Writing in the Huffington Post, Leah Zallman -- a research scientist at the Institute for Community Health, a primary care doctor at Cambridge Health Alliance, and an instructor of medicine at the Harvard Medical School -- and Steffie Woolhandler -- an internist in the South Bronx, professor at the City University of New York School of Public Health at Hunter College, and lecturer in medicine at Harvard Medical School -- attempt to take Donald Trump to task for his claims about the health care costs from illegal immigrants:

Throughout the primary season, leading Republican presidential candidates vied over who could bash immigrants the hardest. And they were promising more than border walls. Donald Trump is the most extreme immigrant-blamer; according to his website, "Providing healthcare to illegal immigrants costs us some $11 billion annually. If we were to simply enforce the current immigration laws and restrict the unbridled granting of visas to this country, we could relieve healthcare cost pressures on state and local governments." As with many of Trump's claims, this one is wrong. But unlike some of his other falsehoods, the media has left this one unchallenged.

Well then, now is a good time to challenge it.

The RAND Corporation published a study that calculated health care costs from illegal immigrants for the year 2000:

Of the $430 billion in national medical spending in 2000, native-born residents accounted for 87 percent of the population but for 91.5 percent of the spending. Foreign-born residents, who include undocumented immigrants, accounted for 13 percent of the population but for only 8.5 percent of the spending. Undocumented immigrants -- 3.2 percent of the population -- accounted for only about 1.5 percent of medical costs.

Some basic math reveals that in 2000, illegal immigrants accounted for $6.45 billion of national medical spending.

Since 2000, "national medical spending" has increased by about 162% (i.e., a factor of >2.6), and the share of the U.S. population from illegal immigrants has -- if we take the likely underestimates at face value -- increased to 3.5%.

Consequently, crunching the numbers, we arrive at a projected current annual cost from providing health care to illegal immigrants of $18.5 billion.

Thus, it appears Trump is indeed wrong, as Zallman and Woolhandler claim, just not in the direction they believe. The actual cost of giving illegals health care is likely to be nearly twice as much as Trump's website states.

In other words, the problem is far worse than even the most "radical" Republican views have imagined.