On 22 Oct 1996, Cynthia M. Galloway wrote:
> Just talked to a collegue whose Anatomy & Physiology class just revived the
> old, old story of colored toilet paper causing cancer. One student brought
> it up but, about half the class agreed that they had heard this. Does
> anyone else remember this story or how it even started. I really hate to
> bring a question like this up but, we wanted to find something in the
> literature refuting this or even suggesting this and, there's nothing to be
> found. Sorry for throwing out something as trivial as this.
No one else is answering this, so I'm going to take a guess:
When I was a kid, we had colored toilet paper to match the bathroom
wallpaper, and then sometime in the late 60's we decided to use only
white toilet paper. I can't remember what was the suspected
problem with color, but this was around the same time when
artificial food coloring, red dye # whatever, was shown to be
carcinogenic in rats. My guess is that someone made up a list of all
the household products that contained these carcinogenic dyes, and the
list included toilet paper.
You might get information on this by calling the consumer relation number
for the toilet paper manufacturers. They'll undoubtedly say it's just
a myth, but they may be able to tell you how it started.
In any event, I'd take advantage of students' interest in the topic
to discuss how we find things out. How would you design an study
to determine if colored toilet paper is carcinogenic? What would be
the problem in doing a retrospective study asking cancer patients what
kind of toilet paper they used throughout their lives? If toilet paper
dyes were found to cause cancer when large amounts are rubbed on a rat's
skin, should we assume that it's dangerous for humans to use them in the
usual way? What would you use as a control? Is white toilet paper
free of chemicals, or is it bleached to get that brilliant white color?