Almost half of the world’s aquatic environments are severely contaminated by waste
A study by researchers at the Federal University of São Paulo synthesized data from 6,049 contamination records on all continents over the last decade.
“Dirty” or “extremely dirty”: these are the classifications of 46% of the world’s aquatic environments. This conclusion comes from a study that compiled and systematized data from 6,049 records of waste contamination in aquatic environments on all continents over the last decade.
The study, coordinated by researcher Ítalo Braga de Castro and led by doctoral student Victor Vasques Ribeiro from the Institute of Marine Science at the Federal University of São Paulo (IMar-UNIFESP) in Brazil, analyzed articles published between 2013 and 2023. The researchers calculated the cleanliness level of rivers, estuaries, beaches, and mangroves based on the Clean-Coast Index (CCI), an international metric that quantifies the density of solid waste in coastal environments. The results were published in the Journal of Hazardous Materials.
The study revealed an uneven distribution of monitoring efforts. Here, Brazil stands out, leading the number of records in the period. “But that doesn’t guarantee that the monitored environments are in good condition and clean. The results show that about 30% of Brazilian coastal environments were considered dirty or extremely dirty according to the CCI scale,” Castro says.
One of the most critical contamination cases is in the mangroves of Santos, Brazil, which are among the most contaminated spots on the planet.
The team’s global summary showed surprising homogeneity in waste composition, regardless of cultural, economic, or geographical differences. Plastics and cigarette butts account for nearly 80% of the waste found worldwide. “Places that are completely free of waste are extremely rare,” the researcher comments.
Plastics account for 68% of the recorded items. They dominate because they persist in the environment, fragment into micro- and nanoplastics, and are transported by ocean currents over long distances. Cigarette butts account for 11% of the waste and release more than 150 toxic substances that can harm aquatic organisms.
The study confirmed the positive role played by environmental protection areas with quantitative data. “We analyzed 445 protected areas in 52 countries. The conclusion is unequivocal: protection reduces contamination by up to seven times. About half of the protected areas investigated were classified as ‘clean’ or ‘very clean.’ Even so, protection is no guarantee of immunity from increasing human pressure. About 31% of protected areas were classified as ‘dirty’ or ‘extremely dirty,’ showing that they aren’t effectively immune to contamination by litter in the sea,” says Danilo Freitas Rangel, a master’s student at IMar-UNIFESP who participated in the research team.
One more sophisticated result of the work is the “edge effect” observed at the boundaries of conservation units. The team calculated the distance from each sampling point to the boundaries of the protected areas and identified a pattern. Waste accumulates mainly at the edges, which highlights the direct influence of surrounding human activities. “This effect is reinforced by external pressures such as tourism, nearby urbanization, and waste transport by rivers and ocean currents. The vulnerability of the edges suggests the need for territorial buffer policies, integrated management, and enforcement beyond the formal boundaries of conservation units,” Castro emphasizes (read more at agencia.fapesp.br/56473).
The study also broke new ground by cross-referencing contamination data with global socioeconomic indicators. The researchers used the Global Gridded Relative Deprivation Index (GRDI) to estimate development levels on a square-kilometer scale. “We observed a nonlinear pattern: in unprotected areas, contamination increases in the early stages of economic development but begins to decline when the country reaches a certain level of infrastructure and environmental governance. In protected areas, however, development tends to increase contamination – a sign that investments in management and enforcement aren’t yet keeping pace with economic activity,” says Leonardo Lopes Costa, one of the authors of the study.
Tackling waste contamination, especially plastic contamination, requires integrated actions throughout the production chain – from reducing manufacturing to implementing efficient collection and reuse systems to establishing multilateral agreements that prevent cross-border waste movements. Without structural changes in global waste governance, the crisis will only worsen. In this context, one of the most relevant aspects of the study is its direct usefulness in ongoing international processes. “The results offer an unprecedented scientific basis to support public policies and negotiations, such as the Global Plastic Treaty and the Kunming-Montreal Global Biodiversity Framework,” Castro argues.
FAPESP supported the study through a Regular Research Grant awarded to Castro, a postdoctoral fellowship awarded to Costa, and a doctoral scholarship awarded to Ribeiro.
About São Paulo Research Foundation (FAPESP)
The São Paulo Research Foundation (FAPESP) is a public institution with the mission of supporting scientific research in all fields of knowledge by awarding scholarships, fellowships and grants to investigators linked with higher education and research institutions in the State of São Paulo, Brazil. FAPESP is aware that the very best research can only be done by working with the best researchers internationally. Therefore, it has established partnerships with funding agencies, higher education, private companies, and research organizations in other countries known for the quality of their research and has been encouraging scientists funded by its grants to further develop their international collaboration. You can learn more about FAPESP at www.fapesp.br/en and visit FAPESP news agency at www.agencia.fapesp.br/en to keep updated with the latest scientific breakthroughs FAPESP helps achieve through its many programs, awards and research centers. You may also subscribe to FAPESP news agency at http://agencia.fapesp.br/subscribe.
Journal
Journal of Hazardous Materials
Article Title
Influence of protected areas and socioeconomic development on litter contamination: A global analysis
UMD team finds E. coli, other pathogens in Potomac River after sewage spill
Researchers find extremely high levels of disease-causing bacteria including MRSA, an antibiotic-resistant strain, raising public health concerns
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UMD College Park Water Emergency Team collects water samples from the Potomac River after major sewage spill.
view moreCredit: UMD
COLLEGE PARK, Md. – Following one of the largest sewage spills in U.S. history, University of Maryland researchers have detected high levels of fecal-related bacteria and disease-causing pathogens in the Potomac River, raising urgent public health concerns and underscoring the risks posed by aging sewer infrastructure.
Water sample results collected at the site by researchers show high levels of E. coli are present along with Staphylococcus aureus (the bacteria that causes Staph infections). An antibiotic-resistant strain of S. aureus, MRSA, was also identified at the site of the sewage overflow.
“People coming into contact with the impacted water or land are at risk of becoming infected with these bacteria, which can lead to serious health conditions,” said Dr. Rachel Rosenberg Goldstein, microbiologist and assistant professor at UMD’s Department of Global, Environmental, and Occupational Health. “Although most people are not swimming in the frozen river in February, bacteria can survive in freezing temperatures and become active again when temperatures rise.”
Results include:
E. coli bacteria – on Jan. 21 water samples from where sewage entered the Potomac were over 10,000 times above EPA recreational water quality standards. On Jan. 28 samples at the site were lower, but still over 2,500 times above water quality standards. At a site over 10 miles downstream from the sewage overflow on Jan. 28, E. coli were 1.5 times above the standard.
Staphylococcus aureus – on Jan. 21 and 28, the pathogen was detected at the site where sewage entered the Potomac and at a site nine miles away. Of the sites sampled, 33% were positive for S. aureus, higher than found in other surface waters containing this bacteria. An antibiotic-resistant strain of S. aureus, MRSA, was also identified at the site of the sewage overflow.
Out of an abundance of caution, people near the spill site in Maryland, Washington, D.C. and downstream should avoid contact with impacted river water and land until E. coli levels meet water quality standards again, says Goldstein. For people who come into contact with impacted water or soil, she recommends washing skin with soap and water or an alcohol-based sanitizer and laundering clothes with detergent at the warmest temperature and machine dry.
The team’s testing began after hundreds of millions of gallons of sewage gushed from a broken pipe into the Potomac River on Jan. 19. Goldstein’s Water Quality, Outreach and Wellness Lab (WOW) went directly to the source and other sites downriver to test the water for fecal-related bacteria and pathogens shortly afterward. The team returned one week later, working with members of the Potomac Riverkeeper Network (PRKN), to take more samples. The results analyzed by the WOW Lab point to major public health concerns and highlight the risks of crumbling sewer infrastructure.
Up to 75,000 sewage overflows happen every year in the United States, according to UMD’s Water Emergency Team (WET), exposing residents to raw sewage, waterborne pathogens and possibly antibiotic-resistant bacteria. The effects are serious, including illnesses such as bacterial infections that can cause serious illness and death. The overflows can also raise feelings of anxiety.
Goldstein and Dr. Marccus D. Hendricks, associate professor of Urban Studies and (Environmental) Planning at UMD, co-lead the WET project, a UMD Grand Challenges awardee and joint venture between the WOW Lab and the Stormwater Infrastructure Resilience and Justice (SIRJ) Lab. WET was developed as a community-driven rapid-response to sewer overflows and backups in underserved African American communities in Baltimore and the surrounding region.
WET’s earlier research showed that marginalized urban communities are often most vulnerable to sewage overflows, and along with the physical effects, these overflows can contribute to stigma and feelings of disenfranchisement in the communities.
Studies by Hendricks’ SIRJ Lab in Washington, D.C. shows that above-ground development in the city has outpaced stormwater and sewer infrastructure development, likely straining the capacity of already outdated systems.
“Investment, maintenance and rehabilitation of drainage and other water resources infrastructure have been slow and the effects of this are clear in this Potomac sewage spill,” Hendricks said. “National reporting has consistently shown over time that water resources infrastructure, such as stormwater and sewer systems, are underfunded compared to other essential systems like transportation. And then you have incidents like this.”
Despite bipartisan efforts to invest and update infrastructure, such as the 2021 Bipartisan Infrastructure Law and provisions in the 2022 Inflation Reduction Act, Hendricks says it is likely that incidents similar to the Potomac spill will continue to happen at various scales due to underfunding and the enormity of the job.
“This issue isn’t going away – solving the recent Potomac spill is not a simple one-time fix. We need significant and ongoing investment in system upgrades and maintenance,” said Hendricks.
The WOW Lab team and PRKN, a non-profit working to protect the right to clean water in the Potomac and Shenandoah watersheds, worked together to increase the number and sites of water samples tested. They continue to take water and soil samples in the area. The WET project regularly works directly with community organizations and neighborhood associations, with a commitment to sharing lab research findings with affected communities and local policymakers.
The WET project, led by the UMD School of Public Health and School of Architecture, Planning, & Preservation, is one of 16 UMD Grand Challenges Team Grants that provide three years of funding to research teams seeking solutions to the grand challenges of our time.
To request an interview with Dr. Goldstein, please contact sph-comm@umd.edu. To request an interview with Dr. Hendricks, please contact mapp-communicate@umd.edu.
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