Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

General considerations

A basic assumption made in this hazard assessment and throughout this CSR (in accordance to the same assumption made in the EU RA process) is that the ecotoxicity of cadmium and cadmium compounds is due to the Cd++ion. As a consequence, all aquatic and sediment PNEC's in this report are expressed as “cadmium”, not as CdTe as such, because ionic cadmium is considered to be the causative factor for toxicity. The only way cadmium compounds can differ in this respect is in their capacity to release cadmium ions into (environmental) solution. That effect is checked eventually in the transformation/dissolution tests.

Classification

Classification of CdTe was made based on CdTe-specific ecotoxicity data. Ecotoxicity tests were performed using Daphnia magna, Pseudokirchneriella subcapitata and Danio rerio as standard test species.

1. Acute toxicity results

Toxicity results were available for fish, daphnia and algae.

 species LC50 (mg Cd Te/L) reference 
 Danio rerio > 1000 Lab research (2011) 
 Daphnia magna 1.14 Vito (2012a,b) 
 Pseudokirchneriella subcapitata  3.1 Vito (2012d)

The lowest LC50 was observed for Daphnia magna; which is 1.14 mg CdTe/L. This leads to no acute classification.

Besides determining classification on ecotoxicity results, classification can also be determined from the T/D results. The ERV of Cd2+ is 18 µg/L. The results of the T/D tests indicates that 1mg CdTe/L brings 15 µg Cd/L into the solution. This indicates that the ERV of 18 µg Cd/L is not reached; which leads to no acute classification. This confirms the classification based on the ecotoxicity results.

2. Chronic ecotoxicity of CdTe

Test results were available for Daphnia magna and Pseudokirchneriella subcapitata. The fish test was waived based on the results of the acute ecotoxicity test, combined with the knowledge that invertebrates are the most sensitive taxonomic group for the Cd++ ion, as follows from the extensive database on chronic toxicity of soluble Cd compounds: invertebrates mean toxicity 3.04µg Cd/l (22 species NOECs, lowest value 0.21µg/l); fish mean toxicity 10.8µg Cd/l (18 species NOECs, lowest value 0.47µg/l); algae mean toxicity 9.13µg Cd/l (8 species NOECs, lowest value 0.85µg/l).

The lowest NOEC was found for Daphnia magna.

species NOEC reference
 Daphnia magna 0.2 mg CdTe/L  Vito (2012c) 
 Pseudokirchneriella subcapitata 0.37 mg CdTe/L  Vito (2012d)

For setting classification criteria, the “degradability” of the substance needs to be determined. Cadmium, like all metals, is an element, and therefore the criterion “degradability” cannot be applied as it is for organic substances. As a surrogate for assessing “degradability”, the concept of “removal from the water column” was developed to assess whether or not a given metal ion would remain present in the water column upon addition (and thus be able to excert a chronic effect) or would be rapidly removed from the water column. In this concept, “rapid removal” (defined as >70% removal within 28 days) is considered as equivalent to “rapidly degradable”. The rapid removal of Cadmium from the water column is documented. Consequently, the metal is considered as equivalent to being ‘rapidly degradable” in the context of classification for chronic aquatic effects. As a result, the chronic 1 criterion = 10µg/l. Considering this in combination with the ecotoxicity data given above, results in classification of CdTe for aquatic effects as "chronic 3".

The T/D results of CdTe (see section 5.6.) with a loading of 1 mg/L resulted after 28 days in 19.0 µg Cd/L. This indicates that the ERV value of 0.21 µg Cd/L is not reached at 0.01 mg/L loading but at 0.1 mg/L loading. This would lead to a chronic classification of 2. However, the results of the ecotoxicity experiments are considered to overrule the T/D results, so CdTe is classified as "chronic 3" for aquatic effects.