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Biodegradable vs. Non-Biodegradable Soap

The distinction between biodegradable and non-biodegradable soap is blurred. Biodegradable soap is a product that decomposes naturally and quickly – usually within six months – by the action of microorganisms or other biological processes. Non-biodegradable soap may take between many months and many decades to decompose. Both soap varieties consist of a mixture of natural and synthetic substances. All soap forms have some detrimental effect on the environment.

  1. Standards

    • The term "biodegradable" refers to the ability of a substance to decompose. There is no clear, legal definition of "biodegradable." What standards exist usually apply to plastics. In the United States, ASTM International defines test methods for biodegradable plastics. There is no definition of a biodegradable soap or detergent and any manufacturer may label a soap “biodegradable.” The European Union requires that a "biodegradable" substance must decompose by 90 percent within six months. The Australian standard requires 80 percent of a substance to decompose within 21 days to carry a “biodegradable” label.

    Composition

    • Soap is a chemical compound that derives from the reaction between a fatty acid and an alkali such as sodium or potassium hydroxide. Traditionally, the fats used were either vegetable or animal fats or a combination of the two. Animal fats alone produce a very hard soap. Coconut oil alone produces a soft soap that is soluble in seawater.

    Cleaning Properties

    • Soap works because it consists of chemicals known as surfactants. These break down the surface tension of water, dissolve grease and remove some dirt from any fabric or article that is washed. Antibacterial chemicals such as “carbolics,” or phenols, were added to soaps from the early 20th century. These did not break down in the environment, and waste foam from domestic or industrial cleaning clogged drains and waterways.

    Builders

    • Soap manufacturers sought to make soap “biodegradable” by adding compounds to enable the soap residue to decompose as quickly as possible. These compounds, or builders, react with calcium and magnesium ions present in all water supplies to avoid the creation of scum and foam. Phosphate compounds remain some of the most common builders. These produce environmental problems in waterways by creating excessive algal blooms and depleting the amount of oxygen present in water. Aluminosilicates and sodium citrate are alternative builders to phosphates. But these are estrogen mimics and also leave detrimental effects on ecosystems.

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