GERMANTOWN, Md. - Asked what they could do back in their native Chile, the four scientists in their 30s talk about solving problems such as the occasional "red tide" poisonings that can hit the fishing industry, or improving the forestry and mining industries.

But they say it will be difficult to return home after completing their research programs at the National Institutes of Health, a dilemma common to scores of Latin American scientists studying in the United States.

Scarce private-sector jobs and limited teaching slots or well-equipped research laboratories in their home countries keep most young Latin American scientists in the United States. Although Chile and a few other Latin American countries have started programs to lure scientists home, a $130,000-plus salary at a U.S. biotech firm and the possibility of working alongside the vast network of U.S. scientists are often too good to resist.

"Those who return go into academia," said Jorge Contreras, who at the NIH studies the movement of certain proteins in cell membranes. But with too many specialists chasing too few positions, he added, "the system is becoming saturated."

Contreras, one of the four Chilean scientists interviewed in the Washington suburb of Germantown, pointed to a chart showing how just two Chilean universities gobbled up nearly 45 percent of the government's research grants in 2006.

Cuban-born Arlyn Garcia-Perez knows the brain drain phenomenon firsthand. Raised in Puerto Rico, Garcia-Perez studied at the Massachusetts Institute of Technology and Michigan State University, then did cutting-edge work in renal physiology at the NIH in the 1980s. She chose to remain at the NIH, where she oversees postdoctoral programs.

"What was my choice? Stay at the mecca of research, the NIH, or go back and struggle like crazy to try and set up in Puerto Rico?" she asked. "For me, it was a no-brainer."

She estimates that less than 20 percent of the 143 Latin Americans doing postdoctoral work at the NIH will return home.

The brain drain is not new. World Bank studies from 2000 showed that small and poor countries in Africa, the Caribbean and Central America suffered massive losses of brain power.

More than 83 percent of Haiti's most qualified workforce emigrate, and Cuba leads Latin America in the number of emigrated university-educated professionals, with 332,000.

The phenomenon is not limited to the poorest nations. Britain recorded the world's highest number of university-educated professionals who emigrated, with 1.4 million.

The influx of foreign talent keeps fueling the U.S. grip on scientific know-how. According to the World Bank, a 10 percent increase in the number of foreign graduate students raises patent applications by 4.7 percent in the United States.

And, Garcia-Perez noted, U.S.-born scientists are in short supply. "A career in science is something that takes a long commitment," she said.

While Chile does not have a legacy of producing scientists of international caliber, a steady, thriving economy and political stability are producing a boom in Ph.Ds.

The Chilean agency that finances academic investigations awarded just 50 postgraduate scholarships in 1990. In 2005, it awarded 391.

The number of Ph.D. graduates from Chilean universities shot up from 75 in 1999 to 244 in 2004. More than half those new doctorates were in basic sciences.

Aspiring scientists usually spend several years doing postdoctoral work in Europe or at U.S. institutions, such as the NIH. The problem is that few countries can equal the scientific heft of the NIH, with 27 in-house institutes and centers.

The NIH can give grant money to foreign researchers who return home, she said, citing Gerardo Gamba, a renowned Mexican kidney specialist who won an NIH grant to do work in Mexico.

The NIH also is working with Chile to set up a program for five promising Chilean scientists who would spend five years in Bethesda before returning to Chile and a university faculty position for two or three years.