From REUSABLEBAGS.COM

...What is clear from the numbers is that feel-good policies have again trumped sound environmental analysis.  Some will argue that reusable bags are the solution, but that ignores the fact that reusable bags are lost or are not reused.  In fact they may be the least environmentally friendly solution of all.

One more thing: "In California, bag manufacturers successfully sued Oakland and Manhattan Beach after those cities banned plastic bags. The bag makers complained that officials didn't prepare a report detailing the environmental impact, such as the increased use of paper sacks." 

Kauai and Maui County have no EIS.  How ironic is that?  

Issue 1: Energy and natural resources
It takes more than four times as much energy to manufacture a paper bag as it does to manufacture a plastic bag.
ENERGY TO PRODUCE BAG ORIGINALLY (BTUs)
--Safeway Plastic Bags: 594 BTUs
--Safeway Paper Bags: 2511 BTUs
(Source: 1989 Plastic Recycling Directory, Society of Plastics Industry.)
Of course, most paper comes from tree pulp, so the impact of paper bag production on forests is enormous. In 1999, 14 million trees were cut to produce the 10 billion paper grocery bags used by Americans that year alone. Paper bag production delivers a global warming double-whammy forests (major absorbers of greenhouse gases) have to be cut down, and then the subsequent manufacturing of bags produces greenhouse gases.

Issue 2: Pollution
The majority of kraft paper is made by heating wood chips under pressure at high temperatures in a chemical solution. As evidenced by the unmistakable stench commonly associated with paper mills, the use of these toxic chemicals contributes to both air pollution, such as acid rain, and water pollution. Millions of gallons of these chemicals pour into our waterways each year; the toxicity of the chemicals is long-term and settles into the sediments, working its way through the food chain. Further toxicity is generated as both plastic and paper bags degrade.
POLLUTANTS PAPER V.S. PLASTIC
--Paper sacks generate 70% more air and 50 times more water pollutants than plastic bags.
Source: "Comparison of the Effects on the Environment of Polyethylene and Paper Carrier Bags," Federal Office of the Environment, August 1988

Issue 3: Recycling
It takes 91% less energy to recycle a pound of plastic than it takes to recycle a pound of paper. But recycling rates of either type of disposable bag are extremely low, with only 10 to 15% of paper bags and 1 to 3% of plastic bags being recycled, according to the Wall Street Journal.
ENERGY TO RECYCLE PACKAGE ONCE (BTUs)
--Safeway Plastic Bags: 17 BTUs
--Safeway Paper Bags: 1444 BTUs
Source: 1989 Plastic Recycling Directory, Society of Plastics Industry.
Although paper bags have a higher recycling rate than plastic, each new paper grocery bag you use is made from mostly virgin pulp for better strength and elasticity.

Issue 4: Degradability
Current research demonstrates that paper in today's landfills does not degrade or break down at a substantially faster rate than plastic does. In fact, nothing completely degrades in modern landfills because of the lack of water, light, oxygen and other important elements that are necessary for the degradation process to be completed. A paper bags takes up more space than a plastic bag in a landfill, but because paper is recycled at a higher rate, saving space in landfills is less of an issue.

From: www.reusablebags.com:80/facts.php?id=7

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