Frequently Asked Questions
Do plastics degrade in the environment?
Is it true that (NOAA has found that) 100,000 marine mammals and/or sea turtles die each year due to marine debris/plastics/plastic bags?
Is plastic a large portion of the debris that enters our oceans? How much?
Have there been studies by NOAA on impacts of plastics to marine mammals and fish?
Are all plastics created equal once they are in the environment? Do some cause more damage than others?
Is there a source/reference to see an actual plot of plastic marine debris occurrence?
Is it true that our fish are being poisoned by marine debris? (plastics and pollutants)
1. Do plastics degrade in the environment?
Plastic photo-degrades–breaking down into smaller and smaller pieces due to exposure to solar UV radiation. However, when in water plastic does not get direct sunlight exposure, therefore breakdown happens much more slowly in the aquatic environment. So far as we know based on research to date, plastics do not ever fully "go away," but rather break down into smaller and smaller pieces, sometimes referred to as microplastics.
2. Is it true that 100,000 marine mammals and/or sea turtles die each year due to marine debris/plastics/plastic bags?
Origin of statement:
Wallace, N. 1985. Debris entanglement in the marine environment: A review. Pp. 259-277. In: R.S. Shomura, H.O. Yoshida (eds.) Proceedings of the Workshop on the Fate and Impact of Marine Debris 27-29 November 1984, Honolulu, Hawaii, July 1985. NOAA-TM-NMFS-SWFC-54.
NOTE: This proceedings document was published prior to the implementation of MARPOL Annex V.
"Debris entanglement is estimated to cause 50,000 to 90,000 deaths per year in the northern fur seal. The population in 1983 was dropping on the main rookery in Alaska at about 8% per year. At least 50,000 deaths are thought to be due to entanglement; the other 40,000 deaths possible entanglement or possibly some unknown factor such as disease (Fowler 1983)."*
In Conclusions: "Up to one hundred thousand marine mammals and possibly more die each year. Half or more of the individuals of certain marine reptile species are affected by the plastic litter, and beachcombing land mammals become snarled in nets and die."
*Fowler, 1983 is a background paper for the 26th Annual Meeting of the Standing Scientific Committee of the North Pacific Fur Seal Commission.
Origin of plastic bag statement: We were able to find no information to support this statement. An erroneous statement attributing these figures to plastic bags was published in a 2002 report published by the Australian Government; it was corrected in 2006. See the 2002 report published by Environment Australia entitled, "Plastic Shopping Bags – Analysis of Levies and Environmental Impacts" or click here.
In 2006, Environment Canada recanted the statement "A figure of 100,000 marine animals killed annually has been widely quoted by environmental groups; this was from a study in Newfoundland which estimated the number of animals entrapped by plastic bags in that area from a four-year period from 1981-1984" and replaced it with "A figure of 100,000 marine animals killed annually has been widely quoted by environmental groups; this was from a study in Newfoundland which estimated the number of animals entrapped by plastic debris in that area from a four-year period from 1981-1984."
The original study cited by Environment Canada, and thus, Environment Australia, is:
Piatt, J.F. and D.N. Nettleship. 1987. Incidental catch of marine birds and mammals in fishing nets off Newfoundland, Canada. Marine Pollution Bulletin 18(6B): 344-349.
3. Is plastic a large portion of the debris that enters our oceans? How much?
Because marine debris of all types enter our oceans, plastics of every type can be found, from the PET used to make many plastic bottles, to the polystyrene or "Styrofoam" cups and the nylon line used in fishing nets. Plastic likely makes up a sizeable portion of the marine debris that exists today. Exactly how much plastic debris is out there, or even what percentage plastic debris makes up, is very difficult to know and can vary by location. There is simply so much that we do not see.
4. Have there been studies by NOAA on impacts of plastics to marine mammals and fish?
The NOAA Marine Debris Program and other NOAA offices have supported numerous studies on the impacts of plastics to marine mammals, fish, and their habitats. Many of these studies have dealt with plastic derelict fishing gear (e.g., nylon fishing nets), a debris type that can pose a significant threat to a wide range of marine species and habitats.
5. Are all plastics created equal once they are in the environment? Do some cause more damage than others?
In terms of what we know, derelict fishing gear (DFG) (much of which is made of plastic) has numerous and quite severe impacts not only to living marine resources, but navigation safety as well. Numerous studies have documented the impacts of DFG to wildlife, including entanglement, ghostfishing (continuation of derelict fishing gear to capture marine life), habitat degradation, and even alien species transport. All of these likely having a related economic cost.
6. Is there a source/reference to see an actual plot of plastic marine debris occurrence?
Currently, there is no comprehensive map plotting plastic debris occurrence. Because marine debris moves with winds and currents, sometimes far from its origin, it has become a global problem. If there were a map of plastic debri occurrence, it would most likely include coastal areas worldwide – monitoring and debris accumulation studies and survey results could be used. Of course, the map would only show marine debris that can be seen or that is washing ashore. Studies are now also being done on marine debris that is more difficult to see: benthic (seafloor) marine debris (e.g., Monterey Bay, CA and the Gulf of Mexico), and microplastics and small plastic particles.
An accurate and quantitative marine debris map would be very useful, and through collaborative efforts like the Hawaii Marine Debris Action Plan working group, this can be done on a state or local level as a beginning to fully understanding the occurrences of marine debris.
7. Is it true that our fish are being poisoned by marine debris? (plastics and pollutants)
There have been a number of studies on persistent organic pollutants (POPs) binding to plastic debris in the oceans. One of the leading scientists on the topic is Dr. Richard Thompson (Marine ecologist, University of Plymouth, UK), who along with other experts in this topic area, was invited to an international workshop on the occurrence, effects, and fate of microplastic debris in September of 2008 hosted by the MDP and the University of Washington - Tacoma. You can find additional information, including a proceedings document of this workshop, here.
Recent studies have focused on the uptake potential of organic contaminants from the marine environment to plastic debris.
Plastic debris can transport organic contaminants in the oceans.
Plastics have the potential to adsorb organic contaminants from the marine environment. It is possible, though not proven, that plastics could also desorb these contaminants to biota that ingest plastics.
Plastic debris attracts and accumulates hydrophobic organic toxins such as PCBs (polychlorinated biphenyls) up to 105-106 times ambient seawater concentrations.
Mato, Y., T. Isobe, H. Takada, H. Kanehiro, C. Ohtake, and T. Kaminuma. 2001. Plastic Resin Pellets as a Transport Medium for Toxic Chemicals in the Marine Environment. Environ. Sci. Technol. 35: 318-324.
Research on benthic-feeding invertebrates suggests that toxins may be transferred from plastics, to sediment, to the organism. Further research is needed, taking into consideration the range of contaminant types, types of plastic, and environmental exposure effects.
Teuten, E., S. Rowland, R. Galloway, and R. Thompson. 2007. Potential for Plastics to Transport Hydrophobic Contaminants. Environ. Sci. and Tech. 35: 318-324.