Cov Khoom Siv Hauv Sab Saum Toj (SMT) tseem hu ua cov thev naus laus zis sib dhos (PCB
Feem ntau, cov khoom siv hluav taws xob peb siv tau tsim los ntawm PCB ntxiv rau ntau yam khoom siv hluav taws xob yuav tsum muaj ntau yam tshuaj siv hluav taws xob raws li cov txheej txheem .

