Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was reviewed?
This systematic review evaluates cassava hydrogen cyanide safety in cassava and cassava-based products and compares processing methods that mitigate toxicant burdens relevant to HTMC certification. It synthesizes observational and experimental studies (1980–2025) on hydrogen cyanide (HCN), aflatoxins, pathogens, and heavy metals, benchmarking reported concentrations against international food safety criteria, notably the FAO/WHO limit of 10 mg/kg HCN. The article collates HCN measurements for traditionally soaked chips, biscuits, gari, flours, roots, and paste/dough, and links variability primarily to processing efficacy. It also summarizes evidence on arsenic, mercury, lead, and cadmium in cassava, emphasizing soil and mining-area influences, and outlines reduction efficiencies for boiling, fermentation, drying, and combined detoxification workflows.
Who was reviewed?
Studies covering households, processors, and consumers across cassava-consuming regions—predominantly sub-Saharan Africa with comparisons to Latin America and Asia—were included irrespective of language. Eligible designs ranged from cross-sectional surveys and case series to controlled field trials assessing product HCN levels and processing performance. Particular attention is given to vulnerable populations, including children, pregnant women, and the elderly, due to heightened susceptibility to chronic cyanide exposure and associated neurological sequelae such as konzo and thyroid effects. The review also considers supply-chain actors in household and industrial settings, where enforcement and testing infrastructure vary markedly, shaping residual HCN burdens and overall cassava hydrogen cyanide safety.
Most important findings
| Critical point | Detail |
|---|---|
| International benchmark | FAO/WHO Codex maximum HCN in edible cassava products: 10 mg/kg; numerous products exceed this without adequate processing. |
| Product HCN variability | Averages reported: traditionally soaked chips 46.6 mg/kg (range up to 200), biscuits 14.3 mg/kg, gari 5.7 mg/kg (0–23.9), cassava flour 71.1 mg/kg (peaks up to 200), roots 60.98 mg/kg, paste/dough 38.1 mg/kg. Processing heterogeneity explains differences. |
| Processing efficacy—best | Peeling + soaking + fermentation + controlled frying reduces HCN ≈100% to ~1.5 mg/kg; robust for HTMC-level compliance when standardized. |
| Processing efficacy—effective | Traditional soaking reduces ≈20% (final ~50.7 mg/kg); sun drying ≈30% (final ~30.5 mg/kg); both are commonly non-compliant without additional steps. fsufs-9-1497609 |
| Processing efficacy—insufficient | Traditional soaking reduces ≈20% (final ~50.7 mg/kg); sun drying ≈30% (final ~30.5 mg/kg); both are commonly non-compliant without additional steps. |
| Regional disparities | Flour from some Ugandan settings and chips from Western Mongu showed high HCN, while Nigerian and Malawian gari frequently met or approached limits, underscoring localized standards and training needs. |
| Heavy metals | The review considers As, Hg, Pb, and Cd as WHO priority elements; levels are soil- and context-dependent, with elevated Hg documented near gold-mining watersheds and potential plant uptake via roots and foliage, indicating location-based sourcing controls for HTMC. |
| Co-contaminants | Aflatoxin risk increases with poor hygiene and storage; microbial hazards are processing- and moisture-dependent, necessitating GMPs alongside cyanide detoxification. |
| Vulnerable groups | Children and pregnant women face disproportionate morbidity from chronic cyanide exposure (e.g., konzo, thyroid dysfunction), justifying tighter HTMC safety margins and batch testing frequency. |
| Market opportunity | Gari, rich in roughage and commonly ≤10 mg/kg when well-fermented/dried, is a promising export product if standardized SOPs and verification testing are enforced. |
Key implications
For HTMC, primary regulatory impacts include codifying the 10 mg/kg HCN ceiling with validated lab methods and regional risk stratification. Certification requirements should mandate documented peeling–soaking–fermentation workflows or 30-minute boiling equivalents, plus aflatoxin and heavy-metal panels for mining-adjacent sourcing. Industry applications favor gari and controlled-process flours under GMP and HACCP. Research gaps concern quantified heavy-metal baselines across geographies and the scale-up of enzymatic or genetic low-HCN solutions. Practical recommendations prioritize SOP standardization, batch testing, and targeted community training to sustain cassava hydrogen cyanide safety.
Citation
Forkum AT, Wung AE, Kelese MT, Ndum CM, Lontum A, Kamga EB, Nsaikila MN, Okwen PM. Safety of cassava and cassava-based products: a systematic review. Frontiers in Sustainable Food Systems. 2025;9:1497609. doi:10.3389/fsufs.2025.1497609
