Most of us have been told off by a parent or grandparent for sampling raw cookie dough or cake batter. The adult would usually mutter something about raw eggs making you sick, while whisking away the delicious goop. It turns out that the raw flour in doughs can also put tasters at risk for infection, specifically one by E. coli. As Health Canada points out, flour grains can come into contact with bacteria while in the field, and need to be cooked to remove risk of illness. Raw eggs do still carry a risk, although you don't need to worry about them if you buy pasteurized eggs!

@AdaMcVean