Introduction Electroplating is required in printed circuit board (PCB) manufacturing factories. Electroplating workers may expose to metals in electroplating processes, and metals exposure will increase cellular oxidative stress and induce insulin resistance. Since insulin resistance is known to be associated with metabolic syndrome, we assessed the relationships between metals exposure and metabolic syndrome among electroplating workers.

Methods We recruited 172 electroplating workers and 84 office workers from 4 factories. Volunteers were required for overnight fasting, and we collected questionnaire, urine and blood samples in the morning. We used homeostasis model assessment of insulin resistance (HOMA-IR) to assess insulin resistance, and the criteria of metabolic syndrome was according to Taiwan Health Promotion Administration.

Result The study showed urinary concentration of vanadium (0.11 vs 0.07 µg/g creatinine, p<0.001), iron (8.81 vs 6.88 µg/g creatinine, p=0.03), nickel (1.66 vs 1.4 µg/g creatinine, p=0.02), zinc (351 vs 298.2 µg/g creatinine, p=0.002) in the exposed group are statistically significant higher than those of the reference group. By using the multivariate-linear regression, urinary nickel, arsenic, cadmium, lead showed significant positive correlation with HOMA-IR, and urinary zinc, arsenic, cadmium, lead showed significant positive correlation with fasting glucose. Besides, some urinary metal levels showed significant positive correlation with triglycerides, waist circumference, or blood pressure. Some of the urinary levels had negative correlation with high-density lipoprotein.

Conclusion Urinary nickel, copper, chromium, cadmium, lead are associated with metabolic syndrome. Elevating urinary concentrations of these five metals may induce metabolic syndrome.