NEWKIRK, Okla. (AP) – The Department of Homeland Security said Thursday it is suspending plans to conduct bioterrorism drills near the Kansas-Oklahoma border over concerns about their impact on grounds Native American tribes consider sacred because more than 100 children are buried there.

Homeland Security spokesman John Verrico said in an email that the tests were suspended over objections to them taking place at the Chilocco Indian Agricultural School. The Chilocco school, which operated from the late 1800s until 1980, was one of several federally-run boarding schools where the U.S. once sought to assimilate Native American children. The tribes say the federal agency is failing to protect a site with religious and cultural significance.

The agency's environmental assessment for the test said several inert chemical and non-hazardous biological materials were to be released to evaluate the ability of buildings to protect occupants from outdoor biological hazards. The proposed testing was planned for the months of February and June and July.

"While the work remains very important for the security of our nation, further evaluation will be conducted to identify the best location for future testing," Verrico said.

Sen. Jerry Moran, R-Kan., said he was pleased Homeland Security has suspended plans for testing near the Kansas border.

"While the chemicals DHS planned to use in these tests do not pose any bodily harm, Kansans deserve a thorough explanation when an event of this magnitude is occurring so close to where they live and raise their families," Moran said.

Homeland Security said the chemicals it planned to use are found in common household products such as sunscreen, cosmetics and laundry detergents.

One chemical that's caused the most worry, especially among the many farmers who live nearby, is called DiPel, a biological insecticide that's been commercially available since the 1970s and approved for use in organic farming. The Homeland Security project manager has said the chemicals won't pose harm to humans, animals or hundreds of acres of nearby cropland and pasture.