FACTBOX: Illegal immigrants and U.S. healthcare debate

(Reuters) - The number of illegal immigrants in the United States who lack health insurance is a source of controversy in the debate over President Barack Obama’s plan to overhaul the $2.5 trillion healthcare sector.

Some of those opposed to Obama’s effort accuse the government and media of undercounting illegal immigrants in order to inflate the total tally of uninsured Americans and make the need for reform more urgent.

Critics also argue that healthcare costs are higher in the United States because illegal immigrants, who often lack insurance and don’t pay taxes, drain precious healthcare dollars through trips to emergency rooms and clinics.

Supporters of the Obama plan tend to dismiss the overall impact that illegal immigrants have on the healthcare sector.

Here are some facts about illegal immigrants and healthcare in the United States:

- There are 45.7 million people, or 15.3 percent of the U.S. population, who lack health insurance, according to the U.S. Census Bureau’s Current Population Survey, which is based on 2007 data.

- A total of 9.7 million among the uninsured said they were “not a citizen.” Foreign students and workers legally in the country as well as illegal immigrants are included in this sub-group, according to Census Bureau researchers.

- Census Bureau researchers are not allowed to ask respondents about their immigration status. Almost all estimates of the number of uninsured illegal immigrants are based on extrapolations from Census surveys.

- There are 6.1 million uninsured adults who are illegal immigrants and 700,000 uninsured children who are illegal immigrants, according to an estimate by the non-partisan Pew Hispanic Center, which was based on Census data.

- U.S. citizens accounted for the bulk of the 8.6 million additional people who reported joining the ranks of the uninsured between 2000 and 2006, according to survey data. Two million of these were non-citizens, while half a million were naturalized citizens.

- Some 20 percent of adult citizens have been to an emergency room in the last year, compared to 13 percent of non-citizens adults.

- Illegal immigrants work disproportionately in jobs that do not provide health insurance.

- There is no widely accepted national estimate of the annual cost of healthcare for illegal immigrants, partly because hospitals do not collect immigration figures.

The Federation for American Immigration Reform, which advocates a temporary moratorium on most immigration, puts the total cost at $10.7 billion and calls the estimate conservative.

Sources: U.S. Census Bureau; Pew Hispanic Center; Kaiser Commission on Medicaid and the Uninsured; Center for Immigration Studies; Leighton Ku, professor of public health policy, George Washington University, Federation for American Immigration Reform, Migration Policy Institute

Writing by Matthew Bigg, editing by Paul Simao