ABSTRACT
Background Aluminum and fluoride are neurotoxic, and aluminum exposure alone is closely related to the overall cognitive function of operational workers. It is unclear about the effect of aluminum and fluoride interactions on cognitive function. Objective To evaluate a potential interaction effect of blood aluminum and urinary fluoride on the overall cognitive function of workers working in an aluminum plant. Methods Using cluster sampling, 230 workers in the electrolysis workshop of an aluminum group company in Shanxi Province were selected, and plasma aluminum concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS) and urinary fluoride by ion-selective electrode. The study participants were divided into a low blood aluminum group and a high blood aluminum group according to the median (M) of blood aluminum concentration, and a low urinary fluoride group and a high urinary fluoride group by a predetermined cutoff point (2.160 mg·L−1). The Montreal Cognitive Assessment-Beijing (MoCA-BJ) was used to assess overall cognitive function of the workers. Logistic regression model was used to analyze the relationship between blood aluminum, urinary fluoride, and mild cognitive impairment (MCI), including multiplicative interaction analysis and correlation analysis; R language was used to fit an additive interaction model of blood aluminum and urinary fluoride on MCI and to calculate synergy index (S), relative excess risk due to interaction (RERI), and attributable proportion due to interaction (API). Results Among the 230 operational workers, the median blood aluminum concentration (P25, P75) was 40.11 (25.16, 58.89) µg·L−1, and there were 104 cases of abnormal urinary fluoride, with an abnormality rate of 45.2%. There was a multiplicative interaction (OR=7.783, 95%CI: 1.377, 43.991) and no additive interaction (RERI=0.030, 95%CI: −0.498, 0.559; API=0.018, 95%CI: −0.279, 0.316; S=1.049, 95%CI: 0.519, 2.118) for the effect between blood aluminum and urinary fluoride on overall cognitive function of the workers. The logistic regression analysis showed that the risk of MCI was 12.105 (95%CI: 2.802, 52.287) times higher in workers with both high blood aluminum and high urinary fluoride than in those with low blood aluminum and low urinary fluoride, after adjusting for selected influencing factors. Conclusion Occupational exposure related high blood aluminum and high urinary fluoride are risk factors for cognitive dysfunction, and the coexistence of both indicators increases the risk of MCI in workers with occupational aluminum exposure, with a multiplicative interaction.
ABSTRACT
Objective@#To examine the correlation between visuospatial construction ability and occupational aluminum exposure among aluminum workers, so as to provide the evidence for early protection of occupational injury among aluminum workers.@*Methods@#A total of 442 workers in an aluminum factory in Shanxi Province were selected using a cluster sampling method, and participants' demographic features and occupational history were collected. The blood aluminum concentration was measured using inductively coupled plasma mass spectrometry (ICP-MS), and the visuospatial construction ability was evaluated with the Cube Copying Test (CCT) of the Chinese version of the Montreal Cognitive Assessment (MoCA). The correlation between the visuospatial construction ability and blood aluminum concentration was examined using a multivariable logistic regression model.@*Results@#A total of 442 aluminum workers were enrolled, and all participants were male, with a mean age of (43.40±7.31) years, labor service duration of (23.64±8.35) years and a mean blood aluminum concentration of 33.87 µg/L. Of all participants, there were 206 workers with impaired visuospatial construction ability (46.61%), including 127 workers with blood aluminum concentrations of >33.87 µg/L (61.65%); 190 workers with educational duration of 6 to 9 years (92.23%), 118 electrolytic aluminum workers (57.28%), 114 workers with work shifts (55.34%), and 123 workers with a very good sleep quality (59.71%). Multivariable logistic regression analysis revealed that blood aluminum concentrations of >33.87 µg/L (OR=2.490, 95%CI: 1.531-4.052), educational duration of 6 years or more (OR: 0.075-0.246, 95%CI: 0.015-0.622), work type as a non-electrolytic aluminum worker (OR=0.838, 95%CI: 0.425-0.987), work shift (OR=1.179, 95%CI: 1.078-1.435) and a very good sleep quality (OR=0.104, 95%CI: 0.012-0.896) significantly correlated with impaired visuospatial construction ability among aluminum worker.@*Conclusion@#Impaired visuospatial construction ability correlates with occupational aluminum exposure among aluminum workers.