1. Cov khoom siv raw: Txhua yam khoom siv yog cov hlau lead dawb huv 99.997%, peb yuav qhia koj cov ntsiab lus hauv peb lub Hoobkas lub tsev rau khoom. Qhov no tseem ceeb heev, vim tias muaj ntau lub Hoobkas siv cov hlau lead rov ua dua tshiab, cov khoom sib xyaw ua ke sab hauv yuav ua rau lub roj teeb zoo tsis ruaj khov. Tshwj xeeb tshaj yog cov arsenic el...