Aqueous photolysis of the sunscreen agent octyl-dimethyl-p-aminobenzoic acid. Formation of disinfection byproducts in chlorinated swimming pool water

Environmental fate of organic UV filters: Global occurrence, transformation, and mitigation via advanced oxidation processes

Organic UV filters are used in personal care products, plastics, paints, and textiles to protect against UV radiation. Despite regulatory limits, these compounds still enter the environment through direct wash-off during swimming, evaporation, leaching from products, and incomplete removal in wastewater treatment plants. They have been detected in various environmental matrices worldwide. Once in the environment, organic UV filters can undergo phototransformation and biotransformation, forming transformation products that, together with parent substances, pose health risks to humans and wildlife and harm marine ecosystems, especially coral reefs. The increasing concern over water scarcity and the environmental impact of pollutants underscores the importance of eliminating these contaminants from aquatic environments. This review primarily focuses on organic UV filters approved for use in sunscreens, many of which are also utilized in other materials, with a few exceptions including UV stabilizer UV-328. It includes an in-depth analysis of 155 peer-reviewed articles published from 2015 to 2024, assessing the concentrations of these filters in various environmental matrices, including water and solid matrices, air and biota. Moreover, this review explores the environmental transformation of these chemicals and assesses the effectiveness of advanced oxidation processes (AOPs) in removing these pollutants. The findings highlight the pervasive presence of organic UV filters in the environment and the promising potential of AOPs to mitigate the associated environmental challenges.

Degradation of organic UV filters in the water environment: A concise review on the mechanism, toxicity, and technologies

Organic ultraviolet filters (OUVFs) have been used globally for the past 20 years. Given that OUVFs can be quickly released from sunscreens applied on human skins, they have been frequently detected in aquatic environments and organisms. Some byproducts of OUVFs might be more recalcitrant and toxic than their parent compounds. To further assess the toxicity and potential risk of OUVFs' byproducts, it is necessary to determine the fate of OUVFs and identify their transformation products. This review summarizes and analyzes pertinent literature and reports in the field of OUVFs research. These published research works majorly focus on the degradation mechanisms of OUVFs in aquatic environments, their intermediates/byproducts, and chlorination reaction. Photodegradation (direct photolysis, self-sensitive photolysis and indirect photolysis) and biodegradation are the main transformation pathways of OUVFs through natural degradation. To remove residual OUVFs' pollutants from aqueous environments, novel physicochemical and biological approaches have been developed in recent years. Advanced oxidation, ultrasound, and bio-based technologies have been proven to eliminate OUVFs from wastewaters. In addition, the disinfection mechanism and the byproducts (DBPs) of various OUVFs in swimming pools are discussed in this review. Besides, knowledge gaps and future research directions in this field of study are also mentioned.

Status quo on identified transformation products of organic ultraviolet filters and their persistence

Organic micropollutants of concern-including organic UV filters (UVF)-are getting increasing attention. Personal care products such as sunscreens or cosmetic articles often contain large quantities of UVF. These substances enter the environment either directly (during outdoor activities) or indirectly (via sewages from households). Therefore, the removal or degradation of UVF by natural or technical treatment processes is important to understand. UVF are often incompletely removed and transformed to side products of incomplete mineralization by abiotic and biotic processes. An extensive overview on transformation products (TPs) is essential to systematically identify knowledge gaps and to derive research needs. While there are many reviews on the UVF themselves, the number of reviews which focus on their TPs is limited. Consequently, this review gives an overview on the latest findings regarding TPs of UVF. In this publication, known TPs of UVF, which were formed during abiotic and biotic processes, are reviewed. Target substances were defined and a literature database was reviewed for studies on TPs of the target substances. The first list of studies was shortened stepwise, thus generating a final list of studies which contained only the relevant studies. Since biodegradation is one of the most important pathways for removal of organic compounds from the environment, this review presents an overview on known TPs of organic UVF and their biodegradability, which determines their environmental fate. In this way, all identified TPs of UVF were listed and checked for information on their biodegradability. A total of 2731 records of studies were assessed. Forty-two studies, which assessed 46 processes that lead to the formation of identified TPs, were included in this review. One hundred and seventyseven different TPs resulting from 11 different UVF were identified. Little to no data on the biodegradability was found for TPs. This indicates a severe lack of data on the biodegradability of TPs of organic UVF substances. Since most TPs lack information on biodegradability, further research should provide information on both-identity and biodegradability-of formed TPs to be able to assess their hazardousness for the environment.

Application of gas chromatographic data and 2D molecular descriptors for accurate global mobility potential prediction

Mobility is a key feature affecting the environmental fate, which is of particular importance in the case of persistent organic pollutants (POPs) and emerging pollutants (EPs). In this study, the global mobility classification artificial neural networks-based models employing GC retention times (RT) and 2D molecular descriptors were constructed and validated. The high usability of RT was confirmed based on the feature selection step performed using the multivariate adaptive regression splines (MARS) tool. Although RT was found to be the most important, according to Kruskal-Wallis ANOVA analysis, it is insufficient to build a robust model, which justifies the need to expand the input layer with 2D descriptors. Therefore the following molecular descriptors: MPC10, WTPT-2, AATS8s, minaaCH, GATS7c, RotBtFrac, ATSC7v and ATSC1p, which were characterized by a high predicting potential were used to improve the classification performance. As a result of machine learning procedure ten of the most accurate neural networks were selected. The external validation showed that the final models are characterized by a high general accuracy score (85.71-96.43%). The high predicting abilities were also confirmed by the micro-averaged Matthews correlation coefficient (MAMCC) (0.73-0.88). To evaluate the applicability of the models, new retention times of selected POPs and EPs including pesticides, polycyclic aromatic hydrocarbons, pharmaceuticals, fragrances and personal care products were measured and used for mobility prediction. Further, the classifiers were used for photodegradation and chlorination products of two popular sunscreen agents, 2-ethyl-hexyl-4-methoxycinnamate and 2-ethylhexyl 4-(dimethylamino)benzoate.

Halogenated ingredients of household and personal care products as emerging endocrine disruptors

The everyday use of household and personal care products (HPCPs) generates an enormous amount of chemicals, of which several groups warrant additional attention, including: (i) parabens, which are widely used as preservatives; (ii) bisphenols, which are used in the manufacture of plastics; (iii) UV filters, which are essential components of many cosmetic products; and (iv) alkylphenol ethoxylates, which are used extensively as non-ionic surfactants. These chemicals are released continuously into the environment, thus contaminating soil, water, plants and animals. Wastewater treatment and water disinfection procedures can convert these chemicals into halogenated transformation products, which end up in the environment and pose a potential threat to humans and wildlife. Indeed, while certain parent HPCP ingredients have been confirmed as endocrine disruptors, less is known about the endocrine activities of their halogenated derivatives. The aim of this review is first to examine the sources and occurrence of halogenated transformation products in the environment, and second to compare their endocrine-disrupting properties to those of their parent compounds (i.e., parabens, bisphenols, UV filters, alkylphenol ethoxylates). Albeit previous reports have focused individually on selected classes of such substances, none have considered the problem of their halogenated transformation products. This review therefore summarizes the available research on these halogenated compounds, highlights the potential exposure pathways, and underlines the existing knowledge gaps within their toxicological profiles.

Magnetic Nanoparticle-Based Dispersive Solid-Phase Microextraction of Three UV Blockers Prior to Their Determination by HPLC-DAD

The need for proper handling of environmental samples is significant, owing to their environmental effects on both humans and animals, as well as their immediate surroundings. In the current study, magnetic nanoparticle-based dispersive solid-phase microextraction was combined with high-performance liquid chromatography using a diode array as the detector (HPLC-DAD) for both the separation and determination of three different UV blockers, namely octocrylene, ethylhexyl methoxycinnamate, and avobenzone. The optimum conditions for the extraction were found to be as follows: Stearic acid magnetic nanoparticles (20 mg) as the sorbent, acetonitrile (100 µL) as the eluent, as well as a sample pH of 2.50, adsorption and desorption time of 1.0 min, with a 3.0 mL sample volume. The limits of detection were as low as 0.05 µg mL-1. The coefficient of determination (R2) was above 0.9950, while the percentages of relative recoveries (%RR) were between 81.2 and 112% for the three UV blockers from the environmental water samples and sunscreen products.

Stability and Removal of Benzophenone-Type UV Filters from Water Matrices by Advanced Oxidation Processes

Benzophenone (BP) type UV filters are common environmental contaminants that are posing a growing health concern due to their increasing presence in water. Different studies have evidenced the presence of benzophenones (BP, BP-1, BP-2, BP-3, BP-4, BP-9, HPB) in several environmental matrices, indicating that conventional technologies of water treatment are not able to remove them. It has also been reported that these compounds could be associated with endocrine-disrupting activities, genotoxicity, and reproductive toxicity. This review focuses on the degradation kinetics and mechanisms of benzophenone-type UV filters and their degradation products (DPs) under UV and solar irradiation and in UV-based advanced oxidation processes (AOPs) such as UV/H₂O₂, UV/persulfate, and the Fenton process. The effects of various operating parameters, such as UV irradiation including initial concentrations of H₂O₂, persulfate, and Fe²⁺, on the degradation of tested benzophenones from aqueous matrices, and conditions that allow higher degradation rates to be achieved are presented. Application of nanoparticles such as TiO₂, PbO/TiO₂, and Sb₂O₃/TiO₂ for the photocatalytic degradation of benzophenone-type UV filters was included in this review.

Chromatographic methods for the determination of a broad spectrum of UV filters in swimming pool water

This paper describes an analytical approach based on solid-phase extraction (SPE) followed by analysis using liquid and gas chromatography coupled to mass spectrometry detectors for a determination of 18 organic UV filters from water samples. Extraction method parameters were optimized: 250 ml of water sample loaded on Chromabond C18 cartridges after adjustment to pH 4 and then eluted with acetonitrile. The mobile phase and the parameters of the mass spectrometer, as well as those of the ionization source, were tested to enhance detection sensitivity. During method validation, the extracted target compounds showed good recoveries (> 68%) with acceptable values in terms of repeatability (RSD_r) and reproducibility (RSD_R), where relative standard deviations values were lower than 20%. The validated method was applied to 10 water samples collected from different swimming pools located in Lebanon from which eight UV filters among the eighteen targets compounds were detected at concentrations ranged between 1 and 2526 µg L^-1. The most detected compounds were padimate-O (OD-PABA) and octocrylene (OCR). This study represents the first available data on the occurrence of UV filter residues in Lebanese swimming pool opening hence future perspectives and insights to evaluate their degradation by-products and their toxicity on human health and marine ecosystem.

Transformation of Organic Compounds during Water Chlorination/Bromination: Formation Pathways for Disinfection By-Products (A Review)

The purity of drinking water is an important issue of the human life quality. Water disinfection has saved millions people from the diseases spread with water. However, that procedure has a certain drawback due to formation of toxic organic disinfection products. Establishing the structures of these products and the mechanisms of their formation and diminishing their levels in drinking water represent an important task for chemistry and medicine, while mass spectrometry is the most efficient tool for the corresponding studies. The current review throws light upon natural and anthropogenic sources of the formation of disinfection by-products (DBPs) and the mechanisms of their formation related to the structural peculiarities and the presence of functional groups. In addition to chlorination, bromination is discussed since it is used quite often as an alternative method of disinfection, particularly, for the purification of swimming pool water. The benefits of the contemporary GC/MS and LC/MS methods for the elucidation of DBP structures and study of the mechanisms of their formation are discussed. The reactions characteristic for various functional groups and directions of transformation of certain classes of organic compounds in conditions of aqueous chlorination/bromination are also covered in the review.

Analyzing the Photoprotection Efficiency of Sunscreens Containing Antioxidants under Disinfection Conditions

Sunscreens ensure thorough protection against sunburn. The delivery of UV filters into the stratum corneum and viable epidermis could be reduced by the use of antioxidants (such as β-carotene and trans-resveratrol, alone or combined). The presence/absence of antioxidants (trans-resveratrol and β-carotene) in formulations containing benzophenone-3 (UV-filter) and their efficiency under disinfection and neutral conditions are studied and compared. The trial was conducted on 38 people. The prepared ointments were applied to the participants’ forearms, irradiated and monitored by reflectance colorimetry after 0, 4, 6, and 8 min. Descriptive statistics were used to describe the skin color’s main characteristics and the F-ratio was used to test overall differences. The ointments containing antioxidants and benzophenone-3 were the most efficient, followed by those with benzophenone-3 alone. It was proven that photoprotection with benzophenone-3 is still effective, despite the formation of its chlorinated products. Due to the short time of exposure to disinfecting conditions, it could be assumed that benzophenone-3 was only partially chlorinated. This clinical study demonstrated that formulations containing antioxidants are likely to be more suitable for protecting skin against UVB irradiation than a UV filter alone.

Fabrication of Cementitious Microfiltration Membrane and Its Catalytic Ozonation for the Removal of Small Molecule Organic Pollutants

In this study, a low-cost cementitious microfiltration membrane (CM) with a catalytic ozone oxidation function for the removal of organic pollutants was fabricated by using cementitious and C-10 μm silica powders at a certain silica–cementitious particle ratio (s/c). The effect of the s/c on the pore size distribution and mechanical strength of the membrane was investigated. The membrane pore size showed a bimodal distribution, and the higher the s/c, the closer the second peak was to the accumulated average particle size of silica. The increase in the s/c led to a decrease in the bending strength of the membrane. The cross-sectional morphology by SEM and crystal structure by XRD of CMs confirmed that a calcium silicate hydrate gel was generated around the silica powder to improve the mechanical strength of the CM. Considering the bending strength and pore size distribution of CMs, s/c = 0.5 was selected as the optimal membrane fabrication condition. The FT-IR results characterizing the surface functional groups of CMs were rich in surface hydroxyl groups with the ability to catalyze ozone oxidation for organic pollutant removal. Six small molecule organic pollutants were selected as model compounds for the efficiency experiments via a CM–ozone coupling process to prove the catalytic property of the CM. The CM has an alkaline buffering effect and can stabilize the initial pH of the solution in the catalytic ozonation process. The reuse experiments of the CM–ozone coupling process demonstrated the broad spectrum of the CM catalytic performance and self-cleaning properties. The results of this study provide the basis and experimental support to expand the practical application of CMs.

Determination of environmental properties and toxicity of octyl-dimethyl-para-aminobenzoic acid and its degradation products

Octyl-dimethyl-para-aminobenzoic acid (ODPABA) is one of compounds of emerging concern. It undergoes transformations under the influence of oxidizing or chlorinating agents and UV radiation forming products with different properties. There is very little experimental data concerning the environmental fate of ODPABA and its transformation products. Therefore, the purpose of the studies was to determine environmental parameters: water solubility, soil - water partition coefficient, octanol - air partition coefficient, bioconcentration factor as well as half-life in air, water and soil. Based on the results obtained, the persistence and migration possibilities of ODPABA and its transformation products in the aquatic environment were estimated. Moreover, the ecological toxicity of oxidation and chlorination products was investigated. Microtox®, Daphtoxkit F® and Artoxkit M® tests were used to determine toxicity. LC₅₀ for Fish and Daphnia magna was calculated by Ecosar module. Studies have shown that as a result of ODPABA transformations, chloroorganic products are formed, which are lipophilic, are bioconcentrated in organic matter, are characterized by significant environmental persistence, can spread over considerable distances and are toxic. Oxidation products have significantly smaller impact on the environment. They are characterized by higher water solubility, lower bioconcentration factor and are less toxic.

Degradation studies of UV filter hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]-benzoate (DHHB) in aqueous solution

High performance liquid chromatography coupled with ultra-violet, diode array detection (HPLC-UV-DAD), was used to study the degradation reactions of ultraviolet (UV) filter hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]-benzoate (DHHB). Degradation by-products were detected and identified by means of liquid chromatography coupled with diode array detection and mass spectrometry (LC-DAD-MS). Environmentally-relevant characteristics, such as water pH, chlorine levels, water temperature and dissolved organic matter (DOM) concentration, were modulated and studied in order to determine their influence on the degradation reactions. Results show that DHHB degrades quite rapidly in typical drinking water disinfection conditions, displaying a kinetic rate constant of k_obs = 0.0060 ± 0.0002 s^-1 and a half-life period of merely t_1/2 = 116 ± 4 s. As far as the non-volatile disinfection by-products (DBPs) are concerned, only the mono and dichlorinated forms of DHHB were detected in the degradation reactions. Regarding influential variables on DHHB degradation, the presence or absence of DOM in solution did not alter the trends that were found (degradation of DHHB is more significant at lower pH values and higher levels of active chlorine in solution). Chlorinated DBPs have also been found to predominate under higher pH values and lower levels of chlorine, whereas they were found to be unstable and further degradable, quite likely into smaller and more volatile compounds, when in lower pH and higher chlorine concentrations. As for the photo-degradation studies, DHHB was found to be extremely photo-stable, with only about 15% degradation rate detected during artificial irradiation periods of 6 h.

+Chlorination by-products in indoor swimming pools: Development of a pilot pool unit and impact of operating parameters

Chlorine addition in swimming pools ensures the microbiological quality of the water and the bathers' safety. However, water chlorination is associated with disinfection byproducts (DBP) formation and adverse health effects. The impact of operating parameters and innovative water treatment systems on DBPs levels has been reported in several studies, but sampling campaign in real pools remain difficult to carry out, mainly due to unexpected attendance variations. This study presents the development of a pilot pool plant allowing to perform experiments under controlled and reproducible conditions. Bathers inputs were simulated both for the organic load and for the mechanical agitation of water. Two sampling campaigns were performed during the building of the pilot, before and after the hall was closed. Key operating parameters such as chlorine dose, water temperature and attendance were controlled and monitored. DBP levels in the pilot plant were representative of French indoor swimming pools and the impact of bathers' activity was visible on volatile DBPs. Furthermore, correlations could be stated between operating parameters and DBP levels. Stripping effectively reduced volatile DBP concentrations in water. Moreover, energy consumption data, which are usually very scarce in experimental studies, showed the influence of heat pump consumption on the global energy consumption.

Sunscreens as a New Source of Metals and Nutrients to Coastal Waters

Studies detailing the environmental impact of sunscreen products on coastal ecosystems are considered a high priority. In the present study, we have determined the release rate of dissolved trace metals (Al, Cd, Cu, Co, Mn, Mo, Ni, Pb, and Ti) and inorganic nutrients (SiO₂, P-PO₄^3-, and N-NO₃^-) from a commercial sunscreen in seawater, and the role of UV radiation in the mobilization of these compounds. Our results indicate that release rates are higher under UV light conditions for all compounds and trace metals except Pb. We have developed a kinetic model to establish the release pattern and the contribution to marine coastal waters of dissolved trace metals and inorganic nutrients from sunscreen products. We conservatively estimate that sunscreen from bathers is responsible for an increase of dissolved metals and nutrients ranging from 7.54 × 10^-4 % for Ni up to 19.8% for Ti. Our results demonstrate that sunscreen products are a significant source of metals and inorganic nutrients to coastal waters. The normally low environmental concentrations of some elements (e.g., P) and the toxicity of others (e.g., Pb) could be having a serious adverse effect on marine ecology in the Mediterranean Sea. This risk must not be ignored.

The use of fast molecular descriptors and artificial neural networks approach in organochlorine compounds electron ionization mass spectra classification

Developing of theoretical tools can be very helpful for supporting new pollutant detection. Nowadays, a combination of mass spectrometry and chromatographic techniques are the most basic environmental monitoring methods. In this paper, two organochlorine compound mass spectra classification systems were proposed. The classification models were developed within the framework of artificial neural networks (ANNs) and fast 1D and 2D molecular descriptor calculations. Based on the intensities of two characteristic MS peaks, namely, [M] and [M-35], two classification criterions were proposed. According to criterion I, class 1 comprises [M] signals with the intensity higher than 800 NIST units, while class 2 consists of signals with the intensity lower or equal than 800. According to criterion II, class 1 consists of [M-35] signals with the intensity higher than 100, while signals with the intensity lower or equal than 100 belong to class 2. As a result of ANNs learning stage, five models for both classification criterions were generated. The external model validation showed that all ANNs are characterized by high predicting power; however, criterion I-based ANNs are much more accurate and therefore are more suitable for analytical purposes. In order to obtain another confirmation, selected ANNs were tested against additional dataset comprising popular sunscreen agents disinfection by-products reported in previous works.

Bioaccumulation and biochemical effects of ethylhexyl methoxy cinnamate and its main transformation products in zebrafish

The purpose of this study was to investigate the bioaccumulation and biochemical responses exposed to one of the main organic ultraviolet (UV) pollutants in the environment, ethylhexyl methoxy cinnamate (EHMC), and its main transformation product, either alone or in combination in zebrafish (Danio rerio). Four-month-old zebrafish were exposed to EHMC (34.4, 344 nmol/L) solution for 14 days, the species and contents of EHMC transformation products in zebrafish were determined and 3,5-dichloro-2-hydroxyacetophenone (3,5DCl₂HAcP) was the one with the highest concentration in transformation products. Then, zebrafish were exposed to EHMC, 3,5DCl₂HAcP alone and mixed solution for 21 days. At 7, 14 and 21 d, the related indexes of antioxidant defense system were determined. Results showed that both EHMC and 3,5DCl₂HAcP can lead to the increase of malondialdehyde (MDA) and glutathione (GSH) contents, superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) activities in visceral mass compared with the corresponding control group, thus produced oxidative stress effect in organism and 3,5DCl₂HAcP even showed stronger oxidative stress than EHMC. The effects of the two lower concentration co-exposure groups were similar and more significant to that of single exposure groups, while excessive oxidative stress occurred at the highest co-exposure group indicated by the decrease of GSH content, SOD, CAT, GR activities and the continued increase of MDA content. At 21 d, estradiol (E₂), vitellogenin (Vtg) and testosterone (T) contents, estrogen receptor (Esr), progesterone receptor (Pgr), androgen receptor (Ar), Vtg1, P450 aromatase (Cyp19a1) and 17β-hydroxysteroid dehydrogenase (Hsd17b3) expression were all significantly increased when exposed to 3,5DCl₂HAcP alone, showing complex estrogen and androgen effects. When exposed to EHMC alone, E₂ and Vtg contents, Esr, Pgr, Vtg1, Cyp19a1 and Hsd17b1 gene expression levels decreased significantly, and T content and Ar and Hsd17b3 expression increased significantly, indicated that EHMC can produce anti-estrogen and androgen effect. Last, the decrease of estrogen effect and increase of androgen effect in co-exposure group suggested that 3,5DCl₂HAcP might weaken the estrogen effect and promote the androgen effect of EHMC.

Effecting Partial Elimination of Isocyanuric Acid from Swimming Pool Water Systems

It is essential to disinfect the water in swimming pools in order to deactivate pathogenic microorganisms. Chlorination of swimming pool water provides rapid and long-lasting disinfection, but leads to the formation of potentially toxic compounds, including isocyanuric acid, that are used to stabilize chlorine in pool water. Hygiene and health guidelines require an isocyanuric acid concentration in swimming pools of 25 to 75 ppm and that there be no level in excess of 100 ppm. This paper provides a new method to partially remove isocyanuric acid from the water of swimming pool systems with the use of melamine-based reagents. A melamine-photometry process stabilizes the isocyanuric acid. The melamine-based reagent that is added to the raw water reacts with the isocyanuric acid and forms a precipitated salt. The reaction also creates turbidity that is proportional to the isocyanuric acid concentration in the water. It was noted in this study that the optimum functioning range of melamine doses in the raw water was 0.04 to 0.06 g/L and that the reduction of isocyanuric acid in raw water increased as the dose of melamine was increased. Thus, it is necessary to obtain an estimate of the dose of melamine that is necessary to reduce the isocyanuric acid in the water without needing to add fresh water from the network to dilute it. Finally, it can be stated that eliminating isocyanuric acid that has accumulated in a pool’s water by treatment with melamine provides an efficient process, as it eliminates the amount of isocyanuric acid that is necessary to conform to the human health criteria of the European Union Directive 2006/7/EC. Treatment with melamine also reduces water network consumption and sewer discharge by successive purges that eventually will become unnecessary. Therefore, this proposed method is environmentally and economically beneficial.

Regulation, formation, exposure, and treatment of disinfection by-products (DBPs) in swimming pool waters: A critical review

The microbial safety of swimming pool waters (SPWs) becomes increasingly important with the popularity of swimming activities. Disinfection aiming at killing microbes in SPWs produces disinfection by-products (DBPs), which has attracted considerable public attentions due to their high frequency of occurrence, considerable concentrations and potent toxicity. We reviewed the latest research progress within the last four decades on the regulation, formation, exposure, and treatment of DBPs in the context of SPWs. This paper specifically discussed DBP regulations in different regions, formation mechanisms related with disinfectants, precursors and other various conditions, human exposure assessment reflected by biomarkers or epidemiological evidence, and the control and treatment of DBPs. Compared to drinking water with natural organic matter as the main organic precursor of DBPs, the additional human inputs (i.e., body fluids and personal care products) to SPWs make the water matrix more complicated and lead to the formation of more types and greater concentrations of DBPs. Dermal absorption and inhalation are two main exposure pathways for trihalomethanes while ingestion for haloacetic acids, reflected by DBP occurrence in human matrices including exhaled air, urine, blood, and plasma. Studies show that membrane filtration, advanced oxidation processes, biodegradation, thermal degradation, chemical reduction, and some hybrid processes are the potential DBP treatment technologies. The removal efficiency, possible mechanisms and future challenges of these DBP treatment methods are summarized in this review, which may facilitate their full-scale applications and provide potential directions for further research extension.

Environmental exposure of anthropogenic micropollutants in the Prut River at the Romanian-Moldavian border: a snapshot in the lower Danube river basin

The Prut River, the second longest tributary of the Danube river, was investigated for a wide range of anthropogenic organic pollutants to fill the data gap on environmental contamination in eastern European surface waters. In this study, the occurrence of a wide range of organic pollutants was measured along the transboundary Prut River, between Sculeni and Branza in 2010-2012. Using two different analytical methods, gas chromatography coupled to mass spectrometry and liquid chromatography coupled to high-resolution mass spectrometry, over 300 compounds were screened for and 88 compounds were determined in the Prut River. In general, the chemicals occurred at low levels. At the last sampling site upstream of the confluence with the Danube river at Branza, the highest average concentrations (≥ 100 ng L^-1) were determined for the artificial sweetener acesulfame, the pharmaceuticals metformin, 4-acetamidoantipyrene, and 4,4,5,8-tetramethylchroman-2-ol, the antioxidants 2,4-di-tert-butylphenol, 3-tert-butyl-4-hydroxyanisol, and 3,5-di-tert-butyl-4-hydroxy-toluene, the personal care products HHCB (galaxolide), 4-phenyl-benzophenone, and octyl dimethyl-p-aminobenzoic acid, the industrial chemical diphenylsulfone, and the sterol cholesterol. Low concentrations of agricultural pesticides occurred in the catchment. At Branza, the total accumulated load of all measured compounds was calculated to be almost 19 kg day^-1. In comparison to the Rhine River, the loads in the Prut, determined with same LC-HRMS method for the same set of analytes, were two orders of magnitude lower. Discharge of wastewater without proper treatment from the city of Iasi in the Jijia catchment (Romania) as well as from the city of Cahul (Moldova) revealed a distinct increase in concentrations and loads in the Prut at Frasinesti and Branza. Thus, an implementation of wastewater treatment capacities in the Prut River basin would considerably reduce the loads of micropollutants from urban point sources.

Degradation of methadone by the sunlight/FC process: Kinetics, radical species participation and influence of the water matrix

Free chlorine sunlight photolysis (sunlight/FC) markedly enhances the degradation rate of methadone, a synthetic opioid used medically, over that obtained using sunlight alone. The pseudo-first-order rate constants of methadone degradation under acidic conditions ([methadone] = 0.2 μM, [free chlorine] = 4 μM, and pH = 4) for sunlight/FC and sunlight photolysis are 7.0 ± 1.1 × 10^-2 min^-1 and 1.4 ± 0.2 × 10^-2 min^-1, respectively. The improved methadone degradation can be attributed to the production of HO and reactive chlorine species (RCS) during sunlight/FC photolysis. HO and RCS predominantly accounted for degradation during sunlight/FC photolysis under acidic and neutral conditions, while direct photolysis was the major contributor towards methadone degradation in alkaline conditions. The initial pH (pH 4-11) and free chlorine concentration (1-6 μM) significantly influenced the overall degradation efficiency of methadone. The presence of HCO₃^-, Cl^- and dissolved organic matters, which may competitively react with HO and RCS, retard the degradation of methadone in synthetic wastewater. Consequently, a 50% lower methadone degradation rate was observed when deionized (DI) water was replaced with tap water. These results emphasize the need to consider different water matrices when applying sunlight/FC photolysis for water treatment.

Removal of 2-phenylbenzimidazole-5-sulfonic acid using heterogeneous photocatalysis

UV filters are classified as environmental pollutants (emerging pollutants). One of the most frequently detected UV filters in real samples is 2-phenylbenzimidazole-5-sulfonic acid (PBSA). It has been shown that conventional technologies applied in sewage treatment plants are not adapted for complete removal of sunscreen agents. Therefore, there is a trend to undertake activities leading to improvement of water quality by enhancing treatment methods. This is important due to the fact that in an aqueous environment, in the presence of UV radiation or sunlight irradation, PBSA generates reactive oxygen species that can damage the DNA of living organisms. The aim of study was to investigate an effect of pH and TiO2 on PBSA stability in the presence of UV radiation. It was found that the rate of PBSA degradation depends on the catalyst dose and pH of solution. The photocatalysis reaction was carried out in a Heraeus laboratory exposure set equipped with a 150 W mediumpressure mercury lamp. The course of PBSA degradation process as a function of time was monitored using UV/VIS spectrophotometer and liquid chromatograph equipped with UV-Vis detector.

Estimation of physicochemical properties of 2-ethylhexyl-4-methoxycinnamate (EHMC) degradation products and their toxicological evaluation

The organic UV filters, commonly used in personal protection products, are of concern because of their potential risk to aquatic ecosystems and living organisms. One of UV filters is ethylhexyl-4-methoxycinnamate (EHMC) acid. Studies have shown that, in the presence of oxidizing and chlorinating factors, EHMC forms a series of products with different properties than the substrate. In this study, the toxicities of EHMC and its transformation/degradation products formed under the influence of NaOCl/UV and H₂O₂/UV systems in the water medium were tested using Microtox® bioassay and by observation of mortality of juvenile crustaceans Daphnia magna and Artemia Salina. We have observed that oxidation and chlorination products of EHMC show significantly higher toxicity than EHMC alone. The toxicity of chemicals is related to their physicochemical characteristic such as lipophilicity and substituent groups. With the increase in lipophilicity of products, expressed as log K_OW, the toxicity (EC₅₀) increases. On the basis of physicochemical properties such as vapour pressure (VP), solubility (S), octanol-water partition coefficient (K_OW), bioconcentration factor (BCF) and half-lives, the overall persistence (P_OV) and long-range transport potential (LRTP) of all the products and EHMC were calculated. It was shown that the most persistent and traveling on the long distances in environment are methoxyphenol chloroderivatives, then methoxybenzene chloroderivatives, EHMC chloroderivatives, methoxybenzaldehyde chloroderivatives and methoxycinnamate acid chloroderivatives. These compounds are also characterised by high toxicity.

Degradation kinetics of organic chloramines and formation of disinfection by-products during chlorination of creatinine

Organic chloramines can interfere with the measurement of effective combined chlorine in chlorinated water and are potential intermediate products of highly toxic disinfection by-products (DBPs). In order to know more about the degradation and transformation of organic chloramines, a typical organic chloramine precursor creatinine was selected for investigation and a corresponding individual organic chloramine chlorocreatinine was prepared in this study. The preparation condition of chlorocreatinine by chlorination was established as chlorine/creatinine = 1 M/M, reaction time = 2 h and pH = 7.0. Then the degradation kinetics of chlorocreatinine during further chlorination was studied, and a second-order rate constant of 1.16 (±0.14) M^-1 s^-1 was obtained at pH 7.0. Solution pH significantly influenced the degradation rate, and the elementary rate constants of chlorocreatinine with HOCl+H⁺, HOCl, OCl^- and chlorocreatinine^- with OCl^- were calculated as 2.43 (±1.55) × 10⁴ M^-2 s^-1, 1.05 (±0.09) M^-1 s^-1, 2.86 (±0.30) M^-1 s^-1 and 3.09 (±0.24) M^-1 s^-1, respectively. Besides, it was found that chlorocreatinine could be further converted into several C-DBPs (chloroform and trichloroacetone) and N-DBPs (dichloroacetonitrile (DCAN) and trichloronitromethane (TCNM)) during chlorination. The total yield of DBPs increased obviously with increasing pH, especially for TCNM. In addition, the presence of humic acid in creatinine solution could increase the formation of DCAN obviously during chlorination. Based on the UPLC-Q-TOF-MS analysis, the conversion pathways of chlorocreatinine were proposed. Several kinds of intermediate products were also identified as organic chloramines and some of them could even exist stably during the further chlorination.

Degradation of Organic UV filters in Chlorinated Seawater Swimming Pools: Transformation Pathways and Bromoform Formation

Organic ultraviolet (UV) filters are used in sunscreens and other personal-care products to protect against harmful effects of exposure to UV solar radiation. Little is known about the fate of UV filters in seawater swimming pools disinfected with chlorine. The present study investigated the occurrence and fate of five commonly used organic UV filters, namely dioxybenzone, oxybenzone, avobenzone, 2-ethylhexyl-4-methoxycinnamate, and octocrylene, in chlorinated seawater swimming pools. Pool samples were collected to monitor the variation of UV filter concentrations during pool opening hours. Furthermore, laboratory-controlled chlorination experiments were conducted in seawater spiked with UV filters to investigate the reactivity of UV filters. Extracts of chlorination reaction samples were analyzed using high-resolution mass spectrometry and electron-capture detection to identify the potentially formed byproducts. In the collected pool samples, all the UV filters except dioxybenzone were detected. Chlorination reactions showed that only octocrylene was stable in chlorinated seawater. The four reactive UV filters generated brominated transformation products and disinfection byproducts. This formation of brominated products resulted from reactions between the reactive UV filters and bromine, which is formed rapidly when chlorine is added to seawater. Based on the identified byproducts, the transformation pathways of the reactive UV filters were proposed for the first time. Bromoform was generated by all the reactive UV filters at different yields. Bromal hydrate was also detected as one of the byproducts generated by oxybenzone and dioxybenzone.

A Potential New Threat to Wild Life: Presence of UV Filters in Bird Eggs from a Preserved Area

The present study uses bird eggs of seven wild species as a biomonitoring tool for sunscreens occurrence. Seven UV filters (UV-Fs), including 3 hydroxy-metabolites of oxybenzone (benzophenone 3, BP3) were characterized in unhatched eggs from Doñana Natural Space (Spain). High frequency of detection was observed for all UV-Fs, ranging from 95% to 100%. The oxybenzone metabolite 4-hydroxybenzophenone (4HB) was ubiquitous at concentrations in the range 12.0-3348 ng g^-1 dry weight (dw). The parent compound, oxybenzone, was also present in all samples at lower concentrations (16.9-49.3 ng g^-1 dw). Due to the three BP3's metabolites, benzophenone 1 (BP1), 4HB, and 4,4'-dihydroxybenzophenone (4DHB) presence in unhatched eggs, it can be inferred that parent compounds are absorbed into the bird through the upper gut and the OH-derivatives formed are transferred by the mother to the egg before the lying. White stork (Ciconia ciconia) and western marsh harrier (Circus aeruginosus) were the most contaminated species, with mean total UV-Fs concentrations of 834 and 985 ng g^-1 dw, respectively. Results evidenced that biomagnification process across the bird species studied cannot be ruled out.

Occurrence and formation of disinfection by-products in the swimming pool environment: A critical review

Disinfection of water for human use is essential to protect against microbial disease; however, disinfection also leads to formation of disinfection by-products (DBPs), some of which are of health concern. From a chemical perspective, swimming pools are a complex matrix, with continual addition of a wide range of natural and anthropogenic chemicals via filling waters, disinfectant addition, pharmaceuticals and personal care products and human body excretions. Natural organic matter, trace amounts of DBPs and chlorine or chloramines may be introduced by the filling water, which is commonly disinfected distributed drinking water. Chlorine and/or bromine is continually introduced via the addition of chemical disinfectants to the pool. Human body excretions (sweat, urine and saliva) and pharmaceuticals and personal care products (sunscreens, cosmetics, hair products and lotions) are introduced by swimmers. High addition of disinfectant leads to a high formation of DBPs from reaction of some of the chemicals with the disinfectant. Swimming pool air is also of concern as volatile DBPs partition into the air above the pool. The presence of bromine leads to the formation of a wide range of bromo- and bromo/chloro-DBPs, and Br-DBPs are more toxic than their chlorinated analogues. This is particularly important for seawater-filled pools or pools using a bromine-based disinfectant. This review summarises chemical contaminants and DBPs in swimming pool waters, as well as in the air above pools. Factors that have been found to affect DBP formation in pools are discussed. The impact of the swimming pool environment on human health is reviewed.

Photolysis and cellular toxicities of the organic ultraviolet filter chemical octyl methoxycinnamate and its photoproducts

Organic ultraviolet filter chemicals (UVFCs) are the active ingredients used in many sunscreens to protect the skin from UV light; these chemicals have been detected in numerous aquatic environments leading to concerns about how they might affect aquatic organisms and humans. One commonly used organic UVFC is octyl methoxycinnamate (OMC), better known by its commercial name, octinoxate. Upon exposure to UV light, OMC degrades rapidly, forming numerous photoproducts, some of which have been previously identified. In this study, we isolated and completely characterized the major products of OMC photolysis, including the two major stable OMC cyclodimers. One of these cyclodimers is a δ-truxinate, resulting from a head-to-head dimerization of two OMC molecules, and the other cyclodimer is an α-truxillate, resulting from a head-to-tail dimerization of two OMC molecules. Additionally, the cellular toxicities of the individual photoproducts were determined; it was found that the parent UVFC, OMC, 4-methoxybenzaldehyde, and two cyclodimers are significantly toxic to cells. The photoproduct 2-ethylhexanol is not cytotoxic, demonstrating that different components of OMC photolysate contribute differently to its cellular toxicity. This study thus provides an enhanced understanding of OMC photolysis and gives toxicity data that can be used to better evaluate OMC as a sunscreen agent.

Studies on the formation of formaldehyde during 2-ethylhexyl 4-(dimethylamino)benzoate demethylation in the presence of reactive oxygen and chlorine species

In order to protect the skin from UV radiation, personal care products (PCPS) often contain chemical UV-filters. These compounds can enter the environment causing serious consequences on the water ecosystems. The aim of this study was to examine, the effect of different factors, such as UV light, the presence of NaOCl and H₂O₂ on the formaldehyde formation during popular UV filter, 2-ethylhexyl 4-(dimethylamino)benzoate (ODPABA) demethylation. The concentration of formaldehyde was determined by VIS spectrophotometry after derivatization. The reaction mixtures were qualitatively analyzed using GC/MS chromatography. The highest concentration of formaldehyde was observed in the case of ODPABA/H₂O₂/UV reaction mixture. In order to describe two types of demethylation mechanisms, namely, radical and ionic, the experimental results were enriched with Fukui function analysis and thermodynamic calculations. In the case of non-irradiated system containing ODPABA and NaOCl, demethylation reaction probably proceeds via ionic mechanism. As it was established, amino nitrogen atom in the ODPABA molecule is the most susceptible site for the HOCl electrophilic attack, which is the first step of ionic demethylation mechanism. In the case of irradiated mixtures, the reaction is probably radical in nature. The results of thermodynamic calculations showed that abstraction of the hydrogen from N(CH₃)₂ group is more probable than from 2-ethylhexyl moiety, which indicates higher susceptibility of N(CH₃)₂ to the oxidation.

Effect of bromide on the transformation and genotoxicity of octyl-dimethyl-p-aminobenzoic acid during chlorination

Octyl-dimethyl-p-aminobenzoic acid (ODPABA), one of the most commonly used organic UV filters, can undergo considerable transformation in water when entering into the disinfection process. The impacts of bromide on degradation kinetics, formation and speciation of transformation products, regulated disinfection by-products (DBPs) as well as genotoxicity changes during ODPABA chlorination were investigated in this study. Results indicated that the reaction of ODPABA with chlorine followed pseudo-first-order and second-order kinetics. Adding bromide noticeably enhanced the degradation rate of ODPABA, but reduced the impact of chlorine dose. Four halogenated transformation products (Cl-ODPABA, Br-ODPABA, Cl-Br-ODPABA and Br₂-ODPABA) were detected by LC-MS/MS. Mono-halogenated products were stable during 24-h chlorination, while di-halogenated products constantly increased. The total yields of trihalomethanes (THMs) and haloacetic acids (HAAs) were both low, but predominated by bromine substitution at high levels of bromide. In addition, SOS/umu tests showed that genotoxicity was generated after ODPABA chlorination, which was increased at least 1.5 times in the presence of bromine. Whereas, no significant genotoxicity variation was observed following bromide concentration change.

Occurrence of pharmaceuticals and UV filters in swimming pools and spas

The occurrence of 32 pharmaceuticals and 14 UV filters in swimming pools and spas was studied. Fifty-one water samples were collected from 17 pools located in sport centres and hotels in Catalonia, Spain. The samples were analysed by liquid chromatography-tandem mass spectrometry. The pharmaceuticals atenolol, carbamazepine, hydrochlorothiazide, metronidazole, ofloxacin, sulfamethoxazole, acetaminophen, ibuprofen, ketoprofen and phenazone were measured in water samples at concentrations higher than their limit of quantification (LOQ). The highest concentration of any individual pharmaceutical was measured for the diuretic hydrochlorothiazide (904 ng/L). The most frequently detected pharmaceutical was carbamazepine, as it was observed in more than half of all the water samples measured (53 %, 27/51). The UV filters at concentrations higher than LOQ in water samples were BP1, BP2, BP3, BP8, THB, 4DHB, 4MBC, OD-PABA, 1HBT, MeBT and DMeBT. The highest concentration of UV filter observed was 4MBC (69.3 ng/L) while the most frequent UV filters in the samples were 1HBT (59 %, 30/51). The results also showed that pharmaceuticals and UV filters were most frequently found in spas. Finally, from a water treatment technology perspective, the lowest occurrence of pharmaceuticals was in the pools applying sand filters followed by disinfection by sodium hypochlorite, while the lowest occurrence of UV filters was in the pools applying coagulation, sand filtration, UV and salt electrolysis.

UV filters interaction in the chlorinated swimming pool, a new challenge for urbanization, a need for community scale investigations

Sunscreen products and some personal care products contain the Ultraviolet (UV) chemical filters, which are entering the surface water. Public concerns about secondary effects of these compounds are growing because of the contamination of the aquatic environment that may reach to potentially toxic concentration levels. This article highlights the reaction of certain UV filters with hypochlorite disinfectant in the presence of sunlight. Due to urbanization and industrialization, use of outdoor plastic swimming pools is increasing. The relatively smaller volume of these pools compared to larger pools may increase the concentration of the UV filters in the pool and their potential interactions with materials of human origin (urine, sweat, cosmetics, skin cells, and hair) to the levels of toxicity concerns for children through the creation of disinfection by products (DBP). Based on our analysis, the minimum concentration levels of 2.85, 1.9, 1.78 and 0.95g/L, respectively, for EHMC, OC, 4-MBC and BP3 UV filters in children pools are predicted. Therefore, this article calls for an urgent investigation of potential toxic effects of the UV filters, the creation of DBPs and their subsequent impacts on human health.

Photochemical transformation of sunscreen agent benzophenone-3 and its metabolite in surface freshwater and seawater

The occurrence of sunscreen agents and their metabolites in surface waters gives rise to public concerns. However, little is known about the environmental fate of these pollutants at present, especially for their metabolites. In this study, we investigated the photochemical of sunscreen agents and their metabolites in natural waters, adopting benzophenone-3 (BP-3) and its human metabolite 4-hydroxybenzophenone (4-OH-BP3) as examples. Results show that only anionic forms of both BP-3 and 4-OH-BP3 can undergo direct photodegradation. The photolytic rates of both compounds in natural waters are faster as compared to those in pure water. Radical scavenging experiments revealed that triplet-excited dissolved organic matter ((3)DOM(∗)) was responsible for the indirect photodegradation of BP-3 and 4-OH-BP3 in seawater, whereas in freshwater, the indirect photodegradation of these two compounds was attributed to (3)DOM(∗) and ·OH. (1)O2 plays a negligible role in their photodegradation because of the weak (1)O2 reactivity. Furthermore, we probed the contribution of ·OH and (3)DOM(∗) to the photodegradation of both compounds in freshwater, and the results revealed that ·OH accounted for 56% and 59% of the observed photodegradation for BP-3 and 4-OH-BP3, respectively, whereas (3)DOM(∗) accounted for 43% and 12% of the observed photodegradation for BP-3 and 4-OH-BP3, respectively. These results are helpful in assessing the ecological risk of BP-3 and its metabolite in the aquatic environment.

Solid-phase microextraction of benzophenones coupled with gas chromatography analysis

In this study, solid-phase microextraction method combines with gas chromatography-flame ionization detector. The proposed method is used for the preconcentration of some benzophenones. Influence of different factors on the efficiency of extraction is described in detail. The analytical procedure was optimized for fiber coating selection, extraction time, temperature, sample pH, ionic strength. For all benzophenones, the highest enrichment factors were achieved using carboxen/polydimethylsiloxane/divinylbenzene fibre immersed directly into the water samples, containing 100 mg/mL of sodium chloride, at room temperature. The optimum pH range is 5.0 – 7.0. The relative standard deviations (RSDs) were from 1.3 to 10.0 % (n = 3). The method was applied to the determination of benzophenone, benzophenone-3, 2-hydroxybenzophenone in the lake water and urine.

Formation of chlorinated breakdown products during degradation of sunscreen agent, 2-ethylhexyl-4-methoxycinnamate in the presence of sodium hypochlorite

In this study, a new degradation path of sunscreen active ingredient, 2-ethylhexyl-4-methoxycinnamate (EHMC) and 4-methoxycinnamic acid (MCA) in the presence of sodium hypochlorite (NaOCl), was discussed. The reaction products were detected using gas chromatography-mass spectrometry (GC-MS). Since HOCl treatment leads to more polar products than EHMC, application of polar extracting agents, dichloromethane and ethyl acetate/n-hexane mixture, gave better results in terms of chlorinated breakdown products identification than n-hexane. Reaction of EHMC with HOCl lead to the formation of C=C bridge cleavage products such as 2-ethylhexyl chloroacetate, 1-chloro-4-methoxybenzene, 1,3-dichloro-2-methoxybenzene, and 3-chloro-4-methoxybenzaldehyde. High reactivity of C=C bond attached to benzene ring is also characteristic for MCA, since it can be converted in the presence of HOCl to 2,4-dichlorophenole, 2,6-dichloro-1,4-benzoquinone, 1,3-dichloro-2-methoxybenzene, 1,2,4-trichloro-3-methoxybenzene, 2,4,6-trichlorophenole, and 3,5-dichloro-2-hydroxyacetophenone. Surprisingly, in case of EHMC/HOCl/UV, much less breakdown products were formed compared to non-UV radiation treatment. In order to describe the nature of EHMC and MCA degradation, local reactivity analysis based on the density functional theory (DFT) was performed. Fukui function values showed that electrophilic attack of HOCl to the C=C bridge in EHMC and MCA is highly favorable (even more preferable than phenyl ring chlorination). This suggests that HOCl electrophilic addition is probably the initial step of EHMC degradation.

Advances in analytical methods and occurrence of organic UV-filters in the environment--A review

UV-filters are a group of compounds designed mainly to protect skin against UVA and UVB radiation, but they are also included in plastics, furniture, etc., to protect products from light damage. Their massive use in sunscreens for skin protection has been increasing due to the awareness of the chronic and acute effects of UV radiation. Some organic UV-filters have raised significant concerns in the past few years for their continuous usage, persistent input and potential threat to ecological environment and human health. UV-filters end up in wastewater and because wastewater treatment plants are not efficient in removing them, lipophilic compounds tend to sorb onto sludge and hydrophilics end up in river water, contaminating the existing biota. To better understand the risk associated with UV-filters in the environment a thorough review regarding their physicochemical properties, toxicity and environmental degradation, analytical methods and their occurrence was conducted. Higher UV-filter concentrations were found in rivers, reaching 0.3mg/L for the most studied family, the benzophenone derivatives. Concentrations in the ng to μg/L range were also detected for the p-aminobenzoic acid, cinnamate, crylene and benzoyl methane derivatives in lake and sea water. Although at lower levels (few ng/L), UV-filters were also found in tap and groundwater. Swimming pool water is also a sink for UV-filters and its chlorine by-products, at the μg/L range, highlighting the benzophenone and benzimidazole derivatives. Soils and sediments are not frequently studied, but concentrations in the μg/L range have already been found especially for the benzophenone and crylene derivatives. Aquatic biota is frequently studied and UV-filters are found in the ng/g-dw range with higher values for fish and mussels. It has been concluded that more information regarding UV-filter degradation studies both in water and sediments is necessary and environmental occurrences should be monitored more frequently and deeply.

Degradation in chlorinated water of the UV filter 4-tert-butyl-4'-methoxydibenzoylmethane present in commercial sunscreens

4-tert-Butyl-4'-methoxydibenzoylmethane (BMDM) is a widely used ultraviolet A filter. In this work, we have studied the effect of chlorine and dissolved organic matter (DOM) concentrations on the stability of UV filter (BMDM) present in two commercial sunscreen cream formulations in water. An experimental design was used to assess the effect of the two experimental factors on the degradation of BMDM. Higher concentrations of chlorine lead to higher degradation percentages of BMDM and higher concentrations of DOM inhibit its degradation. Moreover, a mono and a dichloro derivate of BMDM were identified as by-products.

Optical Characteristics and Chemical Composition of Dissolved Organic Matter (DOM) from Riparian Soil by Using Excitation-Emission Matrix (EEM) Fluorescence Spectroscopy and Mass Spectrometry

Understanding the quantity and quality of soil dissolved organic matter (DOM) in riparian buffer zones is critical for explaining the biogeochemical processes of soil DOM in river ecosystems. Here, we investigated the dissolved organic carbon, fluorescent DOM (FDOM), and DOM molecules from riparian soils on Chongming Island in eastern China. Simultaneously, the soil DOM was extensively characterized in terms of the total aromaticity index (TAI) and several optical indices. The excitation (Ex)-emission (Em) matrix parallel factor analysis results showed that two humic-like components were present (Ex/Em = 283(364)/454 nm; 337/410 nm), a fulvic-like component (Ex/Em = 241/426 nm) and a microbial degradation component (Ex/Em = 295/382 nm). The humic-like and fulvic-like substances were the main components in the riparian soil FDOM, accounting for ~90% of the FDOM. Mass spectrometry provided more detailed information for the soil DOM molecules. Six chemical fractions, amino acids, carbonyl compounds, fatty acids, lipids, proteins and sugars, were identified using liquid chromatography with quadrupole time-of-flight mass spectrometry. Lipids, proteins, and carbonyl compounds were dominant in the soil DOM, accounting for >85% of the detected molecules (m/z < 1000). Significant differences were observed between the quantities of the six soil DOM chemical fractions at the different sampling locations. Discriminant molecules verified the hypothesis that the chemical soil DOM fractions varied with the land use of the adjacent watersheds. The TAI for the soil DOM could provide more reliable information regarding the biogeochemical processes of DOM. The carbonyl compounds and lipid fractions controlled this index. Overall, the optical indices and TAI values can improve our understanding of soil DOM quality; however, the optical indices did not provide quantitative evidence regarding the sources or properties of the soil DOM. The observations from this study provided detailed information regarding the soil DOM quality and the presence of specific molecules and improved our understanding of the biogeochemical processes of DOM.

Chemical contaminants in swimming pools: Occurrence, implications and control

A range of trace chemical contaminants have been reported to occur in swimming pools. Current disinfection practices and monitoring of swimming pool water quality are aimed at preventing the spread of microbial infections and diseases. However, disinfection by-products (DBPs) are formed when the disinfectants used react with organic and inorganic matter in the pool. Additional chemicals may be present in swimming pools originating from anthropogenic sources (bodily excretions, lotions, cosmetics, etc.) or from the source water used where trace chemicals may already be present. DBPs have been the most widely investigated trace chemical contaminants, including trihalomethanes (THMs), haloacetic acids (HAAs), halobenzoquinones (HBQs), haloacetonitriles (HANs), halonitromethanes (HNMs), N-nitrosamines, nitrite, nitrates and chloramines. The presence and concentrations of these chemical contaminants are dependent upon several factors including the types of pools, types of disinfectants used, disinfectant dosages, bather loads, temperature and pH of swimming pool waters. Chemical constituents of personal care products (PCPs) such as parabens and ultraviolet (UV) filters from sunscreens have also been reported. By-products from reactions of these chemicals with disinfectants and UV irradiation have been reported and some may be more toxic than their parent compounds. There is evidence to suggest that exposure to some of these chemicals may lead to health risks. This paper provides a detailed review of various chemical contaminants reported in swimming pools. The concentrations of chemicals present in swimming pools may also provide an alternative indicator to swimming pool water quality, providing insights to contamination sources. Alternative treatment methods such as activated carbon filtration and advanced oxidation processes may be beneficial in improving swimming pool water quality.

Degradation and mineralization of organic UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA) using UV-254nm/H2O2

Various studies have revealed the non-biodegradable and endocrine disrupting properties of sulfonated organic UV absorbers, directing people's attention toward their risks on ecological and human health and hence their removal from water. In this study, UV-254nm/H2O2 advanced oxidation process (AOP) was investigated for degrading a model UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA) and a structurally similar compound 1H-benzimidazole-2-sulfonic acid (BSA), with a specific focus on their mineralization. At 4.0mM [H2O2]0, a complete removal of 40.0μM parent PBSA and 25% decrease in TOC were achieved with 190min of UV irradiation; SO4(2-) was formed and reached its maximum level while the release of nitrogen as NH4(+) was much lower (around 50%) at 190min. Sulfate removal was strongly enhanced by increasing [H2O2]0 in the range of 0-4.0mM, with slight inhibition in 4.0-12.0mM. Faster and earlier ammonia formation was observed at higher [H2O2]0. The presence of Br(-) slowed down the degradation and mineralization of both compounds while a negligible effect on the degradation was observed in the presence of Cl(-). Our study provides important technical and fundamental results on the HO based degradation and mineralization of SO3H and N-containing UV absorber compounds.

Formation pathways of brominated products from benzophenone-4 chlorination in the presence of bromide ions

The brominated products, formed in chlorination treatment of benzophenone-4 in the presence of bromide ions, were identified, and the formation pathways were proposed. Under disinfection conditions, benzophenone-4 would undertake electrophilic substitution generating mono- or di-halogenated products, which would be oxidized to esters and further hydrolyzed to phenol derivatives. The generated catechol intermediate would be transformed into furan-like heterocyclic product. The product species were pH-dependent, while benzophenone-4 elimination was chlorine dose-dependent. When the chlorination treatment was performed on ambient water spiked with benzophenone-4 and bromide ions, most of brominated byproducts could be detected, and the acute toxicity significantly increased as well.

Study of the transformation of two salicylates used in personal care products in chlorinated water

Disinfection of swimming pool water is essential to inactivate pathogenic microorganisms. However chlorine based disinfectants, the most commonly used, are known to lead to the formation of disinfection by-products (DBPs), some of which have been associated with adverse health effects. Precursors of DBPs include the organic matter present in the water used to fill the swimming pool, human body fluids and personal care products (PCPs) used by swimmers and bathers. The increased use, in the last years, of PCPs lead to an increased concern about the fate of PCPs in swimming pool waters and potential health risks of formed DBPs. In this study, the chemical transformations of two salicylates, benzyl salicylate (BzS) and phenyl salicylate (PS), incorporated in several PCPs, in chlorinated water were investigated. High-performance liquid chromatography (HPLC) with UV-diode-array detection (HPLC-UV-DAD) was used to follow the reaction kinetics and HPLC with mass spectrometry (HPLC-MS) was used to tentatively identify the major transformation by-products. Under the experimental conditions used in this work both salicylates reacted with chlorine following pseudo-first order kinetics: rate constant k = (0.0038 ± 0.0002) min(-1) and half-life t1/2 = (182 ± 10) min for BzS and rate constant k = (0.0088 ± 0.0005) min(-1) and half-life t1/2 = (79 ± 4) min for PS (mean ± standard deviation). The reactions of the two salicylates in chlorinated water led to the formation of DBPs that were tentatively identified as mono- and dichloro- substituted compounds. Most probably they result from an electrophilic substitution of one or two hydrogen atoms in the phenolic ring of both salicylates by one or two chlorine atoms.

The chemical composition and source identification of soil dissolved organic matter in riparian buffer zones from Chongming Island, China

Dissolved organic matter (DOM) that is derived from the soil of riparian buffer zones has a complex chemical composition, and it plays an important role in the transport and transformation of pollutants. To identify the source of DOM and to better understand its chemical and structural properties, we collected 33 soil samples from zones with fluctuating water levels along the major rivers on Chongming Island, evaluated the DOM contents in riparian soil, analyzed the chemical composition and functional groups and traced DOM origins by using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) combined with clustering analysis. All sampling sites were divided into four groups by principal component analysis (PCA) on the basis of the DOM molecules. The results showed that there was no significant difference in the DOM contents between every two groups; however, the DOM fractions differed significantly among the different site groups in the following order: Σ lipids and Σ proteins>Σ sugars and Σ fatty acids>Σ amino acids, Σ indoles and Σ alkaloids. DOM in the riparian buffer zones originated from riparian plants, domestic sewage and agricultural activities, and the hydrophobic and amphiphilic fractions accounting for over 60% of the identified molecules were the dominant fractions. Our study has confirmed the heterogeneous properties of DOM, and it is of vital importance to isolate and characterize the various DOM fractions at the molecular level for a better understanding of the behavior and roles of DOM in the natural environment.

Seasonal occurrence, removal efficiencies and preliminary risk assessment of multiple classes of organic UV filters in wastewater treatment plants

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.

LC/MS study of the UV filter hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]-benzoate (DHHB) aquatic chlorination with sodium hypochlorite

The fate of modern personal care products in the environment is becoming a matter of increasing concern because of the growing production and assortment of these compounds. More and more chemicals of this class are treated as emerging contaminants. Transformation of commercially available products in the environment may result in the formation of a wide array of their metabolites. Personal care products in swimming pools and in drinking water reservoirs may undergo oxidation or chlorination. There is much data on the formation of more toxic metabolites from original low toxicity commercial products. Therefore, reliable identification of all possible transformation products and a thorough study of their physicochemical and biological properties are of high priority. The present study deals with the identification of the products of the aquatic chlorination of the hexyl 2-[4-(diethylamino)-2-hydroxybenzoyl]-benzoate ultraviolet filter. High-performance liquid chromatography/mass spectrometry (HPLC/MS) and HPLC/MS/MS with accurate mass measurements were used for this purpose. As a result, three chlorinated transformation products were identified.