Aluminum cobalt oxide

Endpoint summary

Additional information

Hydrolysis of cobalt aluminium oxide is not expected, and testing is not required as the substance is highly insoluble in water.

Biodegradation in water, sediment and soil is not an applicable endpoint for cobalt aluminium oxide as the substance is inorganic.

No bioaccumulation data are available for cobalt aluminium oxide, however various reliable data exist for cobalt and aluminium (measured as environmental concentrations) and different analogue cobalt and aluminium substances.

In general, the bioaccumulation potential of cobalt in natural ecosystems is relatively low. First of all, low BAFs have been reported in eight laboratory (steady state) studies and four field studies; five BSAF-sediment values have been found to be well below 1; and four (out of four) average BSAF-soil values have been reported to be well below 1. In addition, results from six field investigations plus two laboratory studies indicate the absence of biomagnification of cobalt in natural food webs. Finally, cobalt is an essential micro-nutrient, the uptake of which is expected to be regulated to some extent by many organisms (Environment Canada, 2011). The data demonstrates that cobalt, like other essential elements, shows homeostatic control by organisms.

For aluminium, the available evidence shows the absence of aluminium biomagnification across trophic levels both in the 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 trophic levels in the food chain.

No adsorption/desorption data are available for cobalt aluminium oxide, however various reliable data exist for cobalt and aluminium (measured as environmental concentrations) and different analogue cobalt and aluminium substances showing statistical or conservative partition coefficients for suspended matter, soil, STP, sediments in freshwater and in coastal waters.

For cobalt, log Kd values for all types ranged from 0.41 to 5.83.

The amount of aluminium associated with suspended particles is dependent on the chemical conditions. Factors that are known to affect aluminium speciation, such as pH and DOC, are also known to affect adsorption and desorption from particle surfaces. The amount of aluminium bound to particles as a result of surface complexation (i.e. adsorption) was shown to be pH dependent, but was typically less than 8% of the total aluminium at pH 6, and was further reduced to below 1% at pH values above 7. The corresponding Log Kd values for this distribution ranged between 3 and 5.