Biodegradation of the ultraviolet filter benzophenone-3 under different redox conditions.
ABSTRACT Biodegradation of the ultraviolet (UV) filter benzophenone-3 (BP-3) was investigated in the laboratory to understand its behavior and fate under oxic and anoxic (nitrate, sulfate, and Fe [III]-reducing) conditions. Biodegradation experiments were conducted in microcosms with 10% of activated sludge and digested sludge under oxic and anoxic conditions, respectively. Benzophenone-3 was well degraded by microorganisms under each redox condition. Under the redox conditions studied, the biodegradation half-life for BP-3 had the following order: oxic (10.7 d) > nitrate-reducing (8.7 d) > Fe (III)-reducing (5.1 d) > sulfate-reducing (4.3 d) ≥ anoxic unamended (4.2 d). The results suggest that anaerobic biodegradation is a more favorable attenuation mechanism for BP-3. Biodegradation of BP-3 produced two products, 4-cresol and 2,4-dihydroxybenzophenone, under oxic and anoxic conditions. Biotransformation of BP-3 to 2,4-dihydroxybenzophenone by way of demethylation of the methoxy substituent (O-demethylation) occurred in cultures under each redox condition. The further biotransformation of 2,4-dihydroxybenzophenone to 4-cresol was inhibited under oxic, nitrate-reducing, and sulfate-reducing conditions.
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ABSTRACT: In this work we have compared the ability of Pandoraea pnomenusa B356 and of Burkholderia xenovorans LB400 to metabolize diphenylmethane and benzophenone, two biphenyl analogs in which the phenyl rings are bonded to a single carbon. Both chemicals are of environmental concern. P. pnomenusa B356 grew well on diphenylmethane. On the basis of growth kinetics analyses, diphenylmethane and biphenyl were shown to induce the same catabolic pathway. The profile of metabolites produced during growth of strain B356 on diphenylmethane was the same as the one produced by isolated enzymes of the biphenyl catabolic pathway acting individually or in coupled reactions. The biphenyl dioxygenase oxidizes diphenylmethane to 3-benzylcyclohexa-3,5-diene-1,2-diol very efficiently, and this metabolite is ultimately transformed to phenylacetic acid which is further metabolized by a lower pathway. Strain B356 was also able to co-metabolize benzophenone through its biphenyl pathway although in this case, this substrate was unable to induce the biphenyl catabolic pathway and the degradation was incomplete with accumulation of 2-hydroxy-6,7-dioxo-7-phenylheptanoic acid. Unlike strain B356, B. xenovorans LB400 did not grow on diphenylmethane. Its biphenyl pathway enzymes metabolized diphenylmethane but they poorly metabolize benzophenone. The fact that the biphenyl catabolic pathway of strain B356 metabolized diphenylmethane and benzophenone more efficiently than that of strain LB400 brings us to postulate that in strain B356, this pathway may have evolved divergently to serve other functions not related to biphenyl degradation.Journal of bacteriology 06/2013; · 3.94 Impact Factor
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ABSTRACT: Organic ultraviolet (UV) filters are applied widely in personal care products (PCPs), but the distribution and risks of these compounds in the marine environment are not well known. In this study, the occurrence and removal efficiencies of 12 organic UV filters in five wastewater treatment plants (WWTPs) equipped with different treatment levels in Hong Kong, South China, were investigated during one year and a preliminary environmental risk assessment was carried out. Using a newly developed simultaneous multiclass quantification liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, butyl methoxydibenzoylmethane (BMDM), 2,4-dihydroxybenzophenone (BP-1), benzophenone-3 (BP-3), benzophenone-4 (BP-4) and 2-ethyl-hexyl-4-trimethoxycinnamate (EHMC) were frequently (≥80%) detected in both influent and effluent with mean concentrations ranging from 23 to 1290 ng/L and 18-1018 ng/L, respectively; less than 2% of samples contained levels greater than 1000 ng/L. Higher concentrations of these frequently detected compounds were found during the wet/summer season, except for BP-4, which was the most abundant compound detected in all samples in terms of total mass. The target compounds behaved differently depending on the treatment level in WWTPs; overall, removal efficiencies were greater after secondary treatment when compared to primary treatment with >55% and <20% of compounds showing high removal (defined as >70% removal), respectively. Reverse osmosis was found to effectively eliminate UV filters from effluent (>99% removal). A preliminary risk assessment indicated that BP-3 and EHMC discharged from WWTPs may pose high risk to fishes in the local environment.Water Research 01/2014; 53C:58-67. · 4.66 Impact Factor
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ABSTRACT: Benzophenone-3 (BP-3) has been widely used in sunscreens and many other consumer products, including cosmetics. The widespread use of BP-3 has resulted in its release into the water environment, and hence its potential impact on aquatic ecosystem is of concern. To better understand the risk associated with BP-3 in aquatic ecosystems, we conducted a thorough review of available articles regarding the physicochemical properties, toxicokinetics, environmental occurrence, and toxic effects of BP-3 and its suspected metabolites. BP-3 is lipophilic, photostable, and bioaccumulative, and can be rapidly absorbed via oral and dermal routes. BP-3 is reported to be transformed into three major metabolites in vivo, i.e., benzophenone-1 (BP-1), benzophenone-8 (BP-8), and 2,3,4-trihydroxybenzophenone (THB). BP-1 has a longer biological half-life than its parent compound and exhibits greater estrogenic potency in vitro. BP-3 has been detected in water, soil, sediments, sludge, and biota. The maximum detected level in ambient freshwater and seawater is 125ng/L and 577.5ng/L, respectively, and in wastewater influent is 10,400ng/L. The major sources of BP-3 are reported to be human recreational activities and wastewater treatment plant (WWTP) effluents. BP-3 and its derivatives have been also detected in fish lipid. In humans, BP-3 has been detected in urine, serum, and breast milk samples worldwide. BP-1 has also been detected in placental tissues of delivering women. While sunscreens and cosmetics are known to be major sources of exposure, the fact that BP-3 has been detected frequently among young children and men suggests other sources. An increasing number of in vitro studies have indicated the endocrine disrupting capacity of BP-3. Based on a receptor binding assay, BP-3 has shown strong anti-androgenic and weak estrogenic activities but at the same time BP-3 displays anti-estrogenic activity as well. Predicted no effect concentration (PNEC) for BP-3 was derived at 1.32μg/L. The levels observed in ambient water are generally an order of magnitude lower than the PNEC, but in wastewater influents, hazard quotients (HQs) greater than 1 were noted. Considering limited ecotoxicological information and significant seasonal and spatial variations of BP-3 in water, further studies on environmental monitoring and potential consequences of long-term exposure in aquatic ecosystem are warranted.Environment international. 06/2014; 70C:143-157.