title: What do the trace metal contents of urine and toenail samples from Qatar׳s farm workers bioindicate?
abstract: Qatar׳s farm workers provide a unique population for exposure study: they are young, healthy males. This study combined trace element profiles in urine and toenail with survey information from 239 farm workers to assess the extent to which the biomarkers provide complementary exposure information. Urinary Mo levels (average=114 µg/L) were elevated; average urinary values (µg/L) for all other elements were: V (1.02), Cr (0.55), Mn (2.15), Fe (34.1), Co (0.47), Ni (2.95), Cu (15.0), As (47.8), Se (25.7), Cd (1.09), Ba (22.5), Pb (2.50) and U (0.15). Average toenail concentrations (mg/kg) were: Mn (2.48), Cu (4.43), As (0.26), Se (0.58), Mo (0.07), Cd (0.03), Ba (1.00), Pb (0.51) and U (0.02). No significant association was found between corresponding elements in urine and toenails. Elemental profiles suggest groundwater (with the exception of Mo) and soil-dust-crop exposure pathways cannot account for elemental variations. The main factors moderating trace element contents are related to depuration processes involving participants׳ trace element body burden prior to work in Qatar, and interactions of trace element metabolic cycles which over-ride the exposure footprint. Toenail and urine need to be carefully validated before reliable use as biomarkers of exposure in general populations for most elements in the study.
authors.affiliation: Qatar Environment and Energy Research Institute (QEERI), Qatar Foundation, P.O. Box 5825, Doha, Qatar.
authors.forename: Nora
authors.initials: N
authors.lastname: Kuiper
authors.affiliation: Qatar Environment and Energy Research Institute (QEERI), Qatar Foundation, P.O. Box 5825, Doha, Qatar.
authors.forename: Candace
authors.initials: C
authors.lastname: Rowell
authors.affiliation: Department of Environmental Health Sciences, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109, USA.
authors.forename: Jerome
authors.initials: J
authors.lastname: Nriagu
authors.affiliation: Qatar Environment and Energy Research Institute (QEERI), Qatar Foundation, P.O. Box 5825, Doha, Qatar. Electronic address: bshomar@qf.org.qa.
authors.forename: Basem
authors.initials: B
authors.lastname: Shomar
mesh_terms: D000328:Adult; D004784:Environmental Monitoring; D006801:Humans; D008297:Male; D008670:Metals / Q000652:urine*; D008875:Middle Aged; D009262:Nails / Q000737:chemistry; D011780:Qatar; D014171:Transients and Migrants; D055815:Young Adult
chemical_list: D008670:Metals
keywords: Biomonitoring; Farm workers; Toenails; Trace elements; Urine