The Association between Olfactory and Cognitive Function Tests with Aluminum Biomarkers in an Occupationally Exposed Population from Zunyi, China

摘要

High aluminum (AI) exposure has been associated with neurological and olfactory disorders; however, the degree to which AI damages the brain remains unknown. Therefore, the aim of this cross-sectional study of factory workers from Zunyi, China was to determine the relationship between cognitive and olfactory function with three AI biomarkers: bone (BnAI) (n=43), blood (WbAI) (n=60) and fingernail (FnAI) (n=61). Olfactory function was assessed with the University of Pennsylvania Smell Identification Test and cognitive function was assessed with the WHO/UCLA Auditory Verbal Learning Test (AVLT). Bone measurements were taken noninvasively with a compact in-vivo neutron activation analysis system and both WbAI and FnAI samples were analyzed using inductively coupled plasma mass spectrometry. Other variables were self-reported via questionnaire. Linear regression models adjusted for age, education, factory, current alcohol consumption and current smoking status. Median AI values were: 235 μg/L (interquartile range (IQR)=72) WbAI; 35 μg/g (IQR=50) FnAI and 15 μg/g (IQR=28) BnAI. Unadjusted regressions indicated a significant decrease in olfactory function related to an increase in AI for both FnAI (β=-0.045, 95% confidence interval (CI)=-0.086, -0.004) and WbAI (β=-0.011, 95% CI=-0.018, -0.004). Adjusted regression models showed a significant association between increasing WbAI and increased AVLT intrusions (worse performance) for trial 3 (β=-1.002, p=0.004) and 7 (β=-2.473, p=0.002). Our study found some, but not all, measures of short-term Al exposure were significantly associated with olfactory and cognitive tests. None of the test outcomes were significantly associated with BnAI, a novel measure of cumulative Al exposure. Larger studies are needed to definitively confirm the lack of association between BnAI with cognitive and olfactory function.