Paraben concentrations in human fingernail and its association with personal care product use

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.

New analytical method for the determination of endocrine disruptors in human faeces using gas chromatography coupled to tandem mass spectrometry

Endocrine-disrupting chemicals are environmental pollutants that can enter our bodies and cause diverse pathologies. Some bisphenols and parabens have been shown to be capable of modifying proper functioning of the endocrine system. Among other dysfunctions, endocrine-disrupting chemicals can cause changes in intestinal microbiota. Faeces are a convenient matrix that can be useful for identifying the quantity of endocrine disruptors that reach the intestine and the extent to which the organism is exposed to these pollutants. The present work developed a new analytical method to determine 17 compounds belonging to the paraben and bisphenol families found in human faeces. The extraction method was optimized using an ultrasound-assisted extraction technique followed by a clean-up step based on the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) technique. Optimization was performed using the design of experiments technique. In validation analysis, the method was proven to be linear over a wide range. R-squared outcomes were between 95 and 99%. Selectiveness and sensitivity outcomes were acceptable, with detection limits being between 1 and 10 ng g-1 in all cases, whilst quantification limits were between 3 and 25 ng g-1 in all instances, with the exception of bisphenol AF. The method was deemed accurate, with recovery values being close to 100% and relative standard deviations being lower than 15% in all cases. Applicability was examined by analysing 13 samples collected from volunteers (male and female). All samples were contaminated with at least one of the analytes studied. The most commonly found compounds were methylparaben and bisphenol A, which were detected in almost all samples and quantitatively determined in 11 and 12 samples, respectively. Of the 17 compounds analysed, 11 were found in at least one sample. Outcomes demonstrate that faeces can be a good matrix for the determination of exposure to contaminants of interest here.

Methylparaben induces hepatic glycolipid metabolism disorder by activating the IRE1α-XBP1 signaling pathway in male mice

Methylparaben (MP), a preservative widely used in daily supplies, exists in both the environment and the human body. However, the potential health risks posed by MP remain unclear. This study aimed to unravel the mechanisms by which MP disrupts glucose and lipid homeostasis. For this, we administered MP to mice and observed changes in glucose and lipid metabolism. MP exposure led to hyperglycemia, hyperlipidemia, visceral organ injury, and hepatic lipid accumulation. RNA sequencing results from mice livers indicated a close association between MP exposure and endoplasmic reticulum (ER) stress, inflammatory response, and glucose and lipid homeostasis. Western blotting and quantitative reverse transcription-polymerase chain reaction revealed that MP activated ER stress, particularly the inositol-requiring enzyme 1 (IRE1)/X-box binding protein 1 (XBP1) pathway, which further promoted the activation of the nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways. The activation of these pathways phosphorylated insulin receptor substrate-1 (IRS1) (ser 307), resulting in decreased phosphorylation of protein kinase B (Akt) (ser 473), leading to insulin resistance. Additionally, MP exposure promoted lipogenesis through ER stress. To explore potential remedies, we administered the ER stress inhibitor 4-phenylbutyric acid (4-PBA) and the IRE1α-XBP1 pathway inhibitor toyocamycin to mice, both of which protected against metabolic disorders and organ injury caused by MP. These findings suggest that MP induces disruptions in glucose and lipid metabolism through ER stress, primarily through the IRE1α-XBP1 pathway.

Distribution of phthalate metabolites, benzophenone-type ultraviolet filters, parabens, triclosan and triclocarban in paired human hair, nail and urine samples

In this study, the distribution of nineteen ingredients of personal care product (PCPs), including seven metabolites of phthalates (mPAEs), five benzophenone-type ultraviolet filters (BPs), and seven antimicrobial agents (AAs), were investigated in paired human hair, nail and urine samples. The median concentrations of ΣmPAEs, ΣBPs and ΣAAs were 135, 2.76 and 179 ng/g in hair, 37.3, 2.95 and 297 ng/g in nails, and 345, 4.03 and 50.1 ng/mL in urine, respectively. Mono-methyl phthalate (49%), 2,4-dihydroxybenzophenone (45%) and triclosan (71%) were the most abundant mPAE, BP and AA in hair samples, respectively, and had similar abundance in nail samples. In contrast, mono-n-butyl phthalate (45%), 4-hydroxy benzophenone (29%) and methyl paraben (54%) were the predominant mPAE, BP and AA in urine samples, respectively. Significant differences in the concentrations of some target compounds were observed between male and female but inconsistent across different matrices. Moreover, most compounds with significant correlations had quite different correlation coefficients in each matrix. No significant correlations were found between hair, nail and urine samples for most of the target analytes. These results suggest these analytes have matrix-specific distribution, and it is necessary to use multiple matrices to comprehensively assess the risk of ingredients of PCPs to human health.

Human nails as a valuable noninvasive alternative for estimating exposure to parabens

Exposure of human to parabens (commonly used preservatives) is inevitable due to their extensively applied in numerous consumer products. Thus, a reliable noninvasive matrix reflecting long-term exposure to parabens is essential for human biomonitoring study. Human nails are potentially a valuable alternative for measuring intergrated exposure to parabens. In this work, we collected 100 paired nail and urine samples from university students in Nanjing, China, and measured simultaneously for six parent parabens and four metabolites. Methylparaben (MeP), ethylparaben (EtP), and propylparaben (PrP) were three predominant paraben analogue in both matrices, with the median concentrations being 12.9, 0.753, and 3.42 ng/mL in urine, and 1540, 154, and 961 ng/g in nail, respectively, while 4-hydroxybenzoic acid (4-HB) and 3,4-dihydroxybenzoic acid (3,4-DHB) were the most abundant metabolites (median values of 143 and 35.9 ng/mL, respectively) in urine. Gender-related analysis suggested that females exposed to more higher parabens than males. Significantly positive correlations were found between levels of MeP, PrP, EtP, and OH-MeP (r = 0.54-0.62, p < 0.01) in paired urine and nail samples. Our result here suggests that human nails, as an emerging biospecimen, are a potentially valuable biological matrix to evaluate human long-term exposure to parabens.

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.

Occurrence and profile characteristics of environmental phenols in human urine from a rural area in Northwestern China

Many environmental phenols, such as bisphenols, benzophenones and parabens, are known as endocrine disruptors and can adversely affect human health. However, the knowledge of human exposure to common environmental phenols in Chinese rural areas is insufficient. In this context, 181 urine samples were collected from participants in a rural area in Northwest China and were analyzed for nine bisphenols, three benzophenones and four parabens. Bisphenol A (BPA), bisphenol S, benzophenone-1 (BP-1), benzophenone-3 (BP-3), 4-hydroxybenzophenone, methylparaben (MeP), ethylparaben and propylparaben (PrP) were detected in more than 50% of the urine samples, with median concentrations of 0.938 ng/mL, 0.0111 ng/mL, 0.191 ng/mL, 1.30 ng/mL, 0.0320 ng/mL, 25.9 ng/mL, 4.31 ng/mL and 1.94 ng/mL, respectively. A significant positive correlation was observed between BP-1 and BP-3, as well as between MeP and PrP, indicating metabolic transformation and combined use, respectively. The concentrations of MeP and PrP in females were significantly higher than those in males, suggesting that females were exposed to more MeP and PrP than males. Urinary concentrations of BPA, BP-3, MeP and PrP could be influenced by age. Other demographic information, such as annual household income, education and occupation was not associated with the exposure level of the targeted phenols in adults. The estimated daily intakes of the analytes except BPA were all below their respective tolerable/acceptable daily intake levels. This study profiles the demographic differences in the exposure to environmental phenols in general populations from rural areas and provides information on risk assessments.

Contaminants of emerging concern in marine areas: First evidence of UV filters and paraben preservatives in seawater and sediment on the eastern coast of Tunisia

UV filters (UVFs) and paraben preservatives (PBs) are widely used components in many personal care products. However, there has been a rising concern for their endocrine-disrupting effects on wildlife once they reach aquatic ecosystems via recreative activities and wastewater treatment plants effluents. This study addresses UVFs and PBs occurrence in seawater and sediment impacted by tourism and sewage discharges along the coast of Mahdia, center East Tunisia. Samples of water and sediment were collected for 6 months from 3 coastal areas. Among the 14 investigated UVFs, 8 were detected in seawater and 4 were found in sediment. All PBs were present in seawater and only methylparaben (MePB) was detected in sediment. Benzophenone-3 (oxybenzone, BP3), benzocaine (EtPABA), and MePB were present in all water samples with concentrations in the ranges 16.4-66.9, 7.3-37.7, and 17.6-222 ng/L, respectively. However, the highest value, 1420 ng/L, corresponded to octinoxate (EHMC). In sediments, avobenzone (AVO), 4-methyl benzylidene camphor (4MBC), EHMC, 5-methyl-1-H-benzotriazole (MeBZT), and MePB were detected at concentrations within the range 1.1-17.6 ng/g dw, being MePB the most frequently detected (89%). MePB and MBZT presented the highest sediment-water partition coefficients and MePB also showed a positive correlation with total suspended solids' water content. Overall, pollutants concentrations remained rather constant along the sampling period, showing little seasonal variation. This study constitutes the first monitoring of UVFs and PBs on the Tunisian coastline and provides occurrence data for reference in further surveys in the country.

Association between parabens concentrations in human amniotic fluid and the offspring birth size: A Sub-study of the PERSIAN birth cohort

OBJECTIVE

Parabens are extensively used, and cause widespread exposure of the general population including pregnant women and developing fetuses to these pollutants. In this study, we aimed to investigate the association between the maternal exposure of parabens to study their transfer passed through the placental barrier to amniotic fluid; the second objective was to determine the association of paraben concentration in the amniotic fluid with the offspring birth size.

METHODS

This cross-sectional study was conducted from June 2019 to March 2021 in Isfahan, Iran. Samples of amniotic fluid were collected as set from 128 pregnant women at Cesarean section. The amniotic fluid concentrations of four parabens including methylparaben (MP), ethylparaben (EP), propylparaben (PP), and butylparaben (BP) were determined using gas chromatography tandem mass spectroscopy (GC-Mass).

RESULTS

The pointed parabens were extracted from yielded clear supernatant using a dispersive liquid-liquid microextraction (DLLME) method. Four paraben derivatives including MP (normal: 0.68 ± 0.7; overweight: 1.40 ± 1.76; obese: 0.30 ± 0.26; p-value: 0.275), EP (normal: 0.14 ± 0.09; overweight: 0.72 ± 0.72; obese: 0.38 ± 0.05; p-value: 0.434), PP (normal: 0.05 ± 0.05; overweight: 0.06 ± 0.06; obese: 0.20 ± 0.17; p-value: 0.770), and BP (normal: 2.89 ± 1.80; overweight: 3.89 ± 6.48; obese: 5.80 ± 7.56; p-value: 0.341) were simultaneously detected in samples of maternal amniotic fluid using GC-MS. In 92.2% (n = 118) of pregnant women, the paraben derivatives (MP, EP, PP, BP) were detected. We found that considerable levels of MP, EP, PP, and BP existed in 22.6% (n = 29), 21.9% (n = 28), 29.7% (n = 38), and 85.2% (n = 109) of samples, respectively. In addition, the correlation between paraben concentrations in amniotic fluid and birth size was investigated. The results showed that an inverse significant association between MP and head circumference, chest, hip, and arm circumference. While a positive correlation between MP and height of newborn was observed. Similar correlations were observed for EP and weight, height, head circumference, chest, hip, and arm.

CONCLUSION

The current study indicated that parabens have been detected in amniotic fluid samples and a strong/possible correlation between exposure of pregnant women to parabens and the birth size of newborns.

Parabens Permeation through Biological Membranes: A Comparative Study Using Franz Cell Diffusion System and Biomimetic Liquid Chromatography

Parabens (PBs) are used as preservatives to extend the shelf life of various foodstuffs, and pharmaceutical and cosmetic preparations. In this work, the membrane barrier passage potential of a subset of seven parabens, i.e., methyl-, ethyl-, propyl- isopropyl, butyl, isobutyl, and benzyl paraben, along with their parent compound, p-hydroxy benzoic acid, were studied. Thus, the Franz cell diffusion (FDC) method, biomimetic liquid chromatography (BLC), and in silico prediction were performed to evaluate the soundness of both describing their permeation through the skin. While BLC allowed the achievement of a full scale of affinity for membrane phospholipids of the PBs under research, the permeation of parabens through Franz diffusion cells having a carbon chain > ethyl could not be measured in a fully aqueous medium, i.e., permeation enhancer-free conditions. Our results support that BLC and in silico prediction alone can occasionally be misleading in the permeability potential assessment of these preservatives, emphasizing the need for a multi-technique and integrated experimental approach.

Endocrine-Disrupting Chemicals and Breast Cancer: Disparities in Exposure and Importance of Research Inclusivity

Endocrine-disrupting chemicals (EDCs) are known contributors to breast cancer development. Exposures to EDCs commonly occur through food packaging, cookware, fabrics, and personal care products, as well as external environmental sources. Increasing evidence highlights disparities in EDC exposure across racial/ethnic groups, yet breast cancer research continues to lack the inclusion necessary to positively impact treatment response and overall survival in socially disadvantaged populations. Additionally, the inequity in environmental exposures has yet to be remedied. Exposure to EDCs due to structural racism poses an unequivocal risk to marginalized communities. In this review, we summarize recent epidemiological and molecular studies on 2 lesser-studied EDCs, the per- and polyfluoroalkyl substances (PFAS) and the parabens, the health disparities that exist in EDC exposure between populations, and their association with breast carcinogenesis. We discuss the importance of understanding the relationship between EDC exposure and breast cancer development, particularly to promote efforts to mitigate exposures and improve breast cancer disparities in socially disadvantaged populations.

A Pilot Study: Nails as a Non-invasive Biospecimen of Human Exposure to Phthalate Esters

Human biomonitoring provides a scientific approach that systematically reveals exposure to phthalates through all possible routes. In this pilot study, fingernail was chosen as a non-destructive biospecimen to assess human exposure to nine phthalates. Concentrations of total phthalates ranged from 17.8 to 176 µg/g (median: 65.4 µg/g). Di(2-ethylhexyl) phthalate, dibutyl phthalate (DBP), and di-isobutyl phthalate were the major compounds found in fingernails, accounting for 64.3%, 19.4%, and 12.9% of the total phthalates, respectively. No significant difference in phthalates concentrations was found among genders and age-related distribution (p > 0.05). The concentration of DBP was positively correlated with participant's body mass index (r = 0.83). Our results suggested that fingernail can be used as a non-invasive biospecimen for the biomonitoring of human exposure to phthalates. Further studies are needed to investigate the relationship between phthalates or their metabolites in fingernail and other biological samples, such as urine and blood.

Minireview: Parabens Exposure and Breast Cancer

There is increasing recognition that environmental exposure to chemicals, such as endocrine-disruptive chemicals (EDCs), contributes to the development of breast cancer. Parabens are a group of EDCs commonly found in personal care products, foods, and pharmaceuticals. Systemic exposure to parabens has been confirmed by the ubiquitous detection of parabens in human blood and urine samples. Although evidence from in vivo and epidemiological studies linking parabens exposure to breast cancer is limited, the current evidence suggests that parabens may negatively interfere with some endocrine and intracrine targets relevant to breast carcinogenesis. So far, most studies have focused on a single paraben's effects and the direct modulating effects on estrogen receptors or the androgen receptor in vitro. Recent studies have revealed that parabens can modulate local estrogen-converting enzymes, 17β-hydroxysteroid dehydrogenase 1 and 2 and increase local estrogen levels. Also, parabens can crosstalk with the human epidermal growth factor receptor 2 (HER2) pathway and work with ER signaling to increase pro-oncogenic c-Myc expression in ER+/HER2+ breast cancer cells. Future studies investigating paraben mixtures and their crosstalk with other EDCs or signaling pathways both in vitro and in vivo in the context of breast cancer development are warranted.

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.