Assessment of risk to human health associated with aflatoxins in the Kenyan dairy value chain
Abstract
Aflatoxins are considered a food safety priority in Kenya in light of the recurrent outbreaks of
aflatoxicosis in humans and livestock and a possible role in childhood stunting and immunosuppression.
Nonetheless information is lacking on the health risks posed to public health by
aflatoxins in the Kenyan dairy value chain. This study looked into the levels of contamination by
aflatoxins along the dairy value chain and developed a quantitative risk assessment model to assess
their public health impact.
A survey of 286 farmer households was carried out in Kwale (n=37), Isiolo (n=56), Tharaka-Nithi
(n=65), Kisii (n=64) and Bungoma (n=64) Counties, chosen to represent different agro-ecological
zones (AEZ). Determination of aflatoxin levels was carried out by use of competitive enzymelinked
immunosorbent assay. Literature review was conducted to determine the impacts of
aflatoxin standards on health and nutrition in Sub-Saharan Africa considering the case of Kenya.
Finally this study used the World Organisation for Animal Health (OIE) risk assessment
framework consisting of release assessment, exposure assessment, consequence assessment, and
risk estimation to estimate the risk of liver cancer from aflatoxin exposure.
Overall, 26% of maize, 10% of millet and 11% of sorghum had aflatoxin B1 (AFB1) exceeding
the Kenyan limit of 5 ppb. In samples collected during the rainy season, maize from Kisii and
Bungoma, (temperate AEZ), had the lowest mean contamination whereas maize from Kwale (subhumid
AEZ) had the highest contamination. Millet and sorghum from Tharaka-Nithi (humid AEZ)
and Isiolo (semi-arid AEZ), respectively, had the highest mean contamination (p<0.05).
Dairy feed concentrates from farmers had AFB1 levels from less than 1 ppb to 9,661 ppb. The
percentages of dairy feeds with AFB1 above Kenyan limits of 5ppb were 73% from farmers, 90%
from feed retailers and 62% from feed manufacturers. AFM1 levels in milk were up to 6,999 ppt
and the prevalence was lowest in Kwale (3.5%) and highest in Tharaka-Nithi (64.5%). Exposure
to AFM1 through milk was estimated at between 0.3 and 1 ng AFM1 per kg body weight per day
through the consumption of milk. The annual incidence rates of cancer attributed to the
consumption of AFM1 in milk were 3.5 × 10−3 (95% CI: 3 × 10−3–3.9 × 10−3), 2.9 × 10−3 (95%
CI: 2.5 × 10−3–3.3 × 10−3), 1.4 × 10−3 (95% CI: 1.2 × 10−3–1.5 × 10−3) and 2.7 × 10−3 (95% CI: 2.3
× 10−3–3 × 10−3) cancers per 100,000 in adult females, adult males, children 6–18 years old, and
in children less than five years old, respectively. These annual incidence rates are quite low,
nonetheless, risk managers should take action based on cumulative exposure from all sources of
aflatoxins and hence the need to know the importance of different sources.
The prevention of aflatoxins in dairy feeds would effectively curb the presence of aflatoxin
residues in milk and other animal products meant for human consumption. Strategies to reduce
aflatoxins in animal feeds include keeping the moisture and temperature of feeds moderately low
(<13% moisture; temperature range of 20 - 35oC) to inhibit mould growth, maintaining cleanliness
of on-farm equipment, and, where possible, using mould inhibitors or aflatoxin binders. The use
of binders in feeds should be further investigated to determine safety and efficacy. The
understanding and awareness of the feed manufacturers, retailers, producers (dairy and grains) and
consumers on aflatoxins should be improved so that they produce/demand aflatoxin free foods/
feeds.
Publisher
University of Nairobi
Subject
Assessment of risk to human health associated with aflatoxins in the Kenyan dairy value chainRights
Attribution-NonCommercial-NoDerivs 3.0 United StatesUsage Rights
http://creativecommons.org/licenses/by-nc-nd/3.0/us/Collections
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