In the event that the impurity of food and medical products and such like which come from non-Muslim countries is not ascertained, there is no problem in buying and selling them. Like when it is probable that milk, cheese and oil coming from such countries are processed through mechanized processes. Buying and selling the meat which is imported from non-Muslim countries or which is taken from the hands of disbelievers is invalid. Unless one knows that it is taken from an animal which has been slaughtered in accordance with the Islamic law or under the supervision of Muslims. The halal logo is of value if it makes you certain that it is halal. However, if purchased from the bazaar of Muslims, the meat is deemed halal. It is not permissible to engage in business transactions with companies as long as one is certain that the profits earned by these companies belong to Zionists, Israel or countries that are in war with Muslims. However, it is permissible for those living in those countries to do so. Furthermore, there is no problem in consuming whatever one has previously purchased unknowingly.