[1] Harbin Med Univ, Inst Kashin Beck Dis Control & Prevent, Chinese Ctr Dis Control & Prevent, Harbin 150081, Heilongjiang, Peoples R China
[2] Harbin Med Univ, Harbin Med Univ 23618504, Natl Hlth Commiss, Heilongjiang Prov Lab Trace Element & Human Hlth, Harbin 150081, Peoples R China
[3] Harbin Med Univ, Harbin Med Univ 23618504, Educ Bur Heilongjiang Prov, Key Lab Etiol & Epidemiol,Heilongjiang Prov Lab Tr, Harbin 150081, Peoples R China
[4] Beihua Univ, Sch Publ Hlth, Jilin 132013, Jilin, Peoples R China