Summary of public comments received on the science approach document for the ecological risk classification of inorganic substances

Comments on the Science Approach Document: Ecological Risk Classification of Inorganic Substances (ERC-I) were submitted by the Mining Association of Canada and the Canadian Consumer Specialty Products Association.

A summary of comments and responses is provided below:

Summarized/Rolled-up Comment Summarized/Rolled- up Response
It is not clear what the various levels of risk represent and what action would be taken if a chemistry changed risk level. The ecological risk classification levels relate to the frequency and magnitude of exceedances, if any, of predicted no-effect concentrations in measured and modelled exposure datasets.   There are no risk management actions that follow directly from a Science Approach Document.
The overall approach taken to characterize risk appears appropriate.   There may be some bias in the results due to certain sectors, such as mining and oil and gas, being more data-rich than other sectors, such as agriculture or wastewater treatment effluent. Noted.    
A conservative approach was taken to establishing predicted no-effect concentrations (PNEC). However, we are concerned that future readers might take the PNEC values out of context and may apply them inappropriately without further refinement or additional data input. While the hazard information collected for the Ecological Risk Classification of Inorganic Substances (ERC-I) Science Approach Document and the approaches used to derive preliminary and conservative PNEC values provide a reasonable basis for ecological risk classification, these PNEC values should not be used in other contexts.
The report does not provide adequate detail or justification of the assessment factors used to derive PNECs.     Assessment factors were derived systematically by first standardizing ecological endpoints (acute-to-chronic, lethal-to-sublethal, and median-to-low level effects). Standardized endpoints were then divided by a species variation factor which accounted for both the number of species, and the number of species categories represented in the dataset (primary producers, invertebrates, vertebrates).   The final assessment factor is the product of the endpoint standardization factor and the species variation factor, and these values were used to derive preliminary PNECs.   Some assessment factors in Table 4-3 have been updated to align with the data used in the supporting document.
Tables of the background concentration ranges that are discussed in Section 4.2.1 should be included in the report. The approach to estimating background concentration ranges has recently been published in the open literature (Proulx et al. 2018). A second manuscript, currently in preparation, will describe the background concentrations calculated.
The supporting documentation does not provide information on toxicity modifying factors (TMF) or indicate whether the effects concentrations are nominal or measured. Several of the compounds in this report are also sparingly soluble at typical conditions. Effects studies selected in this report maximize bioavailability, which may be altered by site-specific conditions. The preliminary PNECs derived for the purpose of ERC-I do not generally take into account toxicity modifying factors or bioavailability corrections. This information would be important to consider for higher-tier analysis and refinement. Bioavailability and TMFs are discussed where appropriate in screening assessment reports of substances identified as requiring further ecological assessment.  
The ranking of “not performed” in the reliability column of the supporting documentation is not clear. For preliminary PNECs derived by the critical toxicity value/assessment factor (CTV/AF) approach, it was ensured that the study producing the critical toxicity value was evaluated for reliability. Other studies in the database inform the species variability factor and were not necessarily evaluated, as denoted by the “not performed” terminology.
The PNEC determined for bismuth appears to be low and does not consider good laboratory practice (GLP) data that are present in the registration dossier submitted to the European Chemicals Agency (ECHA) for bismuth oxide salicylate. Additional data from the bismuth oxide salicylate dossier would further inform the species variation factor for the bismuth preliminary PNEC under the approach used for ERC-I. However, the ecological risk classification result would not change.    
The PNEC determined for lanthanum appears to be low relative to the PNEC derived in the registration dossier submitted to ECHA for lanthanum chloride, and the PNEC for lanthanum derived by Herrmann et al. (2016).     The PNEC derived in the registration dossier for lanthanum chloride, the lanthanum PNEC derived by Herrmann et al. (2016), and the preliminary PNEC developed for ERC-I ultimately use the same assessment factor (10).   The three PNECs differ in the selection of the CTV to which the AF is applied. Herrmann et al. (2016) selects the lowest long-term NOEC (Barry and Meehan 2000). The registration dossier submitted to ECHA appears to select a higher value (Unnamed Study Report, 1995). Conversely, ERC-I selects the soft water LC50 of Borgmann et al. (2005), as it produces the most sensitive standardized endpoint.  
The PNECs determined for praseodymium and neodymium are supported by limited data.   The registration dossier submitted to ECHA for praseodymium further suggests there are multiple uncertainties regarding fate, water solubility, and bioavailability, and that effects characterization in the aquatic compartment is not necessary. The preliminary PNEC values for praseodymium and neodymium are indeed based on limited data, but adequate for the purposes of ERC-I. Additional data have been identified since the time of drafting and should be considered if developing a refined PNEC for other purposes.
While the species sensitivity distribution (SSD) approach is agreeable, the PNEC determined for lithium appears to be low relative to the PNECs derived in ECHA registration dossiers for lithium, lithium carbonate, and lithium chloride. The freshwater PNECs derived in the registration dossiers submitted to ECHA use assessment factors of 1 applied to the no observed effect concentrations (NOECs) that are not necessarily the lowest available in the datasets. If the most sensitive NOECs and a higher assessment factor (e.g., no less than 10) were to be used, the difference between the registration dossier PNECs and the preliminary PNEC developed for ERC-I would be insignificant.
More recent data exists that could further inform the PNEC determined for molybdenum (for example, Heijerick and Carey, 2017). The development of a refined PNEC should indeed evaluate and consider the most recent, reliable data available. However, the results of Heijerick and Carey (2017) would not change the ecological risk classification result.
Three additional acute studies and 24 additional chronic studies for germanium dioxide should be considered in the weight of evidence for determining a chronic PNEC for germanium.   Based on precedence for other substances, values of 1 should be applied for both the Endpoint Standardization Factor and Species Variation Factor for germanium. An analysis was conducted to determine the potential impact of the additional data on the critical toxicity value and species variability factor for the germanium PNEC. It was found that the classification of low potential for ecological concern from ERC-I would not change as a result of the additional data.


Barry MJ, and Meehan BJ. 2000. The acute and chronic toxicity of lanthanum to Daphnia carinata. Chemosphere. 41:1669-1674

Borgmann U, Couillard Y, Doyle P, Dixon DG. 2005. Toxicity of sixty-three metals and metalloids to Hyalella azteca at two levels of water hardness. Environmental Toxicology and Chemistry. 24(3): 641-652.

Heijerick DG and Carey S. 2017. The toxicity of molybdate to freshwater and marine organisms. III. Generating additional chronic toxicity data for the refinement of safe environmental exposure concentrations in the US and Europe. Science of the Total Environment. 609: 420-428.

Herrmann H, Nolde J, Berger S, Heise S. 2016. Aquatic ecotoxicity of lanthanum – A review and an attempt to derive water and sediment quality criteria. Ecotoxicology and Environmental Safety. 124: 213-238.

Proulx CL, Kilgour BW, Francis AP, Bouwhuis RF, Hill JR. 2018. Using a conductivity-alkalinity relationship as a tool to identify surface waters in reference condition across Canada. Water Quality Research Journal. 53(4): 231-240.

Unnamed Study Report. 1995. Long-term toxicity to aquatic invertebrates.  European Chemicals Agency (ECHA) Registered substances database. Substance dossier for “Lanthanum chloride, anhydrous” (EC number: 233-237-5, CAS numbers 10025-84-0 and 10099-58-8). Helsinki (FI): ECHA. [accessed 2018 August].

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