Summary of Public Comments Received on the Government of Canada’s Draft Screening Assessment Reports on C.I. Pigment Yellow 34 (CAS RN 1344-37-2) and C.I. Pigment Red 104 (12656-85-8)

Since silica encapsulation of pigments increases their heat stability and chemical resistance in plastics, they would likely be used in plastic processing requiring high temperatures. 

As noted in the screening assessment, these pigments, silica encapsulated or otherwise, are not used for the manufacture of products for use by the general population.

With regards to hobbyists, the screening assessment indicates that the use of artists’ paints that contain these pigments or activities such as automotive restoration and repair of vehicles painted with these pigments could lead to increased exposure.  However, information is not available to further quantify these exposures.  The Surface Coating Materials Regulations under the Hazardous Products Act (Canada 2005) limit the total lead concentration to not more than 600mg/kg when a dried sample is tested.  This requirement does not apply to the above situations (touch-up paints for metal surfaces or materials used in arts, crafts or hobbies, unless it is for children).  Those types of products may exceed the 600 mg/kg lead limit but must display a specified warning on the product label.

In terms of residents in close proximity to industrial facilities manufacturing or using these pigments, since theses pigments have negligible vapour pressure, any industrial releases would be in the form of particulates which would be expected to settle before significant transport had occurred.  Extremely conservative estimates of exposure through ambient air predicted a low concentration of 0.36 μg/m³.

The information gathered through the Challenge may be used as the basis for additional actions to minimize exposure of workers through the appropriate federal and/or provincial statutes.   Information was not available regarding the possibility of transfer of these pigments to workers homes

As mentioned in the screening assessment, the Surface Coating Materials Regulations limit the total lead concentration in surface coatings materials to not more than 600 mg/kg when a dry sample is tested.  This limit does not apply to surface coating materials for the purposes of arts, crafts or hobbies for adults and for other defined uses outlined in the screening assessment.   However, in the instances where the total lead concentration exceeds 600 mg/kg for these purposes, a specified lead-content warning must appear on the label of the surface coating container which includes the statement "Do not apply to surfaces accessible to children or pregnant women".

Although the Surface Coating Materials Regulations do not apply to the use of surface coating materials on playground structures, the Canadian Standards Association has published a voluntary standard entitled "Z614-07 Children’s playspaces and equipment".  Some provinces and/or school boards mandate that the requirements of this standard be met for playground structures.  This standard requires that all paints or other similar finishes be non-toxic and that non-lead-based paints be used in all new equipment and when repainting existing equipment to eliminate the risk of childhood lead poisoning from playground equipment.

Items 2, 9 and 18 of Schedule I, Part I to the Hazardous Products Act prohibit furniture and other articles for children, toys, equipment and other products for use by a child in learning or play and pencils and artists’ brushes that have had a surface coating material applied to them that contains more than 600 mg/kg of total lead.

The screening assessment does not provide experimental data to support the following claims:

1. That both pigments have low water solubility but there will be dissolution and dissociation of the pigments into the moieties – Pb²⁺ and CrO₄^2- with the lead sulphate portion having greater solubility than the lead chromate portion. 

2.   Encapsulation with amorphorous silica will further decrease the solubility of these pigments therefore reducing the bioavailability of the moieties in water, sediments and soil. 

The screening assessments contains data that support these two claims:

1.  The experimental solubilities of both pigments and their constituents are available in Table 2.

2.  Although experimental data regarding the solubility of silica encapsulated pigments are not available, information indicative of reduced bioavailability of silica encapsulated pigments is available from experimental animal data cited in the screening assessment (Clapp et al. 1991; Pier et al. 1991).  This information coupled with professional judgement lead to the statement that encapsulation with amorphorous silica will further decrease the solubility of these pigments. 

It should be noted that the ecological assessment of effects to aquatic organisms considered the acute effects to aquatic organisms due to the presence of both metals in solutions assumed saturated.

These pigments have not been shown to be carcinogenic or genotoxic in studies specific to lead chromate pigments.

As well, they were aware of no credible experimental data developed using actual lead chromate pigments in the form sold in commerce which substantiates this claim. Nor is any such data cited in the screening assessment.

Although no significantly increased risk of lung cancer incidence were observed in some of the epidemiological investigations (Davies et al. 1979, 1984; Cooper et al. (EEH) 1983) conducted in the lead chromate pigment production plants, the authors speculated that the numbers of observed and expected deaths were too small in these studies for definitive conclusions. In the Kano et al. study (1993), the authors speculate that exposures may have been reduced due to improved workplace hygiene practices, thereby reducing lung cancer risk among the workers in the production of various chromate pigments, including lead chromate, zinc chromate and strontium chromate pigments. The exposure levels in the Kano et al (1993) study were not quantified.

The description of these studies has been refined in the screening assessment and noted in the uncertainties.

The ecological assessments of effects to aquatic organisms are based on experimental toxicity data for Pigment Yellow 34; therefore, they already consider the potential for acute effects to aquatic organisms due to the measured presence of both metals in solution.

A cumulative or additive analysis is beyond the scope of the health screening assessment for the two pigments.   For most classes of substances, the available data are insufficient to conduct a cumulative risk assessment.  

Comments were received indicating both agreement and disagreement with the draft CEPA 64c conclusions in the screening assessment reports for C.I. Pigment Yellow 34 and C.I. Pigment Red 104.

One commenter disagreed with the human health conclusions of the screening assessment based on the assumption that the pigments are inhaled carcinogens, which is not a relevant route of exposure to the general population.

As stated in the screening assessment, Health Canada agrees that inhalation exposure to the general population is negligible.

With respect to carcinogenicity, consistent with the Ministers' Notice of Intent (December 9, 2006), Health Canada considers that evidence of carcinogenicity (i.e., classification by one or more international/national agencies), in the absence of a fully elucidated mode of action analysis, is sufficient to propose a conclusion that there is a probability of harm at any level of exposure and that the criterion in paragraph 64c of CEPA 1999 is met.  The application of a precautionary approach is required under CEPA 1999.

Information regarding the assessment of non-threshold toxicants under the Existing Substances Program is available at http://www.hc-sc.gc.ca/ewh-semt/pubs/contaminants/approach/
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The screening assessments for human health are prepared in light of the stated intents of the Challenge, to conduct screening assessments of high priority substances.  For these high priorities it is considered appropriate to base information on health hazards principally on weight of evidence based assessments by other agencies.  

The European Commission classifications were specifically for C.I. Pigment Yellow 34 and C.I. Pigment Red 104.   As well, Health Canada’s Priority Substances List assessment on chromium, included consideration of some of the toxicological information on lead chromate and its derived pigments in its evaluation of chromium.  The PSL assessment concluded that chromium VI compounds, as a whole, were carcinogenic to humans.

A reasonable worst-case exposure scenario for the receiving water bodies and the aquatic organisms showed that the substances were not found to cause acute aquatic ecotoxic effects. It is also unlikely that terrestrial wildlife or other organisms living in other compartments (e.g. soils/sediments) would be harmed by exposure to this substance or by contaminated food considering the low solubility of these pigments.

A quantitative estimation of risks, including the calculation of exposure concentrations and risk quotients was thus not warranted considering the properties of these pigments (particularly their low solubility).

Furthermore, the  particles containing these pigments may be removed during sewage treatment. The low solubility of the pigments would prevent dissolution of the pigments, leading to extremely low concentrations of dissolved metals from this source.

In the context of the mass flow tool, releases from waste management sites were not considered in the calculations because they are difficult to estimate and are expected to be small. In the case of landfills, considering the properties of the substances (low vapour pressure, low solubility, moderate to very high partition coefficients for the dissolved metals), the presence and the migration of the dissolved metals through soil or leaching to groundwater is expected to be minimal.  Additionally, the dissolution of the pigments is further reduced by the incorporation of the substances in products (plastics, paints and coatings).

Additionally, it is important here to note that all products sent to waste disposal and incineration are managed through waste management programs at Environment Canada and/or provincial jurisdictions, such as programs to meet the Canada Wide Standards for dioxins and furans.

In the Notice of Intent published in Canada Gazette, Part 1, the Government of Canada invited industry and other stakeholders to provide specific information that may be used to inform risk assessment and to develop and benchmark best practices for the risk management and product stewardship of those substances identified as the highest priorities.

In addition to the data collected under the section 71 surveys, the screening assessments use the available scientific data from a range of sources including published literature in scientific journals and other international reviews.

The Government of Canada has stated that the absence of new information will not preclude the Ministers from issuing a decision that safeguards human health and the environment. Thus the process being used for the Challenge substances is not to wait until data gaps are filled, but to act on what we know now.

The manufacture, use, release and disposal of lead chromate pigments in Canada are regulated through the complete life cycle in Canada.

Termination or unnecessary additional restriction on the production of lead chromate pigments would unnecessarily impact a number of high paying manufacturing jobs in Canada.

The impact of such restrictions must be analyzed against the gain in safety or environmental protection, which, in the case of lead chromate pigments would be minimal or nonexistent.

There are potential alternatives, but not one for one substitutes for lead chromate pigments. The alternative products require tradeoffs in performance characteristics and in formulation with multiple replacement ingredients for final products. When cost is considered there are no substitutes which perform equivalently to C.I. Pigment Yellow 34 or C.I. Pigment Red 104 in most product formulations.

There are specialized industrial and military uses for these pigments for which there are yet no suitable alternatives.

The predominant current use of these pigments as well as their entry into the environment is due to their use as traffic marking paint.   After December 31, 2010 this use will no longer be permitted.  As a result of this use pattern change we can expect a reduced potential human exposure to these substances.