[1] Harbin Med Univ, Ctr Endem Dis Control, Chinese Ctr Dis Control & Prevent, 157 Baojian Rd, Harbin 150081, Peoples R China
[2] Harbin Med Univ, Key Lab Etiol & Epidemiol, Natl Hlth Commiss & Educ Bur Heilongjiang Prov, Harbin, Peoples R China
[3] Harbin Med Univ, Heilongjiang Prov Key Lab Trace Elements & Human, Harbin, Peoples R China
[4] Xuzhou Med Univ, Sch Publ Hlth, Key Lab Environm & Hlth, Xuzhou, Jiangsu, Peoples R China