One example: For decades, we ate large amounts of vegetable shortening and margarine made from a chemical process that creates trans fats. Only relatively recently we became sure that trans fats cause heart disease, and restrictions about trans fat contents where put in place in many countries. See this Wikipedia article.
A major problem seems to be that many engineered things we eat every day were invented before rigorous food testing was mandatory. Since retroactively banning all this stuff is not realistic, we have to live with the risk of finding more such cases in the future. Similar things hold for other products, like specialized substances in food packaging, etc.
One example: For decades, we ate large amounts of vegetable shortening and margarine made from a chemical process that creates trans fats. Only relatively recently we became sure that trans fats cause heart disease, and restrictions about trans fat contents where put in place in many countries. See this Wikipedia article.
A major problem seems to be that many engineered things we eat every day were invented before rigorous food testing was mandatory. Since retroactively banning all this stuff is not realistic, we have to live with the risk of finding more such cases in the future. Similar things hold for other products, like specialized substances in food packaging, etc.