Professional welders risk losing their sense of smell

Researchers at the University of Pennsylvania School of Medicine have found that professional welders who work in enclosed spaces with poor ventilation may be at risk for loss of sense of smell. The study appears in Neurology.

“This is the first study to clearly demonstrate that welders who work in confined spaces without adequate respiratory protection are at risk for damaging their sense of smell,” says Richard Doty, PhD, Director, Smell & Taste Center, Professor, Department of Otorhinolaryngology, and senior study author.

“Although underappreciated, loss of smell function significantly alters quality of life. This important sense not only determines the flavors of foods and beverages, but serves as an early warning system for the detection of fire, dangerous fumes, leaking gas, spoiled foods, and polluted environments.”

Using the University of Pennsylvania Smell Identification Test (UPSIT) – a self-administered standardized test incorporating 40 “scratch-and-sniff” odors with multiple choice options to identify the odor – the researchers quantitatively evaluated the olfactory function of 43 professional welders who worked in confined spaces on the San Francisco/Oakland Bay Bridge, and compared their test scores with those of matched normal controls.

Dr. Doty and colleagues found that the mean UPSIT scores of the welders were, on average, seven points lower than those of their matched controls (29.62 and 36.90). Thirty eight (88%) performed more poorly than their controls, although only 3 (7%) had a total loss of their sense of smell. The percentages of those with mild, moderate, or severe loss of the sense of smell were 30.2, 18.6, and 16.3. The researchers report that interestingly, of the 42 subjects who provided information regarding their sense of smell before being tested, more than half were unaware of a problem.

Blood tests were administered to test for blood levels of chemicals found in welding fumes. The blood tests revealed that 40.5% of the welders had abnormally elevated levels of manganese (Mn). Although this suggests that the welders were exposed mainly to Mn, it is not entirely clear whether Mn is the basis of their olfactory problems. In fact, the welders with the highest Mn blood levels exhibited better olfactory function than those with the lowest Mn blood levels.

The welders also underwent a neuropsychological test battery. Dr. Doty notes, however, that, “The results of this study suggest that exposure to the fumes of welding can alter the ability to smell, and that changes in this important sensory system are not correlated with alterations in cognitive function, which also can be induced by toxins in welding fumes.”

The researchers conclude that the basis of the smell loss among the welders is not entirely clear. They suggest that although the research shows that the welders had smell dysfunction in relation to the matched controls, additional groups, such as ones consisting of non-welder industrial workers, might be of value in better defining the causality.

Marcelo B. Antunes, Penn, and Rosemarie Bowler, San Francisco State University are co-authors on this study.

This study was supported, in part, by grants from the National Institutes of Health.

Disclosure: Dr. Doty is a major shareholder in Sensonics, Inc., the manufacturer of the olfactory test used in this study.

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