Nonoccupational Environmental Exposure to Manganese is Linked to Deficits in Peripheral and Central Olfactory Function

• Published in: Chemical senses Vol. 38; no. 9; pp. 783 - 791
• Main Authors: GUARNEROS, Marco, ORTIZ-ROMO, Nahum, ALCARAZ-ZUBELDIA, Mireya, DRUCKER-COLÍN, René, HUDSON, Robyn
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01-11-2013
• Subjects: Adult; Air Pollutants - chemistry; Air Pollutants - toxicity; Biological and medical sciences; Environment. Living conditions; Environmental Exposure; Female; Fundamental and applied biological sciences. Psychology; Hair - chemistry; Hair - metabolism; Humans; Male; Manganese - chemistry; Manganese - toxicity; Medical sciences; Middle Aged; Odorants; Olfaction. Taste; Olfactory Bulb - drug effects; Olfactory Bulb - physiopathology; Perception; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Public health. Hygiene; Public health. Hygiene-occupational medicine; Sensory Thresholds - drug effects; Smell - drug effects; cognitive function; Health and environment; olfactory performance; Olfaction; Perception; manganese exposure; Cognition; Exposure; Performance; Age; Manganese; age
• ISSN: 0379-864X; 1464-3553
• DOI: 10.1093/chemse/bjt045

Manganese is of growing concern as a toxic air pollutant. It is readily transported from the olfactory epithelium to the olfactory bulb, and unlike other metals, it is transported transynaptically to structures deep within the brain. However, little is known regarding the possible effect of nonoccupational exposure to manganese on olfactory function. Using the Sniffin' Sticks test battery, we compared the olfactory performance of subjects from a manganese mining district living <1 km from a manganese processing plant, with nonexposed subjects living 50 km from the closest source of exposure (N = 30/group). Groups were matched for age, sex, and schooling, and none had ever worked in mining-related activities. Concentrations of manganese in hair were measured as a biomarker of exposure; exposed subjects had significantly higher concentrations than nonexposed subjects. They were also significantly outperformed by the nonexposed subjects on all olfactory measures (threshold, discrimination, and identification), indicating adverse effects of manganese exposure on a range of olfactory functions, including those involving higher order cognitive processes. This contrasts with previous findings showing adverse peripheral but not central effects on olfactory function of big city air pollution, which mostly consists of toxicants known to affect the olfactory epithelium but with lower transynaptic transport capacity compared with manganese. We conclude that nonoccupational exposure to airborne manganese is associated with decrements in both peripheral and central olfactory function.