title: Compliance with the proper use of an individual radiation dosimeter among children and the effects of improper use on the measured dose: a retrospective study 18-20 months following Japan's 2011 Fukushima nuclear incident.
abstract: OBJECTIVE
  To identify profiles of children who did not properly use individual radiation dosimeters following Japan's 2011 Fukushima nuclear incident, and to assess how much error is generated by improper dosimeter use.
  
  
  METHODS
  The participants in this study comprised 1637 school children who participated in the external radiation exposure screening programme administrated by Minamisoma City (located 20-30 km from the Fukushima nuclear plant) between 18 and 20 months after the Fukushima incident.
  
  
  METHODS
  We assessed the factors associated with improper use (non-use) of the dosimeters at specific time periods during the day (school commuting hours, at school, at home, outdoors and at bedtime) using logistic regression analyses. Ratios of the measured dose to regression estimates of the 'expected' dose (referred to as an error due to non-use) were also examined.
  
  
  RESULTS
  Only 119 children (7.3%) used the dosimeters properly in all time periods. This low rate was attributed primarily to non-use when children were in the home and outdoors, rather than at school. School level, air dose rate at home, gender, membership in outdoor sports clubs and time spent outdoors on weekends, were significantly associated with improper use, after adjustment for covariates. Data from children who did not wear the dosimeters to school and outdoors had statistically significant (but clinically insignificant) errors (ratio: 1.13, p<0.01; and 0.97, p<0.05, respectively), whereas improper use of the dosimeters at school, at home and at bedtime did not generate significant errors.
  
  
  CONCLUSIONS
  Well-targeted rigorous instructions on the use of the dosimeter are required, with particular focus on time periods other than school hours. However, given the small dose error due to the improper use of the dosimeters, even if the dosimeters are improperly used, solid evaluation of the radiation exposure may be possible with some accuracy.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Nomura
authors.affiliation: Department of Radiation Protection, Minamisoma Municipal General Hospital, Fukushima, Japan Division of Social Communication System for Advanced Clinical Research, The Institute of Medical Science, University of Tokyo, Tokyo, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Tsubokura
authors.affiliation: Department of Physics, Graduate School of Science, University of Tokyo, Tokyo, Japan.
authors.forename: Ryugo
authors.initials: R
authors.lastname: Hayano
authors.affiliation: Department of Statistical Science, School of Advanced Sciences, The Graduate University for Advanced Studies, Tokyo, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yoneoka
authors.affiliation: Department of Radiation Protection, Minamisoma Municipal General Hospital, Fukushima, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Ozaki
authors.affiliation: Department of Radiation Protection, Minamisoma Municipal General Hospital, Fukushima, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Shimada
authors.affiliation: Faculty of Policy Management, Keio University, Fujisawa, Kanagawa, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Furutani
authors.affiliation: Department of Radiation Protection, Minamisoma Municipal General Hospital, Fukushima, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kanazawa
authors.affiliation: Department of Radiation Protection, Minamisoma Municipal General Hospital, Fukushima, Japan.
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Oikawa
mesh_terms: D000396:Air Pollutants, Radioactive / Q000032:analysis; D016902:Air Pollution, Indoor / Q000032:analysis; D002648:Child; D005260:Female; D005373:Film Dosimetry / Q000706:statistics & numerical data*; D062406:Fukushima Nuclear Accident; D006801:Humans; D007564:Japan; D016015:Logistic Models; D008297:Male; D008403:Mass Screening / Q000379:methods; D010349:Patient Compliance / Q000706:statistics & numerical data*; D000069079:Radiation Exposure / Q000517:prevention & control; D012189:Retrospective Studies; D012574:Schools; D057566:Self Report; D013334:Students / Q000706:statistics & numerical data*
chemical_list: D000396:Air Pollutants, Radioactive
keywords: OCCUPATIONAL & INDUSTRIAL MEDICINE; PUBLIC HEALTH