SALEM, Ore. (AP) — During the nationwide Black Lives Matter protests, federal, state, and local law enforcement agencies have increasingly been using tear gas — traditionally used as a measure of last resort — offensively. Witnesses and human rights advocates say peaceful protesters, children and pregnant women have sometimes been hit by excessive amounts of tear gas with police failing to provide an escape route. Law enforcement officials say the gases are effective tools for crowd control and are safe. But despite its widespread use, there are few studies on the health effects of tear gas. The AP also found that there is no oversight of the use and manufacture of tear gas.