“Paper or plastic?” Everyone wants to know. And the definitive answer is “It depends.” Paper means cutting down trees and operating paper mills; plastic means pumping oil, operating refineries and chemical plants. Which is less environmentally harmful? This is the type of question ad­dressed by the field of Life-­cycle Assessment, or LCA. While it is possible to use LCA to make choices among materials for specific uses, the actual su­periority of one material to another still depends on how you quantify the intrinsic cultural and economic value of a number of environmental at­tributes such as:

• Water pollution.
• Air pollution.
• Global warming.
• Environmental degradation.
• Ozone depletion.
• Habitat destruction.
• Human health.

One of the leading systems in the U.S. for evaluating environmentally preferable products (EPP) for public and private purchasing is called Building for Environmental and Economic Sustainability (BEES), put out by the National Institute of Standards and Technology (NIST). According to NIST: 

BEES measures the environmental performance of building products by using the life­cycle assessment approach specified in the ISO 14040 series of standards. All stages in the life of a prod­uct are analyzed: raw material acquisition, manufacture, trans­portation, installation, use and recycling and waste management. Economic performance is measured using [a] standard life cycle cost method, which covers the costs of initial investment, replace­ment, operation, maintenance and repair and disposal. Environ­mental and economic performance combine into an overall per­formance measure.

For a manufacturer, an LCA would involve making detailed measurements of energy and water use, waste generation and other environmental im­pacts associated with the manufacture of the product, from the mining of the raw materials used in its production and distribution, through to its use, possible reuse or recycling and eventual disposal. LCA enables a man­ufacturer to quantify how much energy and raw materials are used and how much solid, liquid and gaseous waste is generated at each stage of the product’s life. Using one of the comprehensive assessment methods such as BEES, a manufacturer can then determine how its products stack up against direct competitors and substitutes.
According to a 2006 report prepared for the U.S. Environmental Pro­tection Agency:

Life­cycle assessment is a ‘cradle to grave’ approach for assessing industrial systems…By including the impacts throughout the product life cycle, LCA provides a comprehensive view of the en­vironmental aspects of the product or process and a more accu­rate picture of the true environmental trade­offs.