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Abstract

In the olfactory epithelium the primary olfactory neurons are in contact with the environment in the nasal cavity and they are also connected to the olfactory bulbs of the brain. These neurons may therefore provide a pathway by which foreign materials may reach the brain. Inhalation of cobalt-containing dust or fumes occurs in several workplaces, which may result in high exposure of the nasal tissues. In the present study, we used autoradiography and gamma-spectrometry to examine the transport of cobalt in the olfactory system after intranasal administration of Co-57(2+) in rats. The results showed an uptake of the metal in the olfactory mucosa and a transport to the olfactory bulbs of the brain. The metal accumulated in the olfactory nerve layer and the terminals of the primary olfactory neurons in the glomerular layer of the bulb. In addition, low levels of cobalt were seen to migrate into the interior of the bulbs and the anterior parts of the olfactory cortex, indicating that the metal is able to leave the terminals of the primary olfactory neurons. Occupational exposure to cobalt, which is a neurotoxic metal, occurs in several workplaces, e.g. the hard metal industry. Memory deficits have been observed among workers exposed to hard metal via inhalation, and it was considered that cobalt may be the neurotoxic component of the hard metal. We propose that inhaled hard metal (as a dust powder or in a mist form) is deposited in the nasal passages and that released cobalt, after uptake into the brain via the olfactory pathway, may cause neurtoxicity. We consider that the olfactory route of entry of cobalt into the brain may be important and should be taken into account when risk assessments are performed concerning occupational inhalation of this metal. (C) 2003 Elsevier Ireland Ltd. All rights reserved.

Keywords

olfactory; cobalt; brain; rat

Published in

Toxicology Letters
2003, volume: 145, number: 1, pages: 19-27
Publisher: ELSEVIER SCI IRELAND LTD

SLU Authors

UKÄ Subject classification

Neurosciences

Publication identifier

  • DOI: https://doi.org/10.1016/S0378-4274(03)00266-2

Permanent link to this page (URI)

https://res.slu.se/id/publ/1310