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Abstract
Mycotoxins are secondary metabolites of Aspergillus, Fusarium and Penicillium fungi.
Even though more than 400 mycotoxins have been identified, Aflatoxins (AFs) and
Fumonisins (FNs) are highly toxic with significant public health implications.
The International Agency on Research Cancer classified Aflatoxin B1(AFB1) as
Group I carcinogens and Fumonisins B1(FB1) as Group IIB, possibly carcinogenic
to humans. More than 25% of the world’s food supply is contaminated including
cereals,legumes, oilseeds, nuts, milk and meat products, spices, coffee, and tea.
The recommended maximum limit for total AFs and FNs in foods is 20 μg/kg and
4mg/kg respectively. Up to 4.5 billion people are exposed through dietary staples
and in occupational settings. This dissertation study seeks to assess AFs and FNs
exposure among children 6 - 12years using biomarkers. AFB1-lysine adducts,
urinary free FB1 and sphingolipids are validated biomarkers for AFs and FNs
exposure quantified by High Performance Liquid Chromatography.
Participants were recruited from Kenyan counties of Siaya and Makueni
where naturally co-occurrence of Aspergillus and Fusarium fungi is documented.
All children had detectable levels of AFB1-lysine adducts in sera, geometric mean (GM)
10.5 (95%CI 9.4 – 11.7) and range 0.65 - 518.9 pg/mg albumin. Makueni county children
had higher exposures, GM 14.0 (95%CI 12.5, 15.7) pg/mg albumin,
and Siaya’s 8.2 (95%CI 7.6, 8.8) pg/mg albumin, p<0.001.
Children were also exposed to fumonisins. The GM of urinary FB1
when adjusted for creatinine levels were 0.07 ng/mg for Siaya and slightly higher in
Makueni at 0.08 ng/mg, p-value > 0.05. Additionally, Sphinganine and Sphingosine
were detectable in 95.07% and 98.94% of the urine samples. Creatinine adjusted
mean±SD of Sphinganine and Sphingosine were 1.23±2.18nM, and 4.99±8.3nM
while the Sphinganine/Sphingosine ratio was 0.296±0.587. After adjusting for
demographic information, socio-economic indicators, farming practices, and
household dietary patterns, children with higher AFB1- lysine adducts and
urinary FB1 were more likely to suffer from growth impairments. Overall,
dietary exposure to mycotoxins is a public health issue and efforts geared
towards mitigating exposure in children are imperative in regions where corn
and peanuts are staple diets.
Even though more than 400 mycotoxins have been identified, Aflatoxins (AFs) and
Fumonisins (FNs) are highly toxic with significant public health implications.
The International Agency on Research Cancer classified Aflatoxin B1(AFB1) as
Group I carcinogens and Fumonisins B1(FB1) as Group IIB, possibly carcinogenic
to humans. More than 25% of the world’s food supply is contaminated including
cereals,legumes, oilseeds, nuts, milk and meat products, spices, coffee, and tea.
The recommended maximum limit for total AFs and FNs in foods is 20 μg/kg and
4mg/kg respectively. Up to 4.5 billion people are exposed through dietary staples
and in occupational settings. This dissertation study seeks to assess AFs and FNs
exposure among children 6 - 12years using biomarkers. AFB1-lysine adducts,
urinary free FB1 and sphingolipids are validated biomarkers for AFs and FNs
exposure quantified by High Performance Liquid Chromatography.
Participants were recruited from Kenyan counties of Siaya and Makueni
where naturally co-occurrence of Aspergillus and Fusarium fungi is documented.
All children had detectable levels of AFB1-lysine adducts in sera, geometric mean (GM)
10.5 (95%CI 9.4 – 11.7) and range 0.65 - 518.9 pg/mg albumin. Makueni county children
had higher exposures, GM 14.0 (95%CI 12.5, 15.7) pg/mg albumin,
and Siaya’s 8.2 (95%CI 7.6, 8.8) pg/mg albumin, p<0.001.
Children were also exposed to fumonisins. The GM of urinary FB1
when adjusted for creatinine levels were 0.07 ng/mg for Siaya and slightly higher in
Makueni at 0.08 ng/mg, p-value > 0.05. Additionally, Sphinganine and Sphingosine
were detectable in 95.07% and 98.94% of the urine samples. Creatinine adjusted
mean±SD of Sphinganine and Sphingosine were 1.23±2.18nM, and 4.99±8.3nM
while the Sphinganine/Sphingosine ratio was 0.296±0.587. After adjusting for
demographic information, socio-economic indicators, farming practices, and
household dietary patterns, children with higher AFB1- lysine adducts and
urinary FB1 were more likely to suffer from growth impairments. Overall,
dietary exposure to mycotoxins is a public health issue and efforts geared
towards mitigating exposure in children are imperative in regions where corn
and peanuts are staple diets.