[A study on the control of air toxic chemicals in workplace for bakelite manufacturing and casting]

Air concentrations of phenol, formaldehyde and ammonia related to the contents of free phenol, formaldehyde in raw material, and solidifying agent-urotropine in bakelite. Due to the solubility of phenol and formaldehyde, in the manufacture process, water was added to lower contents of phenol and formaldehyde in bakelite, and content of urotropine was reduced in bakelite sand presceription to lower air concentrations of phenol, formaldehyde and ammonia. As contents of phenol and formaldehyde in bakelite reduced to 4.9% and 0.037% from 6.32% and 0.062%, respectively, air concentrations of phenol, formaldehyde and ammonia lowered to 0.61 mg/m3, 0.69 mg/m3, and 5.1 mg/m3 from 2.94 mg/m3, 1.72 mg/m3, and 12.9 mg/m3, respectively, and incidence rate of skin disease in the employees of the workplace decreased to zero from 80.2%. It is recommended that a hygienic standard for allowable concentration of mixed toxic chemicals in the workplace air for bakelite manufacturing be formulated as soon as possible.