Dyes with Effects of Concern

Some of the Azo Solvent Dyes in this assessment have effects of concern based on potential carcinogenicity. The details for supporting the potential carcinogenicity for these substances are outlined in section 7.2 Health Effects Assessment (see specific sub-sections), and generally based on one or more of the following lines of evidence:

• Classifications by national or international agencies for carcinogenicity (may be a group classification).
• Evidence of carcinogenicity in animal studies and/or human epidemiology based on the specific substance.
• Potential to release one or more of the EU22 aromatic amines by azo bond cleavage.
• Read-across to related substances for which one or more of the above lines of evidence apply.