This study surveyed 165 mother-baby dyads to understand feeding practices with particular interest in feeding of cows’ milk in the past 24-hours, it further assessed AFM1 contamination of cows’ milk and the risk of exposure to AFM1 due to consumption of cows milk among infants and young children (IYC) aged 6–36 months.
The surveyed children were reported to consume cow’s milk in the previous 24 hours where, children between one and two years consumed more cows’ milk (mean value of 171.88 ± 88.87 ml) than other age groups because at this age, breastfeeding is relatively reduced and gradually replaced by complementary feeding that include cows’ milk. Children are also feeding on semi solid foods that in most cases are constituted by cows’ milk. Reconstitution of solid and semi-solid foods with cows’ milk was used to soothen the food for good taste, and also to help with milk intake in children who resist plain milk. Children between the age of 6–11 months were consuming less cows’ milk because they are more breastfed, while those between 24–36 months consumed more of other foods including family meals than cows’ milk. In Tanzania milk intake is reported at about 45 litres/ person per year (Katjiuongua and Nelgen 2014). Other study findings done in Tanzania and Kenya estimated that around 50–60% of people in a particular catchment area consume milk (Galiè et al. 2021) which include young children. The study further reported that, milk is consumed plain, mixed in porridge (a term describing a legume and grain-based dish made from a wide variety of ingredients), and tea.
All milk samples collected from household were found un-adultered. This was possible because the participants were informed of the collection of milk samples for educational purposes by the ward executive officer prior to the survey. Adultaration measure explains the quality of milk and that un-adultered milk had no interfere to the measurement of AFM1 concentration. The lactomiter reading was within the range of 1.026–1.032 g/ml (Small Holder Dairy Project (SDP 2004).
Aflatoxin M1 was detected in all raw cows’ milk (n = 100) samples at levels exceeding the limit of 0.05 µg/L set by European Union Commission Regulation (EU) No 165/2010 of 26 February 2010 (EC 2006), and the Tanzania Bureau of Standards (TBS) (Mohammed et al. 2016) for AFM1 in raw cow milk. In 2017, Gonçalves et al. stated that, AFM1 excretion in raw milk is the major consequence of exposing cattle to aflatoxin B1. Approximately, 1–6% of AFB1 can be metabolized into AFM1 following ingestion of AFB1 contaminated feeds (Turna and Wu 2021; Tarannum et al. 2020). Higher AFM1 in cows’ milk is prevalently reported in zero-grazing than in free-range. Zero-grazed dairy cattle are more likely to feed on contaminated feeds such as maize hay, bran, cotton and sunflower seed cakes that are frequently reported to contain high levels of AFs (Mohamed et al. 2016; Kitigwa et al. 2022; Kang’ethe and Lang’a 2009). This is because these feeds emanate mainly from reject and poor-quality grains, which are inadequately stored for a long time, thus provide conducive environment for mycotoxin production (Kang’ethe and Lang’a 2009).
While cereal bran used to feed dairy cattle is contaminated with aflatoxin B1, the milk obtained from the same cattle is found contaminated with aflatoxin M1 (Magoha et al. 2014). Two studies conducted in different locations in Tanzania by Mohamed et al. (2016) and Kitigwa et al. (2022) revealed AFM1 contamination in raw milk ranging from 0.026 to 2.01 µg/L (n = 37) and 0.03 to 43.98 µg/L (n = 141) respectively. A study conducted in Bangladesh which employed ELISA technique to assesses AFM1 in raw (n = 50) and processed (n = 50) milk samples reported that, over 53% of the total sample (n = 100) tested positive for AFM1. Of the contaminated, 70% were raw milk samples at a range of 22.79-1489.28 ng/kg, mean 699.07 ng/kg (Tarannum et al. 2020). A study by Asghar et al. (2018) reported 91.7% contamination of AFM1 (ranging from 20 − 3090 ng /L with mean level of 317 ± 16.6 ng /L) in fresh milk (n = 143) out of 156 samples collected. Another study by Sumon et al. (2021) reported detection of AFM1 in 71.4% of raw milk samples (mean 41.1 ng/L, range 5.0–198.7 ng/L). In 2014, Magoha et al. reported that, all samples of human breast milk tested positive for AFM1 where more than 70% of the samples exceeded limit of 0.05 ng/L set by EU for milk and dairy products. This implies that, children are double exposed to AFM1 through consumption of both animal and human breast milk. In addition to consuming susceptible cows’ milk, children were also fed with mainly cereal-based meals that have been frequently reported to contain aflatoxins (IRC 2015; Mollay et al. 2021). This implies double burden of exposure to both aflatoxins B and G, as well as AFM1.
Dietary exposure to AFM1 (0.0024–0.077 µg/kg bw/day) due to consumption of cows’ milk among children exceeded the limit of not more than 0.000004 µg/kg bw/day reported in EFSA (2020), implying a significant concern to public health. Similarly, Ahlberg et al. (2018) reported mean AFM1 exposure of 0.8 ng/kg bw/day for all recruited children (< 3 years of age) in Kenya. Findings of Kortei et al. (2022) have reported the Estimated Daily Intakes (EDI) of AFM1 in raw cow milk samples from Greater Accra Region were 0.61, 0.36 and 0.14 ng/kg bw/day for infants, toddlers and children respectively.
Margin of Exposure (MOE) was way below 100,000 implying that, AFM1 intake through consumption of cows’ milk can cause significant health problem (Kortei et al. 2022, EFSA 2020). A study by Kortei et al. (2022) reported Margin of Exposure (MoE) values ranging from 197.04 to 655.74 for infants (0–11 months), from 333.33 to 1111.11 for toddlers (12–35 months) and from 888.89 to 2857.14 for children (36 months to 10 years) in four regions of Ghana. Contrariwise a study by Milićević et al. (2021) reported higher values of MoE signifying no public health concern due to AFM1 among toddlers (1–3 years) and children (3–9 years) due to consumption of infant formula, fermented milk products, butter, milk beverages, sour cream, cheese, pasteurized and UHT milk and whey liquid in Serbia.