| Objective: In recent years,the prevalence of hypertension has generally increased and has become one of the most important public health issues worldwide.In addition to genetic factors,poor living habits and dietary habits,the relationship between concentrations of pollutants in the environment and hypertension has gradually attracted attention.Studies have shown that exposure to heavy metals in the environment increases the likelihood of the body developing hypertension.However,there is still a large research gap on how to evaluate the dose-response relationship between metal exposure and hypertension.In addition,it has not been reported whether essential trace elements in the body and their combined effect with heavy metals are related to the development of hypertension.Therefore,the purpose of this study is to explore the correlation between the concentration of metal in urine and the risk of hypertension in different populations,to estimate the benchmark dose and threshold in urinary metals,and to provide more accurate evidence for assessing health risks.Methods: This study selected 2119 subjects from the US National Health and Nutrition Examination Survey and 395 workers from a molybdenum factory and iron and steel foundry in Liaoning Province for cross-sectional analysis.The concentration of 5 metals in workers’ urine were determined by inductively coupled plasma mass spectrometry.For the general population,this study uses the inverse probability of treatment weighting to control confounding bias and uses a parametric or nonparametric approach to compare differences between consecutive or categorical variables of different groups(non-hypertensive and hypertensive),respectively.Logistic regression model was used to assess the relationship between urinary metals concentrations and the prevalence of hypertension,and then the Markov chain Monte Carlo simulation method based on the Bayesian benchmark dose analysis system was used to estimate the benchmark dose and its lower confidence limit in urinary metals,with benchmark response of 5% and 10%,respectively.For the occupational population,this study uses a parametric or non-parametric approach to compare differences between consecutive or categorical variables of different groups(non-hypertensive and hypertensive),respectively.Log-binomial regression was used to assess the association between urinary metal concentrations and the prevalence of hypertension.We further applied a two-piece-wise regression model to examine the threshold effects between the metal concentrations in urine and the prevalence of hypertension.Finally,we performed principal component analysis to eliminate possible collinearity and to further evaluate the joint effects of multiple metals on hypertension among occupationally exposed workers.Results: 1.In the general population,there is a significant difference in demographic characteristics between the hypertensive patients of the unweighted population sample and those with normal blood pressure.The standardized mean differences of all baseline covariates after the inverse probability of treatment weighting method be used were decreased,and both were <0.1.The baseline covariates matched well in the two groups.2.In the unweighted population,the urinary cobalt concentration of hypertensive patients was lower than that of normal blood pressure.On the contrary,the urinary cadmium concentration was significantly higher than that of normal blood pressure(all P <0.05).After the inverse probability of treatment weighting,the concentrations of urinary molybdenum,cobalt,arsenic,cadmium,and lead in patients with hypertension were significantly higher than those with normal blood pressure(all P <0.05).3.We observed that urinary molybdenum and cobalt concentrations have a negative dose-response relationship with the prevalence of hypertension in unweighted populations.Compared with the lowest quartiles,participants in the highest quartiles of molybdenum and cobalt had a 0.19-fold and 0.39-fold decreased the probability of having hypertension,respectively.And the prevalence of hypertension in subjects with urinary cadmium concentration in the highest quartile group was 3.62-fold that in the first quartile group.After the inverse probability of treatment weighting,urinary cobalt and cadmium concentrations were still significantly related to the prevalence of hypertension.The prevalence of hypertension in subjects with urinary cobalt and cadmium concentrations in the highest quartile group was 0.51-fold and 6.21-fold that in the first quartile group,respectively.4.We use Mahalanobis distance to detect outliers in multi-dimensional space.After removing the outliers,we perform the above statistical analysis again,and the analysis results are consistent.5.The benchmark dose of urinary cadmium and its lower confidence limit that cause hypertension in 5% of the population are0.274 μg/L and 0.217 μg/L,respectively;the benchmark dose of urinary cadmium and its lower confidence limit that cause hypertension in 10% of the population are 0.563μg/L and 0.445 μg/L,respectively.6.Compared with those in the non-hypertension group,participants with hypertension had were more advanced in age and had higher BMI,SBP and DBP values(all P<0.05).The percentage of hypertension among the miners/smelters was higher than that among the office workers,while the percentage of hypertension in molybdenum miners was higher than that of the iron and steel foundry workers.7.We observed that increased prevalence ratios for hypertension among the quartile of urinary concentrations of molybdenum,arsenic and lead were positive(all P for trend <0.05).8.Compared with the lowest quartiles,participants in the highest quartiles of molybdenum,arsenic and lead had a 2.58-fold,4.30-fold and4.85-fold increased probability of having hypertension,respectively.9.In the threshold effect analyses,we found the relationship was nonlinear between urinary molybdenum,cobalt,cadmium,arsenic and lead concentrations and the prevalence of hypertension.10.We observed that the principal component analysis identified the five elements into two principal components.Among them,principal component 1(lead,molybdenum,arsenic,and cobalt)has a significant positive correlation with hypertension.And the association between principal component 2(cadmium,lead,and molybdenum)and the prevalence of hypertension is not significant.Conclusion: 1.In the general population,the urinary cobalt concentration has a negative dose-response relationship with the prevalence of hypertension,and the urinary cadmium concentration has a positive dose-response relationship with the prevalence of hypertension.2.There is a significant positive dose-response relationship between the increase in urinary molybdenum,arsenic,lead,and the prevalence of hypertension in the occupational population.There is a non-linear relationship between the concentrations of urine molybdenum,cobalt,cadmium,arsenic,and lead and the prevalence of hypertension.3.The joint effect of molybdenum,cobalt,cadmium,arsenic,and lead may play an important role in the development of hypertension. |
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