MUSCATINE, Iowa—After several months of research and review, the Iowa Department of Public Health (IDPH) released their Health Consultation on Steel Slag on County Roads for Muscatine County report. At the Jan. 20 Muscatine County Board of Supervisors meeting, Planning and Zoning Administrator Eric Furnas presented on the report.
According to toxicology testing performed by the IDPH, manganese, a mineral, represented the only potentially harmful element present in high enough quantities to affect human health in the slag applied on county roads. At the six sites they tested, the IDPH found the slag did not contain enough manganese to affect people if they simply breathed in dust from it. Additionally, manganese levels in the slag would not cause any problems for an adult if they incidentally ingested it from getting dust from the road on their hands or food before eating. In four locations, children, particularly those who might try to put slag in their mouths, could receive a high enough dose of manganese to experience adverse health effects (such as difficulties with memory or learning).
After sharing these results, Furnas cautioned people to not jump to conclusions. He shared that during a recent phone call with the IDPH, “They made it very clear at the beginning that there were some very strong assumptions to even reach this possible threshold of exposure.”
To determine the manganese exposure people would experience at each location, the IDPH assumed that half of the dust people would incidentally ingest contained manganese at the level found in nearby slag. In reality, individuals may receive significantly less exposure because daily activities such as going to work or school take them out of the area. Additionally, the report assumed that people would absorb all the manganese they came into contact with, even though that does not typically happen with any substance.
The report recommended that the county consider slag exposure reduction strategies for the locations with the highest manganese concentrations. Since Muscatine County stopped applying slag to its roads in 2018 and has only used limestone aggregate since then, Furnas believes that, over time, this will dilute manganese levels. Furnas also indicated that the IDPH director agreed with his reasoning.
During his conversation with the IDPH, Furnas learned that the Center for Health Effects of Environmental Contamination, along with the University of Iowa Health Science Research Center, will likely conduct independent air quality samples around Muscatine County to verify the IDPH’s findings.
For more information, view the full Health Consultation on Steel Slag on County Roads for Muscatine County report below.