Photolytic Fate of (E)- and (Z)-Endoxifen in Water and Treated Wastewater Exposed to Sunlight

This study elucidated the fate and susceptibility of (E)- and (Z)-endoxifen (2 μg mL-1, 1:1 weight ratio between the two easily interchangeable isomers) in wastewater and receiving surface water to sunlight. Phototransformation by-products (PBPs) and their toxicity were determined. Sunlight reduced at least 83% of endoxifen concentration in wastewater samples, whereas in surface water samples, 60% of endoxifen was photodegraded after 180 min of the irradiation. In ultrapure water samples spiked with endoxifen, PBPs were mainly generated via con-rotatory 6π-photocyclization, followed by oxidative aromatization. These PBPs underwent secondary reactions leading to a series of PBPs with different molecular weights. Eight PBPs were identified and the toxicity analysis via the Toxicity Estimation Software Tool revealed that seven of these PBPs are more toxic than endoxifen itself. This is likely due to the formation of poly-aromatic core in the PBPs due to exposure to sunlight. Therefore, highly toxic PBPs may be generated if endoxifen is present in water and wastewater exposed to sunlight. The presence, fates and activities of these PBPs in surface water especially at locations close to treated wastewater discharge points should be investigated.PMID:33823193 | DOI:10.1016/j.envres.2021.111121
Source: Environmental Research - Category: Environmental Health Authors: Source Type: research