By Eduardo Santana.

The number of undocumented minors attempting the dangerous trek across the U.S.-Mexico border alone has risen, experts gathered at the University of San Diego's "Children at the Border" forum said.

The director of USD's Trans-Border Institute, David Shirk, who organized the forum, told Efe immigration patterns have changed over the past 20 years for reasons such as the expansion of the metal wall on a portion of the frontier in 1994 and tighter border protection following the Sept. 11, 2001, terrorist attacks.

Due to the difficulty in crossing the border, parents typically make the trek first and then urge their children to make the attempt later, usually alone, he said, adding that procedures for protecting minors' interests and rights must be improved.

The expert said minors who try to make the journey unaccompanied by an adult relative are more likely to be sexually assaulted, fall into the clutches of organized crime gangs or suffer drug abuse or other health problems.

Wayne A. Cornelius, a director of the University of California's Center of Expertise on Migration and Health, told Efe that the "great recession" of 2008-2009 has made undocumented immigrants afraid to travel to their homelands due to fear of losing their jobs and therefore meant that minors must travel unaccompanied to reunite with their families.

U.S. President Barack Obama's administration has deported more than 400,000 people a year, according to Cornelius, who said another 500,000 are detained and given the option of voluntary repatriation, in which case they are not included in deportation statistics, he said.

This situation means that more and more children are caught and "thrown into the system," nearly 8,000 in the first several months of 2012, the expert said.

The conference took its name from the report "Children at the Border: The Screening, Protection and Repatriation of Unaccompanied Mexican Minors," prepared by Appleseed, a non-profit network of 16 public interest justice centers in the United States and Mexico.

Published in April 2011, it is the most thorough study of the problem to date.

According to the report, 59 percent of the 29,624 minors detained by U.S. Customs and Border Protection between October 2009 and the end of August 2010 were unaccompanied.

It also said that 80 percent of the minors detained between October 2009 and September 2010 were of Mexican origin and the rest from Central America.

With the Central American minors, CBP makes a greater effort to contact their families, while nearly all of the unaccompanied Mexican children are immediately repatriated, the study said.

The report said the U.S. Department of Homeland Security is mandated by a 2008 law to interview every unaccompanied Mexican minor to ensure they are not a victim of trafficking, have no possible claim to asylum and voluntarily agree to go back home.

But it added that more than two years after its passage the promise of the William Wilberforce Trafficking Victims Protection and Reauthorization Act of 2008 "remains unfulfilled." EFE