Encounters with UFOs have reportedly left Americans suffering from radiation burns, brain and nervous system damage, and even "unaccounted for pregnancy," according to a massive database of U.S. government reports recently made public through a Freedom of Information Act (FOIA) request.

The database of documents includes more than 1,500 pages of UFO-related material from the Advanced Aerospace Threat Identification Program (AATIP) — a secretive U.S Department of Defense program that ran from 2007 to 2012. Despite never being classified as secret or top secret, the AATIP only became known to the public in 2017, when former program director Luis Elizondo resigned from the Pentagon and released several now-infamous videos of an unidentified aircraft moving in seemingly impossible ways to the media.

Shortly after the AATIP's existence was revealed, the U.S. outpost of the British Tabloid The Sun filed a FOIA request for any and all documents related to the program. Four years later — on April 5, 2022 — the U.S. Defense Intelligence Agency (DIA) honored the request by releasing more 1,574 pages of material to The Sun.

Related: 9 Things we learned about aliens in 2021

According to The Sun, the cache of documents includes reports on the biological effects of UFO sightings on humans, studies on advanced technologies such as invisibility cloaks, and plans for deep space exploration and colonization. Some portions of the documents were "withheld in part" for privacy and confidentiality concerns, the AATIP told The Sun.

One standout document from the collection is a report titled Anomalous Acute and Subacute Field Effects on Human and Biological Tissues, dated March 2010. The report describes alleged injuries to "human observers by anomalous advanced aerospace systems," some of which may be a "threat to United States interests," according to the document.

The report describes 42 cases from medical files and 300 "unpublished" cases where humans sustained injuries after alleged encounters with "anomalous vehicles," which include UFOs. In some cases, humans showed burn injuries or other conditions related to electromagnetic radiation, the report said — some of them appearing to have been inflicted by "energy related propulsion systems." The report also noted cases of brain damage, nerve damage, heart palpitations and headaches related to anomalous vehicle encounters.

It is unclear what kind of vetting process, if any, the AATIP used to investigate these alleged cases. The Sun has yet to share the full contents of the requested reports.

RELATED STORIES

—15 unforgettable images of stars

—9 strange excuses for why we haven't met aliens yet

—The 15 weirdest galaxies in our universe

The report also includes a list of alleged biological effects of UFO sightings on human observers between 1873 and 1994, compiled by the Mutual UFO Network (MUFON) — a civilian non-profit group that studies reported UFO sightings. The reported effects of UFO encounters include "unaccounted for pregnancy," "apparent abduction," paralysis, and experiences of perceived telepathy, teleportation and levitation.

The report concludes that there is sufficient evidence "to support a hypothesis that some advanced systems are already deployed, and opaque to full US understandings."

For more details, check out The Sun's initial report on their FOIA request.

Originally published on Live Science.