Boxer, chairman of the Senate Environment and Public Works committee, convened a hearing June 27 into the explosion at the West Fertilizer Co. facility West, Texas, that killed 15 people and flattened hundreds of homes.
She held a news conference Tuesday in Washington to discuss her conclusions.
"OSHA (U.S. Occupational Safety and Health Administration) should be doing more inspections, there's no doubt about it. EPA (U.S. Environmental Protection Agency) should change their risk management plan. We all have to do more," Boxer said.
OSHA had not inspected the West Fertilizer site since 1985.
Concerns raised at the hearing included storage of explosive material, such as ammonium nitrate, in wooden containers, buildings with a lack of fire codes and lax zoning laws that allowed homes to be built near fertilizer factories, the Dallas morning News reported Tuesday.
"Ammonium nitrate can explode when it is heated or contaminated, and threatens the lives of first responders and people in communities located near facilities that handle this material," Boxer wrote to Texas Gov. Rick Perry, and the states' other governors, urging them to adopt "all available measures" to prevent explosions.