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Although environmental exposure to multiple metals is common, epidemiological studies on the associations of exposure to 23 metals with kidney function have not been analyzed. We aimed to investigate the associations of 23 metals levels with renal function. We conducted a cross-sectional study in four rural regions of Hunan province. Plasma and urine metals levels were determined by inductively coupled plasma mass spectrometer (ICP-MS). Two-level logistic regression was used to investigate the associations of metals levels with estimated glomerular filtration rate (eGFR) with adjustment for confounding factors. We conducted a sensitivity analysis of the results using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. A total of 3553 participants completed the investigation. Five metals (plasma arsenic and molybdenum; urine copper, rubidium, and strontium) were identified to be significantly associated with renal function. Participants in the highest quartile of plasma arsenic and molybdenum were at 17.95 (95% CI: 6.35–50.76) and 24.23 (95% CI: 7.42–79.19) fold risk of abnormal eGFR, respectively, compared with the lowest quartile. The highest quartiles of urine copper, rubidium, and strontium were associated with 3.70 (95% CI:1.92–7.14), 0.16 (95% CI:0.07–0.37) and 0.08 (95% CI: 0.03–0.21) fold risk of abnormal eGFR. The sensitivity analysis revealed that plasma arsenic, molybdenum and urine copper, rubidium and strontium levels retained similar associations with abnormal eGFR. Plasma arsenic and molybdenum, and urine copper are risk factors for abnormal renal function, while urine rubidium and strontium are protective factors for renal function. • A cross-sectional study was conducted in four rural regions of Hunan province. • The associations of multiple metal levels with renal function was investigated. • Multiple metals in plasma and urine are associated with abnormal eGFR. [ABSTRACT FROM AUTHOR]

• The association of multi-metals exposure on children's IQ was assessed. • Ti and Sn had a synergistic relationship, with a decline in IQ score. • The multi-metal mixtures were negatively associated with children's IQ by BKMR. Associations between most single metals and children's intelligence quotient (IQ) scores have been evaluated in previous studies. However, associations between multi-metal exposures and children's IQ scores have not been analyzed. To assess the joint effects of lead (Pb), manganese (Mn), antimony (Sb), tin (Sn) and titanium (Ti) co-exposure on children's IQ scores. A prospective cohort study was conducted in Shimen and Huayuan, Hunan Province, China. Urine metals levels were measured by inductively coupled plasma mass spectrometry (ICP-MS) at baseline. Children's IQ scores were repeatedly measured at baseline and follow-up following the method of Raven's Standard Progressive Matrices (SPM) and standardized as z scores. We fitted linear regression models and Bayesian kernel machine regression (BKMR) models to investigate the associations of metal levels with children's IQ scores after adjusting for covariates. A total of 633 participants aged 7–10 years completed the survey. Urinary Pb (β = -0.028, P = 0.022) and urinary Ti (β = -0.0003, P = 0.001) were inversely associated with children's IQ scores. The BKMR analyses revealed significant negative overall effects of the five metals on children's IQ scores when all the metals were above their median levels, while significant positive associations were shown when all the metal concentrations were below their median levels. The model also showed negative trends of Sn and Ti on children's IQ. Furthermore, Ti and Sn had a synergistic relationship, with a decline in IQ score when Sn exposure was relatively high. The urinary Sn concentration was significantly higher but the urinary Ti concentration was significantly lower in participants from the Shimen area than in those from the Huayuan area. Decreasing trends of the overall effects were observed in both the Shimen and Huayuan areas. Our findings revealed that multi-metal exposures caused a decline in children's IQ scores according to traditional linear regression models and the BKMR model. Our results provide some evidence of the association between multi-metal exposure and children's IQ. Meanwhile, interactions between multi-metal exposures on children's IQ should be given more attention. [ABSTRACT FROM AUTHOR]