Internal Exposure to Mycotoxins and Associated Nutritional Status in Young Children Consuming Maize Porridge in South Kivu, Democratic Republic of Congo: A Pilot Biomonitoring Study

Technical Summary: Internal Exposure to Mycotoxins and Associated Nutritional Status in Young Children Consuming Maize Porridge in South Kivu, DRC

Problem Statement
Mycotoxin contamination of maize-based complementary foods poses a significant, under-recognized public health risk in sub-Saharan Africa (SSA), particularly for infants and young children. While previous research in the Democratic Republic of Congo (DRC) has documented the prevalence of mycotoxins in food ingredients, there is a critical scarcity of data regarding internal systemic exposure and its specific associations with nutritional status in this population. Most existing studies rely on food frequency questionnaires or urinary biomarkers, which may not fully capture the systemic dose capable of exerting biological effects. This pilot study addresses this gap by assessing multi-mycotoxin exposure in young children (11–23 months) in South Kivu, a region with high stunting prevalence, and evaluating links to anthropometric indicators.

Methodology
The study employed a cross-sectional pilot biomonitoring design involving 70 children (38 urban, 32 rural) aged 11–23 months from the Bagira (urban) and Miti-Murhesa (rural) health zones in South Kivu.

• Data Collection: Structured interviews gathered data on household characteristics, maize storage, and feeding practices. Anthropometric measurements (weight, length, mid-upper arm circumference) were taken to calculate Z-scores for height-for-age (HAZ), weight-for-age (WAZ), and weight-for-height (WHZ).
• Biomarker Analysis: Venous blood samples were collected, and serum was analyzed using liquid chromatography tandem mass spectrometry (LC-MS/MS). The panel targeted 39 mycotoxins and metabolites, including aflatoxins (AFs), fumonisins (FUMs), ochratoxin A (OTA), citrinin (CIT), and cyclopiazonic acid (CPA). Additionally, serum samples were screened for the AFB1-lysine adduct, a biomarker of chronic aflatoxin exposure.
• Statistical Analysis: Due to the small sample size and sparse exposure categories, Bayesian logistic regression was utilized to identify determinants of high exposure (defined as the 75th percentile for continuous variables or detection for screening) and to explore associations between exposure biomarkers and undernutrition indicators.

Key Results

• Exposure Profile: The study detected widespread co-exposure to multiple mycotoxins.
  • Citrinin (CIT) and Ochratoxin A (OTA): These were the most frequently quantified toxins. Rural children exhibited significantly higher median concentrations of both CIT (1.3 ng/mL vs. 0.1 ng/mL in urban) and OTA (0.25 ng/mL vs. 0.10 ng/mL in urban).
  • Gender Differences: Boys showed higher median levels of CIT (0.75 vs. 0.50 ng/mL) and OTA (0.18 vs. 0.14 ng/mL), while girls showed higher levels of cyclopiazonic acid (CPA) (0.050 ng/mL vs. 0.008 ng/mL).
  • Aflatoxin: While free AFB1 was rarely detected, AFB1-lysine adducts were found in 56.8% of boys and 48.5% of girls, indicating chronic exposure.
• Nutritional Status: Stunting was the predominant form of undernutrition, affecting 24.3% of the total sample, with a significantly higher prevalence in rural children (37.5%) compared to urban children (13.2%). Stunting was also significantly more prevalent among girls (36.4%) than boys (13.9%). Wasting and underweight affected 10.1% and 18.8% of children, respectively.
• Determinants of Exposure: Bayesian models identified frequent maize porridge consumption as a primary driver of elevated CIT and OTA exposure. Urban residence was consistently associated with lower exposure to CIT and OTA.
• Exposure-Nutrition Associations:
  • High AFB1-lysine exposure was positively associated with stunting (log[OR] = 1.55; OR = 1.70; 95% CrI: 1.02–18.6), though the wide credible interval indicates uncertainty.
  • Associations between CIT/OTA and specific malnutrition indicators (wasting, underweight) showed positive trends but were characterized by wide credible intervals and substantial uncertainty, preventing definitive causal conclusions.
  • High co-exposure to multiple toxins was not significantly associated with any specific undernutrition indicator in this sample.

Key Contributions

1. First Serum Biomonitoring in Region: This study provides the first characterization of multi-mycotoxin serum biomarkers in young children in the South Kivu province of the DRC, moving beyond food-based assessments to measure internal systemic dose.
2. Rural-Urban Disparities: It quantifies significant disparities in internal exposure, demonstrating that rural children relying on home-grown maize stored under traditional conditions face substantially higher burdens of CIT and OTA compared to urban peers.
3. Methodological Proof-of-Concept: The study validates the feasibility of using LC-MS/MS serum biomonitoring coupled with Bayesian modeling in resource-limited settings to assess complex co-exposure patterns and their potential health impacts.
4. Link to Growth: It offers preliminary evidence linking chronic aflatoxin exposure (via AFB1-lysine) to impaired linear growth (stunting) in this specific high-risk population.

Significance and Claims
The authors position this work as a pilot study and a proof-of-concept rather than a definitive epidemiological assessment. They explicitly state that the findings are "exploratory and hypothesis-generating" due to the small sample size (n=70) and the cross-sectional design, which limits causal inference.

The paper claims that its primary significance lies in:

• Highlighting a Hidden Risk: Confirming that young children in South Kivu are subject to widespread, chronic co-exposure to multiple mycotoxins, driven largely by dietary practices (frequent maize porridge consumption) and storage conditions.
• Informing Policy: Providing baseline data to support targeted mitigation strategies, such as strengthening maize post-harvest management and promoting dietary diversification.
• Guiding Future Research: Establishing the feasibility of the methodology to inform the design of future, adequately powered longitudinal studies necessary to elucidate the long-term health impacts of mycotoxin exposure on child growth in high-burden settings.

The authors conclude that while the association between aflatoxin exposure and stunting aligns with existing epidemiological evidence, the results regarding other mycotoxins and nutritional outcomes require confirmation in larger studies to move from preliminary signals to confirmed public health interventions.