No biodegradation in water and toxicity to aquatic life 

Biodegradation can be defined as the destruction of a chemical compound by the biological action of living microorganisms. Surfactants are the main ingredient or active substance in a detergent, thanks to their ability to break the surface tension of water and which allows the detergent to emulsify dirt or non-polar particles in the water. In the case of surfactants as molecules to be degraded, it is the living microorganisms that fulfill this function, mainly bacteria present in the various media that receive wastewater, which are capable of feeding on a wide variety of organic compounds. The most important detergent ingredients to biodegrade are surfactants because they are toxic to aquatic life, change the solubility of 11 fats and proteins, and consequently alter the function of cell membranes in living things. All surfactants can eventually biodegrade, but the big problem is that they do so extremely slowly. The great increase in the use of chemical detergents bought in supermarkets renders the degradation of surfactants in wastewater impossible. For example, those of the APE family were no longer used in the 1980s, and traces were still found in analyzes of aquatic environments carried out in 2003, according to a study carried out for the European Commission. In 2004, the European Commission legislated banning surfactants that do not biodegrade rapidly under aerobic conditions, that is, in the presence of oxygen, which is the case with river or lake water. Specifically, surfactants in household detergents must biodegrade by 60% in 28 days. This European regulation does not solve the problem of the biodegradation of surfactants that continue to increase and contaminate the waters of rivers and seas.

Biodegradable does not mean ecological: some manufacturers use the adjective "biodegradable" as a commercial claim. In many cases it only means that the products are as biodegradable as the law requires, which in the case of detergents is less than what the health of rivers and seas needs.

The European Commission, with the exception of surfactants, has not regulated the biodegradability of other ingredients for which there is no biodegradation requirement, despite the fact that for some of them there are signs of worrisome toxicity and, therefore, it is not appropriate that remain in the water without biodegrading. And they stay there for years. For example, a phosphonate is chronically toxic to Daphnia, a planktonic crustacean that, due to its characteristics, is considered a good measuring organism for ecotoxicity. The most widely used optical brighteners, in addition to not being biodegradable, according to the European Chemical Agency, "May cause long-lasting harmful effects to aquatic organisms." The European Commission considers that "it is necessary to continue studying" all these ingredients that are "suspected" to be especially dangerous for the health of rivers. But without applying the precautionary principle in the meantime.

No biodegradation in sludge and toxicity in agriculture 

Sewage treatment plant sludge is an anaerobic medium: there is no oxygen. In the treatment plants, a large part of the surfactants precipitates towards the bottom sludge and a large part of this sludge is used (after treatment) as fertilizer for agriculture and gardening. The ingredients that do not biodegrade without oxygen, among which are the most used surfactants (those of the LAS family) reach the agricultural soil intact, poisoning it. 12 

Foam

In water treatment plants, the large amount of foam causes operational problems, affects primary sedimentation since it encompasses particles making sedimentation slower, hinders the dilution of atmospheric oxygen in water, and covers work surfaces with sediments that contain high concentrations of surfactants, fats and proteins.

Eutrophication

Eutrophication is an important affectation of aquatic ecosystems, due to an exaggerated arrival of nutrients, mainly phosphates and nitrates, which causes a vegetative explosion of algae (phytoplankton). The problem is so serious that many manufacturers have long since stopped putting phosphates in laundry detergents, even voluntarily. It wasn't until 2012 that the European Commission introduced a regulation that only limits the amount of phosphorus in detergents, leaving that, for dishwasher detergents, the limit didn't take effect until 2017.

Reference 

Ethan, 2017, https://www.safehouseholdcleaning.com/the-trouble-with-laundry-detergents/