WASHINGTON – In the first national study of child sexual abuse in the Roman Catholic Church, researchers hired by the church reported Friday that 4 percent of all the priests who have served since 1950 have been accused of sexually abusing children.

The 11-month study, conducted by the John Jay College of Criminal Justice of the City University of New York, was based on survey responses from 195 Roman Catholic dioceses and 142 religious communities across the country, representing about 80 percent of religious priests nationwide. All Roman Catholic dioceses in the United States were asked to comb through their records, and 97 percent responded, the study reported.

In a companion report, a lay panel of Catholic leaders placed a heavy measure of blame on bishops who failed to report abuse to police, allowed suspected abusers to continue ministering to children, and spent millions of dollars on legal settlements that helped keep allegations quiet.

About $572 million was spent by the church in legal expenses, victim compensation and treatment of victims and priests, the study found. It said the figure does not include a recently reported settlement of $85 million by the Boston diocese.

Robert Bennett, a Washington lawyer who chaired a “causes and context” study by the National Review Board of the U.S. Conference of Catholic Bishops, said that “leadership failures” by top clergymen who permitted the abuse to continue were “shameful to the church.”

In response, Bishop Wilton Gregory, president of the conference, issued an apology “to all of you who have been harmed by those among us who violated your trust.” He said the church would “do everything possible to see that it does not happen again.”

Gregory said, “We are determined that this troubling past will give way to a healing and reconciling future.”

“The information in the John Jay report was sobering, shameful, but ultimately necessary in order to determine if the church is taking effective steps to stop the abuse of children in the future,” said Bishop Joseph Gerry of the Roman Catholic Diocese of Portland, Maine. “The bishops called for and cooperated with this factual and impartial report in order to understand the magnitude of the problem. I am overwhelmed by the information and sorrowful over the pain and suffering it represents. We are committed and determined to work and learn from this information to assure the crimes of the past are not repeated in the future.”

Bennett, who announced the findings at the National Press Club, called the abuse of minors “a national health problem” that extends far beyond the Catholic Church. Nearly 100,000 children were reported abused nationwide in 2001 alone, he said, adding, “As a nation, we should hold our heads in shame.”

But, he said, “there is absolutely no excuse for what occurred in the Catholic Church. … At heart what we are talking about is not a media crisis or a personnel crisis, but an age-old question of right and wrong, good and evil.”

Many dioceses and orders “simply did not screen candidates for the priesthood properly,” allowing “many dysfunctional and psychosexually immature men” to be admitted, Bennett said. In addition, he said, seminarians “were not prepared for the challenges of the priesthood,” including chastity and celibacy in what he called “this hypersexualized American culture of the last few decades.”

Faced with allegations of abuse, “many of the bishops breached their responsibilities as pastors … and put their head in the sand,” Bennett said. They failed to understand “the broad epidemic nature of the problem” and did not share information with others in the church.

Bennett said the panel recommended “enhanced screening” of prospective priests and renewed commitment to victims of abuse, rather than excessive concern about the rights of accused priests and the avoidance of scandal and litigation.

The statistical report by the John Jay College research team found that 109,694 priests have served the church since 1950, and that 4,392 of them have been accused of molesting minors. Of 10,667 abuse claims reported to the church over the past five decades, 6,700 were substantiated. About 3,300 were not investigated because the accused priests had died, and nearly 1,000 claims were not substantiated, the report said.

It said 56 percent of the accused priests were alleged to have abused one victim and that 3.5 percent allegedly had 10 or more victims. The latter group, consisting of 149 priests, accounted for 27 percent of all allegations of sexual abuse by priests.

Overall, the study found, 81 percent of the victims were male and 19 percent female. About 40 percent of the alleged male victims were between 11 and 14 years old, the largest age and gender group.

Researchers said they did not include in their statistics any case in which the accused priest was exonerated or the accusation was withdrawn.

Church officials say the twin studies are the first time any religious denomination or profession has laid itself bare before the public by investigating the frequency of child sexual abuse in its ranks. Judging from other studies that indicate that millions of Americans have been sexually abused as minors, Catholic leaders say it is clear the problem extends well beyond the church.

For years, however, some Roman Catholic leaders have asserted that only a tiny portion – 1 percent or less – of all priests are guilty of sexually abusing minors. Others inside and outside the church, such as the priest-sociologist Rev. Andrew Greeley, have maintained that 5 to 10 percent of all U.S. priests probably have had sexual contact with minors.

The $500,000 study made public Friday provided some reasonably hard, nationwide data on abusive priests and their victims for the first time. But the study was unlikely to put the statistical debates to rest, for two main reasons.

First, there are the possible flaws in the study itself. It is based on voluntary self-reporting by the nation’s Catholic dioceses, which were asked to dig through their records and disclose all accusations of abuse since 1950. Victims’ advocates say that figure is essentially a lower limit, since they believe that false allegations are rare and that unreported cases of abuse are common.

“There are really two questions here,” said David Clohessy, national director of the 4,600-member Survivors’ Network of Those Abused by Priests. “Did the church report everything it knows? And does the church know everything?” In Clohessy’s opinion, there is “reason for skepticism on both counts.”

Gregory said last week he is confident that his colleagues “carefully, prudently and honestly reviewed the records that were available to them.” But “if your question is that there may be other people who are victims who have not come forward, and perhaps will not come forward, that is always a possibility.”

The second, broader reason that the debates will continue is that there are very few data to compare with the statistics produced by the church. National experts on child abuse say there have been studies of Protestant clergy showing a high percentage who have sexual affairs with adults. In a 1993 anonymous survey of Southern Baptist ministers, for example, 14 percent admitted they had engaged in “inappropriate sexual behavior.”