KNUST Study Finds Older Mangrove Wood for Smoking Fish Contains High Levels of Cancer-Causing Agents
Older mangrove wood used for smoking fish found to contain harmful PAHs and heavy metals, posing health risks.
- Kwame Nkrumah University of Science and Technology study finds older mangrove wood contains high levels of cancer-causing PAHs.
- Late-rotation (14-year-old) wood exceeds EU safety limits for carcinogenic compounds in smoked fish.
- Researchers recommend using younger wood and improved smoking practices to protect health and the environment.
Kwame Nkrumah University of Science and Technology researchers have discovered that older mangrove wood used for smoking fish contains elevated levels of cancer-causing compounds, raising concerns about the safety of smoked fish.
The 2026 study, led by Dr. Kwadwo Boakye Boadu at the Department of Wood Science and Technology, investigated polycyclic aromatic hydrocarbons (PAHs) in mangrove wood of different ages collected from the Salo market in Keta. PAHs are organic compounds known to alter genes and increase cancer risk in humans.
Researchers examined three age categories of mangrove wood: early rotation (8 years), mid-rotation (11 years), and late-rotation (14 years), reflecting the typical harvesting cycle of 6 to 15 years. The study detected 18 PAHs, with concentrations increasing as the wood aged.
Four of the compounds—Chrysene, Benzo[a]anthracene, Benzo[b]fluoranthene, and Benzo[a]pyrene—are classified by the European Commission as probable carcinogens. While Benzo[a]pyrene levels were within EU limits (1.0 µg/kg), the total concentrations of the four PAHs exceeded safe thresholds in fish smoked with 14-year-old wood, measuring 12.5 µg/kg against the EU limit of 12.0 µg/kg.
Dr. Boakye explained, “If you wait until the wood is about 14 years old before harvesting, the amount of PAHs produced during smoking becomes high, depositing harmful compounds in the fish and making it unhealthy.”
The study also revealed elevated levels of heavy metals such as cadmium and lead, surpassing EU safety limits.
Although mangrove wood remains popular among fishmongers for its slow-burning properties, strong flavor, and easy availability, the findings have renewed calls from environmental and health experts for safer smoking practices.
The researchers recommend using younger mangrove wood for smoking or adopting improved smoking techniques to reduce PAH and heavy metal contamination, ensuring both food safety and environmental sustainability.
