Reference intervals for cd, hg, Mn and Pb in the general children population (3–14 years) of Kinshasa, Democratic Republic of Congo (DRC) between June 2019 and June 2020

The reference intervals (RIs), proposed by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) and the International Union of Pure and Applied Chemistry (IUPAC), were derived for Cd, Hg, Mn and Pb in the blood and urine of the children population living in Kinshasa (n = 200, aged 3–14 years with 97 girls). Levels of metals were measured using coupled plasma mass (ICP-MS). In blood, the proposed RIs [P5-P95 (GM)] were 0.022–1.112 μg/L (0.074), 35.69–144.50 μg/L (71.43), 0.060 to 1.161 μg/L (0.208) and 6.597–15.740 μg/L (9.882) for Cd, Pb, Hg and Mn, respectively. Urinary levels [(P5-P95 (GM)] were 0.082–1.530 μg/L (0.366) for Cd, 1.827–18.500 μg/L (5.458) for Pb, 0.323–1.953 μg/L (0.709) for Hg and 0.070 to 1.703 μg/L (0.186) for Mn. As compared to the CDC updated blood Pb reference value (35 μg/L), Pb levels remain higher of public health concern. Cd and Mn levels were similar to those found in the same city in 2015 and databases involving non-occupationally exposed populations from other countries. Hg levels significantly lower than those found in the same city in 2015, probably due to exclusion criteria of metal exposure applying in the present survey (occupationally exposed to the studied metals, smoking habits, amalgam tooth fillings, fish consumption habit more than one time per week, etc.). These background metal exposures will be useful for future occupational and/or environmental surveys as well as undertaking a reliable regulation of chemical exposure in Kinshasa via a national HBM program.