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Dishing the dirt on phosphates

Broadcast Date: Feb. 8, 1970

In the 1970s, detergents are a modern miracle, leaving laundry sparkling clean. But their effect on lakes is the exact opposite. The key ingredient is phosphates: minerals that boost the cleaning power of soap and prevent dirt from being re-deposited on clothes. However, when phosphates go down the drain and enter a lake, algae thrive. The result is a slimy, stinking mess that leads to eutrophication — a "dead" lake. What's a conscientious homemaker to do? CBC's Weekend may have the answer.

Dishing the dirt on phosphates

• Phosphates are chemical variations on the element phosphorus. The most common phosphate type used in detergents is STPP, or sodium tripolyphosphate.
• Phosphates occur naturally in food and, therefore, in human and animal sewage. They are a major component of commercial fertilizers.
• In 1972 the Canada Water Act placed a limit on the proportion of phosphates in laundry detergents. No detergent could contain more than five per cent phosphates by weight.

• Another limit on phosphates was introduced in 1972 with the Canada-U.S. Great Lakes Water Quality Agreement. One of its provisions limited the amount of phosphorus in effluent from waste treatment plants.
• Many other states, provinces and municipalities also introduced phosphate limits and bans in the early 1970s.
• Higher levels of phosphates are permitted in industrial and hospital laundries and in dishwasher detergents.

• Before phosphates became a target, detergent foam — visible in many lakes and rivers — was a source of consternation for consumers. Manufacturers touted "long-lasting" suds (which had no effect on their cleansing ability) and formulated detergents with long, branched molecules that broke down very slowly. In response to public demand they reformulated their products and advertised them as "biodegradable."

• Legislation and public awareness surrounding phosphates paid off, and by 1975 Lake Erie appeared to be bouncing back. Algae levels were lower, phosphate loadings (the amount entering the lake) were down 50 per cent, and the smell was gone.

Dishing the dirt on phosphates

Medium: Television

Program: Weekend

Broadcast Date: Feb. 8, 1970

Guest(s): J.J. Greene, Brian Kelly, Peter Middleton

Host: Peter Reilly, Lloyd Robertson, Kay Sigurjonsson

Duration: 12:40

Last updated:
July 26, 2004