Article Toxicology and Industrial Health 2021, Vol. 0(0) 1–9 © The Author(s) 2021 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/07482337211048963 journals.sagepub.com/home/tih Blood lead levels, calcium metabolism and bone-turnover among automobile technicians in Sagamu, Nigeria: Implications for elevated risk of susceptibility to bone diseases Nnenna L Nwobi 1 , Joseph C Nwobi 2 , Esther N Adejumo 3 , Osahon S Usiobeigbe 3 , Opeyemi A Adetunji 4 , Nnodimele O Atulomah 5 and John I Anetor 6  Abstract Lead is an occupational toxicant and a recognised health threat particularly in developing countries. Hence, this study explored the interaction of blood lead level (BLL), a conventional marker of lead exposure, with indices of calcium metabolism and biomarkers of bone-turnover in 120 adult male automobile technicians (AT) with ≥ 1 year duration in professional practice. The AT as well as the control group, which comprised 120 age, body- size and socio-economically matched male administrative workers, were recruited from Sagamu, South West Nigeria. Levels of blood lead, serum indices of calcium metabolism [total calcium (tCa), ionised calcium (iCa), phosphate, albumin, magnesium (Mg) and 25-Hydroxycholecalceferol (25-OHCC)], biomarkers of bone for- mation [bone alkaline phosphatase (BALP) and osteocalcin (OC)] and biomarkers of bone resorption [tartarate- resistant acid phosphatase-5b (TACRP-5b) and urinary hydroxyproline (UHYP)] were determined in all participants. The BLL, 25-OHCC, TRACP-5b and UHYP significantly increased while tCa and iCa significantly reduced in AT compared to control. However, no significant difference was observed in phosphate, albumin, Mg, BALP and OC in AT compared to control. Interestingly, BLL demonstrated a significant negative association with tCa and iCa but a significant positive association with 25-OHCC, TRACP-5b and UHYP. However, BLL did not show significant association with phosphate, albumin, Mg, BALP and OC. Increased lead exposure as well as altered calcium metabolism and bone-turnover demonstrated by the automobile technicians may be suggestive of lead-induced accelerated bone demineralisation. These workers may be predisposed to high risk of increased susceptibility to bone diseases if this sub-clinical picture is sustained. Keywords Automobile technicians, blood lead level, indices of calcium metabolism, biomarkers of bone formation, biomarkers of bone resorption, bone diseases Received 3 March 2021; Revised 30 August 2021; Accepted 8 September 2021 1 Department of Chemical Pathology, BenCarson School of Medicine, Babcock University, Ilishan Remo, Nigeria 2 Department of Biochemistry, BenCarson School of Medicine, Babcock University, Ilishan Remo, Nigeria 3 Department of Medical Laboratory Science, Babcock University, Ilishan-Remo, Nigeria 4 Department of Anatomy, BenCarson School of Medicine, Babcock University, Ilishan Remo, Nigeria 5 Department of Public Health, School of Public and Allied Health, Babcock University, Ilishan Remo, Nigeria 6 Department of Chemical Pathology, College of Medicine, University of Ibadan, Ibadan, Nigeria Corresponding author: Nnenna L Nwobi, Department of Chemical Pathology, BenCarson School of Medicine, Babcock University, Ilishan Remo, Ogun 121103, Nigeria. Email: nwobin@babcock.edu.ng