Lanthanides are increasingly mined. They are vital in many industries and technologies like metallurgy, petroleum, electronics, and medical imagery.

Philippe J. Thomas and colleagues, Carleton University, Ottawa, ON, Canada, tested the toxicity of three rare earth elements (REEs; La, Y, and Ce) on native plants and crops and found that increased concentrations of REEs may become problematic under some environmental conditions.

Their results of dose–response studies performed in artificial soil under greenhouse conditions, chemical analyses of all soils and in plants tested with Ce, as well as the detection of effects on growth parameters continue to support the notion that REEs are of limited toxicity and not considered extremely hazardous to the environment.
However, the team also shows that increased use of REEs will increase environmental levels and that slow accumulation in the environment could become problematic.

More research needs to be done, but they suggest that close monitoring may be needed in areas where REE contamination is likely – e.g., in regions with high REE abundance levels in soil like Russia and Nigeria, where phosphatebased fertilizers mined from monazite deposits are used, or at sites located near landfills with, e.g., improperly disposed batteries, where surface runoff could contaminate the local environment.

• Rare earth elements (REEs): Effects on germination and growth of selected crop and native plant species,
  Philippe J. Thomas, David Carpenter, Céline Boutin, Jane E. Allison,
  Chemosphere 2014, 96, 57–66.
  DOI: 10.1016/j.chemosphere.2013.07.020