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EC number: 215-149-9
CAS number: 1306-25-8
General considerations on the ecotoxicity of CdTe and Cd++ion
Given that Cadmium is the toxic moiety of CdTe, and that the aquatic hazard and environmental risks related to the substance are thus related to the exposure to the Cd++ ion, the PNEC freshwater and aquatic effect classification of CdTe are based on the extensive databases, available for Cd++ ion toxicity. The ecotoxicity data that underly the Cd++ ion-related PNECs have been obtained on soluble Cd compounds and are reported in the related registration files on cadmium metal. Likewise, the classification of CdTe is based on the Cd++ ion related ecotoxicity reference values (see summary section on “Ecotoxicological information: conclusion on classification”).
According to regulation (EC) 1907/2006 (REACH) a PBT and vPvB assessment shall usually be conducted as foreseen in Article 14 (3) (d) in conjunction with Annex I Section 4 and according to the criteria laid down in Annex XIII. However, according to Annex XIII a PBT and vPvB assessment shall not be conducted for inorganic substances.CdTe is an inorganic substance, thus a PBT and vPvB assessment is not required.
Still, the points below are raised:
Cadmium is an element and as such, the criterion “persistence” is not applicable to Cd and Cd-compounds.
"Persistence" or its contasting concept "(bio-)degradability", is relevant for chronic classification. Since degradability is not applicable to inorganic substances, the concept of “removal from the water column” has been developed for inorganic substances as an alternative for degradability.
In section 4.6 (of the CSR), the rapid removal of cadmium from the water column is documented. Following this approach, cadmium and its compounds can be considered as equivalent to (rapidly) “degradable” in a context of chronic toxicity.
Data on bioaccumulation of cadmium are presented and discussed under section 4.3. From this analysis, the following was concluded:
There is a number of data available on the possible accumulation of cadmium in aquatic organisms.
BCF in fish (whole body data) are generally below the criterion for considering a substance bioaccumulative.
Higher BCF /BAF factors are observed in the lower levels of the food chain (algae notably). However, there are some uncertainties with the data: the high BCF/BAF factors observed in the algae are (at least partly) due to external absorption, not to uptake. In general, algae data are not considered in a context of bioaccumulation. The higher levels in invertebrates may be related to lack of gut clearance of the organisms studied.
In terms of hazard identification/classification, several considerations speak further against considering Cd as bioaccumulative substance:
-the BCF/BAF values observed with Cd consistently decrease with increasing exposure, which clearly shows some level of physiological regulation of uptake. One of the key theoretical conditions of the BCF model in terms of its relevance for chronic toxicity and applicability to the hazard identification/classification of chemicals is that the BCF/BAF should be independent of exposure. BCF/BAF values should in other words remain fairly constant over a range of exposures, which is clearly not the case for Cd.
-Evidence related to biomagnification in the aquatic food chain consistently shows that Cd is not biomagnifying.
The data on terrestrial organisms show that cadmium is not bioaccumulating in terrestrial organisms. Based on an extensive review of evidence on a wide variability of taxonomic groups, McGeer et al (2003) concluded that the BCF/BAF criteria, as conceived for organic substances, are inappropriate for the hazard identification and classification of metals, including Cd. They highlighted the inconsistency between BCF/BAF values and toxicological data, as BCF values are highest (suggesting hazard) at low exposure concentrations and are lowest (indicating no hazard) at the highest exposure concentrations, were toxicity is likely.
Considering the elements mentioned above, cadmium and its compounds are considered as not bioaccumulative.
Related to secondary poisoning, the following was concluded from the analysis in section 4.4.:
In the freshwater compartment, the risk of secondary poisoning of fish eating birds by Cd is predicted to be smaller than the direct effects of Cd in the aquatic environment. The EU risk assessment demonstrated, using BCF’s of fish (mentioned in section 4.3) that the Cd concentration in whole fish at the PNECwaterof 0.19 µg Cd/l (section 7.) could be predicted to range between 0.0001 and 0.13 mg Cd/kg fresh weight using the whole range of BCF’s (0.5-684 l/kg fresh weight). It was concluded that these Cd concentrations were below the PNECoral for birds or birds + mammals (ECB 2007).
In the terrestrial compartment, a PNEC for secondary poisoning was calculated from the lowest observed PNECoralvfor mammals and birds, which was derived from feeding studies with Cd salt spiked diets. Nine feeding studies were selected (sub-chronic and chronic studies), four studies with birds and 5 studies with mammals. The PNECoral of 0.9 µg Cd/g DW soil was calculated from the lowest NOEC using an assessment factor (see section 7). It follows from the risk characterisation under section10.2.2. (Environment (combined for all emission sources), that the PNEC secondary poisoning is in general not reached in soil.
The reference values for aquatic toxicity following from section 7 are 18µg/l for acute toxicity, and 0.21 µg Cd/l for chronic aquatic toxicity.
Summary and overall conclusions on PBT or vPvB properties
According to Annex XIII of regulation (EC) 1907/2006 (REACH) a PBT and vPvB assessment shall not be conducted for inorganic substances. Cd is an inorganic substance, thus a PBT and vPvB assessment is not required. Still, based on the elements mentioned above, cadmium and its compounds are considered as non-bioaccumulative and non-persistent.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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