Chronic cyanide exposure--A biochemical and industrial hygiene study

A study was undertaken to assess the health status of workers exposed to cyanide fumes and cyanide aerosols in one of the local factories. Cyanide levels in the breathing zone and the working atmosphere were measured. Cyanide and thiocyanate concentrations in blood and urine were determined colorimetrically. The cyanide and thiocyanate concentrations in blood and urine of exposed workers were much higher than those of control workers. Smokers had higher concentrations than nonsmokers. The highest values of cyanide were found to be 0.8 and 0.2 mg/m3 in the breathing zone and general workroom atmosphere respectively. In spite of such low values, the workers complained of typical HCN poisoning. It is suggested that MAC values of 5 mg/m3 (in terms of CN) should be reviewed in respect to conditions in India.