(read related posts on plastics: HERE, HERE and HERE)

Embargoed for release: 19-Aug-2009 18:00 ET

(19-Aug-2009 22:00 GMT)

Contact: Michael Bernstein

m_bernstein@acs.org

202-872-6042

American Chemical Society 

Plastics in oceans decompose, release hazardous chemicals, surprising new study says

Image: A boy in Japan points out Styrofoam debris from the ocean.

WASHINGTON, Aug. 16, 2009 — In the first study to look at what happens over the years to the billions of pounds of plastic waste floating in the world's oceans, scientists are reporting that plastics — reputed to be virtually indestructible — decompose with surprising speed and release potentially toxic substances into the water.

Reporting here today at the 238th National Meeting of the American Chemical Society (ACS), the researchers termed the discovery "surprising." Scientists always believed that plastics in the oceans were unsightly, but a hazard mainly to marine animals that eat or become ensnared in plastic objects.

"Plastics in daily use are generally assumed to be quite stable," said study lead researcher Katsuhiko Saido, Ph.D. "We found that plastic in the ocean actually decomposes as it is exposed to the rain and sun and other environmental conditions, giving rise to yet another source of global contamination that will continue into the future."

He said that polystyrene begins to decompose within one year, releasing components that are detectable in the parts-per-million range. Those chemicals also decompose in the open water and inside marine life. However, the volume of plastics in the ocean is increasing, so that decomposition products remain a potential problem.

Each year as much as 150,000 tons of plastic debris, most notably Styrofoam, wash up on the shores of Japan alone, Saido said. Vast expanses of waste, consisting mainly of plastic, float elsewhere in the oceans. The so-called Great Pacific Garbage Patch between California and Hawaii was twice the size of Texas and mainly plastic waste.

Saido, a chemist with the College of Pharmacy, Nihon University, Chiba, Japan, said his team found that when plastic decomposes it releases potentially toxic bisphenol A (BPA) and PS oligomer into the water, causing additional pollution. Plastics usually do not break down in an animal's body after being eaten. However, the substances released from decomposing plastic are absorbed and could have adverse effects. BPA and PS oligomer are sources of concern because they can disrupt the functioning of hormones in animals and can seriously affect reproductive systems.

Some studies suggest that low-level exposure to BPA released from certain plastic containers and the linings of cans may have adverse health effects.

Saido described a new method to simulate the breakdown of plastic products at low temperatures, such as those found in the oceans. The process involves modeling plastic decomposition at room temperature, removing heat from the plastic and then using a liquid to extract the BPA and PS oligomer. Typically, he said, Styrofoam is crushed into pieces in the ocean and finding these is no problem. But when the study team was able to degrade the plastic, it discovered that three new compounds not found in nature formed. They are styrene monomer (SM), styrene dimer (SD) and styrene trimer (ST). SM is a known carcinogen and SD and ST are suspected in causing cancer. BPA ands PS oligomer are not found naturally and, therefore, must have been created through the decomposition of the plastic, he said. Trimer yields SM and SD when it decomposes from heat, so trimer also threatens living creatures.

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Funding for Saido's research came from Nihon University.

The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With more than 154,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

For news media only:

The poster on this research, ENVR 168, will be presented at 6:00 p.m., Wednesday, August 19 at the Walter E. Washington Convention Center, Hall D, during the symposium, "General Papers."

Katsuhiko Saido, Ph.D., is with the College of Pharmacy, Nihon University, Chiba, Japan

ALL PAPERS ARE EMBARGOED UNTIL DATE AND TIME OF PRESENTATION, UNLESS OTHERWISE NOTED

The poster on this research, ENVR 168, will be presented at 6:00 PM, Wednesday, August 19, 2009, at the Walter E. Washington Convention Center, Hall D, during the symposium, "General Papers."

ENVR 168 
New contamination derived from marine debris plastics 
Program Selection: Division of Environmental Chemistry 
Topic Selection: General Papers 
Lead Presenter's Email: saido.katsuhiko@nihon-u.ac.jp

Katsuhiko Saido1, saido.katsuhiko@nihon-u.ac.jp, Tadashi Itagaki1, Hideto Sato2, Yoichi Kodera3, Osamu Abe4, Naoto Ogawa5, Seon-Yong Chung6, and Kiyotaka Miyashita7. (1) College of Pharmacy, Nihon University, Chiba, Japan, (2) College of Science & Technology, Nihon University, Japan, (3) National Institute of Advanced Industrial Science and Technology, Japan, (4) Seikai National Fisheries Research Institute, Fisheries Research Agency, Japan, (5) Faculty of Agriculture, Shizuoka University, Japan, (6) College of Engineering, Chonnam National University, (7) National Institute for Agro-Environmental Sciences, Japan

Abstract

There is no report on polymer degradation in the environment. People know marine debris plastics become small particles physically. Styrofoam (foamed polystyrene) is crashed into pieces in the ocean. Low molecular weight compounds like styrene trimer and styrene dimer are not generated naturally. There are no researchers to study how and why those compounds were found in nature. A suspected source is polystyrene scattered in nature. This study would be a first link between the existence of plastics debris in the ocean and the chemical detection of low molecular weight fragments from plastic. We invented a new method to simulate plastic degradation at low temperature range and quantitatively evaluate the degradation. The quantities of plastics which have washed up onto the Japan coast were used as basis for simulating the generation rates of styrene trimer and the results for which were found quite consistent with those from field analysis.

Researcher Provided Non-Technical Summary

Briefly explain in lay language what you have done, why it is significant and what are its implications (particularly to the general public) To date, no studies have been conducted on plastic decomposition at low temperature in the environment owing to the mistaken conception that plastic does not decompose.

The present study was conducted to clarify that drift plastic does indeed decompose to give rise to hazardous chemicals in the ocean.

Due to human carelessness, plastics find their way into rivers and then into the sea.

Moore noted large bulky plastic to be crushed into small aggregates, much in the same manner as is aged PS-foam and some microorganisms ingest these PS fragments.

At present, macroscopic pollution can be observed visually as due to plastic waste in the Ocean. We thus established a method to study plastic decomposition at room temperature, which involves water-soluble heat transfer and use of an extractant.

Polystyrene (PS) was found to decompose at 30°C to produce the styrene (styrene monomer, SM), 2,4-diphenyl-1-butene (styrene dimmer, SD), 2,4,6-triphenyl-1-hexene (styrene trimer, ST) , which was called PS origomer.

The 5g of sea sand and 5L of sea water was extracted by dichloromethane from Malaysia that reaches the West Coast of North America, along the northern Pacific Ocean, were thus examined by GC/MS. All samples were found to contain significant amounts of the PS oligomer. It was existed for 0.01 ppm in the little place, but in the abounding place, there was 150 ppm.

Analyses of noxious chemicals have been extensively conducted on the rivers and oceans of the world and the results clearly demonstrate the presence of nonylphenol, phthalic acid esters (PAE), and bisphenol A (BPA). The sources and elution pathways of these chemicals should be clarified in greater detail. The generation of BPA from epoxy resin (EPX) has clearly been shown a possibility. The cause for BPA generation is difficult to specify since this compound, like PAE, is used as a plasticizer of polyethylene or a raw material of polycarbonate (PC) and EPX. Compounds such as SM, SD , ST may be present in the environment as pollutants. But the PS oligomer does not occur naturally in the ocean.

To study plastic decomposition, polyethylene glycol (PEG) was used as a heating medium or extractant. The presence of PS oligomer generated by thermal decomposition at low temperature from PS using PEG, could be detected at low ppm. PS oligomer concentrations were found less than the ppm level for a liquid/liquid distribution system in which water was used to remove the heating medium.

Velocity constants in the temperature range, 30°C to 250°C, were computed based on generated ST. From Arrhenius plots of the velocity constants, activation energy (ΔE), was determined 42.0 kJ/mol. Kinetic data on PS decomposition in daily life situations or the environment are not available at present.

Each year, as much as 150,000 tons of plastic debris washes up onto the shores of Japan. We consider the sources of contamination of these beaches to come by way of the ocean waste, as suggested by Moore.

Based on kinetic parameters and quantities of drift PS found on the coasts of Japan, the generation of ST from drift PS was computed by simulation. The calculated value of 0.83 ppm was found basically the same as ST in samples taken from beaches in Japan. The results were found fully consistent with data from field analysis.

Considers that plastic may be crashed into small lumps and too, the present study clearly shows the generation of monomer from decomposed plastics such as BPA or PS oligomer to cause serious ocean pollution.

Plastics are not metabolized, subsequent to ingestion, since they are polymers. Low molecular weight compounds such as PS oligomer or BPA from plastic decomposition are toxic and can be metabolized. These compounds were shown adverse effects on the ecosystem and subsequent organism generations. Plastic ingestion and entanglement as well as the generation of new contamination compounds from plastic decomposition in the ocean and environment are clearly indicated by the findings of the present study.

Plastics in daily use are generally assumed quite stable. But plastic waste in the Ocean or nature is not stable on exposure to the sun, rain and various other conditions.

This study clearly shown new micro pollution by compounds generated by plastic decomposition to be taking place out of sight in the Ocean.

Thus, marine debris plastics in the Ocean will certainly give rise to new sources of global contaminations that will persist long into the future.

How new is this work and how does it differ from that of others who may be doing similar research?

We were developed the plastic low-temperature decomposition, the following fact was clarified;

1. •The plastic was decomposed at the natural environment or living life, and being a contributor of the marine pollution.
   
   

2. •Type and quantity of the noxious compounds which generated in temperature treatment of plastic utility. For example, bisphenol A which generates from the baby milk bottle or phthalic acid ester which generates from polyethyreneterephthalate (PET bottle). The food container or medical used supply made by PS generates PS oligomer in storage.
   
   

3. •By decomposing EPX utilized as ship bottom paint, BPA is being generated.
   
   

4. •Of course, the generation rate of compounds which will arise from the marine debris plastic refuse in the ocean in the future can be simulated.
   

Available to talk with news media: Yes

Special Instructions/feedback: We suggest that we should pay attention to polymer itself as a new pollution source.

Katsuhiko Saido 
College of Pharmacy 
Nihon University 
Chiba, 
Japan 
Phone Number: 81-33691-5579 
Email: saido.katsuhiko@nihon-u.ac.jp