Week of 11/28/2004

Dear EarthTalk: My new dishwasher has receptacles for both soap and "rinse-aid." Is rinse-aid safe for the environment, and do I need to use it in my dishwasher?

Britten Clark, Seattle, WA

If your region"s water source is rich in magnesium and calcium salts (“hard” water), adding rinse-aid to your dishwasher along with the detergent may help prevent streaks and spotting on your glassware and dishes.

Rinse-aid—the ingredients of which are usually ethanol, citric acid, sodium, dyes and acrylic acid polymers—breaks down the salts in hard water, thereby preventing the adhesion of soap clumps during the rinse cycle, leaving cleaner-looking results (although consuming food and drinks from streaked or spotted dishes and glassware is not a health hazard in its own right). The National Institutes of Health report that most rinse-aid is completely biodegradable, and while it is neither carcinogenic nor dangerous if used properly, it can cause eye and skin irritation following prolonged exposure and should not be ingested, of course.

While the use of rinse-aid to combat dishwasher streaking is no environmental crime, those concerned about the consumption of resources might think twice about the need for it. Mainstream rinse-aid, like dishwasher soap itself, contains phosphates in its cleaning agents. Wastewater containing phosphates which escapes sewage treatment can cause excessive algae growth in waterways which in turn pollutes drinking water and leads to marine "dead zones"—underwater environments deprived of oxygen and thus unable to support life. Consumers should keep in mind that dishwasher soaps, as well as laundry detergent and many other household items, also contain phosphates that can cause problems if not disposed of properly.

It"s easy to avoid rinse-aid and other household items with phosphates by seeking out products from any of several companies that only use plant-based ingredients. Earth Friendly Products, Ecover and Simply Clean, to name just a few, make environmentally friendly rinse-aid that can be found in most natural foods markets. Beyond avoiding phosphates, these companies also pride themselves in avoiding petrochemicals and dyes in their products.

Also, just because your dishwasher may need rinse-aid does not mean you should fear drinking hard water from the tap. According to the U.S. Environmental Protection Agency (EPA), drinking hard water regularly poses no health threat and can actually help lower the incidence of heart disease, as the abundant magnesium and calcium salts help break down arterial plaque in the bloodstream.

CONTACTS: Earth Friendly Products, (800) 335-3267, www.ecos.com; Ecover, www.ecover.com; Simply Clean, www.simplyclean.ca; U.S. Environmental Protection Agency, www.epa.gov.

Dear EarthTalk: With all the talk of hydrogen fueled vehicles, I can’t help but wonder if millions of cars driving around spewing out water vapor—a well-known “greenhouse gas” itself—is any better than the carbon dioxide emitted by traditional cars?

Kelly Grube, Fleetwood, PA

Climate analysts do believe that water vapor in the atmosphere—mostly due to natural evaporation from bodies of water—is already contributing significantly to climate change. According to the esteemed International Panel on Climate Change, atmospheric water vapor exacerbates warming caused by the emission of fossil fuels by as much as 50 percent. However, the additional water vapor that might be created by millions of fuel-cell vehicles running on hydrogen—while it may sound like a lot—would constitute only a drop in the bucket compared to that which naturally occurs.

Water vapor is actually present in our atmosphere at much higher concentrations than carbon dioxide. According to Mississippi State University meteorologist Jeff Haby, who runs the Weather Prediction Website, the average concentration of water vapor in the atmosphere around the globe is presently between two and three percent, while carbon dioxide levels are only at about .04 percent (four one-hundredths of a percent). "That means there is more than 60 times as much water vapor in the atmosphere than carbon dioxide in average conditions," says Haby.

However, water vapor is far less efficient at trapping heat within Earth"s atmosphere than carbon dioxide, the leading fossil-fuel-based greenhouse gas. Despite its prevalence, water vapor tends to concentrate locally and then get cycled through the meteorological system quickly (in the form of clouds and then rain). Meanwhile, carbon dioxide is an insidious greenhouse gas that lingers in the upper atmosphere for long periods of time and forms a dense barrier to the escape of heat. While water vapor can cause short-term day-to-day warming locally, carbon dioxide can actually raise the Earth"s temperature both globally and permanently.

Meanwhile, fuel cell advocates such as industrial designer Robert Q. Riley do not see the increased production of water vapor by the hoped-for hydrogen-powered vehicles of the future as a major concern. "Natural evaporation from lakes and rivers produces about 1000 times more water vapor than would come from a transportation system that was totally powered by fuel cells," says Riley. "So the increased moisture in the air is pretty much inconsequential."

CONTACTS: International Panel on Climate Change, www.ipcc.ch; The Weather Prediction Website, www.theweatherprediction.com; NASA"s Earth Observatory, www.earthobservatory.nasa.gov.

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