Safety assessment of propyl paraben: a review of the published literature

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;00:1-12. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

In vitro assessment of the antioxidative, toxicological and antimicrobial properties of battery of parabens

The aim of this study was to evaluate antioxidative features using 2,2-diphenyl-1-pycrylhydrazyl free radical (DPPH•) scavenging method, bovine serum albumin (BSA)-binding properties with usage of spectrofluorimetric method, proliferative and cyto/genotoxic status by use of chromosome aberration test, and antimicrobial potential using broth microdilution method, followed by resazurin assay of benzyl-, isopropyl-, isobutyl and phenylparaben in vitro. Our results showed that all parabens had significant antiradical scavenger activity compared to p-hydroxybenzoic acid (PHBA) precursor. Higher mitotic index for benzyl-, isopropyl and isobutylparaben (250 µg/mL) in comparison with control was demonstrated. An increase in the frequency of acentric fragments in lymphocytes treated with benzylparaben and isopropylparaben (125 and 250 µg/mL), and isobutylparaben (250 µg/mL) was observed. Isobutylparaben (250 µg/mL) induced higher number of dicentric chromosomes. An increased number of minute fragments in lymphocytes exposed to benzylparaben (125 and 250 µg/mL) was found. A significant difference in the frequency of chromosome pulverization, between phenylparaben (250 µg/mL) and control, was detected. Benzylparaben (250 µg/mL) and phenylparaben (62.5 µg/mL) caused an increase in the number of apoptotic cells, while isopropylparaben (62.5, 125 and 250 µg/mL) and isobutylparaben (62.5 and 125 µg/mL) induced higher frequency of necrosis. Minimum inhibitory concentration (MIC) of tested parabens ranged 15.62-250 µg/mL for bacteria, and 125-500 µg/mL for the yeast. Minimum microbiocidal concentration ranged 31.25 to 500 µg/mL, and 250 to 1000 µg/mL in bacteria and fungi respectively. The lowest MICs for bacteria were observed for phenyl- (15.62 µg/mL) and isopropylparaben (31.25 µg/mL) against Enterococcus faecalis.

Recent use of consumer and personal care products and exposures to select endocrine disrupting chemicals among urban children with asthma

BACKGROUND

Emerging studies suggest that endocrine disrupting chemicals (EDCs) in personal care and other consumer products are linked with various adverse health effects, including respiratory and reproductive effects. Despite Black persons using more personal care products than other demographic groups and having a high asthma burden, little is known regarding their consumer product use patterns and associated EDC exposures.

OBJECTIVE

To examine the association between recent exposure to select EDCs with specific consumer products and behaviors in a cohort of 110 predominantly Black children with asthma, ages 8-17 years, living in Baltimore City, Maryland.

METHODS

We quantified concentrations of bisphenol A (BPA), bisphenol S (BPS), bisphenol F, two dichlorophenols, four parabens, triclosan, benzophenone-3, and triclocarban in spot urine samples. Questionnaires were used to capture recent (last 24-h) consumer product use and behaviors. Associations between EDCs and consumer product uses/behaviors were assessed using multivariable linear regression, adjusting for age, gender, race/ethnicity, and caregiver income level. Effect estimates were expressed as geometric mean ratios of biomarker concentrations of product-users vs non-users.

RESULTS

Increased concentrations to select EDCs were associated with recent use of air freshener (ratios; BPA: 1.9, 95%CI 1.4-2; BPS 1.7, 95%CI 1-2.97; propyl paraben: 3.0, 95%CI 1.6-5.6), scented candles (methyl paraben: 2.6, 95%CI 1.1-6.1), and scented carpet powder (2,5-dichlorophenol: 2.8, 95%CI 1.2-6.3). Additionally, consuming canned food was associated with some increased biomarker concentrations (ratios: BPA: 1.7, 95%CI 1.2-2.4; BPS: 2.1, 95% CI: 1.2-3.6).

SIGNIFICANCE

These findings add to the body of evidence suggesting that recent use of select consumer products in Black children contributes to exposure of chemicals of concern and could potentially inform exposure mitigation interventions. Findings have broad potential health implications for pediatric populations and Black children who may face exposure and health disparities.

IMPACT

Little is known about how children's personal care product use and consumer behaviors affect their exposures to endocrine disrupting chemicals (EDCs). This is particularly true for Black children who often experience a disparate exposure burden to many EDCs. This is a significant knowledge gap among children that are uniquely vulnerable to EDCs as they undergo critical windows of growth and development. Our findings show associations between consumer products and EDC exposures in predominantly Black children in low-income settings. Identifying EDC exposure determinants has broad health implications as many of these chemicals have been associated with adverse health risks.

Embryonic and larval exposure to propylparaben induces developmental and long-term neurotoxicity in zebrafish model

Parabens are preservatives found in cosmetics, processed foods, and medications. The harmful repercussions on the central nervous system by one of the most common parabens, propylparaben (PrP), are yet unknown, especially during development. In this study, the neurodevelopmental effects of PrP and long-term neurotoxicity were investigated in the zebrafish model, using an integrated approach. Zebrafish embryos were exposed to two different concentrations of PrP (10 and 1000 μg/L), then larvae were examined for their behavioral phenotypes (open-field behavior, startle response, and circadian rhythmicity) and relevant brain markers (cyp19a1b, pax6a, shank3a, and gad1b). Long-term behavioral and cognitive impacts on sociability, cerebral functional asymmetry and thigmotaxis were also examined on juveniles at 30 dpf and 60 dpf. Moreover, proteomics and gene expression analysis were assessed in brains of 60 dpf zebrafish. Interestingly, thigmotaxis was decreased by the high dose in larvae and increased by the low dose in juveniles. The expression of shank3a and gad1b genes was repressed by both PrP concentrations pointing to possible effects of PrP on neurodevelopment and synaptogenesis. Proteomics analysis evidenced alterations related to brain development and lipid metabolism. Overall, the results demonstrated that early-life exposure to PrP promotes developmental and persistent neurobehavioral alterations in the zebrafish model, affecting genes and protein levels possibly associated with brain diseases.

Parabens as environmental contaminants of aquatic systems affecting water quality and microbial dynamics

Among different pollutants of emerging concern, parabens have gained rising interest due to their widespread detection in water sources worldwide. This occurs because parabens are used in personal care products, pharmaceuticals, and food, in which residues are generated and released into aquatic environments. The regulation of the use of parabens varies across different geographic regions, resulting in diverse concentrations observed globally. Concentrations of parabens exceeding 100 μg/L have been found in wastewater treatment plants and surface waters while drinking water (DW) sources typically exhibit concentrations below 6 μg/L. Despite their low levels, the presence of parabens in DW is a potential exposure route for humans, raising concerns for both human health and environmental microbiota. Although a few studies have reported alterations in the functions and characteristics of microbial communities following exposure to emerging contaminants, the impact of the exposure to parabens by microbial communities, particularly biofilm colonizers, remains largely understudied. This review gathers the most recent information on the occurrence of parabens in water sources, as well as their effects on human health and aquatic organisms. The interactions of parabens with microbial communities are reviewed for the first time, filling the knowledge gaps on the effects of paraben exposure on microbial ecosystems and their impact on disinfection tolerance and antimicrobial resistance, with potential implications for public health.

Parabens in indoor dust from houses, university dormitories, and cosmetics stores in Nanjing, China: occurrence and human exposure

Parabens are extensively used as preservatives in consumer products. The widespread exposure of human to parabens has been associated with adverse health effects. In this study, six parabens were measured in 100 indoor dust collected from homes, university dormitories, and cosmetics stores in Nanjing, China. Concentrations of sum of six parabens (∑₆parabens) in dust from homes, university dormitories, and cosmetics stores ranged from 13.1 to 4.22 × 10³, 102 to 3.03 × 10³, and 7.02 × 10³ to 3.41 × 10⁴ ng/g, respectively. The median concentrations of ∑₆parabens in dust from cosmetics stores (1.5 × 10⁴ ng/g) were 1-2 orders of magnitude higher than those found in dust from homes (166 ng/g) and university dormitories (1.23 × 10³ ng/g) (p < 0.01). Methyl-, ethyl-, and propyl-parabens were the predominant compounds found in dust samples, and the sum concentrations of three compounds accounted for 71.9-99.6%, 93.1-99.6%, and 94.7-99.6% of ∑₆parabens in dust from homes, university dormitories, and cosmetics stores, respectively. Significant positive correlations were found between methyl- and propyl-parabens concentrations in three types of dust (r = 0.789-0.909), indicating their coexistence in many consumer products. The estimated daily intake (EDI) of ∑₆parabens for adults via dust ingestion was highest for employees in cosmetics stores (median: 4.6 ng/kg bw/day), followed by university students (0.56-0.64 ng/kg bw/day), and adults in homes (0.075-0.087 ng/kg bw/day). The result provides a better understanding of human exposure to parabens in different indoor environments, and more studies are needed to further investigate the occurrence and potential health risks of parabens in dust from various microenvironments.

GC-MS and HPLC supported phytochemical analysis of watercress and the protective role against paraben toxicity

In this study, the phytochemical content of Nasturtium officinale R. Br. (watercress) leaf extract (Noex) and its protective effects against paraben toxicity were investigated. GC-MS and HPLC analyses were performed to determine the phytochemical content. Paraben toxicity and protective properties of Noex were investigated with the Allium test, and 6 different groups were formed for this purpose. Toxicity in each group was investigated by using physiological, cytogenetic, biochemical, and anatomical parameters. DNA-paraben interaction was investigated with spectroscopic analysis for the genotoxicity mechanism. As a result of the study, paraben (500 mM) caused a regression in the physiological parameters related to germination in Allium cepa L. bulbs. Paraben caused a 43.3% reduction in mitotic index (MI) rates compared to control, which is likely the reason for the decrease in germination-related parameters. With the application of paraben in root tip cells, the frequency of micronucleus (MN) and chromosomal aberrations (CAs) increased and a high genotoxic effect was observed. Paraben promoted CAs such as fragment, sticky chromosome, bridge, unequal distribution of chromatin, and irregular mitosis. It also caused anatomical damage in the form of epidermis cell damage, flattened cell nucleus, cortex cell damage, cortex cell walls thickening, and unclear vascular tissue in root tip meristem cells. Paraben-DNA interaction was caused by bathochromic and hypochromic shifts in the UV spectrum of DNA, indicating the intercalation mode of interaction. Paraben also caused an increase in malondialdehyde (MDA) levels, a decrease in glutathione (GSH) levels, and abnormalities in antioxidant enzyme levels (superoxide dismutase = SOD and catalase = CAT), thereby disrupting the antioxidant/oxidant dynamics in the cell. The basis of physiological, cytological, and genetic abnormalities was attributed to the oxidative stress in the cell. Administration of Noex produced a dose-dependent incremental improvement in paraben-induced abnormalities. The increase in GSH levels and the decrease in MDA levels observed as a result of the Noex application contributed to the restoration of antioxidant/oxidant balance, and this improvement was also reflected in other parameters. Application of 200 mg/L Noex provided a 24.2% improvement in the MI rate reduced by paraben, and accordingly, an increase in germination parameters was observed. Similarly, the frequencies of MN and CAs, which are signs of genotoxicity, decreased with the Noex application. As a result of the phytochemical analysis of Noex with HPLC and GC-MS, the presence of strong antioxidant and antimutagenic substances such as rutin, coumaric acid, ferrulic acid, L-serine, L-proline, and phytol were determined in Noex structure. The curative effects of Noex against paraben toxicity can be attributed to these active ingredients.

Discovery of the mechanism of n-propylparaben-promoting the proliferation of human breast adenocarcinoma cells by activating human estrogen receptors via metabolomics analysis

BACKGROUND

N-propylparaben (PP), a type of paraben, is commonly used as a preservative or antibacterial agent in daily chemicals, medicine, food, cosmetics, feed, and various industrial preservatives. Although PP promotes the growth of human breast adenocarcinoma (MCF-7) cells by activating the human estrogen receptor (ER), the mechanism responsible for this type of programmed cell proliferation is poorly understood.

OBJECTIVE

To clarify the effect of PP on cell metabolic function and the potential molecular mechanism of PP induced MCF-7 cell proliferation from a new perspective.

METHODS

To use high-resolution mass spectrometry-based metabolomics combined with bioinformatics analysis to analyze the molecular mechanism.

RESULTS

The results illustrated that differential endogenous compounds related to the effects of PP on cell metabolic functions were detected. PP was found to promote glycolysis in MCF-7 cells and enhance the tricarboxylic acid cycle (TCA cycle) in mitochondria, thus improving the energy supply to these tumor cells for metabolic function and promotion of rapid proliferation. Moreover, we found that PP promoted cell proliferation by affecting the mitogen-activated protein kinase (MAPK) signaling pathway of MCF-7 cells.

CONCLUSION

Our results revealed the molecular mechanism of low concentration PP promoting MCF-7 cell proliferation by activating ER.

Microbiota analysis for risk assessment of xenobiotics: toxicomicrobiomics, incorporating the gut microbiome in the risk assessment of xenobiotics and identifying beneficial components for One Health

This work explores three areas of relevance to the gut microbiome in the context of One Health; the incorporation of the microbiome in food safety risk assessment of xenobiotics; the identification and application of beneficial microbial components to various areas under One Health, and specifically, in the context of antimicrobial resistance. We conclude that, although challenging, focusing on the microbiota resilience, function and active components, are critical for advancing the incorporation of the gut microbiome in the risk assessment of xenobiotics. Moreover, research technologies, such as toxicomicrobiomics, culturomics and genomics, especially in combination, have revealed that the human microbiota may be a promising source of beneficial taxa or other components, with the potential to metabolise and biodegrade xenobiotics. These may have possible applications in several health areas, including in animals or plants for detoxification or in the environment for bioremediation. This approach would be of particular interest for antimicrobials, with the potential to ameliorate antimicrobial resistance development. Finally, we propose that the concept of resistance to xenobiotics in the context of the gut microbiome may deserve further investigation in the pursuit of holistically elucidating their involvement in the balance between health and disease.

Efficacy of Topical Administration of Corticosteroids for the Management of Dry Eye Disease: Systematic Review and Meta-Analysis

The efficacy of corticosteroids (CS) for dry eye disease (DED) has been investigated in the clinical setting. The present study investigated whether topical CS application improves the clinical outcome at last follow-up compared to the baseline. The present study was conducted according to the PRISMA 2020. All the randomized clinical trials (RCTs), which investigated the efficacy of corticosteroids in the management of DED, were accessed. In September 2022, the following databases were accessed: Pubmed, Web of Science, Google Scholar, and Embase. The following data were extracted at baseline and at last follow-up: Ocular Surface Disease Index (OSDI), tear breakup time test (TBUT), Schirmer I test (SIT), and corneal staining. Data from 425 patients were retrieved. A total of 69.4% (295 of 425 patients) were women. CS were effective to improve SIT (p = 0.02) and corneal staining (p = 0.003) at the last follow-up of 10.0 ± 15.3 weeks. TBUT was greater in the CS than in the control group at the last follow-up (p = 0.002). Concluding, topical CS administration led to an increase of SIT and a reduction of corneal staining at a mean of 10 weeks follow-up in patients with DED. Compared to a control group, topical CS administration evidenced greater values of TBUT. Altogether, a good safety profile was witnessed in DED patients receiving CS. However, different safety profiles of different CS formulations were not investigated due to a lack of quantitative data. The exact dosing frequency, duration of therapy, and favorable potency of the CS are still under investigation. Future randomized, controlled trials with larger sample sizes are warranted to provide higher-quality evidence to establish the role of CS in DED.

Environmental contamination status with common ingredients of household and personal care products exhibiting endocrine-disrupting potential

The continuous use of household and personal care products (HPCPs) produces an immense amount of chemicals, such as parabens, bisphenols, benzophenones and alkylphenol ethoxylates, which are of great concern due to their well-known endocrine-disrupting properties. These chemicals easily enter the environment through man-made activities, thus contaminating the biota, including soil, water, plants and animals. Thus, on top of the direct exposure on account of their presence in HPCPs, humans are also susceptible to secondary indirect exposure attributed to the ubiquitous environmental contamination. The aim of this review was therefore to examine the sources and occurrence of these noteworthy contaminants (i.e. parabens, bisphenols, benzophenones, alkylphenol ethoxylates), to summarise the available research on their environmental presence and to highlight their bioaccumulation potential. The most notable environmental contaminants appear to be MeP and PrP among parabens, BPA and BPS among bisphenols, BP-3 among benzophenones and NP among alkylphenols. Their maximum detected concentrations in the environment are mostly in the range of ng/L, while in human tissues, their maximum concentrations achieved μg/L due to bioaccumulation, with BP-3 and nonylphenol showing the highest potential to bioaccumulate. Finally, of another great concern is the fact that even the unapproved parabens and benzophenones have been detected in the environment.

Cytotoxicity evaluation and mechanism of endocrine-disrupting chemicals by the embryoid body test

Endocrine-disrupting chemicals (EDCs) are a structurally diverse class of synthetic and natural compounds. EDCs can cause non-communicable diseases such as obesity, type 2 diabetes, thyroid disorders, neurodevelopmental disease, hormone-dependent cancers, and reproductive disorders. The embryoid body test (EBT) is a developmental toxicity test method that determines the size of embryoid bodies (EBs) and the viability of mouse embryonic stem cells (mESCs) and fibroblasts (3T3 cells). The present study used the EBT to perform cytotoxicity evaluations of 10 EDCs and assessed the mechanistic relationship between endoplasmic reticulum (ER) stress and cytotoxicity. According to the statistical analysis and prediction model results, methylparaben, butylparaben, propylparaben, ethylparaben, triclosan, octylphenol, methoxychlor, bisphenol A, and diethylstilbestrol were classified as cytotoxic, but trichloroacetic acid was non-toxic. Classification accuracy was 90%. The mechanistic study showed that the cytotoxicities of butylparaben, propylparaben, octylphenol, and triclosan were induced by ER stress. The mRNA expressions of BiP, CHOP, and ATF4 were significantly higher following treatments with four EDCs compared to those after the control treatment. Compared to the control treatment, the mRNA levels of XBP1u and XBP1s increased significantly after butylparaben and propylparaben treatments, but did not increase with octylphenol and triclosan treatments. These results indicate that the EBT can be applied as an alternative toxicity test when evaluating the cytotoxicity of EDCs.

Investigation of combined effects of propyl paraben and methyl paraben on the hypothalamic-pituitary-adrenal axis in male rats

The aim of this study was to investigate the endocrine-disrupting effects of methyl paraben (MeP) and propyl paraben (PrP) mixture on the hypothalamic-pituitary-adrenal axis (HPA). In this study, six experimental groups were designated. These groups included three control groups (control, corn oil control, and positive control (50 mg/kg/day BPA)) and three dose groups (10, 100, and 500 mg/kg/day MeP+PrP). MeP with PrP were mixed in a 1:1 ratio and administered to the 42-day-old male rats by oral gavage for 30 days. At the end of the experiment, adrenocorticotropic hormone (ACTH), corticosterone and aldosterone hormones were analyzed in serum. Effects of MeP+PrP on the adrenal glands were investigated by immunohistochemical staining of 11ß hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) enzymes involved in the synthesis steps of corticosterone and aldosterone. Also, pituitary and adrenal glands were examined histopathologically. In the histopathological findings, cortical nodule, congestion, and edema were found in the tissues. In the pituitary gland, cytokeratin rings were detected in all MeP+PrP dose groups, supporting the increase of corticosterone and ACTH. Serum corticosterone, aldosterone, and ACTH hormone levels were increased in the 100 mg/kg/day MeP+PrP and BPA groups. Results obtained from immunohistochemical staining showed that increased staining parallelled increased corticosterone and aldosterone hormone levels. In summary, the results showed that exposure to the MeP+PrP mixture caused a significant increase in ACTH and corticosterone. Also, the MeP+PrP mixture caused a significant increase of CYP11B1 and CYP11B2. MeP+PrP exposure disrupts the normal HPA axis.

Exposure to Antibacterial Chemicals Is Associated With Altered Composition of Oral Microbiome

Antimicrobial chemicals are used as preservatives in cosmetics, pharmaceuticals, and food to prevent the growth of bacteria and fungi in the products. Unintentional exposure in humans to such chemicals is well documented, but whether they also interfere with human oral microbiome composition is largely unexplored. In this study, we explored whether the oral bacterial composition is affected by exposure to antibacterial and environmental chemicals. Gingival fluid, urine, and interview data were collected from 477 adults (18–47 years) from the RHINESSA study in Bergen, Norway. Urine biomarkers of triclosan, triclocarban, parabens, benzophenone-3, bisphenols, and 2,4- and 2,5-dichlorophenols (DCPs) were quantified (by mass spectrometry). Microbiome analysis was based on 16S amplicon sequencing. Diversity and differential abundance analyses were performed to identify how microbial communities may change when comparing groups of different chemical exposure. We identified that high urine levels (>75th percentile) of propyl parabens were associated with a lower abundance of bacteria genera TM7 [G-3], Helicobacter, Megasphaera, Mitsuokella, Tannerella, Propionibacteriaceae [G-2], and Dermabacter, as compared with low propylparaben levels (<25^th percentile). High exposure to ethylparaben was associated with a higher abundance of Paracoccus. High urine levels of bisphenol A were associated with a lower abundance of Streptococcus and exposure to another environmental chemical, 2,4-DCP, was associated with a lower abundance of Treponema, Fretibacterium, and Bacteroidales [G-2]. High exposure to antibacterial and environmental chemicals was associated with an altered composition of gingiva bacteria; mostly commensal bacteria in the oral cavity. Our results highlight a need for a better understanding of how antimicrobial chemical exposure influences the human microbiome.

Incorporating the Gut Microbiome in the Risk Assessment of Xenobiotics and Identifying Beneficial Components for One Health

Three areas of relevance to the gut microbiome in the context of One Health were explored; the incorporation of the microbiome in food safety risk assessment of xenobiotics; the identification and application of beneficial microbial components to various areas under One Health, and; specifically, in the context of antimicrobial resistance. Although challenging, focusing on the microbiota resilience, function and active components is critical for advancing the incorporation of microbiome data in the risk assessment of xenobiotics. Moreover, the human microbiota may be a promising source of beneficial components, with the potential to metabolize xenobiotics. These may have possible applications in several areas, e.g., in animals or plants for detoxification or in the environment for biodegradation. This approach would be of particular interest for antimicrobials, with the potential to ameliorate antimicrobial resistance development. Finally, the concept of resistance to xenobiotics in the context of the gut microbiome may deserve further investigation.

The Current States, Challenges, Ongoing Efforts, and Future Perspectives of Pharmaceutical Excipients in Pediatric Patients in Each Country and Region

A major hurdle in pediatric formulation development is the lack of safety and toxicity data on some of the commonly used excipients. While the maximum oral safe dose for several kinds of excipients is known in the adult population, the doses in pediatric patients, including preterm neonates, are not established yet due to the lack of evidence-based data. This paper consists of four parts: (1) country-specific perspectives in different parts of the world (current state, challenges in excipients, and ongoing efforts) for ensuring the use of safe excipients, (2) comparing and contrasting the country-specific perspectives, (3) past and ongoing collaborative efforts, and (4) future perspectives on excipients for pediatric formulation. The regulatory process for pharmaceutical excipients has been developed. However, there are gaps between each region where a lack of information and an insufficient regulation process was found. Ongoing efforts include raising issues on excipient exposure, building a region-specific database, and improving excipient regulation; however, there is a lack of evidence-based information on safety for the pediatric population. More progress on clear safety limits, quantitative information on excipients of concern in the pediatric population, and international harmonization of excipients’ regulatory processes for the pediatric population are required.

Propylparaben concentrations in the urine of women and adverse effects on ovarian function in mice in vivo and ovarian cells in vitro

Female reproduction is precisely regulated by hormones, and the ovary is easily affected by environmental endocrine disruptors (EDCs), which are ubiquitous in industrialized societies. Parabens are EDCs that are used as antibacterial preservatives in cosmetics, personal care products (PCPs), medicines, and food. We used ultrahigh-performance liquid chromatography-mass spectrometry to quantitatively detect methyl-, ethyl-, butyl-, and propylparaben (PP) concentrations in urine samples from 74 women of childbearing age. Balb/c mice were subcutaneously injected with 100 mg/kg/day of PP for 21 consecutive days or 100 or 1,000 mg/kg/day of PP during superovulation. Various concentrations of PP (ranging from 1 to 1,000 nM) were added to a human ovarian granulosa tumor-derived cell line (KGN) culture for 24 h. The urinary paraben concentrations of women who used cosmetics and other PCPs within 48 h prior to sample collection were significantly elevated, and the PP concentration was significantly positively correlated with the basal estradiol concentration. After PP injection, the mouse serum estradiol concentrations were significantly increased, estrus cycles were disordered, corpus luteum number was reduced, and number of oocytes retrieved was significantly reduced. In in vitro experiments, PP treatment increased estradiol synthesis and the expression levels of aromatase enzyme (CYP19A1) and steroidogenic acute regulatory protein. This study demonstrates the adverse effects of PP on ovarian estradiol secretion and ovulation, further evaluates the safety of PP as a preservative, and provides guidance for the use of PCPs and cosmetics by women of childbearing age.

Lidocaine: A Local Anesthetic, Its Adverse Effects and Management

The most widely used medications in dentistry are local anesthetics (LA), especially lidocaine, and the number of recorded adverse allergic responses, particularly of hazardous responses, is quite low. However, allergic reactions can range from moderate to life-threatening, requiring rapid diagnosis and treatment. This article serves as a review to provide information on LA, their adverse reactions, causes, and management.

Exposure to environmental phenols and parabens, and relation to body mass index, eczema and respiratory outcomes in the Norwegian RHINESSA study

BACKGROUND

Many phenols and parabens are applied in cosmetics, pharmaceuticals and food, to prevent growth of bacteria and fungi. Whether these chemicals affect inflammatory diseases like allergies and overweight is largely unexplored. We aimed to assess the associations of use of personal care products with urine biomarkers levels of phenols and paraben exposure, and whether urine levels (reflecting body burden of this chemical exposures) are associated with eczema, rhinitis, asthma, specific IgE and body mass index.

METHODS

Demographics, clinical variables, and self-report of personal care products use along with urine samples were collected concurrently from 496 adults (48% females, median age: 28 years) and 90 adolescents (10-17 years of age) from the RHINESSA study in Bergen, Norway. Urine biomarkers of triclosan (TCS), triclocarban (TCC), parabens and benzophenone-3, bisphenols and dichlorophenols (DCP) were quantified by mass spectrometry.

RESULTS

Detection of the urine biomarkers varied according to chemical type and demographics. TCC was detected in 5% of adults and in 45% of adolescents, while propyl (PPB) and methyl (MPB) parabens were detected in 95% of adults and in 94% (PPB) and 99% (MPB) of adolescents. Women had higher median urine concentrations of phenolic chemicals and reported a higher frequency of use of personal care products than men. Urine concentration of MPB increased in a dose-dependent manner with increased frequency of use of several cosmetic products. Overall, urinary biomarker levels of parabens were lower in those with current eczema. The biomarker concentrations of bisphenol S was higher in participants with positive specific IgE and females with current asthma, but did not differ by eczema or rhinitis status. MPB, ethylparaben (EPB), 2,4-DCP and TCS were inversely related to BMI in adults; interaction by gender were not significant.

CONCLUSIONS

Reported frequency of use of personal care products correlated very well with urine biomarker levels of paraben and phenols. Several chemicals were inversley related to BMI, and lower levels of parabens was observed for participants with current eczema. There is a need for further studies of health effects of chemicals from personal care products, in particular in longitudinally designed studies.

Exposure to parabens and associations with oxidative stress in adults from South China

Parabens are widely applied as preservatives in cosmetics, drugs and food. Previous studies suggested that parabens could exhibit potential risks to human health. However, data on human exposure levels and health effects of parabens remain limited, especially in the potential effects on DNA oxidative stress. This study aimed to investigate urinary levels of parabens in adults from South China and explore the relationships between urinary parabens and DNA oxidative stress. Five short chain parabens, including methyl paraben (MeP), ethyl paraben (EtP), n-propyl paraben (PrP), butyl paraben (BuP) and benzyl paraben (BzP), were determined in urine from 319 adults in Shenzhen, China. MeP, EtP and PrP were frequently detected in urine samples (detection frequencies >66.5%), suggesting broad exposure in South China adults. Median concentrations of MeP, EtP, PrP, BuP and BzP were 5.78, 0.39, 0.35, 0.01 and 0.02 μg/L, respectively. A significantly positive correlation was observed between the urinary concentrations of MeP and PrP (p < 0.01), suggesting similar sources for these two chemicals. In addition, participants with alcohol consumption exhibited significantly lower paraben concentrations in urine than those without alcohol drinking (p < 0.05). Significant association was observed between urinary concentrations of parabens and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels (p < 0.01), while no significant dose-response relationship was found (p > 0.05). A potential risk from PrP exposure was found in South China adults.

Review of aluminum, paraben, and sulfate product disclaimers on personal care products

BACKGROUND

Product disclaimers listed on personal care products face limited regulation. These disclaimers may be helpful or may mislead the public.

OBJECTIVE

Review the evidence supporting the potential harms of three compounds commonly addressed by product disclaimers: parabens, aluminum, and sulfates.

METHODS

Reported cases of adverse events to these compounds were identified. Trends in allergic contact dermatitis to chemicals used in place of these compounds were also identified.

RESULTS

There is limited evidence that parabens and aluminum pose a threat to human health; there is even less evidence that topical sulfate containing products pose a danger to consumers. In the setting of paraben avoidence, there has been a steady increase in cases of allergic contact dermatitis to preservatives which are more allergenic, specifically the isothiazolinones.

LIMITATIONS

Assessment of the toxicology of these compounds is ongoing and may change with new data.

CONCLUSION

There is limited evidence that parabens, aluminum, and sulfates used in personal care products pose a health risk. There is evidence that avoidance of parabens has resulted in an epidemic of allergic contact dermatitis to isothiazolonine preservatives.

Exposure to ethylparaben and propylparaben interfere with embryo implantation by compromising endometrial decidualization in early pregnant mice

Ethylparaben (EtP) and propylparaben (PrP) are common preservatives and well-known endocrine-disrupting chemicals. Studies have demonstrated that they can reduce female fertility, but the underlying mechanism, especially that on embryo implantation, is still poorly understood. Endometrial decidualization is a critical event for embryo implantation. In this study, we aimed to explore the effects of EtP/PrP on endometrial decidualization. Pregnant mice were dosed daily by oral gavage with EtP at 0, 400, 800 and 1600 mg/kg or with PrP at 0, 625, 1250 and 2500 mg/kg from Day 1 of pregnancy until sacrifice. The results showed that the rate of pregnant mice with impaired embryo implantation, whose number of implantation sites was less than 7, was significantly increased after exposure to 1600 mg/kg EtP or 2500 mg/kg PrP. Further study found that the expression of endometrial decidualization markers HOXA10, MMP9 and PR was significantly downregulated in 1600 mg/kg EtP group and 2500 mg/kg PrP group. Notably, serum oestrogen and progesterone levels were significantly increased, whereas the expression of uterine oestrogen receptor and progesterone receptor was decreased following 1600 mg/kg EtP or 2500 mg/kg PrP exposure. In the breeding test, fewer offspring were found after females were exposed to 1600 mg/kg EtP or 2500 mg/kg PrP in early pregnancy. This demonstrated that exposure to EtP/PrP interfered with embryo implantation by compromising endometrial decidualization in early-stage pregnant mice. Disorders of reproductive hormones and hormone receptor signals could be responsible for impaired decidualization. This study broadened the understanding on the biological safety of EtP and PrP.

Chemical contaminants in Brazilian drinking water: a systematic review

The goals of this research are to evaluate which chemical contaminations were detected in Brazil's drinking water reported in papers published from 2012 to 2019, to propose guideline values for emerging contaminants and assess which are the priority parameters from a health risk perspective. The methodology used was a systematic review. The chemical contaminants quantified were evaluated according to Brazilian drinking-water standards, and Guideline Values were proposed for emerging pollutants using conservative endpoints from NOAEL and LOAEL available in literature. From 1351 articles evaluated, 15 reached the research goal. Seventy-seven parameters were quantified in Brazilian drinking water from underground, surface and rainwater sources. Soil composition, mining, sewage and agricultural activities were the main sources for the seven classes framed: pesticides, metals, organic, endocrine disruptors, drugs, personal care products and illicit drugs. Twenty-two parameters are listed in the current Brazilian drinking water quality standard and 54 are not. Water was not considered appropriate to drink due to cadmium, aluminum, iron, nickel, mercury, atrazine, propionaldehyde, beryllium, acetone and 17 α-ethinyl estradiol (carcinogenic). Measures to reduce chemical contamination in drinking water need to be taken such as the expansion of sewage treatment and upgrading to tertiary treatment, and controlling and reducing the application of pesticides.

Exposure to Propylparaben During Pregnancy and Lactation Induces Long-Term Alterations to the Mammary Gland in Mice

The mammary gland is a hormone sensitive organ that is susceptible to endocrine-disrupting chemicals (EDCs) during the vulnerable periods of parous reorganization (ie, pregnancy, lactation, and involution). Pregnancy is believed to have long-term protective effects against breast cancer development; however, it is unknown if EDCs can alter this effect. We examined the long-term effects of propylparaben, a common preservative used in personal care products and foods, with estrogenic properties, on the parous mouse mammary gland. Pregnant BALB/c mice were treated with 0, 20, 100, or 10 000 µg/kg/day propylparaben throughout pregnancy and lactation. Unexposed nulliparous females were also evaluated. Five weeks post-involution, mammary glands were collected and assessed for changes in histomorphology, hormone receptor expression, immune cell number, and gene expression. For several parameters of mammary gland morphology, propylparaben reduced the effects of parity. Propylparaben also increased proliferation, but not stem cell number, and induced modest alterations to expression of ERα-mediated genes. Finally, propylparaben altered the effect of parity on the number of several immune cell types in the mammary gland. These results suggest that propylparaben, at levels relevant to human exposure, can interfere with the effects of parity on the mouse mammary gland and induce long-term alterations to mammary gland structure. Future studies should address if propylparaben exposures negate the protective effects of pregnancy on mammary cancer development.

Effect of a bioconverted product of Lotus corniculatus seed on the axillary microbiome and body odor

The skin microbiome, especially the axillary microbiome, consists of odor-causing bacteria that decompose odorless sweat into malodor compounds, which contributes to the formation of body odor. Plant-derived products are a cheap source of bioactive compounds that are common ingredients in cosmetics. Microbial bioconversion of natural products is an ecofriendly and economical method for production of new or improved biologically active compounds. Therefore, in this study, we tested the potential of a Lactobacillus acidophilus KNU-02-mediated bioconverted product (BLC) of Lotus corniculatus seed to reduce axillary malodor and its effect on the associated axillary microbiota. A chemical profile analysis revealed that benzoic acid was the most abundant chemical compound in BLC, which increased following bioconversion. Moreover, BLC treatment was found to reduce the intensity of axillary malodor. We tested the axillary microbiome of 18 study participants, divided equally into BLC and placebo groups, and revealed through 16S rRNA gene sequencing that Staphylococcus, Corynebacterium, and Anaerococcus were the dominant taxa, and some of these taxa were significantly associated with axillary malodor. After one week of BLC treatment, the abundance of Corynebacterium and Anaerococcus, which are associated with well-known odor-related genes that produce volatile fatty acids, had significantly reduced. Likewise, the identified odor-related genes decreased after the application of BLC. BLC treatment enhanced the richness and network density of the axillary microbial community. The placebo group, on the other hand, showed no difference in the microbial richness, odor associated taxa, and predicted functional genes after a week. The results demonstrated that BLC has the potential to reduce the axillary malodor and the associated odor-causing bacteria, which makes BLC a viable deodorant material in cosmetic products.

Thirteen-week subcutaneous repeated dose toxicity study of butylparaben and its toxicokinetics in rats

Parabens are widely used preservatives in cosmetics and pharmaceutical products and are approved as food additives. These chemicals have been considered safe for many years. However, the literature classifies parabens as endocrine-disrupting chemicals, and an assessment of their influence on the endocrine system and systemic toxicity is important. This study explored long-term systemic toxicity, effects on the endocrine system, and toxicokinetic behavior after repeated subcutaneous administration of butylparaben to Sprague-Dawley rats. Rats were treated with vehicle (4% Tween 80) or butylparaben at dose levels of 2, 10, and 50 mg/kg/day for 13 weeks. Assessment of systemic toxicity and endocrine-disrupting effects was based on mortality; clinical signs; body weight; food and water consumption; ophthalmological findings; urinalysis; hematology and clinical biochemistry; organ weights; necropsy and histopathological findings; regularity and length of the estrous cycle; semen quality; and toxicokinetic behavior. Female uterine weight and estrous cycle, and male semen quality indicated no estrogenic effects. Butylparaben induced local irritation at the injection site in both sexes at a dose of 50 mg/kg/day, but systemic toxicity was not observed. Therefore, the no-observed-adverse-effect level of butylparaben is set at 50 mg/kg/day in rats of both sexes. Butylparaben was without endocrine system effects at this dose. Butylparaben displays dose-dependent systemic exposure up to the maximum dose of 50 mg/kg/day and repeated administration of butylparaben for 13 weeks shows no bioaccumulation.

Paraben Compounds—Part I: An Overview of Their Characteristics, Detection, and Impacts

Parabens are widely used in different industries as preservatives and antimicrobial compounds. The evolution of analytical techniques allowed the detection of these compounds in different sources at µg/L and ng/L. Until today, parabens were already found in water sources, air, soil and even in human tissues. The impact of parabens in humans, animals and in ecosystems are a matter of discussion within the scientific community, but it is proven that parabens can act as endocrine disruptors, and some reports suggest that they are carcinogenic compounds. The presence of parabens in ecosystems is mainly related to wastewater discharges. This work gives an overview about the paraben problem, starting with their characteristics and applications. Moreover, the dangers related to their usage were addressed through the evaluation of toxicological studies over different species as well as of humans. Considering this, paraben detection in different water sources, wastewater treatment plants, humans and animals was analyzed based on literature results. A review of European legislation regarding parabens was also performed, presenting some considerations for the use of parabens.

Exposure of Chinese adult females to parabens from personal care products: Estimation of intake via dermal contact and health risks

Parabens are added into foodstuffs, pharmaceuticals and personal care products (PCPs) as additives extensively due to their excellent antiseptic and antibacterial effects. In the past decade, parabens have raised great concerns on their potential harm to humans. Existing studies have suggested positive correlations between PCP application and urinary paraben concentrations in females, but little is known about paraben exposure levels and health risks arising from PCP use. In this study, 150 PCP samples covering eleven categories were collected from South China and measured for the concentrations of five parabens, including methyl paraben (MeP), ethyl paraben (EtP), propyl paraben (PrP), butyl paraben (BuP) and benzyl paraben (BeP). Parabens were widely detected in PCPs, with a detection frequency of 100%, 99.3%, 80.0%, 74.0% and 13.3%, for MeP, EtP, PrP, BuP and BeP, respectively. The median concentration of Σ₅parabens was 126 μg/g with a range of 6.38-424 μg/g across all PCP samples. The contents of MeP, EtP and PrP measured in leave-on PCPs were obviously higher than those in the rinse-off ones (p < 0.05). MeP and PrP were the main paraben analogues, together accounting for 93.6% of Σ₅parabens in all PCPs. The daily intakes of parabens through dermal absorption by Chinese adult females estimated by measurements obtained in the present study were 0.15 and 83.2 μg/kg-bw/day on basis of the application of rinse-off and leave-on PCPs, respectively. Among the eleven categories, sunscreen, body lotion and mask constituted the main exposure sources of parabens to females. The hazard quotients of parabens were far less than 1, indicating no considerable health risk for Chinese adult females.

The potential pathways underlying the association of propyl-paraben exposure with aeroallergen sensitization and EASI score using metabolomics analysis

Propyl-paraben exposure is associated with aeroallergen sensitization, but its association with atopic dermatitis (AD) is inconclusive. No studies have been conducted on the metabolomic pathways underlying these associations. We investigated the associations between propyl-paraben exposure and aeroallergen sensitization, AD, and Eczema Area and Severity Index (EASI) score and identified the underlying pathways using untargeted metabolomics analysis. We enrolled 455 children in a general population study. Skin prick tests were performed with the assessment of EASI score. Urinary propyl-, butyl-, ethyl-, and methyl-paraben levels were measured. Untargeted metabolomics analysis was performed on the first and fifth urine propyl-paraben quintile groups. The highest urine propyl-paraben quintile group was associated with aeroallergen sensitization, but not with AD. Glycine, threonine, serine, ornithine, isoleucine, arabinofuranose, d-lyxofuranose, citrate, and picolinic acid levels were higher, whereas palmitic acid and 2-palmitoylglycerol levels were lower in the highest quintile propyl-paraben group, than in the lowest quintile group. The propyl-paraben-induced metabolic perturbations were associated with serine and glycine metabolisms, branched-chain amino acid metabolism, and ammonia recycling. Propyl-paraben exposure was associated with aeroallergen sensitization and EASI score, partially via metabolomic changes related with oxidative stress, mTOR, peroxisome proliferator-activated receptors pathway, aryl hydrocarbon receptor signaling pathways, and tricarboxylic acid cycle.

Application of grouping and read-across for the evaluation of parabens of different chain lengths with a particular focus on endocrine properties

This article presents the outcomes of higher-tier repeated-dose toxicity studies and developmental and reproductive toxicity (DART) studies using Wistar rats requested for methyl paraben and propyl paraben under the European Union chemicals legislation. All studies revealed no-observed adverse effects (NOAELs) at 1000 mg/kg body weight/day. These findings (absence of effects) were then used to interpolate the hazard profile for ethyl paraben, further considering available data for butyl paraben. The underlying read-across hypothesis (all shorter-chained linear n-alkyl parabens are a ‘category’ based on very high structural similarity and are transformed to a common compound) was confirmed by similarity calculations and comparative in vivo toxicokinetics screening studies for methyl paraben, ethyl paraben, propyl paraben and butyl paraben. All four parabens were rapidly taken up systemically following oral gavage administration to rats, metabolised to p-hydroxybenzoic acid, and rapidly eliminated (parabens within one hour; p-hydroxybenzoic acid within 4–8 h). Accordingly, for ethyl paraben, the NOAELs for repeated-dose toxicity and DART were interpolated to be 1000 mg/kg body weight/day. Finally, all evidence was evaluated to address concerns expressed in the literature that parabens might be endocrine disruptors. This evaluation showed that the higher-tier studies do not provide any indication for any endocrine disrupting property. This is the first time that a comprehensive dataset from higher-tier in vivo studies following internationally agreed test protocols has become available for shorter-chained linear n-alkyl parabens. Consistently, the dataset shows that these parabens are devoid of repeated-dose toxicity and do not possess any DART or endocrine disrupting properties.

Assessing the Public Health Implications of the Food Preservative Propylparaben: Has This Chemical Been Safely Used for Decades

PURPOSE

Parabens are chemicals containing alkyl-esters of p-hydroxybenzoic acid, which give them antimicrobial, antifungal, and preservative properties. Propylparaben (PP) is one paraben that has been widely used in personal care products, cosmetics, pharmaceuticals, and food. In this review, we address the ongoing controversy over the safety of parabens, and PP specifically. These chemicals have received significant public attention after studies published almost 20 years ago suggested plausible associations between PP exposures and breast cancer.

RECENT FINDINGS

Here, we use key characteristics, a systematic approach to evaluate the endocrine disrupting properties of PP based on features of "known" endocrine disruptors, and consider whether its classification as a "weak" estrogen should alleviate public health concerns over human exposures. We also review the available evidence from rodent and human studies to illustrate how the large data gaps that exist in hazard assessments raise concerns about current evaluations by regulatory agencies that PP use is safe. Finally, we address the circular logic that is used to suggest that because PP has been used for several decades, it must be safe. We conclude that inadequate evidence has been provided for the safe use of PP in food, cosmetics, and consumer products.

Environmental Distribution of Personal Care Products and Their Effects on Human Health

Personal care products (PCPs) are generally used for personal hygiene, cleaning, grooming, and beautification. These include hair and skin care products, baby care products, UV blocking creams, facial cleansers, insect repellents, perfumes, fragrances, soap, detergents, shampoos, conditioners, toothpaste, etc., thus exposing humans easily. Personal preferences related to PCPs usage frequency are highly variable and depend on socioeconomic status and lifestyle factors. The increasing availability and diversity of PCPs from the retailer outlets consequently result in higher loading of PCPs into wastewater systems and, therefore, the environment. These compounds persistently and continuously release biologically active and inactive ingredients in the atmosphere, biosphere, geosphere, and demonstrating adverse effects on human, wild, and marine life. Advanced techniques such as granular activated carbon filtration and algae-based system may help biotransformation and remove PCP contaminants from water with improved efficiency. Additionally, harmony among PCPs related regulations of different countries may encourage standard checks to control their manufacturing, sale, and distribution across the borders to ensure consumers' safety. Furthermore, all intended ingredients, their concentrations, and instructions for frequency of use as per age groups may be clearly labeled on packages of PCPs. In conclusion, the emerging environmental contaminants of PCPs and their association with the growing risks of negative effects on human health and globally on the environment emphasize the chemical-free simple lifestyle.

Identification of novel paraben-binding peptides using phage display

Parabens are alkyl esters of 4-hydroxybenzoic acid, which is derived from a family of synthetic esters of p-hydroxybenzoic acid. Among all the kinds of paraben, two parabens (methyl paraben, MP; and n-propyl paraben, PP) are the most generally used as preservatives in personal care products, such as cosmetics, pharmaceuticals, and food also, and are often presented together. However, a number of studies have reported that the toxicity of parabens affects the water environment, and human as well. This study utilized M13 phage display technology to provide easy, efficient, and relatively inexpensive methods to identify peptides that bind to MP and PP, respectively, to remove in wastewater. At first, biopanning was performed, to sort MP and PP specific binding phages, and three cases of experiment, including negative control (NC), which could sort unspecific binding phage, were conducted at the same time. Phage binding affinity tests were substituted by concentration reduction using antibody conjugated magnetic beads, and paraben concentration was measured by HPLC. Analysis showed that the MP concentration reduction of 38% was the highest in M4 phage, while the PP concentration reduction of 44% was the highest in P3 phage. We successfully screened two peptides specific to MP and PP, namely, MP4 and PP3, respectively; the results showed that the MP concentration reduction in MP4 was the highest at 44%, and the PP concentration reduction in PP3 was the highest at 39%, and their specificity was measured by the capture rate between target and control. In conclusion, the phage display technique shows applicability to the removal of parabens in water; furthermore, it also shows the possibility of the detection or removal of other chemicals.

Propylparaben Reduces the Long-Term Consequences in Hippocampus Induced by Traumatic Brain Injury in Rats: Its Implications as Therapeutic Strategy to Prevent Neurodegenerative Diseases

BACKGROUND

Severe traumatic brain injury (TBI), an important risk factor for Alzheimer's disease, induces long-term hippocampal damage and hyperexcitability. On the other hand, studies support that propylparaben (PPB) induces hippocampal neuroprotection in neurodegenerative diseases.

OBJECTIVE

Experiments were designed to evaluate the effects of subchronic treatment with PPB on TBI-induced changes in the hippocampus of rats.

METHODS

Severe TBI was induced using the lateral fluid percussion model. Subsequently, rats received subchronic administration with PPB (178 mg/kg, TBI+PPB) or vehicle (TBI+PEG) daily for 5 days. The following changes were examined during the experimental procedure: sensorimotor dysfunction, changes in hippocampal excitability, as well as neuronal damage and volume.

RESULTS

TBI+PEG group showed sensorimotor dysfunction (p < 0.001), hyperexcitability (64.2%, p < 0.001), and low neuronal preservation ipsi- and contralateral to the trauma. Magnetic resonance imaging (MRI) analysis revealed lower volume (17.2%; p < 0.01) and great damage to the ipsilateral hippocampus. TBI+PPB group showed sensorimotor dysfunction that was partially reversed 30 days after trauma. This group showed hippocampal excitability and neuronal preservation similar to the control group. However, MRI analysis revealed lower hippocampal volume (p < 0.05) when compared with the control group.

CONCLUSION

The present study confirms that post-TBI subchronic administration with PPB reduces the long-term consequences of trauma in the hippocampus. Implications of PPB as a neuroprotective strategy to prevent the development of Alzheimer's disease as consequence of TBI are discussed.

Parabens enhance the calcium-dependent testicular mitochondrial permeability transition: Their relevance on the reproductive capacity in male animals

Parabens, alkyl ester derivatives from p-hydroxybenzoic acid, are extensively used as antimicrobial preservatives. Nonetheless, due to its widespread and massive employment, several studies highlighted the association between parabens and alterations in the reproductive system. This study aimed to relate the adverse effect of the most commonly used parabens in testis mitochondria with male fertility. From all the parabens used, propyl and butyl were the ones that most negatively decreased the respiratory control ratio. In the case of butyl, inhibitions of 20% and 60% were observed, respectively, at the lowest and highest concentration, when compared to the control group. The membrane potential was only significantly affected by propyl (14%) and butyl (31%), and at a concentration of 250 µM. Succinate dehydrogenase, cytochrome c oxidase, and ATPase activities showed a nonsignificant decrease. Cytochrome c reductase, on the other hand, showed statistically significant inhibitions for both propyl (56%) and butylparaben (55%). The susceptibility to the mitochondrial permeability transition pore (MPTP) opening was increased by all parabens, although this increase was markedly significant for propyl and butyl. These results show that the susceptibility of mitochondria to parabens is dependent on the alkyl chain length and parabens hydrophobicity, and the main mitochondrial target is Complex II-III and MPTP. Hence, this study demonstrates the contribution of parabens exposition to the inhibition of testis mitochondrial function and their putative noxious effect on the male reproductive system.

Acute and chronic exposure of the holometabolous life cycle of Aedes aegypti L. to emerging contaminants naproxen and propylparaben

Pharmaceuticals and personal care products (PPCPs) are a class of emerging contaminants commonly detected in environmental waters worldwide. Although reports about their detection in aquatic environments are increasing, limited studies show their effects on holometabolous insects. In this study, acute and chronic exposure to naproxen (0.02, 41, 82, 164, 382, 656, and 1312 mg L^-1) and propylparaben (0.02, 25, 50, 100, 250, 500, and 1000 mg L^-1) were evaluated in Aedes aegypti L. Acute exposure to naproxen (≥0.02 mg L^-1) and propylparaben (≥0.02 mg L^-1) reduced egg eclosion. Propylparaben (≥250 mg L^-1) caused significant larval mortality but naproxen did not even at the highest experimental concentration used. LC₅₀ for naproxen and propylparaben in larvae were 1100 mg L^-1 and 182.6 mg L^-1, respectively. Naproxen (≥0.02 mg L^-1) and propylparaben (≥0.02 mg L^-1) reduced pupation. Emergence was also reduced by naproxen (≥164 mg L^-1) and propylparaben (≥0.02 mg L^-1). The fecundity of females was significantly reduced due to chronic exposure to naproxen (≥0.02 mg L^-1). There was also a reduction in the fecundity of females due to chronic propylparaben exposure but it was statistically insignificant in the concentrations used. In the F1 generation eggs, only 100 mg L^-1 propylparaben reduced eclosion. Eclosion and larval survival were sensitive to acute exposure, particularly to propylparaben. The reduced pupation and emergence indicated a delay in the progression of the life cycle. Chronic exposure also indicated a reduction in fecundity. F1 eggs exhibited tolerance to the negative effect of subsequent exposure. Our findings suggest that propylparaben can affect Ae. aegypti more negatively than naproxen.

Multispecies bioassay of propylparaben to derive protective concentrations for soil ecosystems using a species sensitivity distribution approach

Propylparaben is widely used as a preservative in pharmaceuticals and personal care products and is ultimately excreted by the human body. Thus, propylparaben reaches sewage and enters the soil environment by sludge fertilization and wastewater irrigation. However, there are few existing studies on the toxicity and risks of such chemicals in terrestrial environments. In this study, a multispecies bioassay for propylparaben was performed and protective concentrations (PCs) were derived based on toxicity values by probabilistic ecological risk assessment. Acute and chronic bioassays were conducted on 11 species in eight taxonomic groups (Magnoliopsida, Liliopsida, Clitellata, Entognatha, Entomobryomorpha, Chromadorea, Chlorophyceae, Trebouxiophyceae). Based on the toxicity values calculated, the PC₉₅ values for acute and chronic SSDs were 13 and 6 mg/kg dry soil, respectively. Toxicity varied among taxa, with soil algae emerging as the most sensitive to propylparaben. This may be attributable to differences in exposure pathways among species. The exposure pathway of propylparaben can be altered by adsorption to soil particles. As parabens are presently under-regulated globally in terms of their environmental effects, our findings can serve as the basis to propose standard values for environmental protection.

Disruption of normal adipocyte development and function by methyl- and propyl- paraben exposure

Methyl- and propyl- parabens are generally regarded as safe by the U.S Food and Drug Administration and as such are commonly used in personal care products. These parabens have been associated with increased white adipogenesis in vitro and methyl paraben also increased the white adipose mass of mice. Given brown adipose also plays a role in energy balance, we sought to evaluate whether the effects of methyl- and propyl- parabens on white adipocytes extended to brown adipocytes. We challenged white and brown pre-adipocytes at low doses of both parabens (up to 1 μM) during the differentiation process and examined adipogenesis with the ORO assay. The impact of each paraben on glucose uptake and lipolytic activity of adipocytes were measured with a fluorescent glucose analog and enzymatically, respectively. Methyl- and propyl- parabens increased adipogenesis of 3T3-L1 white adipocytes but not brown adipocytes. In white adipocytes, methyl paraben increased glucose uptake and both parabens reduced basal lipolysis. However, in brown adipocytes, parabens had no effect on basal lipolysis and instead attenuated isoproterenol induced lipolysis. These data indicate that methyl- and propyl- parabens target the differentiation and metabolic processes of multiple types of adipocytes in a cell autonomous manner.

Synthesis of 4-Hydroxybenzoic Acid Derivatives in Escherichia coli

Hydroxybenzoic acids (HBAs) such as 4-hydroxybenzoic acid (4-HBA) and 3,4-dihydroxybenzoic acid (DHB; protocatechuic acid) and its ester with methanol (methylparaben [MP]) are known to have various functional biological properties, including antibacterial, anticancer, antidiabetic, antiaging, antiviral, and anti-inflammatory activities. Since these compounds are widely used in cosmetic, food, and pharmaceutical industries, the use of renewable feedstocks for the production of HBAs is an area of growing interest. In this study, we used Escherichia coli to synthesize these three hydroxybenzoic acid derivatives (4-HBA, DHB, and MP). We overexpressed ubiC in E. coli to synthesize 4-HBA from chorismate, a substrate that is produced by the shikimate pathway in E. coli. For the synthesis of DHB, an additional gene (pobA) was introduced, while hbad and EHT1 were co-expressed to synthesize MP. To supply more chorismate, we introduced the shikimate gene module construct and selected the best construct for increased yields. Using this approach, 723.5 mg/L 4-HBA, 942.0 mg/L DHB, and 347.7 mg/L MP were synthesized. Our study showed that the shikimate gene module constructs can be applicable to increase the yields of HBA derivatives in HBA-tolerant microorganisms.

A Novel HPLC Method for Simultaneous Determination of Methyl, Ethyl, n-propyl, Isopropyl, n-butyl, Isobutyl and Benzyl Paraben in Pharmaceuticals and Cosmetics

INTRODUCTION

The alkyl esters of p-hydroxybenzoic acid at the C-4 position, "the parabens," including methyl, ethyl, propyl, and butyl, are widely used as antimicrobial preservatives in foods, cosmetics, and pharmaceuticals. Official regulations on the use of these compounds make their analysis essential for the estimation of their exposure.

METHODS

On this basis, the presented study was realized to develop a simple, selective and cheap high-performance liquid chromatographic method for the quantitative determination of methylparaben, ethylparaben (EP), n-propyl paraben (NPP), isopropyl paraben (IPP), n-butyl paraben (NBP), isobutyl paraben (IBP) and benzyl paraben (BP) in pharmaceuticals and cosmetic products.

RESULTS

The chromatographic separation of the analytes was achieved under flow rate gradient elution conditions using a C18-bonded core-shell silica particle column (2.6 μm particle size, 150 × 3.0 mm from Phenomenex Co.). The samples were injected into the system as aliquots of 1.0 μL, and the compounds were detected by using a photodiode array detector set at 254 nm wavelength. With this technique, seven paraben derivatives can be determined in the concentration range of 250-2000 ng/mL. The recovery of the method is in the range of 99.95-13.84%, and the RSD is at a maximum value of 3.95%.

CONCLUSION

The proposed method was fully validated and successfully applied to different pharmaceutical and cosmetic samples (n=16), including syrups, suspensions, oral sprays, gels, etc. At least one paraben derivative was detected in six samples and was determined quantitatively. The maximum amount of a paraben derivative found in the analyzed samples was 321.7 ng/mL, which was MP. To the best of our knowledge, this is the first LC method, which is applicable both on pharmaceutical and cosmetic samples.

Allergy to food additives

PURPOSE OF REVIEW

To provide an update of the studies concerning the diagnosis and management of food additives allergy.

RECENT FINDINGS

Additives improve specific characteristics of food products, but they may induce allergic even life-threatening reactions. Physical examination and medical history are basic to assess specific in-vivo and in-vitro tests. The only treatment for allergic patients consists in avoiding the food containing culprit additives. High-risk patients should be able to recognize severe reactions and self-manage them.

SUMMARY

The prevalence of adverse reactions to food additives is low, and it may depend on comorbidities, like asthma or chronic idiopathic urticaria. Food labels may help the correct identification of ingredients. Natural additives like spices should cause immediate reactions because of a pollen-sensitization or panallargen proteins presence. Additive-free diets may help the patient care, but the authors suggest assessing an oral food challenge with the culprit substance if there are no contraindications.

Parabens inhibit hNaV 1.2 channels

Propylparaben, a commonly used antimicrobial preservative, has been reported as an anticonvulsant agent targeting neuronal Na⁺ channels (Na_V). However, the specific features of the Na_V channel inhibition by this agent have so far not been extensively studied. Moreover, it is still unclear if it shares this pharmacological activity with other parabens. Here, we fully characterized the mechanism of action of the inhibitory effect that propylparaben and benzylparaben induce on human Na_V 1.2 channel isoform (hNa_V1.2). We established a first approach to know the parabens structural determinants for this channel inhibition. The parabens effects on hNa_V1.2 channel mediated currents were recorded using the patch-clamp whole-cell configuration on hNa_V1.2 stably transfected HEK293 cells. Propylparaben induced a typical state-dependent inhibition on hNa_V1.2 channel carried current, characterized by a left-shift in the steady-state inactivation curve, a prolongation in the time needed for recovery from fast inactivation and a frequency-dependent blocking behavior. The state-dependent inhibition is increased for butylparaben and benzylparaben and diminished for methylparaben, ethylparaben and p-hydroxybenzoic acid (the major metabolite of parabens hydrolysis). Particularly, butylparaben and benzylparaben shift the steady-state inactivation curve 2- and 3-times more than propylparaben, respectively. Parabens are blockers of hNa_V1.2 channels, sharing the mechanism of action of most of sodium channel blocking antiseizure drugs. The potency of this inhibition increases with the size of the lipophilic alcoholic residue of the ester group. These results provide a basis for rational drug design directed to generate new potential anticonvulsant agents.

Effects of Benzophenone-3 and Propylparaben on Estrogen Receptor-Dependent R-Loops and DNA Damage in Breast Epithelial Cells and Mice

BACKGROUND

Endocrine-disrupting chemicals have been shown to have broad effects on development, but their mutagenic actions that can lead to cancer have been less clearly demonstrated. Physiological levels of estrogen have been shown to stimulate DNA damage in breast epithelial cells through mechanisms mediated by estrogen-receptor alpha (ERα). Benzophenone-3 (BP-3) and propylparaben (PP) are xenoestrogens found in the urine of >96% of U.S.

OBJECTIVES

We investigated the effect of BP-3 and PP on estrogen receptor-dependent transactivation and DNA damage at concentrations relevant to exposures in humans.

METHODS

In human breast epithelial cells, DNA damage following treatment with 17β-estradiol (E2), BP-3, and PP was determined by immunostaining with antibodies against γ-H2AX and 53BP1. Estrogenic responses were determined using luciferase reporter assays and gene expression. Formation of R-loops was determined with DNA: RNA hybrid-specific S9.6 antibody. Short-term exposure to the chemicals was also studied in ovariectomized mice. Immunostaining of mouse mammary epithelium was performed to quantify R-loops and DNA damage in vivo.

RESULTS

Concentrations of 1μM and 5μM BP-3 or PP increased DNA damage similar to that of E2 treatment in a ERα-dependent manner. However, BP-3 and PP had limited transactivation of target genes at 1μM and 5μM concentrations. BP-3 and PP exposure caused R-loop formation in a normal human breast epithelial cell line when ERα was introduced. R-loops and DNA damage were also detected in mammary epithelial cells of mice treated with BP-3 and PP.

CONCLUSIONS

Acute exposure to xenoestrogens (PP and BP-3) in mice induce DNA damage mediated by formation of ERα-dependent R-loops at concentrations 10-fold lower than those required for transactivation. Exposure to these xenoestrogens may cause deleterious estrogenic responses, such as DNA damage, in susceptible individuals. https://doi.org/10.1289/EHP5221.

Interrelationship of anthropogenic activity and parabens in fish from Taihu Lake during 2009-2017

Parabens are alkyl esters widely used as preservatives in foodstuffs, cosmetics, and pharmaceuticals. Taihu Lake is the third largest freshwater lake in China. However, there is no information available on the occurrence of parabens in Taihu Lake. To investigate contamination of parabens in Taihu Lake and the influence of human activities on contamination levels, 199 fish samples, comprising five species, were collected from Taihu Lake from 2009 to 2017. Five parabens, including methylparaben (MeP), ethylparaben (EtP), propylparaben (PrP), butylparaben (BuP), and benzylparaben (BeP), were quantitated using an isotope dilution LC-MS/MS method. The total concentrations of the five parabens ranged from 261 to 1710 pg/g wet weight (ww) with an average of 642 pg/g ww. The predominant compounds were MeP, EtP, and PrP, whose amounts accounted for more than 95% of the total amounts. No significant differences in the concentrations of parabens among the five fish species were observed, suggesting no interspecies differences in bioaccumulation of these compounds. Σ₅parabens in fish showed temporal variations with the means ranging between 532 and 772 pg/g ww during years. The levels of parabens were generally consistent with the economic development and urbanization rates of the regions surrounding Taihu Lake. The "typical" and "high" estimated daily intake (EDI) of parabens were 0.53 and 0.91 ng/kg-bw/day for children, and 0.46 and 0.79 ng/kg-bw/day for adults based on calculations using the means and the 95th concentrations, respectively. The EDIs were much lower than the reference dose values, suggesting that there are no obvious health risks posed by fish consumption.