Biomonitoring for iron, manganese, chromium, aluminum, nickel and cadmium in workers exposed to welding fume: a preliminary study oleh Mulyana, Mierna Reismala, Cynthia Nikopama, Afriyanti Wulandari, Ferry Chandra, Tri Nevita Panjaitan, Dorethea Krisiana, Marlisawati Sukma, Indah Rachmawati, Tri Agus Purnomo, Dina Ratnawati, Wahyu Purwita Sari, Vani Nur Pratami, Bertha Pangaribuan