Did you ever wonder how 51 corporations could become the largest economies on the Earth? That's even larger than most countries. In fact, about 200 giant corporations now control a fourth of the world's economic activity, according to the Institute for Policy Studies.

Philip Morris Corp. is larger in some ways than New Zealand - it encompasses 170 countries. These mega-buck corporations are thriving because the profits are concentrated in a few private hands while the costs to produce their products are externalized and paid by you, me, and the rest of the planet.

Much about our economic system depends on we consumers not knowing anything about the product beyond the price. If we knew how farmers in Brazil went hungry while their coffee beans were sold cheaply to U.S. middlemen, we would insist on buying fairly traded and shade-grown coffee. If we knew how children were exploited in Mexican workhouses to assemble products cheaply for U.S. store shelves, we might pass up a bargain in a big-box store for something we knew was made locally for a fair wage.

Much of the extraction of resources to make our goods and the actual production of these goods happens out of our sight. These hidden costs are called "externalized costs" and are often larger than the purchase price of an item. These are the costs to produce an item that we don't pay for at the register. Instead, we pay these costs through our taxes, through higher health care costs, and heavy environmental tolls like climate change.

Here are some externalized costs behind those "every day low prices:

- A third of the planet's natural resources have already been consumed. The costs of natural resources need to be fairly tallied and paid as part of the cost of producing the goods. For example, some California agro-giants buy water at $5 per acre-foot, while the government estimates the real cost is more like $40 per acre-foot. This water comes from the Oglala Aquifer which is being drained at a rate of 10 feet per year, and recharges at a rate of half an inch per year.

- Polluted air, water and soils are another externalized cost along with the loss of species of plants and animals, and changes in climate that result. This happens because much of the world's resources are held as "commons" and shared by all. When industry pollutes these commons, then we all suffer. It is hard to equate asthma in New York with coal-fired plants in Illinois, so the polluters often get away with it. Pollution gets concentrated as it travels up the food chain making our own precious breast milk one of the most highly polluted on the planet.

- Social costs like the destruction of communities are also untallied. For example, globally 200,000 people move from subsistence farms to cities every day causing burgeoning inner-city slums and poverty. In our country, we see more industry moving overseas and taking our jobs with it. This causes loss of livelihoods, destruction of social fabric and poverty. Our small producers have a hard time competing against government-subsidized cheap imports. Hence, welfare rolls swell and school tax bases crumble.

- Personal costs to labor force are also not counted in the cheap prices we pay. Most giant retail stores don't offer health care or other benefits. Many of their employees wind up on social services like Medicare, or are eligible for food stamps even though they work full time. This is how big-box stores can keep labor costs and prices so low.

Part of creating a sustainable society is calculating the true costs of goods and services. If we want a just and peaceful world, we need to pay that true cost so that our labor, planet and resources are fairly treated. We consumers need to demand that the corporations, and our government, be held accountable for these externalized costs.

Here are a few things you can do to help green the industrial world:

- Think "cradle to grave" and purchase the item that uses the least resources in manufacture, and can be recycled or re-purposed once its usable life is over.

- Research your goods - don't buy on impulse. Where is the factory located that made this item and how environmentally responsible is the company?

- Buy fair-trade labeled items. How are the people treated who grew these bananas? Will their children go hungry tonight so that mine can eat bananas for 29 cents per pound?

- Buy local. Your money stays local longer and so people who live in your community can afford to work there, and people who work there can afford to live there.

Shawn Dell Joyce is an award-winning sustainable artist and writer who lives in a green home in the Hudson Valley of New York. Shawn@ShawnDellJoyce.com