Health-care researchers have long claimed that use of antibacterial soaps can create drug-resistant germs in the home, leaving individuals more imperiled by infectious disease than they would otherwise be. Now there's worry that the major antibacterial ingredient may be fouling up our water systems and introducing mutant germs into our environment.

Triclosan, the controversial chemical, is under new scrutiny after a study revealed that the chemical can sabotage the efforts of helpful bacteria at wastewater treatment facilities. The study, which appears in the journal Environment Science & Technology says that the antimicrobial can hinder the efforts of important sludge-processing microbes while promoting drug resistance in others.

Triclosan, most commonly found in handwash and toothpaste, accumulates in wastewater treatment facilities and high concentrations and destabilizes microbial “communities” that help break up sludge and other sewage solids, which can then be used for fertilizer. Triclosan is also shown to encourage the growth of some microbes that are immune to drugs, which may increase the likelihood that they could be spread throughout the environment through fertilizers.

The antimicrobial, which was initially used as a hospital scrub and handwash in the 1970s, became ubiquitous in U.S. households about a decade ago. It is now prevalent in soaps, shampoos, deodorants, toothpastes, mouthwashes, and cleaning products. The antimicrobial is also incorporated into hard consumer products such as kitchen utensils, toys, bedding, socks, and trash bags. Its use by U.S consumers is so prevalent that it has been found in the urine of 75% of those tested in a 2008 study.

Critics of triclosan's use in household products have long maintained that the chemical creates bacterial resistance in the environment.

Recent scientific research has shown that higher levels of exposure to triclosan among children is linked to higher incidence rates of food allergies and hay fever, possibly because exposure to some bacteria reduces allergies. Other studies have linked triclosan to allergic contact dermatitis. Other studies have shown triclosan has been associated with lower levels of thyroid hormone and testosterone.

In the environment, triclosan is toxic to aquatic bacteria and inhibits photosynthesis in diatom algae, which are responsible for a large part of the photosynthesis on the planet.

The Food and Drug Administration says that there's no evidence that triclosan in personal-care products provides any health benefit, other than its use as an anti-gingivitis and anti-plaque agent in some toothpastes. And because of the alarm created by recent scientific studies, the safety of triclosan is currently under review by the FDA.

In recent months, triclosan has been the focus of regulation efforts by states. Last week, Minnesota banned triclosan from consumer soaps and handwashes sold in the state, and other states are considering similar legislation. The law will take effect in 2017.

Some of the larger personal-care product companies, such as Unilever, Proctor & Gamble, and Johnson & Johnson are said to be considering limiting the use of triclosan in their products. All three corporations dispute claims that triclosan is unsafe, but said they are voluntarily removing the antimicrobial from their products because of consumer demand.â€‹