Aluminum cobalt oxide

Bioaccumulation: terrestrial

Description of key information

BCF/BAF (Co): 0.007 to 0.81 (wet weight basis) in plants
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 trophic levels in the food chain. 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).

Additional information

No data on terrestrial bioaccumulation 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

In terrestrial environments, four acceptable biota-to-soil accumulation factors (BSAF-soil) values were identified for two species, Xerocomus badius (bay bolete), and Morus alba (white mulberry). Measurements for X. badius ranged from 0.007 to 0.81, with an average value of 0.15 in the cap, and 0.11 in the stalk (unitless, based on wet-weight). For M. alba, maximum BSAF-soil values of 0.28 and 0.08 were found. One soil study considered the cobalt concentration in a soil solution, thus providing bioaccumulation factors for three different plant species. These values ranged from 0.100 to 0.146, wet-weight. All values obtained from soil studies were reported using dry-weight measurements and then converted to wet-weight values. It is observed that the average BSAF-soil and BAF values of these acceptable studies are all less than one (Environment Canada, 2011).

References:

Environment Canada. Health Canada (2011). Screening Assessment for the Challenge. Cobalt, cobalt chloride, cobalt sulfate.

Aluminium

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 trophic levels in the food chain. 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).