title: Biomarkers of selenium status in the Amazonian context: blood, urine and sequential hair segments.
abstract: Selenium (Se) is an essential element and deficit or excess of dietary Se is associated with health disorders. Relatively elevated Se levels have been reported in the Brazilian Amazon, where there are also important annual variations in the availability of different foods. The present study was conducted among six riparian communities of the Tapajós River to evaluate seasonal variations in blood and sequential hair cm Se concentrations, and to examine the relationships between Se in blood and hair, and blood and urine. Two cross-sectional studies were conducted, at the descending water (DWS, n=259) and the rising water (RWS, n=137) seasons, with repeated measures for a subgroup (n=112). Blood Se (B-Se), hair Se (H-Se) and urine Se (U-Se) were determined. Match-paired analyses were used for seasonal comparisons and the method of best fit was used to describe the relationships between biomarkers. B-Se levels presented a very large range (142-2447 microg/l) with no overall seasonal variation (median 284 and 292 microg/l, respectively). Sequential analysis of 13 cm hair strands showed significant variations over time: Se concentrations at the DWS were significantly lower compared with the rising water season (medians: 0.7 and 0.9 microg/g; ranges: 0.2-4.3 microg/g and 0.2-5.4 microg/g, respectively). At both seasons, the relationships between B-Se and H-Se were linear and highly significant (r(2)=67.9 and 63.6, respectively), while the relationship between B-Se and U-Se was best described by a sigmoid curve. Gender, age, education and smoking did not influence Se status or biomarker relationships. Variations in H-Se suggest that there may be seasonal availability of Se sources in local food. For populations presenting a large range and/or elevated Se exposure, sequential analyses of H-Se may provide a good reflection of variations in Se status.
authors.affiliation: Centre de recherche interdisciplinaire sur la biologie, la santé, la société et l'environnement (CINBIOSE), Université du Québec à Montréal, Montréal, Québec, Canada.
authors.forename: Melanie
authors.initials: M
authors.lastname: Lemire
authors.forename: Donna
authors.initials: D
authors.lastname: Mergler
authors.forename: Guy
authors.initials: G
authors.lastname: Huel
authors.forename: Carlos J S
authors.initials: CJ
authors.lastname: Passos
authors.forename: Myriam
authors.initials: M
authors.lastname: Fillion
authors.forename: Aline
authors.initials: A
authors.lastname: Philibert
authors.forename: Jean R D
authors.initials: JR
authors.lastname: Guimarães
authors.forename: Isabelle
authors.initials: I
authors.lastname: Rheault
authors.forename: Julie
authors.initials: J
authors.lastname: Borduas
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Normand
mesh_terms: D015415:Biomarkers / Q000032:analysis* / Q000097:blood / Q000652:urine; D001938:Brazil / Q000453:epidemiology; D003710:Demography; D005523:Food Supply / Q000706:statistics & numerical data; D006197:Hair / Q000737:chemistry*; D045483:Rivers; D012424:Rural Population; D012621:Seasons; D012643:Selenium / Q000032:analysis* / Q000097:blood / Q000652:urine
chemical_list: D015415:Biomarkers; D012643:Selenium