I'll try to get back to those challenges, I'm going to be busy for the next few days, so you'll just have to quell the intense need to read my replies.
I'm trying to gather some studies on the issue, but obviously google is not the end-all, be-all of research and I don't particularly want to put in more effort. But here are some things you guys may find interesting:
1) This is a survey of crime statistics involving pornography/sexual offenses. It deals with a claim I made earlier about the impossibility of isolating JUST the posing naked (victim pornography has the child as the subject, as opposed to situations where pornography is used to seduce or molest children):
"...all juvenile victim pornography incidents included other offenses in addition to illegal pornography; the great majority of them were sexual or violent offenses..."
As to the parents being the people who should decide: "Juvenile victim pornography incidents occurred in various locations but overwhelmingly in private residences and homes, which is also where sexual abuse tends to occur..."
"For juvenile victims whose offender could be identified, 25 percent were members of the offender’s family, 64 percent were acquaintances, and 11 percent were strangers."
http://www.ncjrs.gov/pdffiles1/ojjdp/204911.pdf
2) Another big study that reiterates the point that the pure effect of porn cannot be isolated, but discusses other related issues:
"Exposure to pornography is often used as a technique to normalize the practice of prostitution during a pimp's "seasoning" process. Pimps may take photographs of children who are nude in the context of a caring relationship but then threaten to send the images to the child's family or school."
The family and school are just the leverage for blackmail, it could easily say "post on the internet." Is a child who is "nude in the context of a caring relationship" art?
"In one study of adult female prostitutes, 38 percent of the women reported that they had sexually explicit photographs taken of them, while they were children..."
http://www.popcenter.org/problems/child_pornography/PDFs/Klain_etal_2001.pdf
Lot's of sources to dig around in on that one, if anyone cares.
3) Regarding the child's ability to "consent":
"The vast majority of children who appear in child pornography have not been abducted or physically forced to participate. In most cases they know the producer—it may even be their father—and are manipulated into taking part by more subtle means."
http://www.popcenter.org/problems/child_pornography/2
4) "Little research exists on how exposure to and participation in pornography affect children, although it is apparent that such experiences often produce feelings of betrayal, guilt, worthlessness, and rage."
Pierce, R. L. Child pornography: A hidden dimension of child abuse. Child Abuse & Neglect, 1984, 8: 483-493.
I couldn't get that whole thing for free.