Comparative Analysis of the Informative Value of Biological Fluidsfor Biomonitoring Formaldehyde in the Human Body

Introduction: The effectiveness of monitoring formaldehyde levels in the body depends on the correct choice of the biological substrate tested. Objective: A comparative analysis of the representativeness of biological fluids – plasma, serum and whole blood – for biomonitoring formaldehyde in the human body. Materials and methods: The study was conducted on a group of metallurgical workers aged 26 to 58 years (41.0 ± 3.4 years; n = 20) with professional experience ranging from 4 to 30 years (19.3 ± 4.0 years). The formaldehyde content in biological fluids was measured by high-performance liquid chromatography with UV detection after a preliminary derivatization process with 2,4-dinitrophenylhydrazine. Also, as part of a periodic medical examination, clinical blood parameters were tested in all employees in accordance with the Order of the Ministry of Health of the Russian Federation No. 29n dated January 28, 2021. Results: We found that formaldehyde concentrations in plasma and serum were not significantly different (p = 0.9405) and amounted to 0.020 [Q1 = 0.006; Q3 = 0.063] µg/mL and 0.022 [Q1 = 0.016; Q3 = 0.069] µg/mL, respectively. The whole blood level of the toxicant was 1.4–172.9 times higher (4.5 [Q1 = 2.6; Q3 = 16.2]) than in plasma and 1.6–120.7 times higher (4.4 [Q1 = 3.0; Q3 = 8.5]) than in serum and it increased significantly compared to plasma and serum (p = 0.0025; p = 0.0006) with an increase in the platelet count. This might be related to structural features of thrombocyte membranes pierced by holes in the open tubular system and lined from the inside with tubulin, the molecular weight of which is unable to prevent penetration of the toxicant into the cell. As a result, formaldehyde “concentrates” in platelets and determines their count-dependent blood distribution of formaldehyde. Conclusion: Our findings demonstrate that whole blood is a more representative body fluid in terms of formaldehyde biomonitoring compared with blood serum and plasma as it provides more accurate complete indicators of its content in the body.