Cadmium hydroxide

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 Cd(OH)₂, which is a soluble substance, is made by considering 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

Under directive 67/548/EECCd(OH)₂was classified as N, R50/53 (very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment; cfr “group classification “Cd compounds” in Annex I dangerous substances directive 67/548/EEC).

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

Accordingly, under CLP, this classification listed in Annex I to Directive 67/548/EEC was translated as acute 1 (H400) - chronic 1 (H410) (very toxic to aquatic life with long lasting effects) according to Annex VI of the EU CLP Regulation (EU 2008). 

Further, the acute reference value 18 µg/l results in an M-factor of 10.

For setting the chronic M-factor, the reference value of 0.21µg/l is considered against the classification criteria for chronic aquatic effects.

For setting these 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”. 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. As a result, the chronic reference value results in an M-factor of 10 (chronic 1 criterion = 10µg/l).

In conclusion,Cd(OH)₂is classified under CLP as H400, H410. The M-factor for both acute and chronic aquatic effects is 10.

 

General discussion

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.