Cadmium oxide

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.19 µg/L

Assessment factor:

2

Extrapolation method:

sensitivity distribution

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

1.14 µg/L

Assessment factor:

2

Extrapolation method:

sensitivity distribution

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

20 µg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

1.8 mg/kg sediment dw

Assessment factor:

1

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.64 mg/kg sediment dw

Assessment factor:

1

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.9 mg/kg soil dw

Assessment factor:

1

Extrapolation method:

sensitivity distribution

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

0.16 mg/kg food

Assessment factor:

10

Additional information

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, sediment and terrestrial toxicity data in this report are expressed as “cadmium”, not as the test compound as such, because ionic cadmium is considered to be the causative factor for toxicity. A further consequence of this is that all ecotoxicity data obtained on different cadmium compounds, are mutually relevant for each other. For that reason, the available ecotoxicity databases related to cadmium and the different cadmium compounds are combined before calculating the PNECs. 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 and may result in different classifications.

Conclusion on classification

The classification of Cadmium metal and sparingly soluble Cd-compounds is based on the capacity of these substances to release the Cd++ ion in standardized solutions (= “transformation/dissolution test -T/D test - OECD 2001). The Cd++ release measured after a given time (7d for acute effects, 28days for chronic effects) is compared to the ecotoxicity reference values for acute, and chronic aquatic effects, i.e.: 18 µg Cd/l and 0.210 µg Cd/l, resp. (ECB 2007).

Classification under Annex I dangerous substances directive 67/548/EEC

CdO powder

In the EU Risk assessment, CdO powder was classified as N, R50/53 (very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment; cfr Annex I dangerous substances directive 67/548/EEC), based on T/D results showing that at 1mg/l loading of the finest powder on the EU market, the release of Cd++ ions after 7days (0.095 mg/l) and 28 days (0.094 mg/l) was exceeding the reference values for acute and chronic ecotoxicity, resp.(ECB 2007).

 

Revised classification for CdO powder under2nd Adaptation to Technical Progress (ATP) to the CLP Regulation (2^ndATP CLP)

Reconsidering the data mentioned above on CdO powder, the following classification can be derived based on the2^ndATP CLP rules:

-acute aquatic effects: at 1mg/l loading of the finest powder on the EU market, the release of Cd++ ions after 7days (0.095mg/l) was exceeding the reference values for acute (18µg/l) ecotoxicity (ECB 2007). Therefore CdO powder is classified as acute 1.

Further, these results show that the acute reference value would be reached at a loading rate between 100 and 1000µg/l (e.g. at a loading rate of 100 µg CdO powder/l the expected release of Cd++ (9.5µg/l) would not exceed the reference value). However, it was noted that this T/D test was performed in pH 8 medium, so there was some uncertainty on the expected results of the same test performed at pH 6 (expected increase pH 6 versus pH 8 based on data on other Cd-containing materials: factor 2.2 maximum. Taking this into account, the reference value for acute aquatic effects could have been exceeded at pH 6 (9.5 x 2.2 = 21 µg/l). Therefore an M-factor of 10 is set.

Classification of CdO powder: acute 1 - M-factor: 10 , H400 (Very toxic to aquatic life ; cfr GHS)

-chronic aquatic effects: at 1mg/l loading of the finest powder on the EU market, the release of Cd++ ions after 28 days was 0.094 mg/l. Extrapolating these data to the loading criteria under2^ndATP CLP, the Cd++-release at 100 µg/l and 10 µg/l loading of the CdO-powder can be calculated as being 9.4 µg/l and 0.94 µg/l, resp. These releases exceed the reference value for chronic aquatic effects (0.210µg/l). So,CdO powder is classified chronic 1,in any case.

For defining the M-factor, the “degradability” 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”. Under section 4.6., 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. 

Considering the above, the following extrapolations from the maximum observed T/D data can be made:

• at 1 mg/l loading transformation/dissolution is 0.094mg Cd++/l
• at 10µg/l loading, the extrapolated Cd++ release is 0.94 µg/l.
• at 1µg/l loading, the extrapolated Cd++ release is 0.094 µg/l.

The chronic ecotoxicity reference value of 0.21 µg/l would thus not be exceeded by adding 1 µg/l Cd powder (extrapolated Cd release: 0.094µg/l. However, this result was obtained at pH 8. At pH 6, the Cd++ release is expected to be higher, factor 2.2 maximum. This would yield a Cd release of 0.207µg/l. This is very close to the reference value for chronic aquatic effects (0.210µg/l). Consequently,it is considered that the chronic ecotoxicity reference value may be exceeded at 1µg/l loading. At 0.1µg/l loading, the reference value would not be exceeded. Therefore the classification for CdO powder is chronic 1, with M-factor 10, H410 (very toxic to aquatic life with long lasting effects; cfr GHS)