Study On Occupational Exposure To Heavy Metals With Risk Of Diabetes And Dysglycemia In The Jinchang Cohort Population

Objective Environmental exposure to heavy metals may adversely affect cardiometabolic diseases.We performed a cross-sectional analysis on the association of heavy metals with the risk of diabetes?type 2?among Chinese metal-exposed workers who participated in a large prospective cohort study–the China Metal Exposed Workers Cohort Study?Jinchang Cohort?.The Aims of this study were to learn the levels of metal exposures in the study population;to understand theprevalence of diabetes,risk factors of diabetes,and workers impacted by diabetes;to evaluate the associations between occupational metal exposures and risk of diabetes,the dose-responserelationship between urinary metals and fasting plasma glucose?FPG?,and interactions among multiple metals for FPG;and thus providing scientific basis for the prevention of diabetes among those workers.Methods?1?Descriptively analysis of the occupational and environmental health datacollected in the all different production process of the company.Qualitatively evaluation of the degree of metals exposure among those workers by using heath risk assessment methods from International Committee of Military Medicine?ICMM?.?2?We detected 15 urinary metals by using Inductively Coupled Plasma Mass Spectrometry?ICP-MS?among 500 occupationalworkers,who were sampled from the database of the baseline survey in the Jinchang Cohort.?3?Multivariable logistic regressions were modeled to calculate odds ratio?OR?and 95%confidence interval?CI?and to evaluate the associations of occupation categories associated with metalexposure levels,lifestyle factors of male workers,and reproductive factors of female workers with the risk of diabetes.?4?Categorical analyses,multivariable linear regression analyses,andrestricted cubic splines functions?RSC?were used to exam the dose-response relationships between 5 urinary metals and FPG.We also explored the inter-metal relationships.Results?1?The main sources of metals pollution come from the company productionindustry chain,including mine,ore dressing and smelting,and related diverse auxiliary industries.Ni and Cu were main pollutants;other multiple metals,such as Co,Zn,As,and Cr,were alsoincluded.?2?The median urinary Ni concentrations?creatinine adjusted?among 3 occupationcategories of the Jinchang Cohort were:3.26?g/L for office workers,4.03?g/L for production workers,and 4.55?g/L for smelting/refining workers,respectively?H=14.84,P=0.001?;the corresponding median urinary Co level was 4.43?g/L,0.52?g/L,and 0.49?g/L,respectively?H=3.10,P=0.213?.The median level of urinary Ni in those workers was approximately 2.4 times higher than that of the Wuhan general population?5.392 vs.2.255?g/L?.The levels of urinary Co,Cu,As,and Cr were also higher than other reported general populations,such as US and Canada.?3?The overall and standardized prevalence of diabetes among this study was 7.5%?3161/42122?and 7.4%,respectively;the overall prevalence of prediabetes was 28.6%.Compared to office workers,the adjusted OR for diabetes among production workers and smelting/refining workers were 1.43?95%CI:1.28-1.58?and 4.02?95%CI:3.62-4.46?,respectively.?4?For male workers,compared with non-smokers,the adjusted OR of diabetes was 7.3?95%CI:5.3-9.9?for those with>40 pack-years of smoking who had the highest metalexposures,there was significant effect modification under the multiplicative model betweensmoking and occupation categories(P_interaction=0.001).Similarly,compared with non-drinkers,an OR of 6.1?95%CI:4.8-7.8?was observed for those with drinking index?DI?>873 kg who were in the highest urinary metals?smelting/refining workers?(P_interaction=0.018).?5?For female workers,early menarche at age??12 vs.15-16 years?was associated with increased diabetes risk?OR=1.60,95%CI:1.16-2.22?.Both reproductive life span?P=0.02?and age at menopause?P=0.03?were also associated with risk of diabetes with a U-shaperelationship.?6?Increasing levels of urinary Ni and Zn were both positively associated with risk of high-FPG and dysglycemia(P_trend=0.004 for Ni and P_trend=0.01 for Zn).The J-shaped dose-response relationships between urinary Ni?P non-linearity=0.03?and Zn?P non-linearity<0.001?with FPG were also observed.A negative linear relationship between urinary Co and FPG(P _nonlinearity=0.06)was found.The joint effects between urinary nickel and cobalt with FPG were also detected?P interaction=0.04?.Conclusion Occupations associated with higher levels of metal exposures were associated with the increased risk of diabetes among this occupational cohort.There were strong interactions between smoking,drinking,and metal exposures in affecting diabetes risk among male workers.Reproductive factors were associated with diabetes among female workers.There were dose-response relationships between multiple urinary metals,particularly,Ni,Zn,and Co,with higher FPG and dysglycemia risk.The results of this study supported that metal exposures may play a critical role in the development of diabetes.