“Triclosan, when present in consumer products, breaks down into chloroform and dioxin upon release into the environment.”

Direct photolysis of TCS readily occurs, especially in the surface layers of waters that receive abundant ultraviolet radiation during the daytime. Two products, m/z 235 and m/z 252, were produced via reductive dechlorination and nucleophilic substitution with UVC, while three dioxin-like isomer products were generated by dechlorination, cyclization and hydroxylation. Furthermore, the results of biological concerns suggested that the elimination of TCS did not represent the disappearance of biological risks. Specifically, more hazardous and photolysis products were formed during TCS photolysis with ultraviolets. For instance, the dioxin-like isomer products were highly microtoxic and genotoxic, and mildly antiestrogenic.

Experiments performed in both natural and buffered deionized water show that triclosan rapidly photodegrades by direct photolysis, producing both 2,8-dichlorodibenzo-p-dioxin (2,8-DCDD) and 2,4-dichlorophenol (2,4-DCP). These results suggest that triclosan is likely converted to 2,8-DCDD in sunlight-irradiated surface waters.

Despite its high chemical stability, being extremely resistant to high and low pH, triclosan is readily degraded in the environment via photodegradation. Eight photoproducts were tentatively identified, including chlorinated phenols, chlorohydroxydiphenyl ethers, 2,7- and 2,8-dichlorodibenzo-p-dioxin, and a possible dichlorodibenzodioxin isomer or dichlorohydroxydibenzofuran. Free chlorine mediated oxidation of triclosan leads to the formation of chloroform and other chlorinated organics.

In the water environment, TCS will be transformed by photolysis into toxic substances such as 2,3-dichlorodibenzo-p-dioxin, dibenzodioxin and phenol intermediates, which are harmful to the aquatic organisms by bioaccumulation.

TCS chlorinated by-products can produce 2,8-DCDD and 2,4-dichlorophenol following photochemical degradation by sunlight exposure, although one study argued that low concentrations of dioxin compounds would be formed owing to the low efficiency of the direct photolysis of TCS. A recent study of water systems in North America indicated that higher concentrations of TCS, its chlorinated derivatives, and their derivative dioxins in small-scale water systems can be directly attributed to increased TCS use.

Antimicrobial dish detergent reacts with chlorine in tap water to produce significant amounts of chloroform and possibly dioxins, according to research published last week in Environmental Science & Technology News online. The scientists found that triclosan-containing detergent reacted with water containing the U.S. EPA maximum residual disinfectant concentration for chlorine to form more than 50 parts per billion of chloroform.

While chloroform may be produced if a soap containing triclosan comes into contact with chlorinated water, the concentration of chlorine in the water has to be on the order of 20%. With exposure to UV radiation at 254 nm, triclosan can photodegrade to 2,7- and 2,8-dichlorodibenzo-p-dioxin (2,7/2,8-DCDD).

Triclosan (TCS) is a multi-purpose antimicrobial agent used as a common ingredient in everyday household personal care and consumer products. Conventional water and wastewater treatment processes are unable to completely remove the TCS and even form toxic intermediates. Methyl TCS, dioxins, chlorophenols, chloroform are among the degraded byproducts found throughout the environment.

The prevalence of Triclosan in the nation's waterways is a cause for concern since Triclosan is converted into dioxin—a highly toxic compound, when exposed to sunlight in an aqueous environment. Triclosan can also combine with chlorine in tap water to form chloroform, which is listed as a probable human carcinogen.

Researchers who added triclosan to river water and shined ultraviolet light on the water found that between one and twelve percent of the triclosan was converted to dioxin in the water, leading to fears that sunlight could transform triclosan to dioxin naturally. Triclosan is listed as "could be" and "suspected to be" contaminated with dioxins in EPA's draft Dioxin Reassessment.

Lores et al. (2005) reported that, under artificial conditions, triclosan can photodegrade to 2,7- and 2,8- dichlorodibenzo-p-dioxin (2,7/2,8-DCDD). In addition, 2,4-dichlorophenol (DCP), which is not a dioxin, has been identified as a major degradation product under artificial conditions - 93.8-96.6% of the applied triclosan degrades to DCP within 240 minutes post-treatment. ... Overall, some information suggests that photodegradation, likely by UV light, may produce dioxin compounds, but other sources have postulated other photodegradation products that are not dioxin.

Research into Triclosan, the most common anti-bacterial chemical used in consumer products, documented that Triclosan reacts with chlorine in tap water to form significant quantities of chloroform. Chloroform is classified as a probable human carcinogen. Researchers at Virginia Polytechnic and State University estimate that under some conditions the use of triclosan can increase a person's annual exposure to chloroform by as much as 40% above background levels in tap water.

Triclosan persists in the environment, is toxic to aquatic organisms and can transform into cancer-causing chemicals such as dioxins, chloroform and 4-chloroaniline. The widespread use of triclosan and other antibacterial compounds results in contamination of the nation's waterways.

Researchers in the US found that the chlorine added to water in Britain reacted with triclosan to produce chloroform-gas. Professor Peter Vikesland, of Virginia Tech University, who carried out the research, said: "This is the first work that we know of that suggests that consumer products, such as antimicrobial soap, can produce significant quantities of chloroform."

When treated wastewater is released to the environment, sunlight converts some of the triclosan (and related compounds) into dioxins. Additionally, Triclosan can combine with chlorine in tap water to form chloroform, which is listed as a probable human carcinogen.