Human health risk assessment of cyanide levels in water and tuber crops from Kenyasi, a mining community in the Brong Ahafo region of Ghana

Background: Cyanide is among the most harmful substances on Earth and it is harmful to humans and most aquatic life even at low concentrations. Free, total cyanide levels and other physicochemical parameters were determined in fish, cassava, cocoyam, dam and borehole water samples collected from Kenyasi, Ghana. A total of sixteen (16) water samples, five (5) fish samples, twenty (20) cassava and cocoyam tubers were collected from the study area. Free and total cyanide levels were determined using Skalar San⁺⁺ Automated Wet Chemistry Analyser with Continuous Flow method. Results: The mean free cyanide levels in fish, cassava, cocoyam, dam and borehole water samples were 63.09, 33. 26, 15.44, 0.16 and 0.18 mg/L, respectively, while the mean total cyanide levels were 93.60, 43.47, 29.62, 21.70 and 25.09 mg/L in fish, cassava, cocoyam, dam and borehole water samples, respectively. The mean pH value in fish, cassava, cocoyam, dam and borehole water samples were 6.90, 6.46, 6.82, 5.84 and 6.59, respectively. The mean conductivity was 153.64, 156.83, 76.03, 207.39 and 205.99 in fish, cassava, cocoyam, dam and borehole water samples, respectively. Results of two-way Analysis of Variance test showed that the variation in free cyanide levels was significant (p < 0.05) in the fish, cassava, cocoyam, dam and borehole water samples. Moreover, the hazard index results via ingestion and dermal contact with children are >1, including fish ingestion by an adult. This signifies adverse non-carcinogenic risk. The persistent intake of cassava and cocoyam can probably induce adverse health effects. Conclusions: From the results, it can be concluded that fish, cassava and water samples at Dam 4, Dam 7 and BH1 were not safe for consumption since they recorded values higher than the set limits. Therefore, people are advised not to feed on the cassava product, fish and consume water samples located close to Dam 4, Dam 7 and BH1.