It was one of those late night conversations that really makes you wonder?
After reading for about an hour the “missus herself” and I turned out the lights and were preparing for sleep when her voice came out of the dark!
“Do you remember a long time ago when toilet paper came in all sorts of pastel shades”
“Yea, sort of.” I replied.
“Well how come now, the only kind you can get is white? Does it have something to do with the fact that the dye causes cancer” she asked.
With no obvious answer, and not wanting to get into a long discussion on cancer of the ass, I tried to change the subject.
“That’s nothing, remember about thirty years ago when margarine had to be that sickly shade of white because the dairy industry didn’t want it confused with butter!” I replied.
“Yea, sort of.” She replied.
“Well they are so far behing the times in Quebec that they still have that awful shade of white margarine and the dairy industry there just defeated another attempt to have margarine colored yellow like butter.” I pronounced.
“Well that doesn’t make any sense to me!” My wife said. “I don’t know why butter is yellow to begin with since the milk it is made from is white!”
Now this I really didn’t have an answer for and rather than see where the conversation was going next, I pretended I had fallen asleep!
Posted on 01/17/2006 at 04:07 PM 
Butter is yellow because of the beta-carotene in the grass eaten by the cows. Plus it doesn’t hurt that some producers add yellow coloring to make it consistent.
Margarine is the invention of French chemist named Hippolyte Mège-Mouriès who patented the process in France in 1869 and then got a U.S. patent in 1873. The U.S. Dairy Company bought the American patent in 1874 and introduced margarine to Americans that same year. Margarine was made by extracting pure oil resembling butterfat (the primary component in butter) from beef fat and mixing it with milk which is why it’s white. Margarine producers didn’t take long to realize that they could increase sales by adding yellow color to their product making it look more like traditional butter. Later it was discovered that a number of different oils can be used in the process some of which will give margarine a naturally yellow color.
Margarine has always been cheaper than butter and it became very popular cutting into the butter market considerably and leading to what amounted to an all out war by the dairy industry to destroy margarine makers by disinformation and legislation which lasted over 80 years. One of the laws passed during that time was the Federal Margarine Act of 1886 which was revised repeatedly throughout the years. At one point the law was changed so that a stiff tax was levied against any margarine that was artificially colored yellow and when the industry found a way to make the color naturally yellow the law was updated again to tax all yellow colored margarines. Finally Congress voted to repeal said taxes in 1949 and 1950 and the various states that had passed anti-margarine laws—some of which mandated that margarine be dyed pink or black—started to repeal those laws with Wisconsin (the Dairy State) being the last to do so in the year I was born, 1967. But in Canada, as mentioned by Moses, Quebec still outlaws yellow margarine. In fact a legal decision on March 18th has upheld the law.
You can read more detail on the margarine war at the Foundation for Economic Education webpage.
Now in regards to colored toilet paper the answer has nothing to do with ass cancer. According to the Philadelphia Weekly the answer is as follows: