The　objective　of　this　study　was　to　investigate　the　concentrations,　seasonal　variations,　bioaccessibility,　and　associated　human　daily　intake　of　polybrominated　diphenyl　ethers　(PBDEs)　in　in-　and　out-house　dust　collected　in　Shanghai,　China.　The　PBDE　concentrations　varied　from　131.6　to　3,886.7　ng　g(-1)　(with　an　average　of　948.2　ng　g(-1))　in　in-house　dust　and　from　8.7　to　3,116.3　ng　g(-1)　(with　an　average　of　290.8　ng　g(-1))　in　out-house　dust　during　four　seasons.　The　PBDE　concentrations　in　the　autumn　were　the　lowest　for　both　in-　and　out-house　dust.　Among　the　detected　PBDEs,　BDE209　was　the　predominant　congener,　accounting　for　more　than　80%　of　the　total　PBDE　amounts.　The　bioaccessibility　of　PBDEs,　measured　using　a　simulation　system　of　human　gastrointestinal　tract,　was　determined　as　14.2-66.4%　depending　on　individual　PBDE　congeners　and　showed　significant　negative　correlations　with　organic　matter　in　dust.　After　corrected　with　the　bioaccessibility　of　PBDEs,　the　human　daily　intake　of　PBDEs　via　dust　ingestion　was　calculated　to　be　0.4-21.4　and　4.3-40.6　ng　day(-1)　for　an　average　adult　and　child　in　Shanghai,　respectively.　The　values　were　much　lower　than　most　estimates　in　the　literature,　in　which　the　bioaccessibility　of　PBDEs　were　not　taken　into　account,　suggesting　that　the　intake　of　PBDEs　may　have　been　overestimated.　(C)　2011　Elsevier　Ltd.　All　rights　reserved.