Dioxin photoproducts of triclosan and its chlorinated derivatives in sediment cores.

Triclosan, a widely used antimicrobial, is known to undergo phototransformation in aqueous solution to form 2,8-dichlorodibenzo-p-dioxin (2,8-DCDD). Two sediment cores from a wastewater-impacted depositional zone of the Mississippi River were analyzed for triclosan by ultra performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS-Q(3)) and for a suite of polychlorinated dioxins and furans by high resolution gas chromatography-mass spectrometry (HRGC-MS) to provide evidence of this photoreaction in the environment. 2,8-DCDD was detected at levels that trended with the historical use of triclosan since its introduction in the 1960s.

Photochemical formation of halogenated dioxins from hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and chlorinated derivatives (OH-PBCDEs).

The potential photochemical formation of polybrominated and mixed halogenated dibenzo-p-dioxins (PBDDs and PXDDs) from hydroxylated polybrominated and polybrominated/ chlorinated diphenyl ethers (OH-PBDEs and OH-PBCDEs) in aqueous solution was studied. The ortho-hydroxylated BDE47 derivative 6-OH-BDE47, and chlorinated derivatives 3-Cl-6-OH-BDE47, 5-Cl-6-OH-BDE47, and 3,5-Cl-6-OH-BDE47 were photolyzed under sunlight at 45 degrees N latitude in buffered waters, Mississippi River water, Lake Josephine water, and ultrapure water adjusted to the pH of the natural waters. Chemical actinometry was used to determine reactant quantum yields which were calculated to be between 0.