"The lack of documentation is the main factor that contributes to labor segmentation and social exclusion of Mexicans in the U.S. The most effective solution would be to regularize the status of this population, which would improve integration and social mobility."

Among highlights of the report:

• 53.5 percent of Mexican-born immigrants living in the U.S. lacked any type of health coverage;
• more than 70 percent of those who work in the most injury-prone industries (agriculture, for instance) lack health insurance;
• 38 percent don't have a consistent source of medical care, with half relying on community clinics rather than private providers;
• 34.5 percent of Mexican immigrants who become U.S. citizens lack health insurance.

"Mexican immigrants in the U.S. are poorly integrated and face high levels of social exclusion, with many not benefiting from existing health and social protection programs," the researchers reported.

"Mexican immigrants' naturalization rates are far below those of other immigrant groups, and they are more likely to have low incomes, live in poverty, and many among their ranks are undocumented," it said. "These social characteristics contribute to their lack of health insurance and access to care, and have negative consequences for their health in terms of chronic disease and overall wellbeing."

Because the immigrant population, and especially that share that comes from Mexico, is still rapidly rising, "improving the health of immigrants and especially Mexicans is crucial to preparing the way for good population health in the future," the report said.

"Pursuing good health is the right of all human beings, and providing the means for realizing the right to health is, certainly, a binational responsibility," it concludes.

The Patient Protection and Affordable Care Act is not expected to remedy the problem, because undocumented immigrants are not included under the law.