Hard plastics decompose in oceans, releasing endocrine disruptor BPA

March 23, 2010
Organisms live off of the decomposing epoxy and polyurethane plastic paint used to seal the hull of this ship. Credit: Katsuhiko Saido

Scientists today reported widespread global contamination of sea sand and sea water with the endocrine disruptor bisphenol A (BPA) and said that the BPA probably originated from a surprising source: Hard plastic trash discarded in the oceans and the epoxy plastic paint used to seal the hulls of ships.

"We were quite surprised to find that polycarbonate plastic biodegrades in the environment," said Katsuhiko Saido, Ph.D. He reported on the discovery today at the 239th National Meeting of the American Chemical Society, being held here.

Saido and Hideto Sato, Ph.D., and colleagues are with Nihon University, Chiba, Japan. "Polycarbonates are very hard plastics, so hard they are used to make screwdriver handles, shatter-proof eyeglass lenses, and other very durable products. This finding challenges the wide public belief that hard plastics remain unchanged in the environment for decades or centuries. Biodegradation, of course, releases to the environment."

The team analyzed sand and seawater from more than 200 sites in 20 countries, mainly in Southeast Asia and North America. All contained what Saido described as a "significant" amount of BPA, ranging from 0.01 parts per million (ppm) to 50 ppm. They concluded that polycarbonates and coatings and paints were the main source.

In research reported at the ACS’s August 2009 National Meeting, Saido and colleagues first busted the myth of the everlasting quality of plastics. They revealed that light, white-foamed plastic decomposed rapidly at temperatures commonly found in the oceans. In decomposing, that plastic releases potentially toxic substances. In the new report, Saido’s group now has added hard plastics and hard epoxy resins -- to the plastics that decompose under conditions commonly found in the oceans. Millions of gallons of epoxy resins are used each year to seal the hulls of ships, protecting them from rust and fouling with barnacles and other deposits.

“When epoxy resin breaks down, it releases BPA, a typical endocrine disruptor,” Saido explained. “This new finding clearly demonstrates the instability of epoxy, and shows that BPA emissions from epoxy do reach the ocean. Recent studies have shown that molluscs, crustaceans and amphibians could be affected by BPA, even in low concentrations.”

He said that waste plastics are finding their way into the environment through littering, and also may be carried by water into the oceans, spreading this pollution widely. Each year as much as 150,000 tons of plastic debris 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. Plastics are, in fact, the main source of garbage in marine debris, according to Saido. “This process is expedited by the low temperatures at which plastic degradation can occur, temperatures present in oceans,” he added.

"Marine debris plastic in the ocean will certainly constitute a new global contamination for long into the future," Saido predicted

Explore further: Plastic that degrades in seawater could be boon for cruise industry and others

Related Stories

Plastics component affects intestine: study

December 14, 2009

The chemical Bisphenol A used in plastic containers and drinks cans has been shown for the first time to affect the functioning of the intestines, according to a French study published Monday.

Recommended for you

Moonlighting molecules: Finding new uses for old enzymes

November 27, 2015

A collaboration between the University of Cambridge and MedImmune, the global biologics research and development arm of AstraZeneca, has led researchers to identify a potentially significant new application for a well-known ...

A new form of real gold, almost as light as air

November 25, 2015

Researchers at ETH Zurich have created a new type of foam made of real gold. It is the lightest form ever produced of the precious metal: a thousand times lighter than its conventional form and yet it is nearly impossible ...

Getting under the skin of a medieval mystery

November 23, 2015

A simple PVC eraser has helped an international team of scientists led by bioarchaeologists at the University of York to resolve the mystery surrounding the tissue-thin parchment used by medieval scribes to produce the first ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Mar 24, 2010
the article quotes 50 ppm of BPA - what is considered the safe limit by the US FDA? - is this limit contested?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.