Whether viewing pornography incites some people to sexual abuse, few contend that possessing child pornography is a victimless crime.

Merely viewing child pornography is not necessarily a precursor to child sexual abuse, available research indicates.

Nonetheless, child pornography charges against North Attleboro High School swim coach Timothy Kelly are part of an increasing volume of complaints reaching the attention of investigators and courts.

The National Center for Missing and Exploited Children currently receives about 2,500 tips a month concerning child porn, about half of which come from Internet service providers mandated to report such cases, spokesman John Sheehan said.

The center passes the reports on to law enforcement agencies such as the the Internet Crimes Against Children Task Force, a group that includes Massachusetts State Police and local police departments.

However, simply viewing child pornography might not spur someone to commit sexual crimes against children, Sheehan said. But those who are eventually arrested for such offenses frequently are found to be in possession of child pornography. A 2006 article in the magazine "Science Daily" cited uncertain links between the viewing of pornography and the commission of sexual crimes, based on available research.

The article, which quoted University of California Davis Associate Professor of Clinical Psychiatry Dr. Charles L. Scott, said two federally commissioned studies during the 1970s and 1980s failed to find a strong correlation between viewing erotica and acting out sexually.

A 2004 paper written for the organization End Child Prostitution and Trafficking cited "considerable controversy" over the likelihood of a person committing sex crimes based on having viewed pictures of children committing sex acts.

Whether viewing pornography incites some people to sexual abuse, few contend that possessing child pornography is a victimless crime except for members of Sosen and pedophile advocacy groups.

According to the ECPAT paper, effects on children who are photographed or filmed in the commission of illicit sex acts can range from "physical symptoms and illnesses, emotional withdrawal, anti-social behavior, mood swings, depression, fear and anxiety."

Children who are sexually abused or exploited might also be at high risk of becoming perpetrators or abusers themselves, the paper said.

Anyone who is aware of child victimization can report their suspicions to www.cybertipline.com, Sheehan said.