Photolysis of parabens using medium-pressure mercury lamps: Toxicity effects in MCF7, Balb/c 3T3 cells and Ceriodaphnia dubia

Abstract

Degradation studies of the propylparaben (PrP), butylparaben (BuP) and of the propylparaben-butylparaben mixture (PrP-BuP) in deionized water and surface river water was investigated as a function of pH and initial concentration of the reactants using a medium-pressure mercury lamp. The photolysis of parabens (concentration ranging from 5 to 30 mg L) followed apparent pseudo-first-order kinetics, with rate constants (k) in deionized water and surface river water changed from 1.80 × 10 to 3.68 × 10 min and 1.43 × 10 to 1.45 × 10 min, respectively. Degradation reaction was faster at pH 5 in comparison with pH 7 or 11. The photolysis of parabens was greater than 91%, with low mineralization (26.15%) observed in acidic medium after 95 min. Analysis by chromatography coupled to mass spectrometry (LC-MS/MS) showed that only one product was generated during the degradation reaction and has UV bands similar to 3,4-dihydroxybenzoic acid. Estrogenic activity tests showed that non-degraded parabens stimulated the growth of breast adenocarcinoma (MCF-7) cells and this effect was evaluated after the photolysis. Cytotoxicity assays using fibroblasts cells (Balb/C 3T3 clone A31) indicated that the parental compounds and degradation products were not cytotoxic. On the contrary, non-degraded parabens were toxic to Ceriodaphnia dubia, but the product of photolysis was not. Overall, the photolytic method presented was able to degrade these parabens providing safe and non-estrogenic reaction product.

Identifying potential paraben transformation products and evaluating changes in toxicity as a result of transformation

“…UV light facilitates bond lysis, producing smaller molecules. Photolysis of paraben species will occur in the presence of light, with the primary product being PHBA (Gomes et al, 2018). Methyl paraben has maximum absorption at 254 nm.…”

Paraben Compounds—Part II: An Overview of Advanced Oxidation Processes for Their Degradation

“…The study by Gomes et al [93] led to almost complete removal of PP and BuP using UV-Vis radiation, and the study by Álvarez et al [94] achieved 80-99.8% of single degradation for MP, EP, or BuP in 120 min using UV (254 nm) radiation. Both studies performed good results regarding the parabens degradation, but the study by Gmurek et al [35] using UVC radiation only led to about 20-30% mixture degradation for MP, EP, PP, and BuP removal in 120 min (BeP was 80% in 20 min), and the total removal was only achieved after 480 min.…”

“…In fact, Gmurek et al [35] used a higher concentration of parabens (10 mg/L of MP, EP, PP, BuP, and BeP each and 10 mg/L of p-HBA), while Gomes et al [93] only applied 10 mg/L of PP and BuP each (20 mg/L total). Moreover, Álvarez et al [94] only used about 45.65 mg/L of MP, 49.85 mg/L of EP, and 58.29 mg/L of BuP.…”

Comparison of radical-driven technologies applied for paraben mixture degradation: mechanism, biodegradability, toxicity and cost assessment

“…Moreover, the toxicity and oestrogenicity of benzylparaben is comparable to that of bisphenol A (Martins et al 2016). Parabens were detected in influents from WWTPs (even at concentrations of mg/L), and after the treatment in effluents, their concentrations were still high (including BzP) (Canosa et al 2006;Haman et al 2015;Marta-Sanchez et al 2018;Gomes et al 2018a). The presence of paraben was recorded in natural water in Japan, the UK, Portugal, Switzerland, Belgium, China, Spain and the USA in the range of 0.1-676 ng/L (Jonkers et al 2010;Haman et al 2015).…”