Molybdenum and its compounds have been recognized as having a low toxicity to man for several decades and occupational exposures have not been associated with toxicity. On the contrary molybdenum is an essential trace element in the body in which it is a component of at least three enzymes and hence is necessary for normal life and health although this would not preclude poisoning when consumed in excess. In 1989 the Austrian Regulatory Authorities announced their intention to classify molybdenum tri-oxide as 'toxic' as opposed to 'harmful' to health, based upon the reference of a toxicity level in the Environmental Chemicals Data and Information Network (ECDIN List). The implication of this would have been that consignments of the material would be required to carry a special cautionary label warning workers and others involved in transportation and storage of the potential hazard.