ABSTRACT
This chapter provides a detailed discussion on the occurrence and production, uses, chemical and physical properties, exposure and exposure limits, toxicokinetics, and effects of yttrium and lanthanides in humans. The crustal abundance of the naturally occurring rare earths ranges from 0.2 ppm for thulium to 46.1 ppm for cerium. Rare earth metals are recovered from ores containing massive monazite and monazite sand; bastnasite and related Ce group fluorocarbonates; and the yttrium group minerals gadolinite, euxenite, and xenotime. Lanthanide compounds are used in carbon-arc lighting for studio lighting, theater projection, and searchlights. Mixed lanthanide metals and cerium metal are used in lighter flints, magnesium alloys, and some iron alloys. Lanthanides are recovered by precipitation of the oxalates from a sulfuric acid solution of the ore. The effects of yttrium and lanthanides in humans include information on acute toxicity, chronic toxicity, biochemistry, specific organs and systems, teratogenicity, mutagenicity, and carcinogenicity.
