Object This study aims to provide a basis for policy to control the reliability of biological monitoring laboratories in occupational health by analysing data on annual biological monitoring.

Method We collected the survey requesting the number of data provided in 2014 and 2015, which laboratories participating in proficiency test program on biological monitoring responded to. Statistical data for biological monitoring (2003–2004) to reveal the current status of biological monitoring practices in the hospitals or occupational health laboratories were extracted from the KOSHA.

Result The total number of data of biological markers was up to 2 70 000 cases and 4 70 000 cases in 2013, 2014, respectively. Among them, the most dominant markers with regard to organic solvent exposure were urinary hippuric acid, methylhippuric acid and 2,5-hexanedione with 3 47 000 cases reported for 2 years. As for metal exposure, lead and cadmium in blood were the most frequently checked markers with 1 16 000 cases for 2 years. Among 180 occupational health organisations, 44% of them sent their samples to other laboratories for analysis. The problem of lack of proficiency test data was evident in biological markers including 2,5-hexanedione, N-methylformamide, and trichloroacetic acid, which were analysed in major big laboratories. Strict policy on these laboratories as well as tactics to encourage small laboratories to join more proficiency test items, were suggested.

Conclusion From the database of biological monitoring, the lack of reliability of biological monitoring in many biological markers was revealed. Future action to improve the reliability of all the biological monitoring analysis is requested.