Tuesday, August 24, 2010

Plastics Potpouri

Our Oceanic Garbage Patch 
We have all heard of the Great Garbage Patches floating in the oceans.  One question has been why the patches are not increasing over 20 years with increasing plastic production and trash dumping.  This report in Live Science suggests that one reason may be that the plastic pieces are breaking down to particles too small to be retrieved in their nets.  While we may envision a huge floating island of bottles and bags, the area apparently looks normal to the naked eye.  The nets pick up fragments as small as 0.3 millimeters (think a period in this paragraph).  Fragments are sorted and counted by students during the Sea Education Association's SEA Semester annual voyages.
"The term "garbage patch" does not necessarily mean a visible island of trash floating on the waves, researchers said. Only 62 percent of net tows by ships have contained detectable amounts of plastic.
"What we're collecting are really small fragments of plastic from larger consumer items," Lavender Law explained. "If you're on the deck of a ship, you normally can't even see the plastic pieces."
Each half-hour net tow typically turned up just 20 plastic pieces equivalent to about 0.3 grams in all. By comparison, a U.S. nickel weighs 5 grams."
The tiny fragments have bacteria living on them which are not normally found at the oceans surface.  Do the microbes degrade and eventually dissolve the plastic, use it as food, or just a place to attach?  Stay tuned for further research.

BPA or Not-BPA?
 According to a column in "Harvard School of Public Health" researchers have found that college kids who drank from polycarbonate bottles showed a two-thirds increase of the chemical bisphenol A (BPA) in their urine." This has several interesting implications.

The good news is that (a) the levels were slightly higher than a trace, way below the "harmful" range and (b) it was outward bound in the urine.  The bad news is that it did pass through the bloodstream on its way to the kidneys and we don't know how much was stored in fat along the way.  Since we as a nation have accumulated more fat in recent decades, the national BPA storage facilities have increased.  A cynic could say that we may be reducing the environmental levels by our habits.

Does BPA stay in the body?  An article in Environmental Health Perspectives Journal suggests that it does.
"Vandenberg et al. (p. 1055) reviewed 80 published human biomonitoring studies that measured BPA concentrations in human tissues, urine, blood, and other fluids, and found that these studies overwhelmingly detected BPA in adults, adolescents, and children."
Does it matter and what can you do about it?  The risks of BPA in humans is currently unknown.  The article entitled Live Science has information on the numbers on containers that identify which plastics contain BPA.  Meanwhile, recycle and live green as the modern world will let you.