Well, I said it would be an irregular thing
Anyway, let's start with something down to earth.
I'm sure most of you are familiar with the M&M's candies. They have undergone a number of changes in the past decades - mainly in the colors and dyes used for their shells. A quick look at Wikipedia will give you an idea of the colors and varieties that have popped up in the past.
What you probably didn't know is that some of those dyes went under scrutiny for possible side effects. For example, the dye used in the preparation of red M&M's in the '40s was a suspected carcinogen, and was later replaced by another dye, Allura Red AC. While it is still used in most o the world, the latter dye is banned in several European countries due to concerns that it may be linked to mental retardation if taken up by children during a relatively long time span. Conversely, a variant of the blue dye has been demonstrated to help after spinal cord injury (the rats who were given the drug recovered better and had a lower incidence of paralysis compared to control rats), with the only side effect of turning them blue. The
actual scientific article made a good case for the benefits of the dye used as a drug (although it also suggested a high dosage is needed for the benefits to become apparent, possibly being the cause of the blue color in the rat).
