Scientists highlight the danger of consumption of these mollusks and warn about the risks of coastal urbanization and the importance of proper wastewater management.
An international collaboration of scientists led by the University of California Irvine (UCI), in the United States, revealed the presence of bacteria and human waste in oysters that live in the Mergui Archipelago, in Myanmar.
The study will be published in the September issue of the journal Science of the Total Environment, and reports the presence of plastics, kerosene, paint, talc and even milk supplement powders in the animals’ bodies.
The researchers used modern technology, such as DNA sequencing, to analyze contaminants in seawater and in oysters. According to them, 5,459 possible human pathogens belonging to 87 species of bacteria were found.
Scientists also used a method known as infrared spectroscopy to examine the particles of waste in oysters. The 1,225 individually studied particles were divided into groups and, according to the researchers, come from 78 different types of contaminant materials.
“While 48 percent of the microparticles were microplastics – a finding representative across numerous ocean ecosystems – many other particles were not plastic and originated from a variety of human-derived materials that are constituents of fuels, paints and cosmetics,” said Joleah Lamb, assistant professor of ecology and evolutionary biology at UCI and co-author of the research, in a statement. “We were particularly surprised to find three different brands of milk powder formula, which comprised 14 percent of the microdebris contaminants.”
The presence of microorganisms and debris in these animals is detrimental to their health, and of course, poses a threat to humans who consume them.
“It’s important to keep in mind that much of our seafood is imported from overseas, from places that may be contaminated, emphasizing the importance of both adequate testing and improvements to coastal water quality worldwide,” said Raechel Littman, co-author of the study and a postdoctoral scholar in ecology & evolutionary biology at UCI.
The researchers also pointed out that even the indirect consumption of waste (mainly microplastics) can be dangerous. That is, even if people do not eat the contaminated oysters, ingesting other animals that, in turn, fed on the mollusk, can also be dangerous.
“This study has important global implications,” said co-author Douglas Rader. According to him, there is strong evidence that oysters in other parts of the world are also contaminated. “These findings highlight both the risks of coastal urbanization and the importance of adequate wastewater and stormwater management.”