Food safety issues are as old as mankind and since time immemorial humans have developed strategies to ensure that the food they eat does not harm them. To produce food with any new technology, there must be appropriate safeguards to protect human and animal health.
There exist few written records, but it is reasonable to assume that, historically, the safety of new products of food was established by trial and error. The foods consumed today are generally viewed as safe, based on their long history of safe use.
It is worth noting that this general acceptance of historical safety does not necessarily mean that some traditional foods may not cause adverse health effects under some circumstances.