Cadmium

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

a) Cd metal powder

In the EU Risk assessment, Cd metal 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 (0.192 mg/l) and 28 days (0.198 mg/l) was exceeding the reference values for acute and chronic ecotoxicity, resp.(ECB 2007).

From these results, it followed also that the acute reference value would be reached at a loading rate between 10 and 100µg/l (e.g. at a loading rate of 100 µg Cd powder/l the expected release of Cd++ (19.2µg/l) would still exceed the reference value), so the M-factor was 10. This T/D test was performed in pH 8 medium. Although in pH 6 waters, the release of Cd++ is anticipated to be higher then at pH8, the increase is expected not to change the conclusion (expected increase pH 6 versus pH 8 based on data on Cd-containing materials:factor 2.2 maximum). 

b) Cd metal in massive form

Forthe massive form of cadmium metal, the EU risk assessment also concluded to a classification as as -N, R50/53. This conclusion was based on 7-d T/D data obtained cadmium metal particles, which gave highly variable results. The rate of transformation/dissolution was not related to loading.

On the basis of the single highest Cd++ release value, observed in the 10mg/l loading test, (0.138mg/l; average of the 3 replicates was 0.062 mg/l) and considering also that these results were obtained at pH 8, exceedance of the acute ecotoxicity reference value could be anticipated with 1mg/l loading (0.014 x 2.2= 0.031mg/l), so this classification seemed to be supported by the limited data.

In the meantime, more refined techniques have been developed for assessing the release of metal ions from massive metal , and analysis is ongoing at pH 6 (where release is highest). While awaiting these results, the revised classification of cadmium metal in massive form is still based on the data of the EU risk assessment.

Revised classification under 2nd Adaptation to Technical Progress (ATP) to the CLP Regulation (2nd ATP CLP)

a) Cd-metal powder

Reconsidering the data mentioned above onCd-powder, the following classification can be derived based on the2^ndATP CLPrules:

-acute aquatic effects: at 1mg/l loading of the finest powder on the EU market, the release of Cd++ ions after 7days (0.192mg/l) was exceeding the reference values for acute (18µg/l) ecotoxicity (ECB 2007). ThereforeCd powder is classified as acute 1. M-factor: 10 , H400 (Very toxic to aquatic life)(see above 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 0.198 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 Cd-powder can be calculated as being 19.8 µg/l and 1.98 µg/l, resp. These releases exceed the reference value for chronic aquatic effects (0.210µg/l). So, Cd 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 0.198mg Cd++/l

ðat 10µg/l loading, the extrapolated Cd++ release is 1.98 µg/l.

ðat 1µg/l loading, the extrapolated Cd++ release is 0.198 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: 0.198µg/l. However, this result was obtained at pH 8. At pH 6, the Cd++ release will be higher, factor 2.2 maximum. Consequently, the chronic ecotoxicity reference value is expected to be exceeded at 1µg/l loading. At 0.1µg/l loading, the reference value would not be exceeded. Thereforethe classification for Cd metal powder is chronic 1, with M-factor 10,H410 (very toxic to aquatic life with long lasting effects).

b) Cadmium metal in massive form

Acute aquatic effect: the acute ecotoxicity reference value is exceeded at 1mg/l loading (see above: the single highest Cd++ release value, observed in the 10mg/l loading test, was 0.138mg/l); considering also that these results were obtained at pH 8, the anticipated T/D at pH 6 can be estimated as 0.014 x 2.2= 0.031mg/l, which exceeds the acute reference value). It can be further calculated from these data that the reference value is reached at about 550µg/l loading (by extrapolation: 1mg/l loading: 0.031mg/l; so, 0.018mg/l is reached at 1 x 18/31= 0.55mg/l loading).In conclusion, Cadmium metal in massive form is classified acute 1, with an M-factor of 1,H400 (Very toxic to aquatic life).

Chronic aquatic effect: no tests were performed for longer than 7 days on Cd massive metal. As indicated above, the results obtained after 7 days were not consistent (e.g. no relationship between loading and Cd-release could be measured). However, in the lowest loading series (10mg/l, giving the highest release!), 2 out of 3 replicas were reaching equilibrium at 7days (ECB 2007). So these data can be extrapolated to 28 days, with reservation: the transformation/dissolution at 28 days is assumed the same as at 7 days.

Considering Cd further as equivalent to “rapidly degradable” (see above), the reference value for chronic ecotoxicity is exceeded at 10µg/l loading (1.4µg Cd/l versus 0.21µg/l), so the substance is classified chronic 1.

M-factor: the chronic ecotoxicity value is still exceeded at 1µg/l loading (0.14µg/l x 2.2 (see above)= 0.31µg/l), but not at 0.1µg/l loading. In conclusion, cadmium metal in massive form is classified chronic 1, with an M-factor of 10,H410 (very toxic to aquatic life with long lasting effects).

As indicated, the T/D data on Cd metal in massive form were not consistent and unreliable. Therefore, cadmium in massive form is being re-tested , using the more advanced techniques that have in the meantime been developed for massive metal T/D testing. These tests are ongoing; the classification of cadmium metal in massive form will be reconsidered based on these data; in the meantime however, the analysis as above is proposed.