People in south Superior are concerned about whether it’s safe to plant vegetables or work with soil after a series of explosions and fires at the Husky Energy oil refinery. University of Wisconsin-Extension officials are looking to calm people’s fears by seeking out soil tests. Some have questioned whether people may be at risk due to last week’s fires, including Steven Sternberg, an associate professor of chemical engineering at the University of Minnesota Duluth. Sternberg said he would limit contact with soil to avoid any long-term health problems associated with polycyclic aromatic hydrocarbons (PAHs), which are groups of chemicals that are released from things like burning coal, oil and gasoline.