Reference levels of biomarkers of toxic chemicals in biosamples of workers operating under harmful working conditions

Introduction. For the first time, the concept was introduced and a theoretical justification was carried out for the values of “biomarkers’ control levels” (BCL) of a number of harmful chemicals, the excess of which indicates an increased chemical risk to the health of workers and can serve as the basis for predictive industrial medicine and personalization of approaches to medical examination.

The aim of the study was to substantiate, using literature data, indicative control levels of biomarkers of harmful chemicals of organic nature: ethylene oxide, epichlorohydrin, trichloroethane, phenol, tri- and tetrachloroethylene, di- and tetrachloromethane, benzene, toluene, styrene, dimethylbenzenes, mixtures of limit hydrocarbons C₆H₁₄–C₁₀H₂₂, vinyl chloride, butanol-1, acetone, N,N-dimethylformamide and N-nitrosodimethylamine.

Material and methods. The initial data for substantiation were obtained from scientific articles, monographs, materials from the Agency for Toxic Substances and Disease Registry (ATSDR, USA), the Russian Register of Potentially Hazardous Chemical and Biological Substances containing information on the physico-chemical properties, toxicity and hazards of chemicals.

Results. The substantiation of the approximate control levels of biomarkers of hazardous chemicals is carried out in two ways: first – by analyzing the literature data on the content of biomarkers in the biological environments of the body working in industrial conditions with different exposure levels to establish mathematical relationships between parameters that can be extrapolated to the OEL level; second – by analyzing literature data on the content of endogenous biomarkers in the biological environment of the body, the excess of which can serve as a criterion for classifying as a group of workers whose health is at increased chemical risk.

Limitations. The control levels were justified only for a number of organic compounds using literature data on the observed concentrations of substances in the air of the work area and concentrations in the biological environments of workers.

Conclusion. In this work, the concept of reference levels of biomarkers of hazardous chemicals in the blood and urine of workers in harmful working conditions is introduced for the first time. The rationale for the control levels of biomarkers of 17 hazardous chemicals of an organic nature, which make up a significant part of the chemical burden on employees of domestic industry enterprises, is proposed.

Compliance with ethical standards: This study does not require approval by the ethics committee.

Аuthors’ сontribution:
Ukolov A.I., Radilov A.S. – сoncept and design of the study;
Orlova O.I. – data collection and processing;
Ukolov A.I., Orlova O.I. – writing the text;
BarinovV.A., Radilov A.S. – editing.
All co-authors are responsible for approving the final version of the article and ensuring the integrity of all parts of the article.

Acknowledgment. The authors are grateful to S.V. Tryashkin, Deputy Head of the Department of Scientific and Technological Support for Chemical, Biological and Radiation Safety of the FMBA of Russia, for valuable comments on the goals and principles of substantiating biomarker levels.

Conflict of interests. The authors declare no conflicts of interest.

Funding. The study had no sponsorship.

Received: May 12, 2025 / Revised: September 15, 2025 / Accepted: October 2, 2025 / Published: November 19, 2025

1. Ukolov A.I., Radilov A.S. On the development of ideas for biological control of industrial exposure to harmful chemicals (discussion). Medicina truda i promy`shlennaya ekologiya. 2022; 62(11): 740–6. (in Russian)

2. The procedure for applying the results of biomedical research to prove harm to public health caused by the negative effects of chemical factors of the environment: methodological recommendations 2.1.10.3165-14. Moscow. (in Russian)

3. OECD (2022), Occupational Biomonitoring Guidance Document, OECD Series on Testing and Assessment, No. 370, OECD Publishing, Paris.

4. Sanotsky I.V., Ulanova I.P., Avilova G.G., Tkacheva T.A. and others. Biological control of industrial exposure to harmful substances: Methodological recommendations No. 5205-90. Moscow; 1990. 30. (in Russian)

5. Interstate standard. A system of occupational safety standards. Harmful substances. Classification and general safety requirements (GOST 12.1.007-76).

6. Guidelines for assessing the risk to public health when exposed to chemicals that pollute the environment. Manual R 2.1.10.3968-23.(in Russian)

7. Ukolov A.I. Kombarova M.Yu., Reynyuk V.L., Barinov V.A., Radilov A.S. Analysis of promising areas for improving the methodological part of the biological monitoring system at potentially chemically hazardous sites (analytical review). Toksikologicheskii vestnik. 2024; 32(3): 137–61. (in Russian)

8. Menshikov V.V. Laboratory specialist and clinical interpretation of laboratory results. Klinicheskaya laboratornaya diagnostika. 2014; 59(5): 60–4. (in Russian)

9. Barr D.B., Wilder L.C., Caudill S.P., Gonzalez A.J., Needham L.L., Pirkle J.L. Urinary creatinine concentrations in the U.S. population: implications for urinary biologic monitoring measurements. Environ Health Perspect. 2005; 113(2): 192–200. https://doi.org/10.1289/ehp.7337

10. WHO 1996. Biological Monitoring of Chemical Exposure in the Workplace. Vol 1. Geneva: World Health Organization.

11. Koh S.B., Cha B.S., Park J.K., Chang S.H., Chang S.J. The metabolism and liver toxicity of N,N-dimethylformamide in the isolated perfused rat liver. Yonsei Med J. 2002; 43(4): 491–9.

12. Käfferlein H.U., Ferstl C., Burkhart-Reichl A., Hennebrüder K., Drexler H., Brüning T., Angerer J. The use of biomarkers of exposure of N,N-dimethylformamide in health risk assessment and occupational hygiene in the polyacrylic fibre industry. Occup Environ Med. 2005; 62(5): 330–6.

13. Wang V.S., Shih T.S., Cheng C.C., Chang H.Y., Lai J.S., Lin C.C. Evaluation of current biological exposure index for occupational N, N-dimethylformamide exposure from synthetic leather workers. J Occup Environ Med. 2004; 46(7): 729–36.

14. Agency for Toxic Substances and Disease Registry (ATSDR). 2022. Toxicological Profile for Acetone. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service.

15. Swiercz R., Korsak Z., Rydzynski K. Kinetics of n-butyl alcohol and m-xylene in blood during single and combined inhalation exposure in rats. Int J Occup Med Environ Health. 1995; 8(4): 361–5.

16. Lin Y.S., Vermeulen R., Tsai C.H., Waidyanatha S., Lan Q., Rothman N., Smith M.T. Albumin adducts of electrophilic benzene metabolites in benzene-exposed and control workers. Environ Health Perspect. 2007; 115(1): 28–34.

17. Boogaard P.J., van Sittert N.J. Biological monitoring of exposure to benzene: a comparison between S-phenylmercapturic acid, trans,trans-muconic acid, and phenol. Occupational and Environmental Medicine. 1995; 52: 611–20.

18. Shayakhmetov S.F., Zhurba O.M., Alekseenko A.N., Merinov A.V., Dorogova V.B. Biological monitoring of organochlorine hydrocarbons in the production of vinyl chloride and polyvinyl chloride. Occupational Medicina truda i promy`shlennaya e`kologiya. 2017; (1): 39–42. (in Russian)

19. Inoue O., Seiji K., Kawai T. et al. Excretion of methylhippuric acids in urine of workers exposed to a xylene mixture: Comparison among three xylene isomers and toluene. Int Arch Occup Environ Health. 1993; 64: 533–9.

20. Casanova M., Deyo D.F., Heck H. Dichloromethane (methylene chloride): metabolism to formaldehyde and formation of DNA-protein cross-links in B6C3F1 mice and Syrian golden hamsters. Toxicol Appl Pharmacol. 1992; 114(1): 162–5.

21. Ukolov A.I., Migalovskaya E.D., Radilov A.S. Chromatograph-mass spectrometric study of biological samples of rats exposed to aliphatic hydrocarbons with the number of carbon atoms from 6 to 10. Biomedicinskij zhurnal Medline.ru. 2015; 16: 335–43. (in Russian)

22. Triebig G., Stark T., Ihrig A., Dietz M.C. Intervention study on acquired color vision deficiencies in styrene-exposed workers. J Occup Environ Med. 2001; 43(5): 494–500.

23. Manautou J.E., Campion S.N., Aleksunes L.M. 9.08 – Regulation of Hepatobiliary Transporters during Liver Injury, Editor(s): Charlene A. McQueen, Comprehensive Toxicology (Second Edition), Elsevier, 2010: 175–220.

24. Mehendale M., 7.19 – Halogenated Hydrocarbons, Editor(s): Charlene A. McQueen, Comprehensive Toxicology (Second Edition). Elsevier; 2010: 459-–74.

25. Ghittori G. et al. Biological Monitoring of Workers Exposed to Carbon Tetrachloride Vapor. Appl Occup Environ Hyg. 1994; 9: 353–7.

26. Waksman J.C., Phillips S.D. Biologic markers of exposure to chlorinated solvents. Clin Occup Environ Med. 2004; 4(3): 413–21.

27. Ikeda M., Ukai H., Kawai T, Inoue O., Maejima Y., Fukui Y., Ohashi F., Okamoto S. Changes in correlation coefficients of exposure markers as a function of intensity of occupational exposure to toluene. Toxicol Lett. 2008; 179(3): 148–54. https://doi.org/10.1016/j.toxlet.2008.05.003

28. Imbriani M., Niu Q., Negri S., Ghittori S. Trichloroethylene in urine as biological exposure index. Ind Health. 2001; 39(3): 225–30. https://doi.org/10.2486/indhealth.39.225

29. Jha A., Jobby R., Kudale S., Modi N., Dhaneshwar A., Desai N. Biodegradation of phenol using hairy roots of Helianthus annuus L. International Biodeterioration & Biodegradation. 2013; 77: 106–13.

30. Hirakawa B. Epichlorohydrin. Editor(s): Philip Wexler, Encyclopedia of Toxicology (Second Edition). Elsevier; 2005: 228–9.

31. de Rooij B.M., Boogaard P.J., Commandeur J.N., Vermeulen N.P. 3-Chloro-2-hydroxypropylmercapturic acid and α-chlorohydrin as biomarkers of occupational exposure to epichlorohydrin. Environ Toxicol Pharmacol. 1997; 3(3): 175–85.

32. Niot-Mansart V., Muhamedi A., Arnould J.P. A competitive ELISA detecting 7-methylguanosine adduct induced by N-nitrosodimethylamine exposure. Hum Exp Toxicol. 2005; 24(2): 89–94.

33. Gallo V., Khan A., Gonzales C., Phillips D.H., Schoket B., Györffy E., Anna L., Kovács K., Møller P., Loft S., Kyrtopoulos S., Matullo G., Vineis P. Validation of biomarkers for the study of environmental carcinogens: a review. Biomarkers. 2008; 13(5): 505–34.

34. Topp H., Sander G., Heller-Schöch G., Schöch G. Determination of 7-methylguanine, N2,N2-dimethylguanosine, and pseudouridine in ultrafiltrated serum of healthy adults by high-performance liquid chromatography. Anal Biochem. 1987; 161(1): 49–56.

35. Scherer G., Urban M., Hagedorn H.W., Serafin R., Feng S., Kapur S. et al. Determination of methyl-, 2-hydroxyethyl- and 2-cyanoethylmercapturic acids as biomarkers of exposure to alkylating agents in cigarette smoke. J Chromatogr B Analyt Technol Biomed Life Sci. 2010; 878(27): 2520–8.

36. Frigerio G., Mercadante R., Polledri E., Missineo P., Campo L., Fustinoni S. An LC-MS/MS method to profile urinary mercapturic acids, metabolites of electrophilic intermediates of occupational and environmental toxicants. J Chromatogr B Analyt Technol Biomed Life Sci. 2019; 1117: 66–76.

37. Eckert E., Schmid K., Schaller B., Hiddemann-Koca K., Drexler H., Göen T. Mercapturic acids as metabolites of alkylating substances in urine samples of German inhabitants. Int J Hyg Environ Health. 2011; 214(3): 196–204.

38. Stevens J.F., Maier C.S. Acrolein: sources, metabolism, and biomolecular interactions relevant to human health and disease. Mol Nutr Food Res. 2008; 52(1): 7–25.