Risk Assessment of Aflatoxin and Fumonisin in Fish Feeds, Kenya: A Review

Fish is a protein source and constitutes other significant nutrients that have been crucial to human health. Aquaculture in Kenya has grown faster than any other food production sector, with fish feeds being prepared from different cereal products commonly contaminated by Mycotoxins. But controlling the growth of fungi that cause mycotoxin has been a challenge due to conditions that enable their development. With fish contamination primarily ignored, there is still high consumption of fish being propagated by improved and increased aquacultural activities. There have been various qualitative and quantitative assessments on Aflatoxin and Fumonisin in animal feed and food with little focus on fish feed which might be the most significant risk factor for cancer development. Kenya's high occurrence warranted the current review, which describes sources of fish feeds, conditions for mould growth, exposure of fish too contaminated feeds, decontamination of fish feed and feed ingredients, effects of Fumonisin and Aflatoxin on fish and human, risk characterization and management strategies. This review provides a platform and insights to novice researchers to pave the way for future research in the area. Keywords: Mycotoxins; Aflatoxins; Fumonisin; Uasin Gishu; Kisumu. DOI: 10.7176/JBAH/11-10-05 Publication date:May 31st 202

Spatial distribution and loss of micronutrients in soils from two different land use management

Land use – land cover changes affect the ecosystems' status and integrity to support and supply the services. Agricultural activities and attendant soil erosion, leaching or depletion of nutrients may result in increased soil degradation. The study investigated micronutrient spatial distribution and concentration in soils within two different agricultural land use management. The study employed RUSLE equations to determine the erosion rate within the selected plots. Topsoils (5-10cm) from different points within the plots were collected and analyzed for micronutrients using ICPMS(QQQ). The plots are located in high potential soil erosion places with soil erodibility (K) factor OF 0.031-ton ha-1MJ-1mm-1 within the Ombeyi river catchment. The soil erosion was estimated to be > 50t ha-1 year-1 , implying the high loss of nutrients; hence, over 52 elements were analyzed. The two plots compared micronutrients iodine (I), calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), selenium (Se), zinc (Zn), and molybdenum (Mo). In Plot 1(no terraces), micronutrients were concentrated at the base of the plot, while in plot 2 ( terraces), some elements were evenly distributed. There is a significant difference in the concentration of elements between the plots; I, Se, Cu, Ca and Mg, depicting a p-Value of 0.05. Elements in plot one were mapped with high concentration at the lower part of the plot as related to plot two which most of the elements were evenly distributed hence reduced micronutrients in plot 2. This encourages educating farmers on the importance of good terrain soil management

Suitability of 210Pbex, 137Cs and 239+240Pu as soil erosion tracers in western Kenya

Land degradation resulting from soil erosion is a global concern, with the greatest risk in developing countries where food and land resources can be limited. The use of fallout radionuclides (FRNs) is a proven method for determining short and medium-term rates of soil erosion, to help improve our understanding of soil erosion processes. There has been limited use of these methods in tropical Africa due to the analytical challenges associated with 137Cs, where inventories are an order of magnitude lower than in the Europe. This research aimed to demonstrate the usability of 239+240Pu as a soil erosion tracer in western Kenya compared to conventional isotopes 210Pbex and 137Cs through the determination of FRN depth profiles at reference sites. Across six reference sites 239+240Pu showed the greatest potential, with the lowest coefficient of variation and the greatest peak-to-detection limit ratio of 640 compared to 5 and 1 for 210Pbex and 137Cs respectively. Additionally, 239+240Pu was the only radionuclide to meet the 'allowable error' threshold, demonstrating applicability to large scale studies in Western Kenya where the selection of suitable reference sites presents a significant challenge. The depth profile of 239+240Pu followed a polynomial function, with the maximum areal activities found between depths 3 and 12 cm, where thereafter areal activities decreased exponentially. As a result, 239+240Pu is presented as a robust tracer to evaluate soil erosion patterns and amounts in western Kenya, providing a powerful tool to inform and validate mitigation strategies with improved understanding of land degradation

Plutonium as a soil erosion tracer in east Africa

Subsistence farmers in Africa are often dependent on food grown within a limited area, and therefore, their health can often be associated with geochemical factors that influence the soil-tocrop transfer of micronutrients (MN) essential for health. Loss of essential MN because of soil erosion can affect both crop yields and the protection of crops against disease, which could dramatically increase the likelihood of food shortages worldwide. In addition to the effects on land, the associated downstream transport of sediments to water bodies associated with soil erosion can impact water security. A large proportion of the degradation caused by soil erosion processes is a direct result of poor land management practises as well as vegetation clearance, and so there is a need for reliable quantitative data detailing rates of soil erosion and sedimentation. This data can then help to reinforce sustainable soil conservation measures in areas where resources to manage soils sustainably can be limited. This research aims to investigate the potential of using plutonium as an alternative tracer of soil erosion in challenging environments such as tropical Africa. This will allow for further research into the extent of soil erosion across East Africa and inform future mitigation efforts to reduce further erosion in the future

Optimisation of plutonium separations using TEVA cartridges and ICP-MS/MS analysis for applicability to large-scale studies in tropical soils

The analysis of plutonium (Pu) in soil samples can inform the understanding of soil erosion processes globally. However, there are specific challenges associated for analysis in tropical soils and so an optimal analytical methodology ensuring best sensitivity is critical. This method aimed to demonstrate the feasibility of sample preparation and analysis of Pu isotopes in African soils, considering the environmental and cost implications applicable to low-resource laboratories. The separation procedure builds upon previous work using TEVA columns, further demonstrating their usefulness for the reduction of uranium (U) interference in ICP-MS analysis with enhanced selectivity for Pu. Here several steps were optimised to enhance Pu recovery, reducing method blank concentration, and improving the separation efficiency through the determination of the elution profiles of U and Pu. The elimination of the complexing agent in the eluent, increased the spike recovery by improving matrix tolerance of the plasma, and simplified the separation procedure, improving throughput by 20%. The subsequent method was validated through the analysis of Certified Reference Material IAEA-384, where high accuracy and improved precision of measurement were demonstrated (measured value 114 ± 12 versus certified value 108 ± 13 Bq kg−1). Optimisation of the column separation, along with the analysis of the samples using O2 gas in ICP-MS/MS mode to mass shift Pu isotopes away from interfering molecular U ions provided a simple, robust, and cost-effective method with low achievable method detection limits of 0.18 pg kg−1 239+240Pu, applicable to the detection of ultra-trace fallout Pu in African soils

Suitability of 210Pbex, 137Cs and 239+240Pu as soil erosion tracers in western Kenya

Land degradation resulting from soil erosion is a global concern, with the greatest risk in developing countries where food and land resources can be limited. The use of fallout radionuclides (FRNs) is a proven method for determining short and medium-term rates of soil erosion, to help improve our understanding of soil erosion processes. There has been limited use of these methods in tropical Africa due to the analytical challenges associated with 137Cs, where inventories are an order of magnitude lower than in the Europe. This research aimed to demonstrate the usability of 239+240Pu as a soil erosion tracer in western Kenya compared to conventional isotopes 210Pbex and 137Cs through the determination of FRN depth profiles at reference sites. Across six reference sites 239+240Pu showed the greatest potential, with the lowest coefficient of variation and the greatest peak-to-detection limit ratio of 640 compared to 5 and 1 for 210Pbex and 137Cs respectively. Additionally, 239+240Pu was the only radionuclide to meet the ‘allowable error’ threshold, demonstrating applicability to large scale studies in Western Kenya where the selection of suitable reference sites presents a significant challenge. The depth profile of 239+240Pu followed a polynomial function, with the maximum areal activities found between depths 3 and 12 cm, where thereafter areal activities decreased exponentially. As a result, 239+240Pu is presented as a robust tracer to evaluate soil erosion patterns and amounts in western Kenya, providing a powerful tool to inform and validate mitigation strategies with improved understanding of land degradation