Dioxin, a highly toxic substance, has been found in 42 soil samples around the Union Pacific rail yard in Houston’s Fifth Ward. Experts are concerned about the potential ongoing risk for nearby residents. According to the EPA, dioxin can harm the human immune, endocrine, and reproductive systems and cause cancer. According to the city, 27% of the samples surpassed federal risk screening standards for what is considered safe for children. Union Pacific, on the other hand, stated that the results were within what state regulators consider acceptable.