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New Loma Linda University study finds inequities in wastewater testing

A more inclusive strategy is needed to protect underserved communities from future pandemics. 

Ryan Sinclair, right, and a research assistant test wastewater in San Bernardino County. (Photo: Courtesy Loma Linda University Health)

LOMA LINDA, Calif. — A new study conducted by researchers from Loma Linda University School of Public Health uncovered inequities in wastewater testing of COVID-19.

Why it matters: These findings highlight a significant gap in disease outbreak data in areas with low-income demographics or small, privately owned wastewater treatment plants. The lack of regular testing could result in delays in identifying outbreaks, potentially putting communities at risk, according to researchers. 

The details: The study, published Feb 16, 2024, advocates for a more inclusive strategy to better protect vulnerable populations in future pandemics. 

Samples collected from wastewater sources such as sinks, showers and toilets can offer crucial data for public health officials to help monitor outbreaks. While media reports previously relied on data from healthcare facilities, in recent years the numbers come from wastewater surveillance.

Wastewater tests can be conducted at little or no cost with funding from the CDC National Wastewater Surveillance System or with other local funding, researchers said. 

Despite this, some local wastewater treatment facilities are reluctant to work with public health officials. Researchers point to a lack of funding or worry that pollutants their facility does not treat will be discovered. 

But there’s a solution: Both concerns could easily be addressed, said Ryan Sinclair, an associate professor of environmental microbiology at Loma Linda University School of Public Health and supervising investigator of the study. Prior to testing, public health departments enter into an agreement with the facility detailing exactly what in the water will be processed. 

Not only does wastewater testing provide communities with information about diseases such as COVID-19, influenza and respiratory syncytial virus, but it can also be used to detect dietary indicators, prescription medication and drug use. All of this information can help officials determine where to focus intervention efforts. 

What they’re saying: “Disadvantaged and underserved communities are experiencing what is almost an injustice because they’re simply not getting monitored for disease,” Sinclair said. “And those are sometimes the communities that need it the most.”

Moving forward: Researchers hope that the study will promote an expansion of wastewater treatment coverage to underserved communities. 

A more inclusive strategy and further research to grow the reach of wastewater-based epidemiology can help safeguard the health of all communities, concluded the study.

Editor's note: An earlier version of this story used the word "inequalities" to describe the gap in wastewater testing. It has since been changed to "inequities" to better describe the unfair access to wastewater testing outlined by the study's authors.