title: Urinary Iodine and Goiter Prevalence in Belarus: experience of the Belarus-American cohort study of thyroid cancer and other thyroid diseases following the Chornobyl nuclear accident.
abstract: BACKGROUND
  Because iodine deficiency can influence background rates of thyroid disease or modify radiation dose-response relationships, we compiled descriptive data on iodine status among participants in a Belarusian-American screening study who were exposed in childhood to radioiodine fallout from the Chornobyl nuclear accident. We have used the data from two consecutive screening cycles to examine whether indicators of iodine status changed before and after documented government initiatives to improve iodine intake.
  
  
  METHODS
  Urinary iodine concentrations in spot samples and prevalence of diffuse goiter by palpation were assessed in 11,676 exposed subjects who were 18 years or younger at the time of the accident on April 26, 1986, and were screened beginning 11 years later in connection with the Belarus-American Thyroid Study. Data for the first ( January 1997-March 2001) and second (April 2001-December 2004) screening cycles, which largely correspond to time periods before and after official iodination efforts in 2000/2001, were compared for the cohort overall as well as by oblast of residence (i.e., state) and type of residency (urban/rural).
  
  
  RESULTS
  Median urine iodine levels among cohort members increased significantly in the later period (111.5 mg/L) compared to the earlier (65.3 mg/L), with the cycle 2 level in the range defined as adequate iodine intake by the World Health Organization. During the same period, a significant decline in diffuse goiter prevalence was also observed. In both cycles, urinary iodine levels were lower in rural than in urban residents. Urinary iodine levels, but not rates of goiter, varied by oblast of residence. In both periods, adjusted median urine iodine concentrations were similar in Gomel and Minsk oblasts, where *89% of cohort members resided, and were lowest in Mogilev oblast. Yet Mogilev oblast and rural areas showed the most marked increases over time.
  
  
  CONCLUSIONS
  Trends in urinary iodine concentrations and prevalence of diffuse goiter by palpation suggest that iodination efforts in Belarus were successful, with benefits extending to the most iodine-deficient populations. Iodine status should be considered when evaluating thyroid disease risk in radioiodine-exposed populations since it can change over time and may influence rates of disease and, possibly, dose-response relationships
authors.affiliation: Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland, USA. hatchm@mail.nih.gov
authors.forename: Maureen
authors.initials: M
authors.lastname: Hatch
authors.forename: Olga
authors.initials: O
authors.lastname: Polyanskaya
authors.forename: Robert
authors.initials: R
authors.lastname: McConnell
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Gong
authors.forename: Vladimir
authors.initials: V
authors.lastname: Drozdovitch
authors.forename: Alexander
authors.initials: A
authors.lastname: Rozhko
authors.forename: Alexander
authors.initials: A
authors.lastname: Prokopovich
authors.forename: Sergey
authors.initials: S
authors.lastname: Petrenko
authors.forename: Alina
authors.initials: A
authors.lastname: Brenner
authors.forename: Lydia
authors.initials: L
authors.lastname: Zablotska
mesh_terms: D000293:Adolescent; D047852:Chernobyl Nuclear Accident; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D006042:Goiter / Q000453:epidemiology*; D006801:Humans; D007223:Infant; D007455:Iodine / Q000008:administration & dosage / Q000652:urine*; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology; D002094:Republic of Belarus / Q000453:epidemiology; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage; D013959:Thyroid Diseases / Q000453:epidemiology; D013964:Thyroid Neoplasms / Q000453:epidemiology
chemical_list: D017673:Sodium Chloride, Dietary; C034024:iodized salt; D007455:Iodine