title: Kidney function and blood pressure in preschool-aged children exposed to cadmium and arsenic--potential alleviation by selenium.
abstract: BACKGROUND
  Early-life exposure to toxic compounds may cause long-lasting health effects, but few studies have investigated effects of childhood exposure to nephrotoxic metals on kidney and cardiovascular function.
  
  
  OBJECTIVE
  To assess effects of exposure to arsenic and cadmium on kidney function and blood pressure in pre-school-aged children, and potential protection by selenium.
  
  
  METHODS
  This cross-sectional study was part of the 4.5 years of age (range: 4.4-5.4 years) follow-up of the children from a supplementation trial in pregnancy (MINIMat) in rural Bangladesh, and nested studies on early-life metal exposures. Exposure to arsenic, cadmium and selenium from food and drinking water was assessed by concentrations in children's urine, measured by ICP-MS. Kidney function was assessed by the estimated glomerular filtration rate (eGFR, n=1106), calculated from serum cystatin C, and by kidney volume, measured by ultrasound (n=375). Systolic and diastolic blood pressure was measured (n=1356) after five minutes rest.
  
  
  RESULTS
  Multivariable-adjusted regression analyzes showed that exposure to cadmium, but not arsenic, was inversely associated with eGFR, particularly in girls. A 0.5 µg/L increase in urinary cadmium among the girls (above spline knot at 0.12) was associated with a decrease in eGFR of 2.6 ml/min/1.73 m(2), corresponding to 0.2SD (p=0.022). A slightly weaker inverse association with cadmium was also indicated for kidney volume, but no significant associations were found with blood pressure. Stratifying on children's urinary selenium (below or above median of 12.6 µg/L) showed a three times stronger inverse association of U-Cd with eGFR (all children) in the lower selenium stratum (B=-2.8; 95% CI: -5.5, -0.20; p=0.035), compared to those with higher selenium (B=-0.79; 95% CI: -3.0, 1.4; p=0.49).
  
  
  CONCLUSIONS
  Childhood cadmium exposure seems to adversely affect kidney function, but not blood pressure, in this population of young children in rural Bangladesh. Better selenium status appears to be protective. However, it is important to follow up these children to assess potential long-term consequences of these findings.
authors: Unit of Metals and Health, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors: Helena
authors: H
authors: Skröder
authors: Medical Research Council (MRC), International Nutrition Group, London School of Hygiene and Tropical Medicine, London, UK.
authors: Sophie
authors: S
authors: Hawkesworth
authors: Unit of Metals and Health, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors: Maria
authors: M
authors: Kippler
authors: International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh.
authors: Shams
authors: S
authors: El Arifeen
authors: Department of Clinical Trial and Clinical Epidemiology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.
authors: Yukiko
authors: Y
authors: Wagatsuma
authors: MRC Human Nutrition Research, Cambridge, UK.
authors: Sophie E
authors: SE
authors: Moore
authors: Unit of Metals and Health, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. Electronic address: marie.vahter@ki.se.
authors: Marie
authors: M
authors: Vahter
mesh_terms: D001151:Arsenic / Q000633:toxicity*; D001794:Blood Pressure / Q000187:drug effects*; D002104:Cadmium / Q000633:toxicity*; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004781:Environmental Exposure; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006801:Humans; D007668:Kidney / Q000187:drug effects* / Q000503:physiopathology; D012643:Selenium / Q000008:administration & dosage*
chemical_list: D002104:Cadmium; D012643:Selenium; D001151:Arsenic
keywords: Arsenic; Cadmium; Selenium; blood pressure; children; kidney function