Cyanide Level in the Environment and Occupational Settings: A Systematic Review

Aims: To assess the safe level of cyanide in environment and occupational related activities.
Methodology: Systematic literature search of the related articles were carried out using the following databases: PubMed, Science Direct, Scopus, Cochrane Library, Science Citation Index Expanded, CINAHL and Ovid. Results were screened for duplicates and assessed for eligibility. Relevant data were extracted and assessment was conducted based on adverse events associated with cyanide exposure in the ambient air.
Results: A total of 8 related studies and 1 unpublished study from US EPA were identified for this review. Only 7 studies mentioned the hazardous level of cyanide with the symptoms in different occupational activity. The hazardous level varies from the lowest of 30µg/m3 to 17 mg/m3.
Conclusion: There is no adverse effects of exposure to the low concentrations of cyanide that are generally present in the general environment (<1 µg/m3 in ambient air). However, exposure of HCN at a concentration of >1,000 µg/m3 in ambient air for at least 5 years may show symptoms of toxicity and >7,000 µg/m3 may show signs of thyroid enlargement. As for at least 8.5 months or 24-hour in a confined area of 27m3 at a concentration of > 17,000 µg/m3 or >8,000 µg/m3 respectively may lead to death.