Tuesday, July 22, 2014

The paper grocery bag: endangered!

April 22, 2011 |

Earth Day developed as a temporal marker for taking stock of the condition of our natural resources and the impacts of our personal and collective behavior on the sustainability of our life support systems.

Recently, there has been a sharp increase in concern about our use of plastic and paper bags used to transport our groceries and other purchases. Typically, we do not give a second thought as to how these conveniences affect our resources and the health of our society.

Each American uses 749 pounds of paper per year — 187 billion pounds for the whole society. With 5 percent of global population, we account for 30 percent of global paper consumption. As for paper bags, we use 40 million of these, up from 10 billion in 1999.

Paper was invented by Africans in the Nile Valley 6000 years ago from reeds that were pounded into flat sheets — papyrus. In 105 AD, Ts’ai Lun, a Chinese courtier, mixed mulberry bark and hemp with water, mixed in scraps of cotton and linen, mashed the mixture into a pulp, pressed the mixture into mats and then dried them in the sun. Voilá! Paper!

Francis Wolle, a clergyman in a Moravian seminary for young women, patented a paper bag machine in 1852, and in 1869 he and his brother founded the Union Paper Bag Machine Co. Margaret Knight, a prolific inventor, invented a device for cutting, folding and pasting paper bag bottoms in 1870.

In 1883, Charles Stilwell, a former Union soldier in the Civil War, was awarded a patent for making a square-bottom paper bag with pleated sides, and in 1890, William Purvis, an African-American inventor, patented an improved paper bag machine, which he sold to the Union Paper Bag Machine Co.

Located near Savannah, Ga., the Union Bag and Paper Corp. operates the largest mill of its kind in the world, producing 35 million paper bags per day — 9 billion per year — enough for 250 bags for each American family.

It comes with costs

Tracing the life cycle of the paper bag gives some idea of its costs to society. That life cycle includes essentially eight stages — the growing of trees; their harvesting and transportation; extraction and processing of wood; manufacturing the bags; packaging; transporting and distributing; use and reuse; and disposal or recycling.

Trees are grown on tree plantations for 20 to 35 years, depending on the species. These tree plantations do not exhibit the biological diversity found in natural forests, thus they require more treatments to maintain yields.

The trees are harvested using heavy machinery, transported to a mill where they are dried for three years before they enter into the manufacturing process, whereupon the logs are debarked, chopped into one-inch-square chips that are cooked under extremely high heat and temperature.

After the cooking phase, the output is then “digested” with the aid of limestone and sulfurous acid until it becomes a pulp. The pulp is thereafter washed, using prodigious amounts of fresh water and bleach before it is pressed into finished paper. Then the sheets of paper are cut and shaped into bags. They are then printed and packaged and shipped to their final destinations.

It does not take much imagination to trace the massive amounts of petroleum used as an energy source as well as the water used in these processes. Moreover, the chemicals used in the process contribute to air and water pollution, including acid rain, which kills natural forests and leads to climate change. Hence, we need to become more conscious of the full cost of paper bags when we take our groceries home.

Our response

We became a part of the problem. But we can become part of the solution.

So what can we do? As a society, we can look at new sources of raw material such as kenaf and hemp, but inevitably there would be large amounts of energy needed, as well as water and chemicals.

We could recycle more — only an estimated 10 to 15 percent of paper bags are recycled. For 10,000 uses, paper bags generate 45.8 cubic pounds of solid waste, 64.2 pounds of atmospheric emissions, as well as 31.2 pounds of water-borne waste.

However, even recycling is not without its own environmental problems. Besides the energy required to pick up, sort, transport and process the paper, recycling uses chemical compounds such as hydrogen peroxide, sodium silicate and sodium hydroxide — not necessarily benign materials. And it requires 1444 BTUs per pound of energy to recycle paper bags.

For a large number of reasons, grocery plastic bags are not a sustainable solution. Hundreds of thousands of sea mammals are killed each year by plastic bags. Turtles, for example, mistake them for jellyfish and choke on them.

The most environmentally sustainable efforts involve avoidance, maximum reuse and lastly recycling. Thus, there is logic for the reusable grocery bag as the most sustainable alternative now available.

— Desmond Jolly, a longtime Davis resident, is an agricultural economics professor emeritus. He served as director of the University of California Statewide Small Farm Program from 1995 to 2006.


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