Researchers from the University of Maryland and the University of Nebraska discovered traces of Staphylococcus aureus (MRSA) in U.S. wastewater treatment plants, according to a new study published November of this year.

The team tested four wastewater treatment plants between October 2009 and October 2010 and found MRSA in 22 out of 44 samples, according to the study. MRSA is a bacterium that causes staph infections, including chest pain, fatigue, headaches and wounds that do not heal, according to the U.S. National Library of Medicine.

The study was done to assess the risks of reusing treated wastewater in the U.S., according to Rachel Rosenberg Goldstein, graduate research assistant at the School of Public Health and the study’s first author.

“As the reuse of treated wastewater expands in the United States, it is important to evaluate the potential risk of antibiotic-resistance bacterial infections from exposure to treated wastewater,” Goldstein wrote in an email. All four sites tested send a portion of their treated wastewater to reuse sites, she wrote.

University of Maryland students are worried about the outcome of the study and believe that more studies should be done.

“You trust that water treatment plants are going to be sending you clean water,” sophomore computer science major Andrew Parrish said. “Now they have found something; I think it’s inevitable that they need to do more studies on more plants.”

There may be a way to reduce the risk of MRSA in treated wastewater, though, according to Goldstein.

“MRSA was only isolated in one treated wastewater sample, and this sample was collected when the treatment plant was not using chlorination,” Goldstein wrote in an email. “Our findings suggest that tertiary wastewater treatment may effectively reduce MRSA in wastewater.”

Sophomore journalism major Zoë King believes more studies are necessary.

“They should investigate further to make sure it’s not a huge issue,” King said.

Goldstein did not comment on the possibility of further studies, but mentioned the relevancy of the study to the current reuse of treated wastewater.

“Around 2.2 billion gallons of reclaimed wastewater (treated wastewater) are being used per day in the United States,” Goldstein wrote in an email. “Our study is the first to demonstrate the occurrence of MRSA in U.S. municipal wastewater.”