Heavy metals in urinary stones in the Democratic Republic of Congo

Abstract

Background: The Democratic Republic of Congo has been a country of intensive mining activities for centuries, but the data on the presence of heavy metals in stones are lacking. This study aimed to identify different heavy metals in urinary tract stones and to investigate their association with the main components of urinary stones. Methods: Thirty-six stones from urolithiasis patients (n = 36) followed in 10 hospitals in the Democratic Republic of Congo between January 2016 and September 2019 were analyzed by Fourier transform infrared spectrophotometry. Further analysis using X-ray fluorescence was conducted at the Laboratory of Solids Physics. Results: Eight heavy metals were detected in all the stones analyzed. The average (SD) number of heavy metals detected by stone was 5 (1.2). Iron and strontium were detected in all the stones analyzed. Other heavy metals detected included zinc, copper, bromine, rubidium, lead and nickel. Rubidium had the highest concentration in the stones regardless of the sampling site. There was no statistically significant association between the content of heavy metals at the center level and at the crown level of the stones. Rubidium had more affinity with phosphates and purines (p ˂ 0.001). Iron and strontium exhibited a high affinity with weddellite than with whewellite. Conclusion: Iron and Strontium were present in all stones analyzed. The presence of heavy metals in stones analyzed might suggest environmental pollution rather than crystalline induction factors.