Research on Aflatoxin B1 in Omena from Kenya
By Esther Marijani 
,1 Harrison Charo-Karisa,2 Emmanuel Kigadye,1 and Sheila Okoth3
Omena (Rastrineobola argentea) is the most consumed fish species in Kenya. In this study, we assessed the occurrence of aflatoxin B1 (AFB1) in Omena and the potential health risk of AFB1 to Kenyan consumers of this fish. A total of 74 samples comprising Omena intended for human consumption and fish feed production were analyzed in this study. Aflatoxin levels in Omena were determined using the enzyme-linked immunosorbent assay (ELISA). Omena intended for fish feed production was most contaminated with a mean concentration of 46.93 μg·kg−1 (2.24–115.23 μg·kg−1) compared with Omena intended for human consumption (mean � 19.42 μg·kg−1, range � 2.01–49.30 μg·kg−1). positive samples (83.3%) exceeded the maximum level permitted (5 μg·kg−1) by the East Africa Community standard for food used for human consumption. Exposure dose of AFB1 from consuming Omena was estimated to be 1.34 ng·kg−1 BW day−1 and margin of exposure (MoE) value for AFB1 was found to be 126.3, which indicates health risk to Omena consumers. results suggest that the current situation of aflatoxin contamination in Omena has an adverse effect on the health of the consumers as well as the animals. more surveys are needed to understand the scope and extent of aflatoxin contamination in Omena.
Introduction
Fish is an important part of nutrition, contributing on average 22% of animal protein intake in the East and Central African regions [1]. Fish and fish products provide vital vitamins, minerals, fatty acids, and other micronutrients crucial to a healthy diet [2]. The most common fish species consumed in Kenya are tilapia and Rastrineobola argentea (locally known as “Omena” or “Dagaa”). Other species include Nile perch (locally known as “Mbuta”) and catfish [1]. According to the FAO [3], the production of Omena,
tilapia, Nile perch, and catfish in Kenya was 69,561, 47,555,43,399, and 11,398, respectively, in 2016.
Fish consumption rates are increasing due to fastgrowing population and awareness of the health benefits associated with consuming fish, as well as rising urbanization [1]. Fish consumption in Kenya is estimated at 4.5 kg per capita/year [4]. Omena is the most important small fish species that contributes immensely to the protein needs of the poor people [5], accounting for 35% of the country’s total fish human consumption. Between 60 and 70% of Omena is processed as animal feed [4]. However, poor handling, processing, and packaging methods and practices are used in Omena operations. traditional practice of drying fish on the ground or on old fishing nets is still common in Kenya [5]. practice results in patho-genic contamination of fish products, such as sun-dried Omena, and smoked catfish by fungi [6–8]. Over an ex-tended period of time, these pathogenic fungi can multiply and their metabolites cause changes in the feed and food quality that can adversely affect the health of animals and humans
Aflatoxins (AFs) are mycotoxins produced by the fungi Aspergillus flavus and A. parasiticus, which grow on numerous food and feedstuffs when environmental conditions are favourable [10]. are four common types of aflatoxins: AFB1, AFB2, AFG1, and AFG2. AFB1 is the most potent, among them, to both humans and ani-mals [11]. Aflatoxins can cause acute poisoning and mortality to humans and animals, usually due to liver cirrhosis. Also, inhalation or absorption of chronic lower-level doses of aflatoxins through the skin can result in cancer of the liver and chronic immunosuppression [12, 13]. All doses have a cumulative effect on increasing the risk of cancer. Cases of aflatoxicosis outbreak have occurred in Kenya after consuming maize, which are highly contaminated by aflatoxins [14]. Due to these outbreaks, aflatoxin contamination studies have focused on maize and maize products, milk, and groundnuts [15–20]. Contamination of fish in Kenya with aflatoxins has been largely ignored. are few studies on afla-toxin contamination of Omena intended for either human or animal consumption [6, 7]. studies report a low level of aflatoxin contamination (0 and 0.33–1.58 μg·kg−1) in dried Omena collected from the outskirts of the main city, Kisumu, in the Nyanza region. Hence, the present study evaluates the occurrence of aflatoxins in Omena intended for both human and fish feed production col-lected in Kisumu city. We further evaluate possible human exposure to aflatoxins as a result of the consumption of Omena.
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