Associations of plasma metal concentrations with the decline in kidney function: A longitudinal study of Chinese adults

Metals are widespread pollutants in the environment which have been reported to be associated with kidney dysfunction in many existing epidemiological studies. However, most of the studies are cross-sectional design and mainly focus on several toxic metals including arsenic, lead and cadmium. Therefore, we conducted this prospective study within the Dongfeng-Tongji cohort to evaluate the associations of plasma multiple metals with the decline in kidney function among Chinese middle-aged and elderly. In total, 1434 participants free of chronic diseases at baseline were included in analysis. We measured baseline plasma concentrations of 23 metals and calculated estimated glomerular filtration rate (eGFR) using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation based on serum creatinine, age, sex and ethnicity. Bonferroni correction was used for multiple testing to reduce the probability of a type I error. Principal component analysis was conducted to evaluate the combined effect of multiple metal co-exposure. Most of the plasma metal concentrations were within the literature reported reference values, whereas the concentration of lead and nickel exceeded the guideline value. We found that plasma concentrations of aluminum, arsenic, barium, lead, molybdenum, rubidium, strontium, vanadium and zinc were significantly associated with the decline in kidney function measured by annual eGFR decline, rapid renal function decline (defined as an annual decline in eGFR >= 5 mL/min/1.73 m(2)) or incident eGFR < 60 mL/min/1.73 m(2), with the adjusted beta coefficients (95% CI) for annual eGFR decline 0.50 (0.30, 0.69), 0.98 (0.74, 1.23), 0.56 (0.32, 0.79), 0.21 (0.03, 0.39), 0.35 (0.16, 0.54), 0.94 (0.71, 1.17), 0.37 (0.15, 0.60), 0.78 (0.54, 1.02), and 0.74 (0.57, 0.91), respectively. The metals exposures were linked with increased risks of impaired kidney function. Associations of principal components representing these metals with the decline in kidney function were significant and suggest a possible additional health risk by co-exposure. Participants engaged in manufacturing had higher plasma levels of several metals compared with those who had been involved in management-or administration-related work. Our findings suggest that exposure to multiple metals contribute to the decline in kidney function among the middle-aged and elderly. Co-exposure to multiple metals may have synergetic effect on the kidney function. Further studies are warranted to confirm our findings and clarify the potential mechanisms.