halides in which Tm is in its 2+ valence state, are promising luminescent materials that can make efficient electricity generating windows based on the principle of a luminescent solar concentrator, possible. Biological role and precautions Soluble thulium salts are mildly toxic, but insoluble thulium salts are completely nontoxic. When injected, thulium can cause degeneration of the liver and spleen and can also cause hemoglobin concentration to fluctuate. Liver damage from thulium is more prevalent in male mice than female mice. Despite this, thulium has a low level of toxicity. In humans, thulium occurs in the highest amounts in the liver, kidneys, and bones. Humans typically consume several micrograms of thulium per year. The roots of plants do not take up thulium, and the dry matter of vegetables usually contains one part per billion of thulium. Thulium dust and powder are toxic upon inhalation or ingestion and can cause explosions. See also References External links Chemical elements Chemical elements with hexagonal close-packed structure Lanthanides Metals Reducing agents