Detergents add a chemical soup to sewers, much of it biodegradable

EARTH MATTERS AT HOME

November 21, 1990|By Susan McGrath | Susan McGrath,Los Angeles Times Syndicate 00TC

Doing the laundry again? In a half-hour, 35 gallons of detergent-laden water will have cascaded down your drain. Have you ever wondered exactly what is in those liquids or powders that you contribute to the great outdoors every week, courtesy of your wash water? Is your laundry detergent safe for the environment?

Many modern detergents are a high-tech cocktail of chemicals. When you dump a cup of detergent into the water, you mobilize an efficient little army: compounds that make the water wetter, disarm the calcium, disperse the dirt, control the alkalinity, make your clothes smell good and coat them so that they wash clean a little more easily next time. Some detergent formulas even make your clothes fluoresce a little in sunlight, so that they look, yes, whiter than white.

The most important ingredient in any laundry detergent or soap is the surfactant, short for surface active agent. Surfactants reduce water's natural surface tension, letting it wet surfaces more effectively. They remove dirt. And they dissolve oil and grease.

Soap is a surfactant made from natural fatty acids, either from plant material, such as coconut oil, or from tallow, rendered animal fat. Soap has one major drawback: It does not work well in hard water, where it leaves a residue on the wash.

Most modern detergents use synthetic surfactants derived from petrochemicals. In fact, "detergent" generally refers to any surfactant other than soap, and that is how I'll use the term here.

Phosphates are added to detergent as "builders," so called because they build up the effectiveness of the surfactant. Other ingredients added to detergent may include bleach, fabric softener, stain-eating enzymes, perfumes and colorants.

What happens to all these ingredients after they sluice through your clothes for half an hour?

Most of the major surfactants in use today biodegrade in the sewage treatment process. The fate of trace ingredients such as whiteners and colorants is not really known.

Phosphates are another matter. These chemicals are not removed by conventional sewage treatment processes. In some areas of the country, chemicals are added during treatment to remove phosphates.

If discharged along with treated water into lakes and streams, phosphates promote the growth of algae, clogging the water with more vegetation than it can handle. This speeds the evolution of lakes into swamps.

Because of this serious problem, phosphates are banned in laundry detergent in many states and communities. If you live in these areas, primarily near the Great Lakes and the Chesapeake Bay, the laundry detergents on your grocery store shelves are essentially phosphate free.

What else is in your laundry detergent? Seattle's water treatment utility recently asked the non-profit Washington Toxics Coalition to take a look.

One of the things the researchers looked for was toxic metals, such as arsenic, cadmium, chromium, lead and mercury, which earlier studies had found in high concentrations. These metals don't biodegrade in water treatment. Instead, they concentrate in sewage sludge or are discharged with treated water.

The coalition didn't find tons of metals. But it did find a surprising correlation: The more phosphates in a detergent, the more arsenic it was likely to contain. In fact, the coalition calculated that if everyone used high-phosphate detergents, it would account for 20 percent of all the arsenic that comes down a city's drain pipes -- about 200 pounds of the deadly stuff a year.

Detergent manufacturers don't add arsenic to their product. The metal is simply attracted to the same materials phosphates are. When phosphates are mined from the earth, arsenic comes along, too.

What does this mean for the average launderer? The Toxics Coalition's Philip Dickey (whose office is awash in cleaning products) suggests that, if you're concerned about the environment, your best bet is to use a phosphate-free laundry detergent with as few additives as you can find, or use laundry soap. And use the minimum amount called for by the manufacturer. Or try using a little less.

Liquid laundry detergents are all free of phosphates. However, most people aren't able to recycle the big plastic jugs they come in.

Does this mean you are doomed to be dingy? Consumer Reports evaluated detergents in their July 1987 issue and concluded that phosphates don't make a huge difference in how clean your clothes get. Buy some enzyme stain remover and spot this on your clothes as needed. And cultivate a taste for cotton clothes. They are easier to clean. And soooo politically correct.

For an excellent fact sheet on laundry detergents, send 75 cents to the Washington Toxics Coalition, 4516 University Way N.E., Seattle, Wash. 98105.

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