Olfaction Testing and Associated Factors among Older U.S. Farmers

TL;DR

This study tested the sense of smell in older U.S. farmers and found factors like age, health history, and season that may affect olfaction.

Contribution

This is the first study to characterize olfaction testing in older farmers and identify associated factors.

Findings

37.8% of older farmers had good olfaction, 34.2% moderate, and 28.0% poor olfaction.

Older age, certain health conditions, and seasonality were linked to poor olfaction.

Pesticide exposure and gasoline use showed lower olfaction scores, though not statistically significant.

Abstract

Poor olfaction is common in older adults and may signify adverse health conditions. We tested olfaction in 2545 older farmers from North Carolina and Iowa between 2020-2021, using the 12-item Brief Smell Identification Test (B-SIT). We compared their B-SIT score with perceived testing experience and examined factors that may associate with the test results, accounting for sampling design, study participation, and covariates. Overall, 37.8% of the farmers had good olfaction (B-SIT score 11-12), 34.2% moderate olfaction (9-10), and 28.0% poor olfaction (0-8). A higher B-SIT score correlated with perceived more odorants identified (Spearman’s ρ = 0.65) and perceived odor strength (Spearman’s ρ = 0.54). Older age, single marital status, North Carolina residence, and a history of asthma, acute recurrent sinus infections, and surgery of the nose or brain were associated with poor olfaction. Seasonality was associated with B-SIT results, with the highest scores in the summer (June to August) and the lowest in the Spring (March to May), with a mean difference of 0.48. Allergic or cold symptoms (e.g., running nose, sore throat, sinus pain) or farming activities (e.g., working in animal confinement areas or around wood/metal dust) in the past 24 hours were generally unrelated to poor olfaction. Although not statistically significant, those who reported loading/mixing/applying pesticides and cleaning hands or machines with gasoline in the past 24 hours had lower B-SIT scores. To our knowledge, this is the first study that characterized the olfaction testing experience in older farmers and reported factors that may associate their olfaction test results.