Aflatoxin Contamination of Maize from Small-Scale Farms Practicing Different Artisanal Control Methods in Kitui, Kenya

Afatoxin contamination of maize is a threat to food security and public health for households that depend on farming in developing countries. Te objective of this study was to determine levels of total afatoxins in maize from farms adopting diferent artisanal afatoxin control methods. A cross-sectional study was conducted with 315 maize farmers who provided maize samples for afatoxin analysis and additional data on artisanal afatoxin control methods applied at farm level. Maize grains were ground, and levels of afatoxins were determined using competitive enzyme-linked immunosorbent assay. Data were analyzed by computing descriptive statistical measures, and binary logistic regression was used to determine the relationship between levels of afatoxin in maize and artisanal control methods applied in diferent farms. Afatoxin was detected in 98% of maize samples with a mean total afatoxin level of 12.86 μ g/kg which was above the maximum tolerable limits. Tere was a signifcant diference in total afatoxin levels in maize obtained from farms which practiced minimum tillage compared to those practicing deep tillage ( p � 0.015). Drying maize on bare ground had a higher likelihood of afatoxin contamination than drying maize on tarpaulin ( p � 0.005). One-third of maize samples had afatoxin levels exceeding the set maximum limit, with maize samples from lowland areas having high proportions of afatoxin-positive cases as compared to uplands. Artisanal afatoxin control technologies such as land tillage, types of platforms for drying maize, and sources of maize seed signifcantly infuence the level of afatoxins in maize samples. We recommend targeted active surveillance for afatoxins, continuous public education, and adoption of farm-level mitigation measures to reduce the impact of afatoxin contamination in farming communities


Introduction
Agriculture is the mainstay of most African countries, and maize is an important cereal crop grown on over 47 million hectares cultivated by small-scale farmers with an annual output of 90 million tons [1].In addition, maize farming supports the livelihoods of millions of subsistence farmers in Kenya.Currently, maize is cultivated on approximately 2.19 million hectares of land, creating employment for more than 3 million smallholder families with an annual output of 3.79 million tons [1].Maize is therefore a staple food for an estimated 50% of the population, and it accounts for 65% of the staple food calorie intake in Kenya [2].
Afatoxins constitute a major challenge to food and nutrition security in Africa and are the most commonly known noninfectious food-borne hazard that constitutes a major public health risk.Afatoxins are a group of structurally related, toxic, secondary metabolites produced by Aspergillus favus and Aspergillus parasiticus which are present in soils, air, seeds, and plant debris and can contaminate maize, peanuts, peanut meal, cotton seed, cotton seed meal, and beans [3].Afatoxin contamination is primarily associated with maize and maize products more than any other food crops.Kenya is one of the world's hotspots for afatoxin contaminations, with a record of what is believed to have been the highest incidence of acute toxicity [4].Te country has sufered severe outbreaks of afatoxin poisoning since the frst reported outbreak which occurred in 1981 with 20 hospitalized victims of which 12 of them died of liver failure [4].In that study, victims were reported to have consumed maize with high levels of afatoxins, and on necropsy, their liver tissues had up to 89 parts per billion of afatoxin B 1 .In 2004, an acute outbreak of afatoxin poisoning occurred in Kenya with a total of 317 reported cases and a case fatality rate of 39% [5].It is argued that most outbreaks of afatoxin poisoning occur in remote villages where access to medical facilities is hampered by the long distance people have to travel and the high incidence of rural poverty, and therefore, the actual number of people afected by afatoxins poisoning could be higher than currently reported [6].Indeed, afatoxin contamination is known to be prevalent in Eastern region of Kenya, where home-grown maize is often contaminated during the postharvest stage of maize grain handling [5].
Human exposure to afatoxin occurs mainly through ingestion of contaminated food [7].Te presence of toxins in food can cause acute and chronic efects referred to as afatoxicoses.Approximately more than 5 billion people in developing countries are at risk of exposure to afatoxins through consumption of contaminated foods [8].Acute toxicity resulting from exposure to high levels of afatoxins is a very rare event worldwide, although some cases have occurred in high-risk regions such as the documented outbreak in Eastern region of Kenya [9].Acute exposure to high doses of afatoxin results in patients showing symptoms of jaundice, vomiting, abdominal pain, and liver failure with case fatality rates of up to 40% [10].Chronic exposure through cumulative ingestion of low quantities of afatoxin in the diet over a period of time is widespread and is the leading cause of liver cancer in adult populations in developing countries [11].Furthermore, chronic exposure to afatoxins has been associated with malnutrition and stunted growth in children [12] and suppression of the immune system [13].It is estimated that up to 28.2% of annual liver cancer cases in humans globally are linked to exposure to afatoxin [14], while an estimated 26,000 people in sub-Saharan Africa die annually from afatoxin-related liver cancers [15].
Afatoxin contamination in food products is regulated in most countries, with maximum limits ranging from 5 to 20 μg/kg in human food [16].Te European Union has the most stringent standard for allowable limits of afatoxin in maize with a maximum limit of 4 μg/kg for total afatoxin [17].Kenya has set a maximum limit of 10 μg/kg for total afatoxins in maize and maize products which are similar to limits established by the Codex Alimentarius Commission and East African Community [18].However, measures for prevention of contamination are sometimes not fully enforced within the context of developing countries, especially for food commodities sold within informal markets.Several technologies have been shown to reduce levels of afatoxin contamination during the preharvest, harvest, and postharvest stages of maize production.At the preharvest stage, adoption of timely planting, application of manure, provision of supplemental irrigation, crop rotation, and application of atoxigenic strains of Aspergillus favus have been demonstrated to reduce levels of afatoxins [3,19].Postharvest control of afatoxin is achieved through proper drying of maize grains, sorting to remove damaged and shriveled kernels, and storage of maize grains in well-aerated facilities or in hermetic bags [20][21][22].
Despite the presence of these known technologies, aflatoxin contamination of maize and other cereals has persisted in rural farming communities, hence increasing risk of households' exposure to the negative consequences of afatoxicoses.Several farms are implementing diferent measures to mitigate the risk of exposure, yet no study has compared levels of afatoxins in maize from farms practicing diferent afatoxin control measures.Te objective of this study was to determine the level of total afatoxins in maize grains and compare the levels of afatoxin in farms practicing diferent control methods in two diferent production areas which were classifed as hilly rugged upland areas and lowland dry areas.Te fndings will be useful in guiding policy formulation and farming practices in order to mitigate afatoxin contamination in similar settings in sub-Saharan Africa.

Study Area.
Te study was carried out in Kitui County, located between latitudes 0 °10′ and 3 °0′ south and longitudes 37 °50′ and 39 °0′ east.Te county is one of the 47 counties in Kenya.It is the sixth largest county with a land size covering 30,496.4km 2 including 6,369 km 2 occupied by Tsavo East National Park (County Government of Kitui (CGoK), 2017).Te county has a human population of 1.136 million based on the 2019 census.It has low-lying topography with arid and semiarid agroecological zones.Rainfall distribution is erratic and unreliable, and topography can be divided to hilly rugged uplands and lowlands areas with altitude ranging between 400 m and 1800 m above sea level.Te county experiences high temperatures throughout the year ranging from 14 °C to 34 °C [23].Te rainfall pattern is bimodal with two rainy seasons (short rains come in the months of October-December while long rains come in April-May) with a high variability in annual rainfall amounts ranging between 500 and 1050 mm [24].Te county was purposively selected for the study because of its high risk for afatoxin contamination of maize since it falls within an afatoxin hotspot [25].Te feld surveys were conducted between the months of May and June 2021 in four wards and 12 villages located in diferent agroclimatic zones.Mutha and Athi wards are located in lowland areas of Kitui south subcounty, while Miambani and Kyangwithya west wards are located in hilly upland areas of Kitui Central subcounty (Figure 1).

Study Design and Sampling.
A cross-sectional study design was employed for the selection of study units which were defned as farming households which planted maize in previous season and got a harvest.However, households which did not plant maize in the previous season and those that did not harvest from their farms were excluded.
Multistage sampling procedure was used.Two subcounties were purposively selected from eight subcounties in Kitui to represent the two main farming areas (upland areas and lowland areas).From the two selected subcounties, two administrative wards were randomly selected from each subcounty to make four wards representing the two farming areas.A list of villages where maize is grown within the two wards was obtained from the ward agricultural ofcers.
Tree villages from each of the four selected wards were randomly selected to form a list of twelve villages which were defned as the study sites.
Te sample size was determined using the formula in [26].Te prevalence of afatoxins in cereals was estimated at 25% [27], with a level of accuracy set at 5%.Te estimated sample size was 288 maize farmers.Tis was adjusted upwards to cater for withdrawals from the study, and sample size of a 315 maize farmers was used.Te sampling proportionate to population size technique was used to select the number of maize farming households in each village.Using the Microsoft Excel random number table function, households were randomly allocated for the study.In total, 315 maize farming households were recruited, and the number of households selected from the wards was 80, 79, 79, and 77 for Athi, Mutha, Miambani, and Kyangwithya West wards, respectively.In each of the selected households, the study respondents were the head of household who was considered to be aged 18 years and above.

Data Collection.
Prior to data collection, each respondent was briefed on the objectives of the study, and oral consent was sought for them to participate.Upon receipt of oral consent, a pretested semistructured questionnaire was administered to the household head using Kamba language, which the frst author and research assistants understood and spoke fuently.Te questionnaire sought to collect data on artisanal methods that small-scale farmers were using to control afatoxin contamination in maize.Tese included data on practices on farm tillage, types of seed and where they obtained seeds from, use of organic manure and commercial fertilizer, crop rotation, method of maize harvesting, maize drying platforms, maize sorting practices, method of maize shelling, method of determining if maize grain was well dried before storage, and maize storage practices.Basic demographic data of the respondents including age, gender of the respondent and household head, marital status, education level, monthly incomes, size of household, size of land, and geo-referenced location of the farm were collected.After the interview, respondents provided 1 kg of maize grain sample from the previous harvest for further afatoxin testing in a laboratory.
Maize grain samples were collected according to the recommended processes published by the Food and Agriculture Organization of the United Nations for afatoxin analysis [18].Briefy, from each farm, shelled maize grains were randomly sampled from diferent parts of the storage vessel.Te incremental sample was thoroughly mixed to form a composite sample of which a maximum of 1 kg was drawn for afatoxin testing.Samples were immediately placed in a brown khaki paper bag, properly labelled, and stored.Te maize samples were transported to the Mycotoxin Research Centre at the Department of Public Health Pharmacology and Toxicology, University of Nairobi, for further laboratory testing.

Sample Preparation for Laboratory
Testing.Te samples were prepared as per the kit manufacturer's instructions [28].Briefy, twenty (20) grams of maize grain samples were weighed and ground at 8.5 revolutions for one and a half minutes and again at 10 revolutions for one minute to obtain a fne particle size with 95% passing through a 20-mesh screen using Retsch Grindomix GM 200.Te milling machine was thoroughly cleaned using a sodium hypochlorite solution, wiped with paper towels soaked in methanol, and allowed to dry between samples to avoid cross contamination.Subsequently, 5 grams of subsample were taken using a digital weighing scale and used to extract afatoxins following the prescribed method [28].Te remainder of the sample was packed in quarter-kilogram paper bags and stored at room temperature as a reference sample.Afterwards, 5 grams of reference material were weighed, awaiting the afatoxin extraction process.

Afatoxin Extraction
Procedure.Extraction solution was prepared by adding 770 ml of methanol to 330 ml of deionized water and properly mixing to make 70% methanol-water solution.To 5 grams ground grain sample, 25 ml of 70% methanol-water solution was added at the ratio of 1 : 5 weight/volume.Te preparation was mixed well using an electric shaker for 3 minutes.After allowing the mixture to settle down on the bench at room temperature, 10 ml of supernatant was fltered through Whatman No. 1 flter paper, and the test fltrate was collected in 2 ml Eppendorf tubes.

Afatoxin Assay
Procedure.Te afatoxin assay procedure was carried out as per the kit manufacturer's (Helica Biosystems, Inc.) instructions without modifcations [28].Briefy, mixing wells containing ground maize samples and standards were placed on a microwell holder.An equal number of antibody-coated microtiter wells were placed in another microwell holder.Using an Eppendorf precision pipette, 200 μL of afatoxin-HRP conjugate was placed in each mixing well.Using a new pipette tip for each sample and standard, 100 μL of both the standard and sample were added to the appropriate mixing well containing conjugate and mixed well by priming the pipette at least 3 times.Te six standards had the following concentrations: 0.0, 0.2, 0.5, 1.0, 2.0, and 4.0 ng/mL in 70% methanol.Using a new pipette tip for each, 100 μL of the content from each mixing well was transferred in duplicates to a corresponding antibody-coated microtiter well and incubated for 15 minutes.Tereafter, contents from the microwells were decanted in a discard basin containing 3.5% sodium hypochlorite.Te microwells were washed by flling each with PBS-Tween wash bufer and decanting of the bufer in the discard basin.Te washing was repeated 5 times.PBS-Tween wash bufer was prepared by mixing 1 pouch (Tween 20) with 1 litre of distilled water and refrigerated.Te microwells were turned upside down and tapped on a layer of absorbent paper towels to remove residual washing bufer.To each microwell, 100 μL of substrate-chromogen was added, shaken, and incubated at room temperature for 5 minutes.After incubation, 100 μL of stop solution was added to each well.Te optical density (OD) of each microwell was read with a Multiskan Plus reader (Labsystems Company, Helsinki, Finland) at a wavelength of 450 nm.Mean ELISA reading values for each standard and sample were determined.For every ELISA plate, a standard curve was generated by placing total aflatoxin standard concentration values on the y-axis and optical density values on the x-axis; these regression curves were used to determine the afatoxin value in each of the samples.

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Journal of Food Quality Te analytical method used was validated with certifed corn reference material at 27 ppb total afatoxin, batch no.02017-000079 (the ofce of the Texas State Chemist, Texas, USA).Furthermore, the laboratory has been participating in an ongoing profciency testing program for total afatoxin in corn.Te limit of detection (LOD) for this assay was 0.2 μg/ kg total afatoxin and the limit of quantifcation (LOQ) was 0.6 μg/kg.Samples with toxin values below the limit of detection were considered as containing no detectable level of toxin.For purposes of data analysis, nondetect levels were based on the detection limits (LOD) of the test method for the toxin.Detectable levels of afatoxin were compared to the East African Community (EAC) that established maximum tolerable limits.Left-censored data involving samples with toxin values below the limit of detection were processed by applying the European Food Safety Authority's substitution method [29].Prior to the survey, each respondent was briefed on the objective of the study and the oral consent was sought.Te interviews were conducted on a voluntary and consensual basis.

Data Management and Analysis.
Data were entered in a database developed in MS Excel ® 2010.Te data were exported to IBM statistical package for social sciences software (version 21) for analyses.Descriptive statistical measures were computed to determine the mean levels of afatoxins in maize samples.Based on East African Community standard, samples were categorized as either having high or low levels of afatoxins.Maize samples with total afatoxin levels above 10 μg/kg were categorized as high, while samples with total afatoxin levels below 10 μg/kg were categorized as low.Inferential analysis using binary logistic regression was performed to compare levels of afatoxin in maize from farms that implemented diferent artisanal aflatoxin control methods from the two diferent maize farming areas.For all inferential analysis, level of signifcance was set at 5%.

Demographic Characteristics of Maize Farmers.
Te age of maize farmers ranged between 20 and 85 years with a mean age of 51 years.About 71% of maize farmers were female, while 76% of farming households were headed by men.About 57.8% of respondents had attained primary level education, 17.5% had secondary education, and 16.5% had no formal education.Te majority (81%) of maize farmers reported a household income that was below the minimum wage in Kenya of Ksh.13,572 (exchange rates: 1 USD � Ksh.120) per month.Te average household size was 6 persons, and the average land size owned by households was 2.6 acres, with the largest farm size holding being 20 acres.Te primary sources of income for households included crop agriculture and livestock farming (96%) with only a small proportion of respondents who were on salary employment [30].

Artisanal Afatoxin Control Technologies Adopted by
Maize Farmers.Te majority of the maize farmers practiced dry planting.With regard to use of soil implements, 63% utilized organic manure, while a few applied chemical fertilizers (9%).Maize farmers relied on local maize seed from previous harvest seasons as opposed to use of certifed seeds which are marketed by commercial seed producers, while oxen ploughing was the most frequently practiced method of land tillage.With regard to postharvest control technologies, 72% of maize farmers interviewed harvested maize by dehusking in felds with 30% drying maize on bare ground.Maize was mainly shelled by placing cobs in a sack and beating them with wooden sticks, and the majority (75.2%) of farmers sorted maize cobs before shelling.Shelled maize grain was stored either in hermetic bags (44%), propylene bags (39%), and gunny bags (13%), while the remainder was stored without shelling.Fifty percent of maize farmers applied insecticides before maize storage, while the majority of farmers placed maize bags on wooden pallets during storage [30].

Occurrence and Prevalence of Afatoxin Contamination in
Maize.Te level of afatoxin contamination in maize samples varied across the study sites.A majority of the maize samples conformed to the threshold set by the Kenyan Bureau of Standards (KEBS) of 10 μg/kg (Table 1).Nevertheless, 35% of maize samples exceeded the regulatory limit with some samples exceeding by 5 times the acceptable limits for human consumption.Total afatoxins were detected in 98% of 315 samples tested with only seven samples having nondetectable levels of afatoxins.Afatoxin contamination ranged from 0.26 μg/kg to 53.91 μg/kg with an average of 12.86 μg/kg which was higher than the maximum acceptable limit.Te level of afatoxin contamination was higher in samples from lowland areas with average levels of 17.61 μg/ kg and 12.77 μg/kg in Athi and Mutha wards, respectively, as compared to upland areas with average levels of 10.16 μg/kg and 10.78 μg/kg in Miambani and Kyangwithya west wards.Te diference in mean afatoxin contamination in the two farming areas was statistically signifcant (p � 0.007).Te highest recorded afatoxin contamination was in Mutha ward in the lowland areas.Athi ward had the highest overall proportion of afatoxin-contaminated maize (46.3%) which exceeded the regulatory limit while Miambani had the least (27.8%).

Farm-Level Practices and Teir Association with Levels of Afatoxin Contamination of Maize.
Tere was a signifcant diference in afatoxin levels in maize obtained from farms Journal of Food Quality which practiced minimum tillage compared to farms which practiced deep tillage (p � 0.015).Afatoxin contamination increased with an increase in types of tillage with farms practicing minimum tillage exhibiting low levels of afatoxin compared to farms practicing deep tillage by use of tractors and use of oxen plough.Farms which used oxen plough and tractors had an increased risk of having high levels of aflatoxin contamination above the acceptable limits.Drying maize on bare ground increased afatoxin contamination of maize, while drying of maize on a raised platform and use of tarpaulin or mat for drying maize reduced the risk of aflatoxin contamination (p � 0.005) (Table 2).Te results also revealed a signifcant diference in afatoxin levels from sources of maize seed, with certifed maize seeds purchased from agrovets (shops selling agricultural inputs) exhibiting the lowest levels of afatoxins (p � 0.009).Similarly, storage of maize grains in hermetic and gunny bags reduced the risk of contamination with afatoxins (p � 0.000).

Discussion
Te average level of total afatoxins in maize samples estimated at 12.86 μg/kg was higher than the acceptable limit of 10 μg/kg based on the East African Community standards [18].Te estimates are comparable to fndings by Kimani [31], who reported a mean afatoxin level of 13.17 ppb in maize grain.However, other studies had previously reported higher estimates of total afatoxins in maize samples in Kenya [6,32].Te study has further revealed that 35% of maize samples contained afatoxins at levels above the acceptable limits and therefore were generally unft for human consumption, a fnding which had also been reported in a previous study [32].Similar results were reported by Mwihia et al. [33] at 35.5% for home-grown maize in Makueni.Mutiga et al. [34] also reported that 37% of maize samples collected from local commercial maize mills during an active outbreak in Kitui were contaminated with afatoxins above the acceptable limits of 10 µg/kg limit.Given the dietary importance of maize as a staple food, it is likely that most rural households in Kitui are frequently exposed to afatoxins.Indeed, previous outbreaks of afatoxicoses in Kitui have been traced back to consumption of contaminated maize [6,32].Similarly, results from a 3-year crosssectional survey in Makueni and Kitui between 2005 and 2007 reported that the overall geometric mean of afatoxins in household maize samples was 17.8 µg/kg [32].In a diferent survey within the same area, Mahuku et al. [35] reported that afatoxin contamination levels in maize samples ranged between 0.98 and 722 µg/kg.Furthermore, a report had documented that 90% of cooked food for consumption by lactating mothers in Makueni had afatoxins levels above acceptable limits [36].Te occurrence of afatoxins has also been associated with seasonality; for example, Obonyo and Salano [27] reported that maize grain harvested in the month of May had lower afatoxin levels as compared to those harvested during the October-December months with high levels of precipitation.From the two seasons, these authors reported 16% and 44% of maize samples, respectively, to have total afatoxins above the maximum acceptable limits.Awuor et al. [37] also reported that one-third of maize samples from farms in Busia, western Kenya, have levels of afatoxin above acceptable limits.Likewise, a report had previously estimated an average aflatoxin level of 12.47 µg/kg in Tanzania [38] and 18.8 µg/kg in freshly harvested maize [39].Even though the study by Seetha et al. [39] reported a high level of afatoxins estimated at 57.2 µg/kg during storage.In Ghana, Kortei et al. [40] reported that 52.2% of maize samples of white and colored grains had afatoxin levels above the acceptable limits sets by the Ghanian standard authority.From that study, the majority (56.9%) of samples analyzed for total afatoxins in white maize samples exceeded the country's set limits for total afatoxins with only 16.7% of colored maize samples found to exceed the limit.Tese reports corroborate our results of 35% level of prevalence of contamination above acceptable limits in maize farms and an average level of total afatoxins of 12.86 μg/kg in maize samples.
Te results of this study revealed that afatoxin levels in maize kernels difered signifcantly between the farming areas with the lowland regions exhibiting high afatoxin levels in maize compared to uplands.Te results of this study are similar to those of Malusha et al. [41], who reported that low altitude areas had more afatoxin-contaminated maize than high altitude areas with the afatoxin positivity rate of maize contamination being 33.3% in low altitude area as compared to 12.5% in high altitude area.Nyangi et al. [42] also found that maize from drier areas had signifcantly higher levels of afatoxin as compared to those from wetter areas.Te low attitude areas are usually characterized by warmer and hotter weather with high temperature and humidity, which are conditions that favor fungal growth and consequent release of afatoxin.Tis is in contrast to high EAC (East African Community) standard maximum limit for total afatoxin in maize is 10 μg/kg.

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Journal of Food Quality altitude areas which are cooler and are characterized by low temperatures and humidity which do not favor fungal growth.Tis argument is corroborated by a previous report that documented that maize grain from temperate regions had a relatively low mean afatoxins contamination as compared to those from semiarid and subhumid zones in Kenya [43].Te authors of this previous report had attributed this to unfavorable climatic conditions in cooler high altitude areas that did not favor fungal growth and afatoxin development.In addition, the eastern region of Kenya has been reported to harbor deadly strains of Aspergillus favus [44].Research has shown that increasing temperatures, particularly when combined with lower precipitation levels during early growing season, lead to higher levels of afatoxin contamination [45].Te risk of chronic afatoxin exposure is therefore a signifcant health risk in the lowland farming region, given that maize is a staple in the region.Likewise, a study conducted in Ghana showed that the occurrence of afatoxins was infuenced by rainfall patterns and levels of humidity in the diferent agroecological zones [46].Preharvest and postharvest farm-level practices play a key role in reducing levels of afatoxin contamination in maize.Our study explored the association between artisanal afatoxin control methods and the level of afatoxin contamination of home-grown maize.Tere was a signifcant diference in afatoxin levels in maize samples obtained from farms that practiced minimum tillage and farms which practiced deep tillage with maize farms practicing deep tillage exhibiting high levels of afatoxins in maize samples.Similar fndings have been reported by Nyangi et al. [42], who found that farms that used hand hoe and oxen plough for tillage had low levels of afatoxin when compared to farms that used tractors.Tese results are contrary to conventional knowledge since minimum tillage has been associated with higher levels of afatoxins contamination as opposed to deep tillage.Tis occurrence is explained by the fact that soil quality highly depends on factors such as soil fertility, soil structure, human infuence, and tillage method which are key management practices afecting soil physical parameters [47].Aspergillus favus is argued to sit on soil surface and often jumps to maize ears during rain splash or wind.However, if the fungal population is submerged due to deep tillage, it will not be able to contaminate crops since it cannot reach the soil surface [48].Furthermore, Helgason et al. [49] have argued that no tillage practices can result in increased bacterial and fungal biomass at the soil surface which may imply that there would be a higher likelihood of fungal growth and mycotoxins production in a farm practicing shallow tillage or under no tillage than in cases of a farm implementing deep tillage.However, our results could have been infuenced by other postharvest handling practices since the maize samples obtained from households had been subjected to other postharvest management practices including methods of maize drying, storage, and shelling, and therefore, the efects of land tillage methods would be masked by afatoxin contamination from these postharvest practices.
Afatoxin contamination was also associated with the sources of maize seed used for planting.Mean afatoxin levels in maize were lower in maize samples from farmers who purchased certifed seeds as compared to other sources including farmers who used maize seeds from their previous harvest.Similar fndings have been documented by Daniel et al. [32], who reported that afatoxin was lower in maize purchased from markets and higher in home-grown maize seeds.While similarities exist in these fndings, the methodology employed in both studies was diferent.Our study sampled home-grown maize obtained from the previous cropping season, while Daniel et al. [32] sampled maize from farm stores that was purchased from the market for consumption.Te agrovets (shops selling agricultural inputs) are a source of certifed seed varieties that are droughtresistant and suitable for that geographical region.Although certifed maize seeds are not necessarily fungal resistant, they are ecologically adapted since they are tested for pest and disease resistance, drought, and low nitrogen tolerance.Other studies have also revealed that purchased maize grains from markets contained higher afatoxin levels compared to home-grown maize.A study by Mutiga et al. [50] reported that Kenyan farmers valued the maize they cultivated and harvested themselves more than what they purchased from millers and markets.Similar fndings were reported by Hofmann and Gatobu [51], who argued that people valued home-grown maize more because they are sure of its safety and quality.Tese could be the drivers for most farmers using maize seeds from the previous planting season as seeds.Tese fndings agree with our study results that about two-thirds (58%) were planting seeds obtained from their own farm-sourced maize grains of local varieties as compared to those purchased from markets, certifed seeds from agrovet, or received donation from the government.Tis practice could also result in the accumulation of afatoxins in the farms since already infected seeds are continuously recycled in the farms, hence maintaining higher levels of afatoxins.Factors associated with the choice of seed variety by the farmers were drought resistant, high yielding, and adaptability to local climatic conditions.Although local varieties are adapted to local conditions as a result of many years of selection, they could still be susceptible to fungal infections [52].
Maize drying methods infuenced afatoxin contamination with maize dried on tarpaulin/mat exhibiting lower levels of afatoxin than maize dried on bare ground.Maize dried on bare ground had a higher predisposition for contamination.Te fndings are consistent with previous reports that had documented that afatoxin contamination of maize grains dried on the ground was signifcantly higher than those dried on tarpaulins and raised racks [53].Pretari et al. [54] reported in their study that maize dried on plastic sheets was 61% less contaminated with afatoxin than that dried on other surfaces.Similarly, Hofmann et al. [55] tested the impact of distributing drying sheets to groundnut farmers and reported a 52% reduction in afatoxin levels compared to farmers who were not given drying sheets.An increase in the level of afatoxin in maize dried on bare ground can be explained by the possible uptake of moisture by maize from the soil.Tis leads to increased water activity that provides favorable condition for fungal growth.Toxigenic fungi are ubiquitous in nature; however, most of them are found in the soil.Allowing maize to come into contact with the soil predisposes it to a higher fungal load, thus increasing the chances for contamination.
Te maize storage bags used by farmers signifcantly infuenced the level of afatoxin in maize.Tere was a signifcant statistical diference in afatoxin in maize stored in hermetic and propylene bags.In a randomized controlled trial performed in Senegal, Bauchet et al. [56] reported that the use of hermetic storage bags causes a signifcant marginal decrease in total afatoxin levels.Ng'ang'a et al. [57] reported that maize stored hermetically had fve to eight times lower total afatoxin levels after 35 weeks compared to maize stored in polypropylene/jute bags.Conversely, Sasamalo et al. [58] reported that maize stored in propylene bags showed an increase in afatoxin levels with time.Nyanga and Ambali [59] reported that hermetic technology was more efective against the increase of afatoxin B 1 in stored maize than in conventional storage facilities.Hermetic storage is impermeable to oxygen, creating anaerobic conditions that inhibit the growth of fungal spores and weevils, while propylene bags lead to build up of moisture, encouraging fungal growth and afatoxin contamination [52].Our study showed that farmers have adopted the use of hermetic bags for maize storage, but some lacked knowledge and skills of their proper use; therefore, efectiveness of the technology was not failsafe.Tere is therefore a need to train farmers on the proper utilization of this technology.

Conclusion and Recommendations
We conclude that 35% of small-scale maize farms had levels of afatoxin contamination exceeding acceptable limits of EAC standards, with a mean total afatoxin of 12.86 μg/kg in maize samples.Artisanal afatoxin control technologies that 8 Journal of Food Quality have an impact on levels of afatoxin contaminations in the area include the use of certifed maize seeds and drying of maize on tarpaulin mat or raised platforms, with farms drying maize on bare grounds having a high risk of afatoxins contamination.Furthermore, farms which stored maize in hermetic bags and gunny bags had reduced risk of afatoxin contaminations.We therefore recommend targeted active surveillance activities to enhance monitoring and changes in levels of afatoxin contamination of maize and the provision of mitigation measures to minimize negative consequences in health and sources of livelihoods for communities.Furthermore, public health education should be implemented to create awareness amongst the community at risk.

Figure 1 :
Figure1: Map of study locations showing farms which had levels of total afatoxins exceeding the acceptable limits and those with levels below acceptable limits in four administrative units in Kitui.
Considerations.Te study was approved by the Faculty of Veterinary Medicine Biosafety, Animal Use, and Ethics Committee of the University of Nairobi, approval no.FVM BAUEC/2021/288 dated 8 th March, 2021.In addition, a research permit was obtained from the National Commission for Science Technology and Innovation (NACOSTI) under License No. NACOSTI/P/21/9773 to conduct research in Kitui County.Oral consent was obtained from study respondents.

Table 1 :
Prevalence of afatoxin contamination in farms and average level of total afatoxins in maize samples in the two farming zones from Kitui.

Table 2 :
Artisanal control technologies associated with risk of afatoxin contamination in maize.