Marine Plastic Pollution and Seafood Safety
Among U.S. agencies, the EPA is delving into the science to answer key questions around marine plastics and human health. In addition to convening the April meeting and producing a forthcoming white paper on its findings, the agency collaborates with and directly funds researchers in the field. Staff from the EPA and the U.S. Fish and Wildlife Service are currently developing a risk assessment to quantify the chemical loading effects of plastic litter on marine life. And by 2016, the EPA plans to launch a similar long-term inquiry into effects on human health, including an evaluation of outcomes such as fetal formation, says Cook.
Any study of human health effects will likely depend on the cooperation of a subject community where many types of seafood are heavily consumed. "We have to have a potential threat and a potential receptor present in a location and a community who is willing to work with us on it," Cook says. "There are a lot of repercussions to a community to find out that their food supply is potentially contaminated." The agency also expects to award a new four-year marine debris research contract designed to gain a better understanding of the movement, distribution, and quantity of plastics off the remote northwestern Hawaiian islands.
Researcher Chelsea Rochman of the University of California, Davis, collaborated with Cook and the EPA on a 2014 study that showed an association between concentrations of certain PBDEs in fish and levels of plastic debris accumulation in the South Atlantic Ocean. However, no such association was seen for concentrations of BPA, alkylphenols, alkylphenol ethoxylates, or PCBs in fish.
Rochman is also working on a separate study funded through NOAA's Marine Debris program. The aim of the NOAA study is to demonstrate for the first time the biomagnification in marine organisms of chemicals introduced via plastics. This highly controlled laboratory experiment involves feeding contaminated plastic pellets to mussels, feeding the mussels to sturgeon, and then testing levels of PCBs within the bodies of the sturgeon. Results are still awaiting analysis and publication.
One of Rochman's collaborators on the project, researcher Mark Browne of the University of California, Santa Barbara, recently received a grant from the Australian Research Council for a three-year program addressing another question in the field: Beyond leaching chemicals, what do plastic particles do when they enter an organism? Browne showed in 2008 that microplastics sized 3.0 and 9.6 μm in diameter can travel beyond a mussel's gut and into its circulatory system and hemocytes (immune cells), where they may remain for a relatively long period of time—in his study, more than 48 days. A 2012 study by another group showed that microplastics taken up by mussels resulted in a strong inflammatory response.
The implications of these findings for humans that consume organisms containing microplastics are not yet understood. Browne says his team is currently working to develop a method to test human tissues for microplastics. "We think that's going to be a big turning point," he says.
Ecotoxicologist Heather Leslie of VU University Amsterdam is among those concerned about the particle toxicity of microplastics themselves. Even without chemical hitchhikers, she says, plastic particles can induce immunotoxicological responses, alter gene expression, and cause cell death, among other adverse effects. "Exposed organisms then deal not only with chemical stress through multiple exposure routes, but also particle stress," she explains. Leslie is currently studying the distribution and environmental fate of microplastics from cosmetics and other sources and potential toxicological effects on marine organisms in Europe's multinational CleanSea Project.
A large body of literature about the mobility of nanoparticles offers a glimpse at how nano-size plastic particles may behave in the human body, Leslie says. "They can pass through the placenta and the blood–brain barrier and can be taken up in the gastrointestinal tract and lungs, potential sites where harm can occur," she says. "There is a lot to learn about microplastics from the fields of particle toxicity and drug delivery technologies that apply to polymeric nanoparticles."
(Enlarge Image)
© Michael Northrop, Joseph Caspermeyer, and Rolf Halden/Biodesign Institute at Arizona State University
(Enlarge Image)
This rainbow runner had consumed 17 plastic fragments. Marine plastic pollution plays an unknown role in human exposures to toxic chemicals. Regardless of what that role may turn out to be, sources for this story believe we have options for realizing the benefits of plastics without the hazards of marine pollution. © 5 Gyres Institute
In another example of ongoing research, Robert Hale, a professor at the Virginia Institute of Marine Science, has funding from both the EPA and NOAA to investigate how particle size, weathering, biofouling (the accumulation of living organisms on wet surfaces), and water characteristics including temperature, salinity, and organic carbon content influence both the sorption of organic contaminants to and the release of various additives from different types of microplastics. "You look at these simple parameters together, and it can get very complex," Hale says. The EPA is particularly interested in evaluating the release of flame retardant additives from plastics, he notes, and may pursue development of a protocol to be used by manufacturers to provide data on chemical migration.
Human Health Questions
Among U.S. agencies, the EPA is delving into the science to answer key questions around marine plastics and human health. In addition to convening the April meeting and producing a forthcoming white paper on its findings, the agency collaborates with and directly funds researchers in the field. Staff from the EPA and the U.S. Fish and Wildlife Service are currently developing a risk assessment to quantify the chemical loading effects of plastic litter on marine life. And by 2016, the EPA plans to launch a similar long-term inquiry into effects on human health, including an evaluation of outcomes such as fetal formation, says Cook.
Any study of human health effects will likely depend on the cooperation of a subject community where many types of seafood are heavily consumed. "We have to have a potential threat and a potential receptor present in a location and a community who is willing to work with us on it," Cook says. "There are a lot of repercussions to a community to find out that their food supply is potentially contaminated." The agency also expects to award a new four-year marine debris research contract designed to gain a better understanding of the movement, distribution, and quantity of plastics off the remote northwestern Hawaiian islands.
Researcher Chelsea Rochman of the University of California, Davis, collaborated with Cook and the EPA on a 2014 study that showed an association between concentrations of certain PBDEs in fish and levels of plastic debris accumulation in the South Atlantic Ocean. However, no such association was seen for concentrations of BPA, alkylphenols, alkylphenol ethoxylates, or PCBs in fish.
Rochman is also working on a separate study funded through NOAA's Marine Debris program. The aim of the NOAA study is to demonstrate for the first time the biomagnification in marine organisms of chemicals introduced via plastics. This highly controlled laboratory experiment involves feeding contaminated plastic pellets to mussels, feeding the mussels to sturgeon, and then testing levels of PCBs within the bodies of the sturgeon. Results are still awaiting analysis and publication.
One of Rochman's collaborators on the project, researcher Mark Browne of the University of California, Santa Barbara, recently received a grant from the Australian Research Council for a three-year program addressing another question in the field: Beyond leaching chemicals, what do plastic particles do when they enter an organism? Browne showed in 2008 that microplastics sized 3.0 and 9.6 μm in diameter can travel beyond a mussel's gut and into its circulatory system and hemocytes (immune cells), where they may remain for a relatively long period of time—in his study, more than 48 days. A 2012 study by another group showed that microplastics taken up by mussels resulted in a strong inflammatory response.
The implications of these findings for humans that consume organisms containing microplastics are not yet understood. Browne says his team is currently working to develop a method to test human tissues for microplastics. "We think that's going to be a big turning point," he says.
Ecotoxicologist Heather Leslie of VU University Amsterdam is among those concerned about the particle toxicity of microplastics themselves. Even without chemical hitchhikers, she says, plastic particles can induce immunotoxicological responses, alter gene expression, and cause cell death, among other adverse effects. "Exposed organisms then deal not only with chemical stress through multiple exposure routes, but also particle stress," she explains. Leslie is currently studying the distribution and environmental fate of microplastics from cosmetics and other sources and potential toxicological effects on marine organisms in Europe's multinational CleanSea Project.
A large body of literature about the mobility of nanoparticles offers a glimpse at how nano-size plastic particles may behave in the human body, Leslie says. "They can pass through the placenta and the blood–brain barrier and can be taken up in the gastrointestinal tract and lungs, potential sites where harm can occur," she says. "There is a lot to learn about microplastics from the fields of particle toxicity and drug delivery technologies that apply to polymeric nanoparticles."
(Enlarge Image)
© Michael Northrop, Joseph Caspermeyer, and Rolf Halden/Biodesign Institute at Arizona State University
(Enlarge Image)
This rainbow runner had consumed 17 plastic fragments. Marine plastic pollution plays an unknown role in human exposures to toxic chemicals. Regardless of what that role may turn out to be, sources for this story believe we have options for realizing the benefits of plastics without the hazards of marine pollution. © 5 Gyres Institute
In another example of ongoing research, Robert Hale, a professor at the Virginia Institute of Marine Science, has funding from both the EPA and NOAA to investigate how particle size, weathering, biofouling (the accumulation of living organisms on wet surfaces), and water characteristics including temperature, salinity, and organic carbon content influence both the sorption of organic contaminants to and the release of various additives from different types of microplastics. "You look at these simple parameters together, and it can get very complex," Hale says. The EPA is particularly interested in evaluating the release of flame retardant additives from plastics, he notes, and may pursue development of a protocol to be used by manufacturers to provide data on chemical migration.