These events were highly publicized, and foam became a common indicator of pollution. Unlike soap, the structure of the ABS molecule was in a branched form which could not be broken down by bacteria. To combat this problem, the detergent industry changed the chemical structure to a simple linear form, LAS, which could be attached by bacteria. Most foam is a product of nature. Small trout streams often have pools of foam where fish will hide.
Organic compounds leached from soil also cause foam.
The Indians were known to have used various materials, such as bark and plant roots, to clean items. Like soap and ABS, these compounds also reduce surface tension. As wind or currents stir the water, foam is produced and may accumulate in quantities on windward shores in coves, or in eddies. The natural foam has a somewhat earthy or fishy aroma, and it breaks down rather quickly. Foam from silt or erosion is usually a dirty brown color.