A study conducted by researchers at the Federal University of São Paulo (UNIFESP) found high levels of contamination on Perequê Beach in Guarujá, a city on the coast of São Paulo state, Brazil, with plastic litter and cigarette butts predominating. The detailed survey, one of only a few of the kind conducted worldwide, will contribute to the implementation of public policies to mitigate the problem.
An article reporting the results is published in Marine Pollution Bulletin.
The project was a partnership between UNIFESP's Marine Research Institute (IMAR) in Santos and the City of Guarujá's Department of the Environment. It set out to understand the sources of contamination of the beach, which is part of an Environmental Protection Area (Área de Proteção Ambiental) called APA Marinha do Litoral Centro, is heavily used by tourists, and is home to one of the largest and oldest communities of fishers in the Baixada Santista metropolitan area, which comprises nine municipalities including Guarujá and Santos.
On the beach, the researchers collected all the litter and waste from ten sites of 100 square meters each, every day in summer and winter including Saturdays and Sundays. "The analysis showed that litter on this beach results mainly from tourism. It's worst in summer, suggesting that visitors are the principal source, although residents may be responsible for some of it," said Ítalo Braga de Castro , last author of the article and a professor at IMAR-UNIFESP.
Levels of contamination by plastics and cigarette butts were considered high according to an internationally recognized beach litter index. In 12 studies conducted worldwide using the same method, Perequê ranked as the dirtiest beach. "Cigarette butts are the type of waste most frequently found on beaches in studies conducted not just here but worldwide. This is alarming because they contain many toxic substances - over 7,000 in some cases. At least 150 are dangerous to human health and biota. They're known as 'chemical bombs'," said Victor Vasques Ribeiro , first author of the article and a PhD candidate at IMAR-UNIFESP with a scholarship from FAPESP .
From plastic to concrete
To arrive at the results, the group picked ten sites on Perequê Beach - five each in the wet and dry parts, delimiting in each site an area of 100 square meters from which all waste with more than 3 centimeters was removed and stored. Some 20 volunteers collected the material with the scientists, in the winter and summer of 2022 and 2023, at weekends and on weekdays.
The waste was later sorted into plastic, metal, glass, paper, cardboard, clothes, textiles and processed wood (used in furniture and buildings). Owing to high incidence and potential impact, cigarette butts were given a separate category. Material that did not fit into any of the categories was considered "Other".
The group collected 2,579 items in an area of 4,000 sq. m., ranking Perequê Beach as "dirty" on the Clean-Coast Index (CCI) scale. The CCI was published in 2007 and has been used in many comparable studies.
The volume of litter increased in summer compared with winter, when it was considered "moderate". This difference was expected in view of the increase in numbers of visitors during the summer tourist season. The results were similar to those found in other studies for Brazilian and Latin American beaches generally.
In both seasons, the volume of waste was larger in the dry part of the beach than in the part that receives the impact of waves. This was also foreseeable since lighter material is normally blown to the dry part by the wind and people use the dry part for picnics and to smoke, throwing away packaging and cigarette butts there. On the other hand, heavier items such as ceramic and concrete shards were more frequently found in the wet part of the beach, given that they could not be moved by wind or tides.
A total of 603 cigarette butts were collected. According to a scientifically recognized estimate of the contaminants that can leak from cigarette butts, affecting humans and other living beings, this amounted to "severe pollution", the highest level found in the 12 studies of beaches and urban areas conducted to date on the basis of this method.
Another beach with almost as high a level of pollution is also in a marine protected area (MPA) around Saint Martin Island in Bangladesh. Comparable, albeit lower, levels were found in Colombia and Iran as well as urban areas in the Brazilian cities of Santos (São Paulo state) and Niterói (Rio de Janeiro state).
"We didn't find a significant difference between the amount of litter on weekdays and weekends, probably because the city sweeps the beach with a tractor on Fridays. But this operation misses the cigarette butts because they're too small to be caught by the chain harrow," Ribeiro said.
Another measure of the amount of waste, in this case comprising material that can injure bathers and fishers, such as ceramics, concrete and metal, as well as potentially infectious medical objects and personal hygiene items, was class 3, meaning "a considerable amount of hazardous litter is seen".
The levels are similar to those found in coastal environments in Chile, Colombia, Morocco and Nigeria, but higher than in most countries surveyed on the same basis, such as Bangladesh, China, Italy and Qatar, among others.
"The results provide a very clear picture of the situation and the need for intervention. Education to raise awareness, installation of ash trays and litter bins, fines, even banning smoking on the beach, as has been done in Barcelona, Spain, are some of the options available to lawmakers and city managers to mitigate the problem," Castro said.
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.
