Blood pressure mediated the effects of cognitive function impairment related to aluminum exposure in Chinese aluminum smelting workers

Abstract

ObjectivesThe aim of this study is to investigate the effects that the Al on blood pressure and the effect of hypertension in aluminum-induced cognitive impairment in electrolytic aluminum worker. MethodsThe study was conducted 392 male aluminum electrolytic workers in an aluminum plant of China. The concentration of alumina dust in the air of the electrolytic aluminum workshop is 1.07 mg/m3–2.13 mg/m3. According to the Permissible concentration-Time Weighted Average of alumina dust is 4 mg/m3, which does not exceed the standard. The blood pressure of the workers was measured. The plasma aluminum concentration of workers was determined by ICP-MS (Inductively Coupled Plasma Mass Spectrometry). Cognitive functions were measured using MMSE (Mini-Mental State Examination), VFT (Verbal Fluency Test), ATIME (Average Reaction Time), FOM (Fuld Object Memory Evaluation), DST (Digit Span Test), CDT (Clock Drawing Test) scales. Modified Poisson regression was used to analyze the risk of hypertension and cognitive impairment with different plasma aluminum concentrations. Generalized linear regression model was used to analyze the relationship between aluminum and cognitive function, blood pressure and cognitive function. Causal Mediation Analysis was used to analyze the mediation effect of blood press in aluminum-induced cognitive impairment. ResultsPlasma aluminum appeared to be a risk factor for hypertension (PR (prevalence ratio) = 1.630, 95 %-CI (confidence interval): 1.103–2.407), systolic blood pressure (PR = 1.578, 95 %-CI: 1.038–2.399) and diastolic blood pressure (PR = 1.842, 95 %-CI: 1.153–2.944). And plasma aluminum increased by e-fold, the scores of MMSE and VFT decreased by 0.630 and 2.231 units respectively and the time of ATIME increased by 0.029 units. In addition, generalized linear regression model showed that blood press was negatively correlated with the scores of MMSE and VFT. Finally, causal Mediation Analysis showed that hypertension was a part of the mediating factors of aluminum-induced decline in MMSE score, and the mediating effects was 16.300 % (7.100 %, 33.200 %). In addition, hypertension was a part of the mediating factors of aluminum-induced decline in VFT score, and the mediating effects was 9.400 % (2.600 %, 29.000 %) ConclusionOccupational aluminum exposure increases the risk of hypertension and cognitive impairment. And hypertension may be a mediating factor of cognitive impairment caused by aluminum exposure.