Aflatoxin Exposure from Milk in Rural Kenya and the Contribution to the Risk of Liver Cancer

Climate change-induced shifts in the food systems and diet-related non-communicable diseases in sub-Saharan Africa: a scoping review and a conceptual framework

OBJECTIVES

To determine the relationship between climate change, food systems and diet-related non-communicable diseases (DR-NCDs) in sub-Saharan Africa (SSA) and propose a conceptual framework for food systems in SSA.

DESIGN

A scoping review.

ELIGIBILITY CRITERIA

Studies included investigated the relationship between climate change and related systemic risks, food systems, DR-NCDs and its risk factors in SSA. Studies focusing on the association between climate change and DR-NCDs unrelated to food systems, such as social inequalities, were excluded.

SOURCES OF EVIDENCE

A comprehensive search was conducted in ProQuest (nine databases), Google Scholar and PubMed in December 2022.

CHARTING METHODS

Data extracted from studies included author, study type, country of study, climate change component, DR-NCD outcomes and risk factors, and impacts of climate change on DR-NCDs. A narrative approach was used to analyse the data. Based on the evidence gathered from SSA, we modified an existing food system conceptual framework.

RESULTS

The search retrieved 19 125 studies, 10 of which were included in the review. Most studies used a cross-sectional design (n=8). Four explored the influence of temperature on liver cancer through food storage while four explored the influence of temperature and rainfall on diabetes and obesity through food production. Cross-sectional evidence suggested that temperature is associated with liver cancer and rainfall with diabetes.

CONCLUSION

The review highlights the vulnerability of SSA's food systems to climate change-induced fluctuations, which in turn affect dietary patterns and DR-NCD outcomes. The evidence is scarce and concentrates mostly on the health effects of temperature through food storage. It proposes a conceptual framework to guide future research addressing climate change and DR-NCDs in SSA.

Quantitative assessment of aflatoxin exposure and hepatocellular carcinoma (HCC) risk associated with consumption of select Nigerian staple foods

Aflatoxin contamination of staple grains and legumes has been linked to hepatocellular carcinoma (HCC) and other adverse health outcomes, constituting a substantial public health concern globally. Low-resource food environments in sub-Saharan Africa are often under-regulated and are particularly vulnerable to adverse health and nutrition outcomes associated with aflatoxin exposure. This study identifies levels of HCC risk in the northern Nigerian adult population, leveraging a systematic review of available evidence on aflatoxin contamination in Nigerian maize, groundnut, rice, cowpea, and soybean. Estimated dietary intake (EDI) was computed using publicly available dietary consumption data and a probabilistic quantitative risk assessment was conducted to determine the relative risk of HCC associated with consumption of selected aflatoxin-contaminated commodities. In total, 41 eligible studies reporting aflatoxin contamination were used to model the distribution of aflatoxin concentrations in Nigerian commodities. EDIs for maize, groundnut, rice, and cowpea exceeded the provisional maximum tolerable daily intake (PMTDI) level of 1 kgbw-1 day-1, with maize yielding the highest mean EDI (36.7 kgbw-1 day-1). The quantitative risk assessment estimated that 1.77, 0.44, 0.43, 0.15, and 0.01 HCC cases per year/100,000 population were attributable to aflatoxin exposure through maize, groundnut, rice, cowpea, and soybean, respectively. Sensitivity analysis revealed that aflatoxin concentration, dietary consumption levels, consumption frequency, and other variables have differing relative contributions to HCC risk across commodities. These findings constitute a novel multi-study risk assessment approach in the Nigerian context and substantiate existing evidence suggesting that there is reason for public health concern regarding aflatoxin exposure in the Nigerian population.

Farmer’s knowledge and suggested approaches for controlling aflatoxin contamination of raw milk in Pakistan

Monitoring of aflatoxin levels in milk is often complicated in developing countries due to the dominance of informal markets channeling milk in raw form. Farmer’s awareness and voluntary participation in aflatoxin mitigation can be critical in such scenarios. Therefore, the present study was conducted to understand the perceptions of dairy farmers about aflatoxins and link it with aflatoxin mitigation programs on milk in Pakistan. Information was collected from 450 peri-urban dairy farmers in seven cities using questionnaires. Majority (77.9%) of the farmers were aware of the negative impact of moldy feed on animal health. However, only 40.6% of the farmers were aware of the transferability of the toxins from moldy feed to milk. The farmers had almost no awareness of aflatoxins as 95% never heard of the term. After receiving an onsite briefing on effects of the toxin on animal and human health, and its transferability to milk, 98.3% farmers showed willingness to buy aflatoxin-safe feedstuffs, while 88.5% showed willingness to control aflatoxin in milk. Around half of the farmers considered aflatoxin control programs as affordable. On average, farmers agreed to pay 10.1% higher price for aflatoxin certified oilseed cakes. Availability of feedstuffs certified of low aflatoxin content was suggested by 22% of the participants as the critical step in reducing aflatoxins in milk. Other important suggestions included; subsidy on quality feeds (18%), raising awareness (18%), and legislation and monitoring (16%). The present results suggest that the current practice of milk monitoring in the country can yield desirable results only if it is coupled with feed certification programs ensuing availability of aflatoxin-safe feeds. Further, awareness can positively impact participation of producers in aflatoxin control programs. In this regard, awareness about effects of aflatoxins on animal health was found to be a more powerful trigger of voluntary control compared with the awareness of the toxin’s transferability to milk.

AFM1 Secretion and Efficacy of NovasilTM Clay in Kenyan Dairy Cows

The occurrence of aflatoxin M1 (AFM1) in milk has been widely reported in Kenya, with levels freqently exceeding national and international thresholds. Exposure to aflatoxin increases the risk of hepatic cancers and can also have other negative health impacts in children such as growth impairment and immunosuppression. Anti-mycotoxin agents (AMAs) included in contaminated feeds can greatly reduce the amount of AFM1 released in milk. A 45-day trial was designed to assess secretion of AFM1 in milk from individual cows fed commercial Kenyan dairy feed, as well as the efficacy of Novasil™ Plus in reducing the levels. A four-by-four Latin square cross-over design was used for the experiment. Four cows were fed on naturally contaminated with AFB1 feed, with levels ranging from 19 to 47 µg/kg, and either no binder or inclusion of binder at the rate of 0.6 or 1.2%. Milk samples were collected each day and analyzed for AFM1. The results showed that AFM1 levels in the milk varied between the cows, even when fed similar levels of contaminated feed. On average, inclusion of 0.6% binder into the diet resulted in 34% decline in milk AFM1 levels, while 1.2% binder dose resulted in a decline of 45%. Significant reduction in AFM1 secretion was observed in all experimental units (p < 0.005), though only minimal reduction was recorded in one of the units (Cow 4) compared to the other three. This trial shows novel data on aflatoxin exposure and excretion in Kenyan dairy cows in a field setting where AFB1 level is uncontrolled. We demonstrate significant reduction in AFM1 secretion in milk using AMA, though AFM1 levels were still above the recommended EC standard of 50 ŋg/kg. This study suggests that AMAs alone cannot be relied on to reduce AFM1 in milk to safe levels. Training and good feeding practices are recommended in addition to use of AMAs.

Assessment of Milk Quality and Food Safety Challenges in the Complex Nairobi Dairy Value Chain

Food networks present varying food safety concerns because of the complexity of interactions, production, and handling practices. We investigated total bacteria counts (TBCs) and total coliform counts (TCCs) in various nodes of a Nairobi dairy value chain and identified practices that influence food safety. A value chain analysis framework facilitated qualitative data collection through 23 key informant interviews and 20 focus group discussions. Content thematic analysis identified food safety challenges. Cow milk products (N = 290) were collected from farms (N = 63), collection centers (N = 5), shops/kiosks (N = 37), milk bars (N = 17), roadside vendors (N = 14), restaurants (N = 3), milk vending machines (N = 2), mobile traders (N = 2) and a supermarket (N = 1). Mean values of colony-forming units for TBC and TCC were referenced to East African Standards (EAS). Logistic regression analysis assessed differences in milk acceptability based on EAS. The raw milk from farms and collection centers was relatively within acceptable EAS limits in terms of TBC (3.5 × 10⁵ and 1.4 × 10⁶ respectively) but TCC in the milk from farms was 3 times higher than EAS limits (1.5 × 10⁵). Compared to farms, the odds ratio of milk acceptability based on TBC was lower on milk bars (0.02), restaurants (0.02), roadside vendors (0.03), shops/kiosks (0.07), and supermarkets (0.17). For TCC, the odds that milk samples from collection centers, milk bars, restaurants, roadside vendors, and shops/kiosks were acceptable was less than the odds of samples collected from farms (0.18, 0.03, 0.06, 0.02, and 0.12, respectively). Comparison of raw milk across the nodes showed that the odds of milk samples from restaurants, roadside vendors, and shops/kiosks being acceptable were less than the odds of samples collected the farm for TBC (0.03, 0.04, and 0.04, respectively). For TCC, the odds of raw milk from collection centers, restaurants, roadside vendors, milk bars, and shops/kiosks being acceptable were lower than the odds of acceptability for the farm samples (0.18, 0.12, 0.02, 0.04, and 0.05, respectively). Practices with possible influence on milk bacterial quality included muddy cowsheds, unconventional animal feed sources, re-use of spoilt raw milk, milk adulteration, acceptance of low-quality milk for processing, and lack of cold chain. Therefore, milk contamination occurs at various points, and the designing of interventions should focus on every node.

Detection of aflatoxin M1 in bovine milk from different agro-climatic zones of Chhattisgarh, India, using HPLC-FLD and assessment of human health risks

Concerns regarding food safety and 'One Health' are increasing globally. Aflatoxin M₁ (AFM₁), a human carcinogenic toxin, is excreted by lactating animals in their milk after consumption of feed contaminated with aflatoxin B₁. The present cross-sectional study aimed to determine the occurrence of AFM₁ in cattle and buffalo milk produced in rural and peri-urban areas under different agro-climatic conditions of Chhattisgarh, India, and assesses human health risks. Analyses of 545 milk samples by validated high-performance liquid chromatography revealed high level of AFM₁ contamination in 224 (41.1%) samples with mean concentration of 0.137 ± 0.029 μg/L. Statistically significant differences (p< 0.05) were observed in the levels and frequency of AFM₁ occurrence among different agro-climatic zones. AFM₁ was more frequently detected in milk samples from Northern hills (64%) followed by Bastar plateau (40.7%) and Chhattisgarh plain (27.3%), with mean concentration levels of 0.396 ± 0.099 μg/L, 0.081 ± 0.025 μg/L and 0.013 ± 0.002 μg/L, respectively. Species wise no significant difference was observed in the detection frequency and concentration of AFM₁ in milk from cattle and buffalo. AFM₁ contamination above maximum permissible limits established by European commission and Food Safety and Standard Authority of India was detected in 21.3% and 4.4% of samples, respectively. The estimated daily intakes for AFM₁ were found to be higher than tolerable daily intakes for both adults and children, especially of Northern hills implying a potentially high risk to consumer's health. This study provides valuable information on the contamination status of milk in one of the fastest developing state of India. It also highlights the importance and need for continuous farmers' awareness on good animal husbandry practices, routine surveillance of mycotoxins in animal feeds and food commodities to safeguard human health.

Oncogenic and tumor suppressor pathways in subchronic aflatoxicosis in rats: Association with serum and urinary aflatoxin exposure biomarkers

In this study, the changes in oncogenic and tumor suppressor signaling pathways in liver and their association with serum and urinary biomarkers of aflatoxin exposure were evaluated in Wistar rats fed diets containing aflatoxin B1 (AFB1) for 90 days. Rats were divided into four groups (n = 15 per group) and assigned to dietary treatments containing 0 (control), 50 (AFB50), 100 (AFB100) and 200 μg AFB1 kg-1 diet (AFB200). Multiple preneoplastic foci of hepatocytes marked with glutathione-S-transferase-placental form (GST-P) were identified in AFB100 and AFB200 groups. Hepatocellular damage induced by AFB1 resulted in overexpression of cyclin D1 and β-catenin. The liver expression of retinoblastoma (Rb) and p27Kip1 decreased in AFB100 and AFB200 groups, confirming the favorable conditions for neoplastic progression to hepatocellular carcinoma. All samples from rats fed AFB1-contaminated diets had quantifiable AFB1-lysine in serum or urinary AFM1 and AFB1-N7-guanine, with mean levels of 20.42-50.34 ng mL-1, 5.31-37.68 and 39.15-126.37 ng mg-1 creatinine, respectively. Positive correlations were found between AFB1-lysine, AFM1 or AFB1-N7-guanine and GST-P+, β-catenin+ and cyclin D1+ hepatocytes, while Rb + cells negatively correlated with those AFB1 exposure biomarkers. The pathways evaluated are critical molecular mechanisms of AFB1-induced hepatocarcinogenesis in rats.

Management strategies for aflatoxin risk mitigation in maize, dairy feeds and milk value chains—case study Kenya

Widespread aflatoxin contamination of a great number of food and feed crops has important implications on global trade and health. Frequent occurrence of aflatoxin in maize and milk poses serious health risks to consumers because these commodities are staple foods in many African countries. This situation calls for development and implementation of rigorous aflatoxin control measures that encompass all value chains, focusing on farms where food and feed-based commodities prone to aflatoxin contamination are cultivated. Good agricultural practices (GAP) have proven to be an effective technology in mitigation and management of the aflatoxin risk under farm conditions. The prevailing global climate change is shown to increase aflatoxin risk in tropical and subtropical regions. Thus, there is an urgent need to devise and apply novel methods to complement GAP and mitigate aflatoxin contamination in the feed, maize and milk value chains. Also, creation of awareness on aflatoxin management through training of farmers and other stakeholders and enforcement of regular surveillance of aflatoxin in food and feed chains are recommended strategies. This literature review addresses the current situation of aflatoxin occurrence in maize, dairy feeds and milk produced and traded in Kenya and current technologies applied to aflatoxin management at the farm level. Finally, a case study in Kenya on successful application of GAP for mitigation of aflatoxin risk at small-scale farms will be reviewed.

MILK Symposium review: Foodborne diseases from milk and milk products in developing countries-Review of causes and health and economic implications

Dairy production is rapidly increasing in developing countries and making significant contributions to health, nutrition, environments, and livelihoods, with the potential for still greater contributions. However, dairy products can also contribute to human disease in many ways, with dairyborne disease likely being the most important. Health risks may be from biological, chemical, physical, or allergenic hazards present in milk and other dairy products. Lacking rigorous evidence on the full burden of foodborne and dairyborne disease in developing countries, we compiled information from different sources to improve our estimates. The most credible evidence on dairyborne disease comes from the World Health Organization initiative on the Global Burden of Foodborne Disease. This suggests that dairy products may has been responsible for 20 disability-adjusted life years per 100,000 people in 2010. This corresponds to around 4% of the global foodborne disease burden and 12% of the animal source food disease burden. Most of this burden falls on low- and middle-income countries (LMIC). However, the estimate is conservative. Weaker evidence from historical burden in high-income countries, outbreak reports from LMIC and high-income countries, and quantitative microbial risk assessment suggest that the real burden may be higher. The economic burden in terms of lost human capital is at least US$4 billion/yr in LMIC. Among the most important hazards are Mycobacterium bovis, Campylobacter spp., and non-typhoidal Salmonella enterica. The known burden of chemical hazards is lower but also more uncertain. Important chemical hazards are mycotoxins, dioxins, and heavy metals. Some interventions have been shown to have unintended and unwanted consequences, so formative research and rigorous evaluation should accompany interventions. For example, there are many documented cases in which women's control over livestock is diminished with increasing commercialization. Dairy co-operatives have had mixed success, often incurring governance and institutional challenges. More recently, there has been interest in working with the informal sector. New technologies offer new opportunities for sustainable dairy development.

Occurrence and Exposure Assessment of Aflatoxin B1 in Omena (Rastrineobola argentea) from Kenya

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). Thirty-five 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. The 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. The 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. Therefore, more surveys are needed to understand the scope and extent of aflatoxin contamination in Omena.

Characteristics, Occurrence, Detection and Detoxification of Aflatoxins in Foods and Feeds

Mycotoxin contamination continues to be a food safety concern globally, with the most toxic being aflatoxins. On-farm aflatoxins, during food transit or storage, directly or indirectly result in the contamination of foods, which affects the liver, immune system and reproduction after infiltration into human beings and animals. There are numerous reports on aflatoxins focusing on achieving appropriate methods for quantification, precise detection and control in order to ensure consumer safety. In 2012, the International Agency for Research on Cancer (IARC) classified aflatoxins B1, B2, G1, G2, M1 and M2 as group 1 carcinogenic substances, which are a global human health concern. Consequently, this review article addresses aflatoxin chemical properties and biosynthetic processes; aflatoxin contamination in foods and feeds; health effects in human beings and animals due to aflatoxin exposure, as well as aflatoxin detection and detoxification methods.

A Review of the Impact of Mycotoxins on Dairy Cattle Health: Challenges for Food Safety and Dairy Production in Sub-Saharan Africa

Mycotoxins are secondary metabolites of fungi that contaminate food and feed and have a significant negative impact on human and animal health and productivity. The tropical condition in Sub-Saharan Africa (SSA) together with poor storage of feed promotes fungal growth and subsequent mycotoxin production. Aflatoxins (AF) produced by Aspergillus species, fumonisins (FUM), zearalenone (ZEN), T-2 toxin (T-2), and deoxynivalenol (DON) produced by Fusarium species, and ochratoxin A (OTA) produced by Penicillium and Aspergillus species are well-known mycotoxins of agricultural importance. Consumption of feed contaminated with these toxins may cause mycotoxicoses in animals, characterized by a range of clinical signs depending on the toxin, and losses in the animal industry. In SSA, contamination of dairy feed with mycotoxins has been frequently reported, which poses a serious constraint to animal health and productivity, and is also a hazard to human health since some mycotoxins and their metabolites are excreted in milk, especially aflatoxin M1. This review describes the major mycotoxins, their occurrence, and impact in dairy cattle diets in SSA highlighting the problems related to animal health, productivity, and food safety and the up-to-date post-harvest mitigation strategies for the prevention and reduction of contamination of dairy feed.