The study published in the journal Food Control showed that 75 (52%) of the 144 breakfast cereal and snack samples collected were contaminated with between 0.10 and 7.43 nanograms per gram (ng/g) of the potentially carcinogenic Ochratoxin A (OTA).
Ten of these contaminated US samples, all oat based products, exceeded the European Commission’s maximum limit of 3 ng/g of OTA in cereal based products. The toxin – produced by several fungal different species – is not currently regulated in the US.
The researchers said: “More surveys of a large number of suspected foods in various areas in the US are necessary to carry out in the future for the evaluation of OTA contamination.”
According to the study the toxin has an unusually long half-life (the amount of time required for a quantity to drop to half its value) and may pose a significant threat to public health.
OTA is one of the most common mycotoxins occurring in foods such as cereal grains including corn, wheat, rice, oat and barley as well as nuts, dried fruits and infant foods.
It has been a source of some concern due to its range of toxicity such as immunotoxic, teratogenic, nephrotoxic, neurotoxic, and carcinogenic effects, yet the researchers said there had been little research in the US since the first natural contamination of OTA in a corn sample was recorded in 1969.
In Europe the maximum limit for cereal grains has been established at five micrograms per kilogram and three micrograms per kilogram for cereal products, with limits for ground roasted coffee, dried vine fruit, wine and baby foods also being set by the European Commission.
The fluorescence detection method used found that 40% of the contaminated samples were labeled organic and had a mean OTA concentration of 1.21 ng/g, the other 60% were non organic and had a mean OTA concentration of 1.07 ng/g.
This higher average rate for organic products was explained in the report by differences in cultivation practices, limited use of non-synthetic fertilizers, pesticides, conditioners of low solubility, and the fact that genetically modified organisms had not been used. The researchers said these elements could easily cause fungi proliferation and mycotoxin production.
The OTA frequency was also highest in oat based samples (84%), followed by wheat (56%), rice (44%), and finally corn (14%). It was suggested that this could be due to the ingredients added to these cereals like sugar, honey, chocolate, and dried fruits – all of which the scientists said can encourage the growth of fungi.
Source: Food Control
Vol. 40, Iss. June 2014, pp. 140-144, http://dx.doi.org/10.1016/j.foodcont.2013.11.041
“Concentration of ochratoxin A in breakfast cereals and snacks consumed in the United States”
Authors: K.T.N. Nguyen and D. Ryu