Cadmium hydroxide

Endpoint summary

Description of key information

Although original studies were not available, data for cadmium oxide and cadmium metal powder suggest that the slightly soluble or insoluble forms ofcadmium (like also cadmium hydroxide and cadmium carbonate) may present lower oral acute toxicity than the soluble cadmium compounds. To date, they are not classified for this endpoint.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

2 330 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

56 mg/m³ air

Acute toxicity: via dermal route

Endpoint conclusion

Value:

mg/kg bw

Additional information

When administered orally, the water soluble cadmium chloride caused mortality at relatively low doses, with LD50s in mouse and rat ranging from 29 to 327 mg Cd/kg bw. On this basis, cadmium chloride has been classified asT; R25 (toxic if swallowed) in Annex I of Directive 67/548/EEC.Under GHS-CLP, the corresponding classification would be ‘Acute toxicity (oral) category 3; H301’. Although no animal studies are available, cadmium sulphate is also classified in Annex I asT; R25, which is justified given its comparable solubility to cadmium chloride. Cadmium nitrate, also highly water soluble, is at present not classified for acute oral toxicity but a similar classification should be considered.

Although original studies were not available, data for cadmium oxide and cadmium metal powder suggest that the slightly soluble or insoluble forms of cadmium (like also cadmium hydroxide and cadmium carbonate) may present lower oral acute toxicity. To date, they are not classified for this endpoint. The only exception is cadmium sulphide which, despite being insoluble, carries an Xn; R22 (harmful if swallowed) in Annex I of Directive 67/548/EEC (the corresponding GHS-CLP classification would be ‘Acute toxicity (oral) category 4; H302).Given that there are no studies to support this classification, a revision of this classification may be appropriate based on solubility properties.

In humans, the no observed effect level (NOEL) of a single oral dose is estimated to be equivalent to3 mg Cd/person(i.e. 0.05 mg/kg bw for a 60 kg person) and the lethal dose is estimated to range from350 to 8,900 mg Cd/person (i.e. 5.8 to 148 mg/kg bw for a 60 kg person).

Cadmium chloride and oxidehave a high acute toxicity by the inhalation route. The most reliable result for these substances is the LC50 value of ca.56 x 10^-3mg Cd/L from the study of Rusch et al.(1986). Based on this values, the substances can be classified asT+; R26(Very toxic by inhalation)in Annex I of Directive 67/548/EEC (the corresponding GHS-CLP classification is‘Acute toxicity (inhalation) category 2;H330). For cadmium carbonate, an LC50 of > 66x 10^-3mg Cd/Lwas identified (Rusch et al.1986). If the value of 66x 10^-3mg Cd/L is used in a conservative approach, the classification for cadmium carbonate would also be T+; R26 (Very toxic by inhalation) according to Directive 67/548/EEC (the corresponding GHS-CLP classification is‘Acute toxicity (inhalation) category 2;H330). Based on the available data and read-across due to comparable toxicity and/or solubility / bioavailability, cadmium sulphate and metal have been classified asT+; R26(Very toxic by inhalation)in Annex I of Directive 67/548/EEC (the corresponding GHS-CLP classification is‘Acute toxicity (inhalation) category 2;H330). Based on comparable toxicity and/or solubility / bioavailability, all other highly and slightly soluble cadmium forms, i.e. cadmium nitrate, hydroxide and carbonate should carry a comparable classification.

For human health, observations indicatethat an 8 hour inhalatory exposure to 5 mg Cd/m3 is lethal and 1 mg Cd/m³is immediately dangerous for life.

No information was located regarding effects in humans after dermal exposure to cadmium. However, acute toxicity via the dermal route is not expected to be significant as uptake of soluble and less-soluble cadmium compounds applied onto the skin of animals appears to be low (<1%) (see Section 5.1.1).Also in view of the risk reduction measures which need to be taken as a result of the carcinogenicity of cadmium metal and some of the cadmium compounds, acute dermal toxicity is not likely to pose an issue for human health. No corresponding classification is therefore required.

Justification for classification or non-classification

Although original studies were not available, data for cadmium oxide and cadmium metal powder suggest that the slightly soluble or insoluble forms of cadmium (like also cadmium hydroxide and cadmium carbonate)may present lower oral acute toxicity. To date, they are not classified for this endpoint. The only exception is cadmium sulphide which, despite being insoluble, carries anXn; R22(harmful if swallowed) in Annex I ofDirective 67/548/EEC (the corresponding GHS-CLP classification would be ‘Acute toxicity (oral) category 4; H302).Given that there are no studies to support this classification, a revision of this classification may be appropriate based on solubility properties.

The acute inhalation 4 h LC50 values were found to be equivalent to > 2.3x 10^-3mg Cd/Lfor cadmium chloride and in the range of > 0.8 x 10^-3to ca. 56 x 10^-3mg Cd/Lfor cadmium oxide. The most reliable result for these substances is the LC50 value of ca.56 x 10^-3mg Cd/L from the study of Ruschet al.(1986). This value will therefore be used for classification and risk assessment purposes. For cadmium carbonate, an LC50 of > 66x 10^-3mg Cd/Lwas identified. Based on the available data and read-across due to comparable toxicity and/or solubility / bioavailability, cadmium sulphate and metal have been classified asT+; R26(Very toxic by inhalation)in Annex I of Directive 67/548/EEC (the corresponding GHS-CLP classification is‘Acute toxicity (inhalation) category 2;H330). Based on comparable toxicity and/or solubility / bioavailability, all other highly and slightly soluble cadmium forms, i.e.cadmium nitrate,hydroxide and carbonate should carry a comparable classification.

No information is available for insoluble cadmium compounds.

For human health, observations indicatethat an 8 hour inhalatory exposure to5 mg Cd/m3 is lethal and 1 mg Cd/m³is immediately dangerous for life.

No information was located regarding effects in humans after dermal exposure to cadmium. However, acute toxicity via the dermal route is not expected to be significant as uptake of soluble and less-soluble cadmium compounds applied onto the skin of animals appears to be low (<1%) (see Section 5.1.1).Also in view of the risk reduction measures which need to be taken as a result of the carcinogenicity of cadmium metal and some ofthecadmium compounds, acute dermal toxicity is not likely to pose an issue for human health. No corresponding classification is therefore required.