Yet public disgust associated with child pornography contrasts dramatically with the ambivalent reaction to extreme adult material.
The distinction protects the hardcore market and provides it with the argument that at least grown-ups are involved.
Even those debating the issue of pornography hesitate to wrap both strands of such material into one.
Others are more emphatic about where they stand.
In the second report of the National Observatory on Violence Against Women, author Monica O’Connor said: “Upholding the notion that there are two distinct markets for adult women and children is not tenable. Entry into the sex industry is almost always a process of abuse from childhood or girlhood leading into adult sexual exploitation.”
However, apart from the people in front of the camera, there are different categories of user in both markets.
Dr Davina Walsh, senior psychologist at the Granada Institute, the Irish treatment centre for paedophiles, said in most cases adult websites were the entry point but paedophiles were looking at a different style of imagery.
She said the content of child pornography was very different to the trends in adult material.
In very few cases was violence involved and most paedophiles would insist the child is looking happy and does not seem upset by what is happening.
“I think it depends on the individual. For some of the men it is because the adult content is no longer fulfilling them and they want something different.
“And with pop-ups coming off sites, they can tempt men to areas of the internet they would not normally go to, to see what else they can get. But in other cases the predominant interest is with children, and adult porn would not be what they are looking for.
“They might have started with adult pornography and it would have served the purpose of eliminating negative feelings, and if they were afraid of getting caught it would be a release, but after a time they would be looking out for child porn,” she said.
A prominent US professor in this area, Gail Dines, said there was a culture in adult production to feed the desire for younger women.
Speaking at Limerick Rape Crisis Centre’s conference last November, Prof Dines said it was impossible to draw a clear distinction. She raised the example of the Barely Legal brand. It sells on the catch line “From the classroom to the bedroom” and, she said, attempts to make it acceptable to sexualise adolescents.
“The material is indeed legal because the women are 18 or older, but they are presented in childlike ways, petite with small breasts, childish expressions and hair in braids or ponytails.
“At these sites men can find images of young, vulnerable girls who look eager to please without any legal risk of accessing real child pornography,” she said.
Dr Walsh said that in the experience of the institute, viewing material does not mean people will progress naturally to physically offending.