Lanthanum(3+) acetate

Bioaccumulation: terrestrial

Description of key information

Based on the available evidence, lanthanum can be concluded not to accumulate in the terrestrial foodchain, since BSAF values for plants and invertebrates are typically below 1.

Additional information

Because rare earth elements are being used as fertiliser to promote plant growth for certain types of crops in certain regions, a substantial amount of literature is available on the transfer of lanthanum to plants in the terrestrial environment. Only a limited amount of data is included in this dossier, however, this amount of information is considered sufficient for drawing conclusions on this endpoint.

Rikken (1995) summarized literature data on the accumulation of rare earth metals in plants, as a part of the investigation of data on the transfer of rare earths in the chain artificial fertilizers - soil - crops - livestock and man. The data for concentration of lanthanum in different vegetables and feeding stuffs and the soil were collected and biota-to-soil accumulation factors (BSAFs) were calculated.

The concentration and accumulation of rare earths in plants differed as a consequence of plant and soil properties (e.g., species, Ca-content). The concentrations of rare earth elements in plants (dry weight) were in general low: < 0.2 mg/kg dw for root and leaf vegetables, < 0.05 mg/kg dw in most fruits and < 1 mg/kg dw in herbs/grasses. BSAFs for rare earth elements are usually within a range of 0.0001 to 0.001 for feed crops and 0.0001 to 0.01 for food crops. For lanthanum specifically, BSAFs were in a range of < 0.00017 - 0.0052 for food crops and 0.00002 - 0.094 for feed crops.

Redling (2006) also concluded that the transfer of rare earth elements from soil into plants is very low. Concentration ratios of rare earths (mass of rare earths in dry weight of plant per mass in dry weight of soil) were reported to be generally in a range of 0.8 to 0.001. Furthermore, the very low concentrations of rare earth elements in cereal grains were confirmed and no significant accumulation was stated.

Furthermore, Tyler (2004) reviewed the information about rare earth elements in soil and plant systems and arrived at the conclusion that concentrations of rare earths in plants are usually very low compared to their total concentration in soils. For example, BSAFs in forest plants of NW Germany were reported to be as low as 0.04 - 0.09.

Next to information on transfer of lanthanum from soil to plants, some information can be added on transfer of lanthanum from sediment to sediment-dwelling organisms. As an example, Moermond et al. (2001, see endpoint 5.3.1) reported BSAF values from 0.043 to 0.823 for the amphipod Corophium volutator based on samples from the field as well as from a laboratorium study. This study indicates that lanthanum also has a low potential for bioaccumulation through transfer from solid phases to organisms living in contact with the solid phase under consideration.

Generally, the reviewed data indicated a low accumulation potential of lanthanum and rare earth elements in general. Therefore, it can be assumed that there is no risk for accumulation in the terrestrial/sediment food chain.

Specific references:

Rikken, M.G.J., 1995. De accumulatie van zeldzamen aardmetalen. RIVM Rijksinstituut voor volksgesondheid en milieu, Bilthoven. Report nr. 601014 013.

Redling, K., 2006. Rare earth elements in agriculture with emphasis on animal husbandry. Dissertation, University of Munich, Germany.

Tyler, G., 2004. Rare earth elements in soil and plant systems. A review. Plant and Soil 267: 191 -206.