Concentrations Of Methyl Paraben Research Articles

A validated high-performance liquid chromatography-ultraviolet method for the determination of valproic acid derivatives in pharmaceutical formulations with a microbiological suitability evaluation

Valproic acid and its derivatives are common drugs used in the treatment of epilepsy, a result of CNS disorders. Because the molecular structure of valproic acid, as a fatty acid, does not contain any chromophore groups, its peak response demanded special conditions to be detected in HPLC, ensuring the best precision results. Still, the current approach illustrates simple, validated procedures for conduction. The conducted chromatographic system consists of the BDS Hypersil C8, 150 × 4.6 mm, 5 µm column using a mobile phase of acetonitrile: phosphate buffer (4:6) at a detection wavelength of 215 nm at room temperature. A full method validation study was conducted and approved to ensure precise, repeatable, and accurate results by implementing system suitability parameters. In microbiological terms, a suitability test is used to validate microbiological testing methods, ensuring their efficacy despite potential interference from antimicrobial properties in the tested materials. The HPLC-UV developed and validated analytical method was evaluated, and it was found to be sensitive for use in the detection of low concentrations of methylparaben, propylparaben, and valproate with an optimum run time of six minutes. limit of detection (LODs) were statistically estimated and found to be 2.27 µg/mL, 39.77 ng/mL, and 1.84 µg/mL for methylparaben, propylparaben, and valproate, respectively. Additionally, the method demonstrated a high recovery of methylparaben, propylparaben, and valproate with an excellent closed-accuracy range (98.84% - 101.34%). An excellent regression coefficient (r) of 0.99924, 0.99998, and 0.99997 for methylparaben, valproate, and propylparaben, respectively, was achieved. Assay determination of various pharmaceutical dosage forms in the local market was implemented, yielding admirable results.

Relationship between mixed exposure to phenyl hydroxides, polycyclic aromatic hydrocarbons, and phthalates and the risk of arthritis

BackgroundTo determine the relationship between mixed exposure to three types of endocrine-disrupting chemicals (EDCs), namely phenyl hydroxides, polycyclic aromatic hydrocarbons (PAHs), and phthalates (PAEs), and risk of arthritis.MethodsParticipants were selected from National Health and Nutrition Examination Survey (NHANES). The relationships between the urinary concentrations of phenyl hydroxides, PAHs, and PAEs and the risk of arthritis were analyzed by generalized linear regression model. The mixed exposure to these EDCs and the risk of arthritis was analyzed by weighted quantile sums (WQSs) and Bayesian kernel machine regression (BKMR) model.ResultsOur analysis showed that participants with urinary benzophenone-3 and methylparaben concentrations in the highest quartile (Q4) had an increased risk of arthritis compared with those in Q1. For each one-unit increase in the natural logarithm-converted urinary concentrations of 1-hydroxynapthalene and 2-hydroxynapthalene, the risk of arthritis increased by 5% and 8%, respectively. Chemical mixing index coefficients were significantly associated with risk of arthritis in both WQS positive- and negative-constraint models. In the BKMR model, there was a significant positive correlation between mixed exposure and the risk of arthritis.ConclusionMixed exposure to phenyl hydroxides, PAHs, and PAEs increased the risk of arthritis, with exposure to PAHs being the key factor.

Methylparaben changes the community composition, structure, and assembly processes of free-living bacteria, phytoplankton, and zooplankton

Parabens are common contaminants in river and lake environments. However, few studies have been conducted to determine the effects of parabens on bacteria, phytoplankton, and zooplankton communities in aquatic environments. In this study, the effect of methylparaben (MP) on the diversity and community structure of the aquatic plankton microbiome was investigated by incubating a microcosm with MP at 0.1, 1, 10, and 100 μg/L for 7 days. The results of the Simpson index showed that MP treatment altered the α-diversity of free-living bacteria (FL), phytoplankton, and zooplankton but had no significant effect on the α-diversity of particle-attached bacteria (PA). Further, the relative abundances of the sensitive bacteria Chitinophaga and Vibrionimonas declined after MP addition. Moreover, the relative abundances of Desmodesmus sp. HSJ717 and Scenedesmus armatus, of the phylum Chlorophyta, were significantly lower in the MP treatment group than in the control group. In addition, the relative abundance of Stoeckeria sp. SSMS0806, of the Dinophyta phylum, was higher than that in the control group. MP addition also increased the relative abundance of Arthropoda but decreased the relative abundance of Rotifera and Ciliophora. The β-diversity analysis showed that FL and phytoplankton communities were clustered separately after treatment with different MP concentrations. MP addition changed community assembly mechanisms in the microcosm, including increasing the stochastic processes for FL and the deterministic processes for PA and phytoplankton. Structural equation modeling analysis showed a significant negative relationship between bacteria richness and phytoplankton richness, and a significant positive relationship between phytoplankton (richness and community composition) and zooplankton. Overall, this study emphasizes that MP, at environmental concentrations, can change the diversity and structure of plankton microbial communities, which might have a negative effect on ecological systems.

Accumulation of Parabens, Their Metabolites, and Halogenated Byproducts in Migratory Birds of Prey: A Comparative Study in Texas and North Carolina, USA.

Parabens are alkyl esters of p-hydroxybenzoic acid that are commonly used as preservatives in personal care products such as cosmetics. Recent studies have revealed the presence of parabens in surface and tap water because of their use as disinfection products; however, little is known about their occurrence in biological samples and their bioaccumulation potential, particularly in raptor birds known as sentinels for pollutant detection. We examined the occurrence and tissue distribution of parabens, their metabolites, and halogenated byproducts in the liver, kidney, brain, and muscle of birds of prey from Texas and North Carolina (USA). Methylparaben (MeP), propylparaben (PrP), and butylparaben (BuP) were detected in more than 50% of all tissues examined, with the kidney exhibiting the highest concentration of MeP (0.65-6.84 ng/g wet wt). Para-hydroxybenzoic acid (PHBA), a primary metabolite, had the highest detection frequency (>50%) and a high accumulation range in the liver, of 4.64 to 12.55 ng/g. The chlorinated compounds chloromethylparaben and chloroethylparaben were found in over half of the tissues, of which dichloromethylparaben (2.20-3.99 ng/g) and dichloroethylparaben (1.01-5.95 ng/g) in the kidney exhibited the highest concentrations. The dibrominated derivatives dibromideethylparaben (Br2EtP) was detected in more than 50% of samples, particularly in muscle and brain. Concentrations in the range of 0.14 to 17.38 ng/g of Br2EtP were detected in the kidney. Dibromidepropylparaben (Br2PrP) was not frequently detected, but concentrations ranged from 0.09 to 21.70 ng/g in muscle. The accumulations of total amounts (sum) of parent parabens (∑P), metabolites (∑M), and halogenated byproducts (∑H) in different species were not significantly different, but their distribution in tissues differed among the species. Positive correlations were observed among MeP, PrP, BuP, and PHBA in the liver, suggesting similar origins and metabolic pathways. Environ Toxicol Chem 2024;43:2365-2376. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Paraben residues in wastewater and surface water: a case study of KwaZulu Natal and Gauteng provinces (South Africa) during the COVID-19 pandemic

Introduction: The presence of pharmaceuticals and personal care products in environmental matrices is considered one of the major scientific concerns. Most of these substances are disposed of unchanged through wastewater treatment plants and sewage systems. Consequently, they are continuously introduced into the water systems and progressively contaminate surface, ground and drinking water. During the COVID-19 pandemic, a large number of emerging contaminants including parabens were released to the environment through various routes. In this study, the occurrence of parabens (methylparaben (MePB), ethylparaben (EtPB), propylparaben (PrPB), and butylparaben (BuPB) was investigated in wastewater samples from various wastewater treatment plants (WWTPs) and the receiving surface waters in KwaZulu Natal and Gauteng Provinces (South Africa).Methods: The samples were collected between October 2020 and December 2021, covering the 2nd, 3rd and 4th waves of the COVID-19 pandemic. A solid phase extraction protocol with high-performance liquid chromatography was used to extract and enrich parabens before analysis.Results and Discussion: Methylparaben (2.02–84.7 μg/L), EtPB (<0.24–24.8 μg/L), PrPB (<0.26–55.1 μg/L), and BuPB (<0.27–17.3 μg/L) were quantified in wastewater influent collected WWTPs of KwaZulu Natal Province. While <0.19–5.43 μg/L, <0.16–5.63 μg/L, <0.17–6.89 μg/L, and <0.19–5.32 μg/L for MePB, EtPB, PrPB, and BuPB, respectively, were quantified in effluent wastewater from the same province. The concentrations of MePB, EtPB, PrPB, and BuPB in influent wastewater from Gauteng Province were 2.58–123 μg/L, <0.24–33.6 μg/L, 3.77–73.4 μg/L and <0.27–85.8 μg/L, respectively. In effluent wastewater, concentrations ranging from 0.24–17.76 μg/L (MePB), <0.16–4.88 μg/L (EtPB), 0.69-12.5 μg/L (PrPB), and <0.19–4.726 μg/L (BuPB) were quantified. During the 4th wave, the concentrations of parabens in surface water were lower compared to the second and third waves of the pandemic. In general, the paraben residues in the surface of KwaZulu Natal Province (<0.08–16.4 μg/L) were higher than those in Gauteng Province (0.08-3.14 µg/L). Methylparaben and propylparaben were dominant in all investigated samples (wastewater and surface water), followed by ethylparaben. The ecotoxicological risk assessment was carried out for aquatic biota, which was estimated in terms of risk quotients (RQs). RQs for the target compounds in river water indicated that MePB and EtPB pose low risk, whereas PrPB and BuPB pose low to medium risk to aquatic organisms.

Exposure assessment of dairy cows to parabens using hair samples analysis

Parabens (PBs) are used as preservatives in various products. They pollute the environment and penetrate living organisms, showing endocrine disrupting activity. Till now studies on long-term exposure of farm animals to PBs have not been performed. Among matrices using in PBs biomonitoring hair samples are becoming more and more important. During this study concentration levels of methyl paraben (MeP), ethyl paraben (EtP), propyl paraben (PrP) butyl paraben (BuP) and benzyl paraben (BeP) were evaluated using liquid chromatography–mass spectrometry (LC–MS) in hair samples collected from dairy cows bred in the Kyrgyz Republic. MeP was noted in 93.8% of samples (with mean concentration levels 62.2 ± 61.8 pg/mg), PrP in 16.7% of samples (12.4 ± 6.5 pg/mg) and EtP in 8.3% of samples (21.4 ± 11.9 pg/mg). BuP was found only in one sample (2.1%) and BeP was not detected in any sample included in the study. Some differences in MeP concentration levels in the hair samples depending on district, where cows were bred were noted. This study has shown that among PBs, dairy cows are exposed mainly to MeP, and hair samples may be a suitable matrix for research on PBs levels in farm animals.

Highly efficient electrocatalytic degradation of methylparaben using BiOx-doped Ti/β-PbO2 anode: Comprehensive electrochemical study and degradation mechanism

Electrochemical degradation of methylparaben (MPB) was successfully performed using Ti/β-PbO2-BiOx anode. The structure of the fabricated electrode was characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), and mapping techniques. The results confirmed the successful preparation of the electrode with favorable morphological and structural properties. This research includes optimization of operating parameters such as solution pH, applied current density, initial MPB concentration and electrolysis time. The results indicate that the prepared electrode has high electrochemical performance and thermal stability. Under optimal conditions, current density of 4.8 mA/cm2, pH = 5 and initial concentration of 0.5 mM, the maximum degradation efficiency of 98.9 % was obtained. In this work, also, based on the data obtained from LC-MS analysis, a detailed mechanism for the degradation of MPB was proposed. In another section of this research, the electrochemical behavior of MPB on glassy carbon electrode was comprehensively studied using cyclic voltammetry at different pH values. The data obtained from this study provide significant insight into the electrochemical behavior of MPB, its pH-dependent properties and adsorption activities. The results of this section can also be used to better optimize the conditions of MPB degradation.

A self-assembly BiOI/Bi4O5Br2 microcluster and its efficiently visible-light-induced photocatalytic degradation of methylparaben

Herein, we developed a self-assembly heterostructured BiOI/Bi4O5Br2 microcluster with the hydrothermal method. Catalysts were mainly characterized by powder X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscope, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and diffuse reflectance spectra. The results showed that due to charge induction, BiOI nanosheets were successfully self-assembled and deposited on Bi4O5Br2, forming a unique heterojunction and achieving strong transient photocurrent response. Performances of catalysts were tested and effects of different initial concentrations of the Methylparaben (MPB), catalyst dosage, initial pH and total organic carbon (TOC) conversion were studied. Results reveal that catalytic activity increased with lower initial concentration of MPB and the best dosage of catalyst is 0.5 g·L-1. The BiOI/Bi4O5Br2 microcluster exhibits excellent photocatalytic activity under visible-light irradiation, which can degrade 97% MPB in 2 h and the TOC value is only 20% of the original. The catalytic degradation process conforms to pseudo-first-order kinetics with a rate constant of 0.030 min-1. The results of detailed active species detection indicate that the photogenerated holes and •O2− radicals play the main role in the photocatalytic system. In addition, photoelectrochemical measurements reveal that the excellent strengthened photocatalytic activity is due to the high separation and transfer efficiency derived from the heterostructure.

Temporal trends in exposure to parabens, benzophenones, triclosan, and triclocarban in adult females in Kyoto, Japan, from 1993 to 2016.

Products used in daily life can contain chemicals such as parabens, benzophenones, triclosan, and triclocarban that have potential endocrine-disrupting effects. Little is known about the temporal trends of exposure levels to some of these chemicals in Japan. Our study assessed the intake and risk associated with exposure to commonly used chemicals. We measured the concentrations of five parabens, four benzophenones, and triclosan and triclocarban in 133 single spot urine samples. The urine samples were collected in 1993, 2000, 2003, 2009, 2011, and 2016 from healthy female residents in Kyoto, Japan. With the exception of methylparaben, ethylparaben, and butylparaben, there were no significant fluctuations in the concentrations of target chemicals over the study period; however, methylparaben, ethylparaben, and butylparaben showed temporal changes in concentrations. Methylparaben concentrations peaked in 2003 with a median value of 309μg/g creatinine, ethylparaben concentrations peaked in 1993 with a median value of 17.3μg/g creatinine, and butylparaben showed a decline, with the median values becoming non-detectable in 2009 and 2016. We calculated estimated daily intakes and hazard quotients for each chemical. In the analysis of total samples, 2.3% (3 samples) for butylparaben and 0.8% (1 sample) for propylparaben were found to surpass a hazard quotient of 1. Overall, 3% (n = 4) of the study participants exceeded a hazard index of 1. The potential health risks associated with exposure to butylparaben and propylparaben emphasize the need for further monitoring and research.

Environmental phenol exposures in 6- to 12-week-old infants: The Infant Feeding and Early Development (IFED) study

BackgroundExposure to phenols, endocrine-disrupting chemicals used in personal care and consumer products, is widespread. Data on infant exposures are limited despite heightened sensitivity to endocrine disruption during this developmental period. We aimed to describe distributions and predictors of urinary phenol concentrations among U.S. infants ages 6–12 weeks. MethodsThe Infant Feeding and Early Development (IFED) study is a prospective cohort study of healthy term infants enrolled during 2010–2013 in the Philadelphia region. We measured concentrations of seven phenols in 352 urine samples collected during the 6- or 8- and/or 12-week study visits from 199 infants. We used linear mixed models to estimate associations of maternal, sociodemographic, infant, and sample characteristics with natural-log transformed, creatinine-standardized phenol concentrations and present results as mean percent change from the reference level. ResultsMedian concentrations (μg/L) were 311 for methylparaben, 10.3 for propylparaben, 3.6 for benzophenone-3, 2.1 for triclosan, 1.0 for 2,5-dichlorophenol, 0.7 for BPA, and 0.3 for 2,4-dichlorophenol. Geometric mean methylparaben concentrations were approximately 10 times higher than published estimates for U.S. children ages 3–5 and 6–11 years, while propylparaben concentrations were 3–4 times higher. Infants of Black mothers had higher concentrations of BPA (83%), methylparaben (121%), propylparaben (218%), and 2,5-dichorophenol (287%) and lower concentrations of benzophenone-3 (−77%) and triclosan (−53%) than infants of White mothers. Triclosan concentrations were higher in breastfed infants (176%) and lower in infants whose mothers had a high school education or less (−62%). Phenol concentrations were generally higher in summer samples. ConclusionsWidespread exposure to select environmental phenols among this cohort of healthy U.S. infants, including much higher paraben concentrations compared to those reported for U.S. children, supports the importance of expanding population-based biomonitoring programs to infants and toddlers. Future investigation of exposure sources is warranted to identify opportunities to minimize exposures during these sensitive periods of development.

Paternal and maternal preconception and maternal pregnancy urinary concentrations of parabens in relation to child behavior.

Epidemiologic studies of the effects of parental preconception paraben exposures on child behavior are limited despite emerging evidence suggesting that such exposures may affect offspring neurodevelopment. We investigated whether maternal and paternal preconception and maternal pregnancy urinary concentrations of parabens were associated with child behavior. We analyzed data from the Preconception Environmental exposure And Childhood health Effects Study, an ongoing prospective cohort of children aged 6-13 years and their parents. We estimated covariate-adjusted associations of loge -transformed urinary methyl, propyl, and butyl paraben concentrations (individually using linear regression models and as a mixture using quantile g-computation) collected prior to conception and during pregnancy with Behavioral Assessment System for Children-3 and Behavior Rating Inventory of Executive Function T-scores (higher scores indicate more problem behaviors). This analysis included 140 mothers, 81 fathers, and 171 children (25 sets of twins); parents were predominantly non-Hispanic white (88% for both mothers and fathers). In single paraben models, higher paternal preconception urinary propyl and methyl paraben concentrations were associated with higher Internalizing Problem T-scores (propyl paraben =1.7; 95% confidence interval: 0.6, 2.8, methyl paraben =2.2; 95% confidence interval: 0.5, 3.9) and higher Behavioral Symptom Index T-scores (propyl paraben =1.4; 95% confidence interval: 0.3, 2.5, methyl paraben =1.6; 95% confidence interval: -0.1, 3.3). Each quantile increase in the paternal mixture of three parabens was associated with a 3.4 (95% confidence interval: 0.67, 6.1) and 2.5 (95% confidence interval: 0.01, 5.0) increased internalizing problem and Behavioral Symptom Index T-scores respectively. Higher paternal preconception ( =1.0; 95% confidence interval: 0.04, 1.9) and maternal preconception ( =1.1 95% confidence interval: -0.1, 2.2) concentrations of propyl paraben were associated with higher Behavior Rating Inventory of Executive Function Metacognition Index T-scores in children, but the paraben mixtures was not. In this cohort, paternal preconception urinary concentrations of propyl and methyl paraben were associated with worse parent-reported child behaviors.

Double ionic liquid reinforced g-CN nanocomposite for an enhanced adsorption of methylparaben: Mechanism, modeling, and optimization

The efficient removal of organic pollutants, especially pharmaceuticals, from aquatic environments has attracted great attentions. Application of green, multipurpose, and inexpensive compounds is being extensively favorite as adsorbent instead of the traditional chemicals or materials. In this study, sulfonated graphitic carbon nitride was modified with two ionic liquids of polyethyleneimine and choline chloride to create a novel nanocomposite (Sg-CN@IL2 NC) and to use for removal of methylparaben (MeP) from aqueous media. After confirmation of the successful synthesized using different methods, the effective parameters for MeP removal, such as initial MeP concentration, adsorbent dose, sonication time, and temperature, as well as their interactions, were experimentally examined and modeled using response surface methodology (RSM), generalized regression neural network (GRNN), and radial basis function neural network (RBFNN). The models were then optimized using desirability function analysis (DF) and genetic algorithm (GA). The results showed that MeP adsorption: a) can be explained more accurate and reliable using GRNN (AARD% = 11.67, MAE = 15.31, RAE % = 45.42, RRSE % = 55.18, MSE = 435.86, RMSE = 20.70, and R2 = 0.995) than the others; b) reached equilibrium within 7.0 min with a maximum uptake of 267.2 mg/g at a temperature of 45 °C and a neutral pH; c) followed from Freundlich (R2 = 0.999) isotherm and PSO kinetic (R2 = 0.95) models; d) is endothermic and spontaneous; e) is mainly due to π-π stacking, electrostatic and hydrogen bonding interactions. Moreover, Sg-CN@IL2 NC showed an appropriate reusability for up to five cycles. These findings demonstrate the potential of as-prepared NC as an excellent adsorbent for removal of MeP from aqueous media.

Evaluating the efficacy of recyclable nanostructured adsorbents for rapid removal of methylparaben from aqueous solutions

In this study, we evaluate the efficiency of two novel nanostructured adsorbents – chitosan-graphitic carbon nitride@magnetite (CS-g-CN@Fe3O4) and graphitic carbon nitride@copper/zinc nanocomposite (g-CN@Cu/Zn NC) – for the rapid removal of methylparaben (MPB) from water. Our characterization methods, aimed at understanding the adsorbents’ structures and surface areas, informed our systematic examination of influential parameters including sonication time, adsorbent dosage, initial MPB concentration, and temperature.We applied advanced modeling techniques, such as response surface methodology (RSM), generalized regression neural network (GRNN), and radial basis function neural network (RBFNN), to evaluate the adsorption process. The adsorbents proved highly effective, achieving maximum adsorption capacities of 255 mg g−1 for CS-g-CN@Fe3O4 and 218 mg g−1 for g-CN@Cu/Zn NC. Through genetic algorithm (GA) optimization, we identified the optimal conditions for the highest MPB removal efficiency: a sonication period of 12.00 min and an adsorbent dose of 0.010 g for CS-g-CN@Fe3O4 NC, with an MPB concentration of 17.20 mg L−1 at 42.85 °C; and a sonication time of 10.25 min and a 0.011 g dose for g-CN@Cu/Zn NC, with an MPB concentration of 13.45 mg L−1 at 36.50 °C.The predictive accuracy of the RBFNN and GRNN models was confirmed to be satisfactory. Our findings demonstrate the significant capabilities of these synthesized adsorbents in effectively removing MPB from water, paving the way for optimized applications in water purification.

Chitosan-Based Molecularly Imprinted Polymer Modified Zinc Oxyde/Graphene Nanocomposite/Screen Printed Carbon Electrode for Electrochemical Detection of Methyl Paraben

A novel electrochemical sensor, chitosan based on molecularly imprinted polymer (MIP), was fabricated by electrodeposition of chitosan in the presence of methyl paraben (MP) on a zinc oxide/graphene nanocomposite (ZnO/GnC) modified screen-printed carbon electrode for selective detection of MP. The obtained chitosan-based MIP modified electrode, namely MIP/ZnO/GnC/SPCE was characterized by scanning electron microscopy, cyclic voltammetry, and differential pulse voltammetry. Under the optimized condition, the prepared sensor MIP/ZnO/GnC/SPCE exhibited satisfactory linearity with certain MP concentrations of 10 to 1000 μM and the limit of detection can reach 9.65 μM with a sensitivity of 0.00445 μA/μM.cm2. This work shows that the incorporation of chitosan-based MIP with ZnO/GnC generates a synergistic effect, increasing the current response in comparison with unmodified SPCE. The developed sensor exhibited satisfactory reproducibility and repeatability. Furthermore, the developed electrode was successfully applied for the determination of MP in cosmetic products and shows similar performance in comparison to UV-visible spectrophotometry analysis. In conclusion, the chitosan-based MIP modified ZnO/GnC/SPCE is promising for monitoring the MP in cosmetic products.

Urinary Paraben Concentrations and Associations with the Periconceptional Urinary Metabolome: Untargeted and Targeted Metabolomics Analyses of Participants from the Early Pregnancy Study.

Parabens, found in everyday items from personal care products to foods, are chemicals with endocrine-disrupting activity, which has been shown to influence reproductive function. This study investigated whether urinary concentrations of methylparaben, propylparaben, or butylparaben were associated with the urinary metabolome during the periconceptional period, a critical window for female reproductive function. Changes to the periconceptional urinary metabolome could provide insights into the mechanisms by which parabens could impact fertility. Urinary paraben concentrations were measured in paired pre- and postconception urine samples from 42 participants in the Early Pregnancy Study, a prospective cohort of 221 women attempting to conceive. We performed untargeted and targeted metabolomics analyses using ultrahigh-performance liquid chromatography quadrupole time-of-flight mass spectrometry. We used principal component analysis, orthogonal partial least-squares discriminant analysis, and permutation testing, coupled with univariate statistical analyses, to find metabolites associated with paraben concentration at the two time points. Potential confounders were identified with a directed acyclic graph and used to adjust results with multivariable linear regression. Metabolites were identified using fragmentation data. Seven metabolites were associated with paraben concentration (variable importance to projection score , false discovery rate-corrected ). We identified four diet-related metabolites to the Metabolomics Standards Initiative (MSI) certainty of identification level 2, including metabolites from smoke flavoring, grapes, and olive oil. One metabolite was identified to the class level only (MSI level 3). Two metabolites were unidentified (MSI level 4). After adjustment, three metabolites remained associated with methylparaben and propylparaben, two of which were diet-related. No metabolomic markers of endocrine disruption were associated with paraben concentrations. This study identified novel relationships between urinary paraben concentrations and diet-related metabolites but not with metabolites on endocrine-disrupting pathways, as hypothesized. It demonstrates the feasibility of integrating untargeted metabolomics data with environmental exposure information and epidemiological adjustment for confounders. The findings underscore a potentially important connection between diet and paraben exposure, with applications to nutritional epidemiology and dietary exposure assessment. https://doi.org/10.1289/EHP12125.

Methylparaben Adsorption onto Activated Carbon and Activated Olive Stones: Comparative Analysis of Efficiency, Equilibrium, Kinetics and Effect of Graphene-Based Nanomaterials Addition

This paper describes a comparative study of the adsorption of methylparaben onto commercial activated carbon and olive stones activated by calcination at 300 °C and treatment with 1 M HCl. The influence of the initial concentration of methylparaben, adsorbent dose, stirring speed and pH on the adsorption capacity of methylparaben on both adsorbents was studied. To find out the isotherm model, the kinetic model and the mechanism that best describe the adsorption process on each adsorbent, the experimental equilibrium data were analyzed using six isotherm models (Langmuir, Freundlich, Elovich, Temkin, Jovanovic and Dubinin–Radushkevich), and the experimental kinetic data were analyzed using four kinetic models (pseudo-first order, pseudo-second order, Elovich and Avrami) and two mechanistic models (Weber–Morris and Boyd). For both adsorbents, the Langmuir model best describes the adsorption equilibrium, the kinetics of the process follow a pseudo-first-order model and boundary layer diffusion is the step that mainly controls the adsorption process. The adsorption capacity of methylparaben on activated carbon is about four times higher than that of activated olive stones. The addition of graphene oxide and reduced graphene oxide to both adsorbents increases their methylparaben adsorption capacity, to a greater extent in the case of graphene oxide, being that increase more important in activated carbon than in activated olive stones.

Influences of Wastewater Treatment on the Occurrence of Parabens, p-Hydroxybenzoic Acid and Their Chlorinated and Hydroxylated Transformation Products in the Brazos River (Texas, USA).

Parabens are ubiquitous, being found in surface waters around the world. Although little is known about the release of paraben transformation products and fate of transformation products in surface water. This study evaluates both parabens and paraben transformation products in the Brazos River upstream and downstream of a wastewater facility located in Waco, Texas. Concentrations of thirteen compounds were reported in this study, five parent parabens and eight paraben disinfection by-products. Analyte concentrations were spatially evaluated to determine if release of wastewater effluent affects their concentrations in the river. Two Brazos River tributaries were also sampled to determine if they released parabens and related compounds to the Brazos. Sampling occurred weekly for one year with at least 40 samples collected at each site. Analyses were completed for both yearly and seasonal data. Sites downstream of wastewater treatment outfalls had lower concentrations of methyl paraben during the yearly analysis and across multiple seasons in the seasonal analysis with average yearly annual methyl paraben concentrations decreasing from 0.83ng/L at site 3 to 0.09ng/L at site 4. Para-hydroxybenzoic acid was the compound present in greatest concentration at most sites across most seasons, with the highest average annual concentration of 10.30ng/L at site 2. Spatial changes in para-hydroxybenzoic acid varied by season, with seasonal trends only identifiable after normalization by flow. Dichlorinated paraben concentrations increased in the river at sites downstream of wastewater treatment with a yearly average dichlorinated methyl paraben concentration of 0.490ng/L at site 3 to 1.53 at site 4, just downstream of the major wastewater treatment plant. Concentration increases indicate that wastewater effluent contains sufficiently high dichlorinated paraben concentrations to effect concentrations downstream of effluent discharges. Dichlorinated species also persisted in the environment, with no significant decreases at sites further downstream during any season with an annual average dichlorinated methyl paraben concentration of 1.23ng/L at site 6. Methyl paraben concentrations decreased at the site furthest downstream to a concentration of 0.081ng/L, while dichlorinated methyl paraben concentrations remained stable with a concentration of 1.10ng/L at the site furthest downstream. Due to the dichlorinated species being released in higher concentrations in effluent than parents and being more resistant to degradation, the dichlorinated parabens are more likely to be environmentally relevant than are parent parabens.

Key factors influencing pollution of heavy metals and phenolic compounds in mangrove sediments, South China

Concentrations of heavy metals (HMs) and phenolic compounds with factors which potentially affected their spatial distribution were investigated in mangrove sediments, South China. Compared to Qi'ao, Futian sediments exhibited higher levels of Pb and nonylphenol (NP), but lower levels of Co and Ni. Seasonal variation showed higher concentrations of Pb, Cr, Co, NP and bisphenol A (BPA), while lower concentration of methylparaben (MP) in wet than dry season. Contaminant levels in sediments collected at different tidal heights showed insignificant variations, except for Zn and NP. MP was found negatively correlated with nearly all HMs and BPA, whereas the latter exhibited positive correlations with each other. Sedimentary total carbon, total nitrogen, C/N and N/P ratios were screened as the most influential factors affecting the distribution of these contaminants. Additionally, both salinity and total phosphate exhibited positive, while both pH and sedimentary particle size registered negative correlation, with one or more contaminants.

Associations between urinary parabens and lung cancer.

Parabens are a family of endocrine-disrupting chemicals. Environmental estrogens may play a vital role in the development of lung cancer. To date, the association between parabens and lung cancer is unknown. Based on the 189 cases and 198 controls recruited between 2018 and 2021 in Quzhou, China, we measured 5 urinary parabens concentrations and examined the association between urinary concentrations of parabens and lung cancer risk. Cases showed significantly higher median concentrations of methyl-paraben (MeP) (2.1 versus 1.8ng/mL), ethyl-paraben (0.98 versus 0.66ng/mL), propyl-paraben (PrP) (2.2 versus 1.4ng/mL), and butyl-paraben (0.33 versus 0.16ng/mL) than controls. The detection rates of benzyl-paraben were only 8 and 6% in the control and case groups, respectively. Therefore, the compound was not considered in the further analysis. The significant correlation between urinary concentrations of PrP and the risk of lung cancer (odds ratio (OR)adjusted = 2.22, 95% confidence interval (CI): 1.76, 2.75; Ptrend < 0.001) was identified in the adjusted model. In the stratification analysis, we found that urinary concentrations of MeP were significantly associated with lung cancer risk (OR = 1.16, 95% CI: 1.01, 1.27 for the highest quartile group). Besides, comparing the second, third, and fourth quartile groups with the lowest group of PrP, we also observed urinary PrP concentrations associated with lung cancer risk, with the adjusted OR of 1.52 (95% CI: 1.29, 1.65, Ptrend = 0.007), 1.39 (95% CI: 1.15, 1.60, Ptrend = 0.010), and 1.85 (95% CI: 1.53, 2.30, Ptrend = 0.001), respectively. MeP and PrP exposure, reflected in urinary concentrations of parabens, may be positively associated with the risk of lung cancer in adults.

Prenatal paraben exposures and birth size: Sex-specific associations in a healthy population - A study from the Odense Child Cohort

ObjectivesTo investigate the sex-specific associations between maternal paraben concentrations in second trimester urine and birth size of the offspring. MethodsA prospective cohort study of 529 mother-child pairs within the Odense Child Cohort. Pregnant women were recruited to the cohort from 2010 to 2012 and provided fasting spot urine samples in second trimester (median 28.7 weeks). Concentrations of methylparaben (MeP), ethylparaben (EtP), iso-propylparaben (i-PrP), n-propylparaben (n-PrP), n-butylparaben (n-BuP) and benzylparaben (BzP) were analyzed by isotope diluted liquid-chromatography tandem-mass-spectrometry and osmolality adjusted. Exposures were categorized into tertiles or above/below level of detection. Data on maternal and birth characteristics were extracted from hospital records. Sex-stratified multiple linear regression analyses were performed according to relevant birth outcomes (length, weight, head/abdominal circumference) adjusting for a priori defined confounders. ResultsHigher paraben levels were detected in pregnant women who were older, more obese, who smoked and were primigravidae. Generally, higher maternal paraben exposure was consistently associated with lower birth size in female but not in male offspring, but with few substantial or statistically significant. Higher maternal exposure to n-BuP during pregnancy was associated with a statistically significant lower birth size in female offspring only [birth weight: −137 g (95 % CI −256; −19), head circumference: −0.48 cm (95 % CI −0.90; −0.05), abdominal circumference: −0.65 cm (95 % CI −1.21; −0.08)]. No differences in birth size were observed for other parabens. ConclusionHigher maternal exposure to n-butylparaben was associated with lower birth size in female but not male offspring.