Occupational Health Hazards Associated With Gari Production and the Possible Environmental Effects Of The Resultant Effluent

Abstract

Cassava (Manihot esculenta, Crantz) is primarily grown for its starch containing tuberous roots, which are a major source of dietary energy in the tropics. It is highly perishable and begins to degenerate shortly after harvest. Cassava in the fresh form contains cyanide, which is extremely toxic to humans and animals. These factors make the processing of cassava into a dry form a necessity. Processing is essential for the removal of cyanides from cassava roots. This post-harvest necessity via gari production is coupled with several disturbing occupationally-related hazards. Exposure to volatile cyanide and smoke makes the frying stage of gari making the most dangerous. Effluent derived from gari production is noted to have a devastating effect on vegetation, as vegetation is hardly observed in areas where effluents are discharged. It also causes the eutrophication of surface water. This research aimed at determining processors’ awareness of occupational health hazards relating to their line of work, and their awareness of the environmental hazards associated with the discharge of untreated cassava effluent. The study further sought to determine the quality of cassava wastewater, and the possible generation of ethanol from the liquid waste using Saccharomyces cerevisiae in varying amounts. Processors from three gari producing districts in Ghana served as respondents. These gari-producing districts were; Awutu Senya, Central Tongu and Ayensuano Districts. Cluster sampling of each district was used in selecting the respondents. Ninety (90) gari producers served as respondents. Processors acknowledged health related hazards associated with their line of work, coupled with a low usage of protective clothing. Processors indicated several undesired effects the discharge of the effluent had on their immediate environment. Effluents obtained from these districts were assessed for wastewater quality, which showed values far outside EPA accepted limits; with the exception of PO4-P (0.125 mg/L) and NO3-N (0.070 mg/L), which were within acceptable limits. Mean values of the other quality parameters measured were; pH (4.02), Conductivity (12223.3 μS/cm), TSS (2078.3 mg/L), TDS (41597 mg/L), COD (60335 mg/L) and BOD (23493 mg/L). These very high wastewater quality parameters indicate that cassava effluent has a strong potential of being deleterious to vegetation and aquatic life. Optimum ethanol concentration (3.25%w/v) was obtained in baker’s yeast at 0.6%w/v. Optimum ethanol concentrations for the different yeast amounts used were obtained at 48 hours. Significant differences were observed (P<0.05) in the different amounts of baker’s yeast used. Appropriate stakeholder institutions should invest resources into educating gari producers on occupational safety and health. The EPA and WRI should develop guidelines relating to the treatment and discharge of the cassava effluent. Optimized fermentation approaches should be exploited in enhancing ethanol production from the cassava effluent.