Effects of sulfur dioxide on the respiratory system of Miyakejima child residents 6 years after returning to the island.
OBJECTIVE
This study investigated the health effects of volcanic gas, mainly sulfur dioxide (SO2), exposure on the children of Miyakejima Island.


METHODS
Health checkups were conducted in November from 2006 to 2011. Health effects were evaluated through a self-administered questionnaire on respiratory and irritative symptoms, and spirometry. SO2 was measured continuously from February 2005 onward at six fixed monitoring stations in inhabitable areas. Based on mean SO2 concentration during 3 months before each health checkup, inhabitable areas were classified into three categories: (1) lower (area L); (2) higher (area H-1); and (3) highest (area H-2).


RESULTS
Average concentrations (ppb) of SO2 decreased year-by-year and ranged from 11.3 to 2.47 in area L, from 32.2 to 12.2 in area H-1, and from 75.1 to 12.1 in area H-2, respectively. In general, prevalence of respiratory and irritative symptoms was higher in area H-2, and the prevalence decreased year-by-year in all three areas by Cochran-Armitage test for trend. We defined a study population in area L in 2008 as a reference population because we had no unexposed population. Applying a logistic regression model, age-, sex-, and hypersusceptibility-adjusted prevalence odds ratios to the reference population showed clear exposure-dependent increases in some irritative symptoms such as "Irritation and/or pain in throat" and "in eyes," and approximately 30 ppb seemed to be the threshold concentration. Spirometry did not show any significant differences.


CONCLUSIONS
Though no pulmonary functions were affected, some subjective symptoms were detected dose-dependently by SO2 exposure concentration in child residents during the 6 years after the eruption.
Department of Preventive Medicine and Public Health, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan. iwasawa@a5.keio.jp.
Satoko
S
Iwasawa
Department of Preventive Medicine and Public Health, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan.
Makiko
M
Nakano
Department of Preventive Medicine and Public Health, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan.
Tazuru
T
Tsuboi
Department of Preventive Medicine and Public Health, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan.
Takeshi
T
Kochi
Department of Public Health, School of Human Life Sciences, Jumonji University, Saitama, Japan.
Shigeru
S
Tanaka
Department of Pediatrics, The Jikei University Daisan Hospital, Tokyo, Japan.
Toshio
T
Katsunuma
Gunma University/Kitakanto Allergy Institute, Maebashi, Gunma, Japan.
Akihiro
A
Morikawa
Department of Preventive Medicine and Public Health, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan.
Kazuyuki
K
Omae
D000293:Adolescent; D002648:Child; D004784:Environmental Monitoring; D005260:Female; D006801:Humans; D019570:Inhalation Exposure / Q000009:adverse effects* / Q000032:analysis; D007564:Japan / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D015995:Prevalence; D012140:Respiratory Tract Diseases / Q000139:chemically induced / Q000453:epidemiology*; D013147:Spirometry; D013458:Sulfur Dioxide / Q000032:analysis / Q000633:toxicity*; D018707:Volcanic Eruptions / Q000009:adverse effects* / Q000032:analysis
D013458:Sulfur Dioxide
Child; Dose–response health effects; Respiratory system; Sulfur dioxide; Volcanic gas