Determinants of recent aflatoxin exposure among pregnant women in rural Zimbabwe

Provision of low-aflatoxin local complementary porridge flour reduced urinary aflatoxin biomarker in children aged 6-18 months in rural Tanzania

Aflatoxins are toxic secondary metabolites of fungi that colonize staple food crops, such as maize and groundnut, frequently used in complementary feeding. In preparation for a large trial, this pilot study examined if provision of a low-aflatoxin infant porridge flour made from local maize and groundnuts reduced the prevalence of a urinary aflatoxin biomarker in infants. Thirty-six infants aged 6-18 months were included from four villages in Kongwa District, Tanzania. The study was conducted over 12 days with a three-day baseline period and a 10 days where low-AF porridge flour was provided. Porridge intake of infants was assessed using quantitative 24-h recalls by mothers. Household food ingredients used in infant porridge preparation and urine samples were collected on Days 1-3 (baseline) and 10-12 (follow-up). Aflatoxins were measured in household foods, and AFM1 was measured in urine. At baseline and follow-up, 78% and 97%, respectively, of the infants consumed porridge in the previous 24 h, with a median volume of 220 mL (interquartile range [IQR]: 201, 318) and 460 mL (IQR: 430, 563), respectively (p < 0.001). All 47 samples of homemade flour/ingredients were contaminated with AFs (0.3-723 ng/g). The overall prevalence of individuals with detectable urinary AFM1 was reduced by 81%, from 15/36 (42%) at baseline to 3/36 (8%) at follow-up (p = 0.003). Provision of low-aflatoxin porridge flour was acceptable to caregivers and their infants and successfully reduced the prevalence of detectable urinary AFM1 in infants, thus, confirming its potential to be tested in future large-scale health outcomes trial.

Dietary determinants of aflatoxin B1-lysine adduct among infants in Nepal

BACKGROUND

Aflatoxins are mycotoxins produced by naturally occurring fungi on food, and aflatoxin B₁ (AFB₁) is carcinogenic, immunotoxic and hepatotoxic. This study assesses the relationship between AFB₁ in Nepali infants at 12 months of age and their diet at 9 and 12 months of age.

METHODS

The study used data collected from 1329 infants enrolled in the AflaCohort Study. Aflatoxin exposure was assessed at 12 months using serum AFB₁-lysine pg/mg albumin biomarker measured using high performance liquid chromatography-fluorescent detection. Dietary data were collected using food frequency questionnaire. We conducted ordinary least squares and quantile regression analyses with backward elimination to assess lagged (9-month diet and 12-month AFB₁) and contemporaneous (12-month diet and 12-month AFB₁) associations.

RESULTS

Eighty-one percent of children at 12 months had detectable levels of serum AFB₁-lysine (geometric mean: 0.79 pg/mg albumin, 95% CI: 0.74-0.83). The levels ranged from 0.4 to 85 pg/mg albumin. Dietary diversity at 9 and 12 months were not associated with serum AFB₁-lysine levels. Consumption of fish and groundnuts at both 9 and 12 months and infant formula and cauliflower at 9 months were associated with higher serum AFB₁-lysine while consumption of bananas and mangoes at 12 months were negatively associated with serum AFB₁-lysine (p < 0.05).

CONCLUSIONS

High prevalence of detectable AFB₁-lysine among infants, and possible links to their dietary patterns argues for more urgent research into which foods in children's diets are most contaminated, and into optimal entry points in the food chain that would allow for effective actions to minimize exposure.

Effects of Prenatal Exposure to Aflatoxin B1: A Review

Aflatoxins are mycotoxins produced as secondary fungal metabolites. Among them, aflatoxin B1 (AFB1) stands out due to its genotoxic and mutagenic potential, being a potent initiator of carcinogenesis. In this review, the outcomes from the published literature in the past 10 years on the effects of AFB1 pathophysiological mechanisms on embryological and fetal development are discussed. In several animal species, including humans, AFB1 has a teratogenic effect_, resulting in bone malformations, visceral anomalies, lesions in several organs, and behavioral and reproductive changes, in addition to low birth weight. The mutagenic capacity of AFB1 in prenatal life is greater than in adults, indicating that when exposure occurs in the womb, the risk of the development of neoplasms is higher. Studies conducted in humans indicate that the exposure to this mycotoxin during pregnancy is associated with low birth weight, decreased head circumference, and DNA hypermethylation. However, as the actual impacts on humans are still unclear, the importance of this issue cannot be overemphasized and studies on the matter are essential.

Prevalence of Aflatoxin- and Fumonisin-Producing Fungi Associated with Cereal Crops Grown in Zimbabwe and Their Associated Risks in a Climate Change Scenario

In most sub-Saharan African countries, staple cereal grains harbor many fungi and some produce mycotoxins that negatively impact health and trade. Maize and three small grain cereals (sorghum, pearl millet, and finger millet) produced by smallholder farmers in Zimbabwe during 2016 and 2017 were examined for fungal community structure, and total aflatoxin (AF) and fumonisin (FM) content. A total of 800 maize and 180 small grain samples were collected at harvest and during storage from four agroecological zones. Fusarium spp. dominated the fungi associated with maize. Across crops, Aspergillusflavus constituted the main Aspergillus spp. Small grain cereals were less susceptible to both AF and FM. AF (52%) and FM (89%) prevalence was higher in maize than in small grains (13-25% for AF and 0-32% for FM). Less than 2% of small grain samples exceeded the EU regulatory limit for AF (4 µg/kg), while <10% exceeded the EU regulatory limit for FM (1000 µg/kg). For maize, 28% and 54% of samples exceeded AF and FM Codex guidance limits, respectively. Higher AF contamination occurred in the drier and hotter areas while more FM occurred in the wetter year. AF exposure risk assessment revealed that small grain consumption posed low health risks (≤0.02 liver cancer cases/100,000 persons/year) while maize consumption potentially caused higher liver cancer rates of up to 9.2 cases/100,000 persons/year depending on the locality. Additionally, FM hazard quotients from maize consumption among children and adults were high in both years, but more so in a wet year than a dry year. Adoption of AF and FM management practices throughout the maize value chain coupled with policies supporting dietary diversification are needed to protect maize consumers in Zimbabwe from AF- and FM-associated health effects. The higher risk of health burden from diseases associated with elevated concentration of mycotoxins in preferred maize during climate change events can be relieved by increased consumption of small grains.

Aflatoxin M1 in Africa: Exposure Assessment, Regulations, and Prevention Strategies - A Review

Aflatoxins are the most harmful mycotoxins causing health problems to human and animal. Many acute aflatoxin outbreaks have been reported in Africa, especially in Kenya and Tanzania. When ingested, aflatoxin B1 is converted by hydroxylation in the liver into aflatoxin M1, which is excreted in milk of dairy females and in urine of exposed populations. This review aims to highlight the AFM1 studies carried out in African regions (North Africa, East Africa, West Africa, Central Africa, and Southern Africa), particularly AFM1 occurrence in milk and dairy products, and in human biological fluids (breast milk, serum, and urine) of the populations exposed. Strategies for AFM1 detoxification will be considered, as well as AFM1 regulations as compared to the legislation adopted worldwide and the assessment of AFM1 exposure of some African populations. Egypt, Kenya, and Nigeria have the highest number of investigations on AFM1 in the continent. Indeed, some reports showed that 100% of the samples analyzed exceeded the EU regulations (50 ng/kg), especially in Zimbabwe, Nigeria, Sudan, and Egypt. Furthermore, AFM1 levels up to 8,000, 6,999, 6,900, and 2040 ng/kg have been reported in milk from Egypt, Kenya, Sudan, and Nigeria, respectively. Data on AFM1 occurrence in human biological fluids have also shown that exposure of African populations is mainly due to milk intake and breastfeeding, with 85-100% of children being exposed to high levels. Food fermentation in Africa has been tried for AFM1 detoxification strategies. Few African countries have set regulations for AFM1 in milk and derivatives, generally similar to those of the Codex alimentarius, the US or the EU standards.

The University of Zimbabwe College of Health Sciences (UZ-CHS) BIRTH COHORT study: rationale, design and methods

BACKGROUND

Commencing lifelong antiretroviral therapy (ART) immediately following HIV diagnosis (Option B+), has greatly improved maternal-infant health. Thus, large and increasing numbers of HIV-infected women are on ART during pregnancy, a situation concurrently increasing numbers of HIV-exposed-uninfected (HEU) infants. Compared to their HIV-unexposed-uninfected (HUU) counterparts, HEU infants show higher rates of adverse birth outcomes, mortality, infectious/non-communicable diseases including impaired growth and neurocognitive development. There is an urgent need to understand the impact of HIV and early life ART exposures, immune-metabolic dysregulation, comorbidities and environmental confounders on adverse paediatric outcomes.

METHODS

Six hundred (600) HIV-infected and 600 HIV-uninfected pregnant women ≥20 weeks of gestation will be enrolled from four primary health centres in high density residential areas of Harare. Participants will be followed up as mother-infant-pairs at delivery, week(s) 1, 6, 10, 14, 24, 36, 48, 72 and 96 after birth. Clinical, socio-economic, nutritional and environmental data will be assessed for adverse birth outcomes, impaired growth, immune/neurodevelopment, vertical transmission of HIV, hepatitis-B/C viruses, cytomegalovirus and syphilis. Maternal urine, stool, plasma, cord blood, amniotic fluid, placenta and milk including infant plasma, dried blood spot and stool will be collected at enrolment and follow-up visits. The composite primary endpoint is stillbirth and infant mortality within the first two years of life in HEU versus HUU infants. Maternal mortality in HIV-infected versus -uninfected women is another primary outcome. Secondary endpoints include a range of maternal and infant outcomes. Sub-studies will address maternal stress and malnutrition, maternal-infant latent tuberculosis, Helicobacter pylori infections, immune-metabolomic dysregulation including gut, breast milk and amniotic fluid dysbiosis.

DISCUSSION

The University of Zimbabwe-College of Health-Sciences-Birth-Cohort study will provide a comprehensive assessment of risk factors and biomarkers for HEU infants' adverse outcomes. This will ultimately help developing strategies to mitigate effects of maternal HIV, early-life ART exposures and comorbidities on infants' mortality and morbidity.

TRIAL REGISTRATION

ClinicalTrial.gov Identifier: NCT04087239 . Registered 12 September 2019.

Protocol for the trial to establish a causal linkage between mycotoxin exposure and child stunting: a cluster randomized trial

Background

The number of stunted children has fallen globally but continues to increase in Africa. Stunting is estimated to contribute to 14–17% of child deaths under 5 years of age and is a risk factor for poor cognitive and motor development and educational outcomes. Inadequate dietary intake and disease are thought to be the immediate causes of undernutrition and stunting. However, improving infant diets through complementary feeding interventions has been shown to only modestly reduce stunting. Multiple observational studies demonstrate a dose response relationship between fetal and post-natal aflatoxin exposure and reduced linear growth.

Methods

This community-based cluster randomized trial will measure the effect of a reduced aflatoxin diet on length-for-age Z scores at 18 months in central Tanzania. All 52 health facilities in the Kongwa District of Dodoma Region were randomized into two groups. Starting at 6 months of age, participants in the intervention group receive a low-aflatoxin pre-blended porridge flour containing maize and groundnut (ratio 4:1 respectively) and low-aflatoxin groundnut flour, whereas in the control group the same porridge mix and groundnut flour are promoted through education but acquired by the household. Both groups will receive the same infant and young child feeding education and a thermos flask. A total of 3120 infants between 6 weeks and 3 months of age will be recruited into the study over 1 year. Data will be collected four times – at recruitment and when the infants are 6, 12 and 18 months of age. In a cohort of 600 infants, additional data will be collected at 9 and 15 months of age. The primary outcome is length-for-age at 18 months. Secondary outcomes include the Z scores for weight-for-age, middle upper arm circumference and head circumference, and the blood biomarker aflatoxin-albumin in the full sample, with the urine biomarker aflatoxin M1 analyzed in the cohort only.

Discussion

Better understanding the etiology of childhood stunting can lead to more appropriate interventions and policies to further reduce linear growth faltering and meet the Sustainable Development Goals.

Trial registration

NCT03940547, (April 24, 2019).

Association between Urinary Levels of Aflatoxin and Consumption of Food Linked to Maize or Cow Milk or Dairy Products

The aim of this analysis was to assess the association between consumption of maize and dairy products and urine and serum levels of aflatoxin FM1 (AFM1) in a sample of 59 males occupationally exposed (29) and non-exposed (30) to aflatoxins. Two urine samples were collected for each person; each sample was accompanied by a questionnaire on food consumption in the preceding 96 h. Given the similar levels of contamination found in exposed and non-exposed workers, the association between food consumption and AFM1 levels was analyzed by pooling samples from exposed and non-exposed workers. No serum sample was found to be positive for AFM1, whereas 74% of the urine samples were positive; the average concentration of positive samples was 0.042 ng/mL (range < limit of detection (LoD) (0.002)-0.399 ng/mL). Of the 21 samples from maize consumers, 13 were positive for AFM1 (62%), with a mean concentration of 0.026 ng/mL (range 0.006-0.088 ng/mL), while 76% (74/94) of the samples from maize non-consumers were positive (mean 0.045, range < LoD (0.002)-0.399 ng/mL). No association was found with milk or dairy products. The high urine level of aflatoxins found in both exposed and non-exposed workers was not associated with the consumption of maize or cow milk products.

Biomass Smoke Exposure Is Associated With Gastric Cancer and Probably Mediated Via Oxidative Stress and DNA Damage: A Case-Control Study

PURPOSE

We investigated the association between gastric cancer and environmental and dietary exposures. In addition, we explored probable mechanistic pathways for the influence of biomass smoke on gastric carcinogenesis.

PATIENTS AND METHODS

The study was conducted in Lusaka, Zambia. Questionnaires were used to collect data on risk factors, whereas enzyme-linked immunosorbent assays and high-performance liquid chromatography were used to measure biologic exposures. Study data were analyzed using contingency tables and logistic regression.

RESULTS

We enrolled 72 patients with gastric adenocarcinoma and 244 controls. Gastric cancer was positively associated with rural residence (odds ratio [OR], 2.9; 95% CI, 1.5 to 5.3), poverty (OR, 4.2; 95% CI, 1.9 to 9.1), and daily consumption of processed meat (OR, 6.4; 95% CI, 1.3 to 32) and negatively associated with consumption of green vegetables (OR, 0.2; 95% CI, 0.1 to 0.5). Gastric cancer was also associated with biomass smoke exposure (OR, 3.5; 95% CI, 1.9 to 6.2; P < .0001), an association that was stronger for intestinal-type cancers (OR, 3.6; 95% CI, 1.5 to 9.1; P = .003). Exposure to biomass smoke in controls was associated with higher urinary levels of 8-isoprostane (P < .0001), 8-hydroxydeoxyguanosine (P = .029), and 1-hydroxypyrene (P = .041). Gastric cancer was not associated with biochemical measures of current exposure to aflatoxins or ochratoxins.

CONCLUSION

In Zambia, exposure to biomass smoke, daily consumption of processed meat, and poverty are risk factors for gastric cancer, whereas daily consumption of green vegetables is protective against gastric cancer. Exposure to biomass smoke was associated with evidence of oxidative stress and DNA damage, suggesting mechanistic plausibility for the observed association, and the association was restricted to intestinal-type gastric cancer.

Mycotoxin exposure and adverse reproductive health outcomes in Africa: a review

It is well established that mycotoxin exposure can have adverse effects on reproductive health resulting to poor reproductive potential. The most studied mycotoxin in relation to poor reproductive health in humans is aflatoxin, although fumonisins, trichothecenes and zearalenone have also been reported to impair reproductive function and cause abnormal foetal development. These potent fungal toxins contaminate many food products making them a prominent agricultural, food safety and public health challenge, especially in Africa due to little or lack of mycotoxin regulation in agricultural products. Neonates can be exposed to aflatoxins in utero, as the toxins pass from mother to the foetus through the placenta. This exposure may continue during breast feeding, to the introduction of weaning foods, and then foods taken by adults. The consequences of aflatoxin exposure in mothers, foetus and children are many, including anaemia in pregnancy, low birth weight, interference with nutrient absorption, suppression of immune function, child growth retardation and abnormal liver function. In males, reports have indicated a possible relationship between aflatoxin exposure and poor sperm quality culminating in infertility. Maternal exposure to fumonisin during early pregnancy has been associated with increased risk of neural tube defects among newborns in regions where maize is the common dietary staple with the possibility of chronic fumonisin exposure. Furthermore, zearalenone has been linked to precocious puberty and premature thelarche in girls, correlating with extremely high serum oestrogen levels. This review presents an overview of the several reports linking aflatoxins, fumonisins, trichothecenes, and zearalenone exposure to poor reproductive health outcomes in Africa, with emphasis on birth outcomes, foetal health and infertility.

Current Status of Mycotoxin Contamination of Food Commodities in Zimbabwe

Agricultural products, especially cereal grains, serve as staple foods in sub-Saharan Africa. However, climatic conditions in this region can lead to contamination of these commodities by moulds, with subsequent production of mycotoxins posing health risks to both humans and animals. There is limited documentation on the occurrence of mycotoxins in sub-Saharan African countries, leading to the exposure of their populations to a wide variety of mycotoxins through consumption of contaminated foods. This review aims at highlighting the current status of mycotoxin contamination of food products in Zimbabwe and recommended strategies of reducing this problem. Zimbabwe is one of the African countries with very little information with regards to mycotoxin contamination of its food commodities, both on the market and at household levels. Even though evidence of multitoxin occurrence in some food commodities such as maize and other staple foods exist, available published research focuses only on Aspergillus and Fusarium mycotoxins, namely aflatoxins, deoxynivalenol (DON), trichothecenes, fumonisins, and zearalenone (ZEA). Occurrence of mycotoxins in the food chain has been mainly associated with poor agricultural practices. Analysis of mycotoxins has been done mainly using chromatographic and immunological methods. Zimbabwe has adopted European standards, but the legislation is quite flexible, with testing for mycotoxin contamination in food commodities being done voluntarily or upon request. Therefore, the country needs to tighten its legislation as well as adopt stricter standards that will improve the food safety and security of the masses.