Environmental pollution and intrinsic metabolism in the foods might explain these differences. Formaldehyde content in the samples did not exceed 15 mg/kg.
In some cases more than five samples from different markets were analyzed.The formaldehyde range was
1.83-1.93 mg/kg for apples,
1.83–4.62 mg/kg for mangos,
1.77–10.48 mg/kg for mango juices and 0.76–2.67 mg/kg for milk.