The organic UV filters are frequently added to personal care products such as cosmetics, skin creams, body lotions, shampoos, spray and hair dyes in order to prevent damage caused by ultraviolet light. For their hydrophobicity, leading to accumulation in biota or sediments, and their potential action as endocrine disruptors, the environmental fate of these organic substances is becoming of increasing concern. In the present study we focused on two organic UV filters, ethylhexyl methoxy cinnamate (EHMC) and 2-ethylexyl-4-(dimethylamino)benzoate (OD-PABA). Although EHMC is one the most used UVB filters worldwide and it is well tolerated by the skin, it has some side effects including its ability to produce reactive oxygen species and estrogenic properties both in vitro and in vivo. OD-PABA was also among the first compounds to be used as sunscreens, but from 2008 it is gradually being replaced by other organic UV filters because of the increasing evidence of photo-allergic reactions. To assess their environmental persistence and photoinduced transformation, the sunscreens were subjected to direct photolysis, by exposure to UVA and UVB radiation, whereas the environmental degradation upon indirect photochemistry was also simulated by the use of heterogeneous photocatalysis with titanium dioxide. The formation and evolution of transformation products (TPs) was followed via HPLC-HRMS for both processes. The study of MSn spectra, obtained using a LTQ Orbitrap mass spectrometer with ESI ion source, provided useful information to identify the TPs formed through the degradation. For EHMC, the main TPs detected in the direct photolysis process were the 4- methoxybenzaldehyde, plus a hydroxylated derivative and two dimeric species. Through the use of heterogeneous photocatalysis, seven addition TPs were identified, most of them resulting from the further degradation of TPs formed through direct photolysis and that might be also found in aquatic systems. For OD-PABA the direct photolysis is shown to play a key role in phototransformation and this fast process is expected to be the main attenuation route in sunlit surface waters. The main detected TPs of OD-PABA would involve a dealkylation or hydroxylation/oxidation process in both direct photolysis and indirect phototransformation.
Study of photochemical transformation of two sunscreens in surface waters by HRMS
CALZA, Paola;VIONE, Davide Vittorio;FABBRI, DEBORA;MEDANA, Claudio;MINERO, Claudio
2015-01-01
Abstract
The organic UV filters are frequently added to personal care products such as cosmetics, skin creams, body lotions, shampoos, spray and hair dyes in order to prevent damage caused by ultraviolet light. For their hydrophobicity, leading to accumulation in biota or sediments, and their potential action as endocrine disruptors, the environmental fate of these organic substances is becoming of increasing concern. In the present study we focused on two organic UV filters, ethylhexyl methoxy cinnamate (EHMC) and 2-ethylexyl-4-(dimethylamino)benzoate (OD-PABA). Although EHMC is one the most used UVB filters worldwide and it is well tolerated by the skin, it has some side effects including its ability to produce reactive oxygen species and estrogenic properties both in vitro and in vivo. OD-PABA was also among the first compounds to be used as sunscreens, but from 2008 it is gradually being replaced by other organic UV filters because of the increasing evidence of photo-allergic reactions. To assess their environmental persistence and photoinduced transformation, the sunscreens were subjected to direct photolysis, by exposure to UVA and UVB radiation, whereas the environmental degradation upon indirect photochemistry was also simulated by the use of heterogeneous photocatalysis with titanium dioxide. The formation and evolution of transformation products (TPs) was followed via HPLC-HRMS for both processes. The study of MSn spectra, obtained using a LTQ Orbitrap mass spectrometer with ESI ion source, provided useful information to identify the TPs formed through the degradation. For EHMC, the main TPs detected in the direct photolysis process were the 4- methoxybenzaldehyde, plus a hydroxylated derivative and two dimeric species. Through the use of heterogeneous photocatalysis, seven addition TPs were identified, most of them resulting from the further degradation of TPs formed through direct photolysis and that might be also found in aquatic systems. For OD-PABA the direct photolysis is shown to play a key role in phototransformation and this fast process is expected to be the main attenuation route in sunlit surface waters. The main detected TPs of OD-PABA would involve a dealkylation or hydroxylation/oxidation process in both direct photolysis and indirect phototransformation.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.