Cultural: Powdered detergents still dominate the market in many countries outside of the United States. These detergents, both used industrially and in the home, contain an inexpensive ingredient called Linear Alkylbenzene Sulfonate (LAS), effective on removing dirt (less effective on greasy or oily stains). Most liquid detergents contain, in addition to LAS, alcohol ethoxylates, which are effective in treating those oily stains.[1] This product makes its way into the homes of many in Mexico as handwashing is preferred over machine washing.

Political: North American Free Trade Agreement (NAFTA: 1994) and General Agreement on Tariffs and Trade (GATT: 1947) significantly affected the Mexican soaps, detergents, and surfactants (SDS) industry by opening up the Mexican market to international multinational corporations, R&D money, revenue streams, distribution networks, and a reduction in local bargaining power; all production and pollution still occurring in Mexico as the income is dispersed globally, rather than locally.[2] Walmex (Walmart in Mexico) was a major driver of change in production. The introduction of Walmex into the Mexican market caused local companies to compete with multinational markets and other local retailers in an unprecedented way. Walmex also increased exports to the United States for the Latino community. The dominance of Walmex changed the sector significantly by introducing efficiencies and modernization in warehousing, distribution, and inventory management. Walmex also reduced bargaining power for local SDS producers. For example, they used “roughly 25 domestically-owned small and medium-sized producers to supply store-brand (marca blanca) detergents and cleaners, each producing a differentiated product.”

Historical: Alkylbenzene sulfonates (ABS) are still widely used in developing countries.[3] These surfactants are beginning to be replaced by a more biodegradable linear alkylbenzene sulfonate (LAS), yet remain the main ingredient in many surfactants. Synthetic ingredients in detergents is a relatively new phenomenon. Until World War I, people washed their clothes with soaps made from fats, oils, and fatty acid salts. During the war, German chemical companies developed an alkyl sulfate surfactant, a synthetic version of the fatty acid salts. After the war, “Proctor & Gamble brought samples back to the US, recreated the surfactant in its labs, and in 1931 launched Dreft powder, the first synthetic detergent in the US.”[4] The chemicals were developed to become more robust at removing soil from clothing and thus began the industrial age of surfactants.

Morphological: Surfactants make their way into water through storm drains, household utilities, and industrial processing. There is some evidence that when surfactants make their way into the soil, it changes the soil surface tension.[5] An alteration of the surface tension influences the soil’s ability to infiltrate micropollutants. Much of the surfactants fate in the soil relies on the availability and concentration of organic and inorganic substances in soils (as OM is the main sorbent of LAS in Mezquital soils).[5] The half-lives of LAS in soil ranges from 7-22 days and from 18-26 days.[6] The relatively short half-life is due to LAS’s ability to be degraded under anaerobic conditions by microbes. Various studies conflict slightly, some illustrating the ability to be degraded quickly and others attest to surfactants ability to destabilize microbial cell membranes which lead to an increased membrane permeability and cell lysis.[6] There is some evidence that reports a reduction in microbial activity due to the presence of surfactants in the soil, while others show respiratory activity increasing or remaining unchanged with the addition of certain surfactants.[6]