Comment »Posted on Friday 21 August 2009 at 2:11 pm by Jacob Aron
In Chemistry, Climate Change & Environment

I’m still surrounded by cardboard boxes and half-built Ikea furniture, with a dodgy wireless connection that isn’t mine, but fellow sci-commer Mia has offered to step in for today:

It has been a few weeks since the second of two research ships of ‘Project Kaisei’ set of from San Francisco bound for the huge “island” of rubbish in the Pacific Ocean. An accidental-island build by swirling currents pushing the waste together in an area supposedly twice State of Texas. Now, a separate research group have published the results of new study looking at just what happens to plastic waste as it floats in the sea.

It has been well documented that plastics pose one of the biggest direct threat to marine animals – when they eat or get caught up in them. Researchers from Nihon University now report that plastics are not as ‘indestructible’ as once thought. With a surprisingly speedy decomposition these versatile convenience materials are resulting in a double whammy of harm as they release toxic substances into the water.

“Plastics in daily use are generally assumed to be quite stable,” said study lead researcher Dr Katsuhiko Saido, “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.”

Dr Saido and his team found that when plastic decomposes it releases potentially toxic bisphenol A (BPA) and PS oligomer (both not normally found naturally) into the water, causing additional pollution. They also discovered that three new compounds not found in nature formed. These are styrene monomer (a known carcinogen) and styrene dimer and trimer- both also suspected to be. Although plastics don’t usually break down in an animal’s body after being eaten, the substances released from decomposing plastic are absorbed and could cause harm. BPA and PS oligomer are of concern because they can disrupt the functioning of hormones in animals and can seriously affect reproductive systems.

The timeframe for this process can be surprisingly short, polystyrene begins to decompose within a year. Cancers, hormonal abnormalities and reproductive problems are just the tip of our knowledge about the long term adverse effects of plastic, and yet we still can’t get enough of the stuff.

Mia Kukathasan studied biology at King’s College, London, and has taught science in secondary schools. She has written bits for Null Hypothesis and in the book Defining Moments In Science and the occasional student publication. Mia also dresses up in gorilla suits in the name taking science to music festivals, as a co-organiser of Guerilla Science. Science aside, she has a show On ICradio based on Free Music.

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