I thought this was worth mentioning. I have pulled all forms of dairy from difficult child diet and have seen a great improvement. A few weeks ago, I got lazy and was letting difficult child eat diary. Last weekend, after a major meltdown episode, I looked at the ingredients for what he ate (hot dog rolls). I was surprised to find this when I looked up Calcium Propionate... Calcium propionate is used as a preservative in a wide variety of products, including but not limited to bread, other bakery goods, processed meat, whey, and other dairy products. Calcium propionate is used in bakery products as a mold inhibitor. According to the Pesticide Action Network North America, calcium propionate is slightly toxic. This rating is not uncommon for food products; Vitamin C is also rated by the same standards as being slightly toxic.  Calcium propionate can be used as a pesticide. Behavioral effects Calcium propionate has been weakly linked to irritability, restlessness, inattention, and sleep disturbance in children. The Ecologist Online claims that it is linked to allergic reactions in bakery workers.