CAIRO: The tear gas used by Egyptian security forces against protesters in the area of Tahrir Square last week was non-toxic, according to researchers from the National Center for Research. Egypt's Ministry of Health received a full report from the National Center for Research about the tear gas. The report said the center received two containers of tear gas. The first type of tear gas was produced in Pennsylvania, and the second was produced elsewhere in the United States. Researchers confirmed that both types of tear gas were non-toxic, refuting claims that the gas contained nerve agents. The Ministry of Health also received other samples of tear gas containers to investigate whether they contain internationally banned substances.