MakotoFutatsuka, TakaoKitano, MegumiNagano, TsukasaInaoka, YoshikiArimatsu, Tatsuro Ueno,Junji Wakamiya, Kenjiro Miyamoto

Study objective-The aim was to determine theactualprevalence ofliver disease andtoinvestigate thecontribution ofvariousriskfactors to liverdisease amongthepopulation inamethylmercury polluted area. Design-Thestudywas a population basedcrosssectional massscreening survey.A case-control studywasdesigned to estimate theroleofvarious riskfactors for liver diseases. Setting-The studywas confinedto a smallruraltown10km northofMinamata City. Subjects-1406 personsaged50to69years were examined (78-3%of the total population ofthisageinthelocality). Measurementsand main resultsMeasurements ofliver disease weremade onthebasis ofhaematological, physical, and ultrasonographic examinations. Data on liverriskfactors werecollected byquestionnaire, and by measurementofbody height, weight(obesity), andhepatitis B surfaceantigen(HBsAg).Theprevalence rateofliver tumourwas05% inmales, liver cirrhosis wasfoundin0-5%ofmalesand 0-1%offemales, andhepatitis wasseenin 5-4%of malesand 1P0% of females. Frequency ratesofriskfactors forliver disease amongsubjects withobesity were significantly higherinthefemalepatient group,andthefrequency rateamongsubjectswithalcoholic drinking habitswas significantly higherinthemalepatient group.Theoddsratioofpasthistory of bloodtransfusion showedthehighest value amongotherrelated factors (773)andthe attributable riskforthiswasveryhigh (871%);HBsAgwasnextinrank(oddsratio 304;attributable risk671%). Conclusions-The prevalence ofliver diseaseinthismethylmercurypolluted area wasnotincreased, contrary towhatwas expected basedonthestandard mortality ratios. Themainriskfactors forliver diseaseinthisareaappeartobe alcoholic drinking habits andahistory ofbloodtransfusion.