Aluminum cobalt oxide

Toxicity to birds

Description of key information

EC10 (14 d) = 251 mg Co/kg feed (Gallus gallus) for pathology (read-across from cobalt chloride hexahydrate)

Additional information

No data on the toxicity to birds are available for the test substance cobalt aluminium oxide. However, there are reliable data available for different structurally analogue substances.

The environmental fate pathways and ecotoxicity effects assessments for cobalt metal and cobalt compounds as well as for aluminium metal and aluminium compounds is based on the observation that adverse effects to aquatic, soil- and sediment-dwelling organisms are a consequence of exposure to the bioavailable ion, released by the parent compound. The result of this assumption is that the ecotoxicological behaviour will be similar for all soluble cobalt and aluminium substances used in the ecotoxicity tests.

As cobalt aluminium oxide has shown to be highly insoluble with regard to the results of the transformation/dissolution test protocol (pH 6, 28 d), it can be assumed that under environmental conditions in aqueous media, the components of the substance will be present in a bioavailable form only in minor amounts, if at all. Within this dossier all available data from cobalt and aluminium substances are pooled and used for the derivation of ecotoxicological and environmental fate endpoints, based on the cobalt ion and aluminium ion. For cobalt, only data from soluble substances were available and for aluminium, both soluble and insoluble substance data were available. All data were pooled and considered as a worst-case assumption for the environment. However, it should be noted that this represents an unrealistic worst-case scenario, as under environmental conditions the concentration of soluble Co2+ and Al3+ ions released is negligible.

Cobalt

Data on birds resulting in high quality information (expressed as Co) on several bird species (n=3) are summarized in the WHO CICAD (2006).

Dietary levels of 251 mg Co/kg feed, tested as cobalt chloride hexahydrate, caused a mortality of 10% in 14 day old broiler chickens, while concentrations of 116 mg Co/kg feed and higher decreased body weight and food intake significantly (Diaz et al., 1994). Another study on 2-week old chickens showed significant adverse effects on growth at 100 mg Co/kg diet, tested as cobalt chloride, and significant mortality at 200 mg Co/kg diet, tested as cobalt chloride, after 5 weeks. The latter study showed similar results at 200 mg Co/kg feed causing lesions and significant mortality at 500 mg Co/kg feed after 28 days in white peking ducklings.

References: World Health Organization (2006). Concise International Chemical Assessment Document 69. COBALT AND INORGANIC COBALT COMPOUNDS.

Aluminium

Aluminium (Al) impairment in birds and mammals is mainly related to its disruptive effect on calcium homeostasis as well as phosphorus metabolism. This adverse effect leads to muscle weakness and decreased growth rates (Scheuhammer 1987). This metal also induces defective eggshell formation and intrauterine bleeding in Al-contaminated pied flycatchers (Ficedula hypoleuca; Nyholm, 1981). Scheuhammer (1991) examined the accumulation of aluminium in different species of ducklings dwelling in an acidified lake in Ontario, Canada. The species of ducks chosen for study have significantly different feeding habits. Young black and ring-necked ducks feed mainly on surface insects in near-shore vegetation; goldeneye and hooded mergansers are pursuit divers that prey on large, mobile invertebrates, although goldeneye take more benthic material, and hooded mergansers probably take some fish and amphibians as well; common mergansers are almost exclusively fish-eaters. Tissue metal concentrations accumulated by ducklings during their first few months of life indicate that dietary exposure of ducklings to toxicologically relevant levels Al is unlikely to occur in acidified environments. Kidney-A1concentrations ranged from undetectable (< 0.01 µg/g) to about 5 µg/g.

Avian toxicity data are used in the assessment of secondary poisoning risks for the aquatic and terrestrial food chains. The available evidence shows the absence of aluminium biomagnification across trophic levels both in aquatic and terrestrial food chains. The existing information suggests not only that aluminium does not biomagnify, but rather that it tends to exhibit biodilution at higher levels of the food chain. The potential for massive aluminium, powders or aluminium oxide to be consumed by birds is extremely negligible. Therefore the need for additional testing for secondary poisoning can be waived. More detailed information can be found in the attached document (White paper on waiving for secondary poisoning for Al & Fe compounds final report 02-02-2010. pdf).

Conclusion
As the effect values derived from analogue cobalt compounds are considerably lower than those derived from analogue aluminium substances, it can be reasoned that the cobalt ion will mainly account for ecotoxicological effects of the substance. Hence, it was concluded to put forward the most sensitive and reliable results derived from analogue cobalt compounds for assessment purposes. Still, it should be noted that this represents an unrealistic worst-case scenario as under environmental conditions in aqueous media, the components of the highly insoluble substance will be present in a bioavailable form only in minor amounts, if at all, and hence, the concentration of soluble Co2+ and Al3+ ions released is negligible.