Longitudinal study of the effects of occupational aluminium exposure on workers’ cognition

To explore the effects of occupational aluminium(Al) exposure on workers’ cognition through a longitudinal study. The study population consisted of 276 workers in an Al factory. In 2014, we used inductively coupled plasma mass spectrometry (ICP-MS) to determine the plasma aluminium (P–Al) concentration of the workers, and a combined questionnaire to test the workers’ cognitive function. Followed-up in 2016, the workers were tested again for cognitive function. Generalized linear regression was used to assess the association between P–Al concentration and cognitive scores, and multivariable logistic regression was used to assess the risk of cognitive decline caused by Al exposure. Generalized linear regression results showed that a non-significant association was found between the P–Al concentration and cognitive test scores (P > 0.05) in 2014. Two years later, each 10-fold increase in P–Al concentration was inversely associated with the score of Mini-Mental state examination (MMSE) (β: −0.53, 95% CI: −0.86, −0.20) and Fuld object memory evaluation (FOME) (β: −0.93, 95% CI: −1.62, −0.24). Each 10-fold increase in P–Al concentration was inversely associated with MMSE2016-2014 (β: −0.38, 95% CI: −0.74, −0.01) and FOME2016-2014 (β: −1.20, 95% CI: −1.95, −0.45). There was a statistically significant difference in the average annual rate of change of MMSE and FOME with the tertile of P–Al concentration increase (P < 0.05). The multivariable logistic regression results showed that as the P–Al concentration increased, the risk of a FOME score decline increased (P trend = 0.009). Continuous occupational Al exposure can damage workers’ overall cognitive ability, especially episodic memory function.