Biodegradation of the ultraviolet filter benzophenone-3 under different redox conditions
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, PR China. Environmental Toxicology and Chemistry
(Impact Factor: 3.23).
02/2012; 31(2):289-95. DOI: 10.1002/etc.749
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.
Available from: Sara Zucchi
- "Furthermore, this degradation of BP-3 was not so obvious in the embryo study, probably due to the more frequent water exchange in this study. Previous studies (Liu et al., 2012; Rodil et al., 2009b) described microbial biodegradation of BP-3 to BP-1 as a common and fast phenomenon under oxic conditions. O-demethylation was proposed as main pathway for BP-3 biodegradation (over photolysis and hydrolysis). "
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ABSTRACT: Organic UV filters including benzophenone-3 (BP-3) are widely used to protect humans and materials from damage by UV irradiation. Despite the environmental occurrence of BP-3 in the aquatic environment, little is known about its effects and modes of action. In the present study we assess molecular and physiological effects of BP-3 in adult male zebrafish (Danio rerio) and in eleuthero-embryos by a targeted gene expression approach focusing on the sex hormone system. Fish and embryos are exposed for 14 days and 120 hours post fertilization, respectively, to 2.4-312 μg/L and 8.2-438 μg/L BP-3. Chemical analysis of water and fish demonstrates that BP-3 is partly transformed to benzophenone-1 (BP-1) and both compounds are accumulated in adult fish. Biotransformation to BP-1 is absent in eleuthero-embryos. BP-3 exposure leads to similar alterations of gene expression in both adult fish and eleuthero-embryos. In the brain of adult males esr1, ar and cyp19b are down-regulated at 84 μg/L BP-3. There is no induction of vitellogenin expression by BP-3, both at the transcriptional and protein level. An overall down-regulation of the hsd3b, hsd17b3, hsd11b2 and cyp11b2 transcripts is observed in the testes, suggesting an antiandrogenic activity. No histological changes were observed in the testes after BP-3 treatment. The study leads to the conclusion that low concentrations of BP-3 exhibit similar multiple hormonal activities at the transcription level in two different life stages of zebrafish. Forthcoming studies should show whether this translates to additional physiological effects.
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ABSTRACT: 2,4-dihydroxybenzophenone (benzophenone-1; BP-1) is an UV stabilizer primarily used to prevent polymer degradation and deterioration in quality due to UV irradiation. Recently, BP-1 has been reported to bioaccumulate in human bodies by absorption through the skin and have the potential to induce health problems including endocrine disruption. In the present study, we examined the xenoestrogenic effect of BP-1 on BG-1 human ovarian cancer cells expressing estrogen receptors (ERs) and relevant xenografted animal models in comparison with 17- β estradiol (E2). In in vitro cell viability assay, BP-1 (10(-8)∼10(-5)M) significantly increased BG-1 cell growth the way E2 did. The mechanism underlying the BG-1 cell proliferation was proved to be related with the up-regulation of cyclin D1, a cell cycle progressor, by E2 or BP-1. Both BP-1 and E2 induced cell growth and up-regulation of cyclin D1 were reversed by co-treatment with ICI 182,780, an ER antagonist, suggesting that BP-1 may mediate the cancer cell proliferation via an ER-dependent pathway like E2. On the other hand, the expression of p21, a regulator of cell cycle progression at G(1) phase, was not altered by BP-1 though it was down-regulated by E2. In xenograft mouse models transplanted with BG-1 cells, BP-1 or E2 treatment significantly increased the tumor mass formation compared to a vehicle (corn oil) within 8 weeks. In histopathological analysis, the tumor sections of E2 or BP-1 group displayed extensive cell formations with high density and disordered arrangement, which were supported by the increased number of BrdU positive nuclei and the over-expression of cyclin D1 protein. Taken together, these results suggest that BP-1 is an endocrine disrupting chemical (EDC) that exerts xenoestrogenic effects by stimulating the proliferation of BG-1 ovarian cancer via ER signaling pathway associated with cell cycle as did E2.
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ABSTRACT: Benzophenone-3 (BP-3), a sunscreen agent widely used in many cosmetic products, has been found to have a wide presence in aquatic environments, which could affect the water quality and human health. We investigated oxidation of BP-3 by aqueous ferrate(VI) (Fe(VI)) to determine reaction kinetics, identify the reaction products, and evaluate the removal efficiency of BP-3 during water treatment with Fe(VI). The obtained apparent second-order rate constant (kapp) for Fe(VI) oxidation of BP-3was 81.8 M-1 s-1 at pH 8.0 and 24 ± 1 °C with the half-life (t1/2) of 167.8 s for BP-3 at an Fe(VI) concentration of 10 mg L-1. The kapp of the reaction decreased with increasing pH values. Species-specific rate constants (k) for the reaction of HFeO4- with each of BP-3's acid-base species were used to model these pH-dependent variations of kapp. The value of k determined for neutral BP-3 was 3.4(±0.5) × 102 M-1 s-1, while that measured for dissociated BP-3 was 8.5(±0.7) × 103 M-1 s-1. The reaction between HFeO4- and the dissociated BP-3 controls the overall reaction. 4-Methoxybenzophenone and 4-methoxybenzoyl cation were formed during Fe(VI) degradation of BP-3. The removal efficiency of BP-3 by Fe(VI) treatment was dependent on coexisting constituents present in source water. Humic acids, Mn2+ and NaCl significantly decreased the removal efficiency of BP-3, while Br- and Cu2+ enhanced the removal. Besides, NH4+, NO3-, Fe3+ and Fe2+ had no effects on BP-3 removal within the tested concentrations. The results showed that Fe(VI) treatment technology appears to be a promising tool for the removal of hydroxylated benzophenone derivatives in water.
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