Development and investigation of a QuEChERS-based method for determination of phthalate metabolites in human milk

Ameliorative effects of zinc and vitamin E against phthalates-induced reproductive toxicity in male rats

OBJECTIVE

Phthalates (PEs) could cause reproductive harm to males. A mixture of three widely used PEs (MPEs) was used to investigate the ameliorative effects of zinc (Zn) and vitamin E (VE) against male reproductive toxicity.

METHODS

Fifty male SD rats were randomly divided into five groups (n = 10). Rats in MPEs group were orally treated with 160 mg/kg/d MPEs, while rats in MPEs combined Zn and/or VE groups were treated with 160 mg/kg/d MPEs plus 25 mg/kg/d Zn and/or 25 mg/kg/d VE. After intervention for 70 days, it's was measured of male reproductive organs' weight, histopathological observation of sperms and testes, serum hormones, PIWI proteins and steroidogenic proteins.

RESULTS

Compared with control, anogenital distance, testes weight, epididymides weight, and sex hormones were significantly decreased, while the sperm malformation rate was markedly increased in MPEs group (p < .05); the testicular tissues were injured in MPEs group with disordered and decreased spermatids, and arrested spermatogenesis. PIWIL1, PIWIL2, StAR, CYP11A1 and CYP19A1 were down-regulated in MPEs group (p < .05). However, the alterations of these parameters were restored in MPEs combined Zn and/or VE groups (p < .05).

CONCLUSION

Zn and/or VE improved steroid hormone metabolism, and inhibited MPEs' male reproductive toxicity.

High-throughput analytical methodology of monoalkyl phthalate esters and the composite risk assessment with their parent phthalate esters in aquatic organisms and seawater

A sensitive, robust, and highly efficient analytical methodology involving solid phase extraction coupled to ultra-high performance liquid chromatography tandem mass spectrometry was successfully established to detect 13 monoalkyl phthalate esters (MPAEs) in aquatic organisms and seawater. After the organisms were preprocessed using enzymatic deconjugation with β-glucuronidase, extraction, purification, and qualitative and quantitative optimization procedures were performed. Under optimal conditions, the limits of detection varied from 0.07 to 0.88 μg/kg (wet weight) and 0.04-1.96 ng/L in organisms and seawater, respectively. Collectively, MPAEs achieved acceptable recovery values (91.0-102.7%) with relative standard deviations less than 10.4% and matrix effects ranging from 0.93 to 1.07 in the above matrix. Furthermore, MPAEs and phthalate esters were detected by the developed methodology and gas chromatography-triple quadrupole tandem mass spectrometer in practical samples, respectively. Mono-n-butyl phthalate and mono-iso-butyl phthalate were the most predominant congeners, accounting for 24.8-35.2% in aquatic organisms and seawater. Comprehensive health and ecological risks were higher after the MPAEs were incorporated than when phthalate esters were considered separately, and greater than their risk threshold. Therefore, the risks caused by substances and their metabolites in multiple media, with analogous structure-activity relationships, should be considered to ensure the safety of aquatic organisms and consumers.

Alleviative effect of quercetin against reproductive toxicity induced by chronic exposure to the mixture of phthalates in male rats

Phthalates (PEs) are widely used plasticizers in polymer products, and humans are increasingly exposed to them. This study was designed to investigate the alleviative effect of phytochemicals quercetin (Que) against male reproductive toxicity caused by the mixture of three commonly used PEs (MPEs), and further to explore the underlying mechanism. Forty-eight male SD rats were randomly and evenly divided into control group, Que group, MPEs group and MPEs+Que group (n = 12); The oral exposure doses of MPEs and Que were 450 mg/kg/d and 50 mg/kg/d, respectively. After 91 days of continuous intervention, compared with control group, the testes weight, epididymis weight, serum sex hormones, and anogenital distance were significantly decreased in MPEs group (P < 0.05); Testicular histopathological observation showed that all seminiferous tubules were atrophy, leydig cells were hyperplasia, spermatogenic cells growth were arrested in MPEs group. Ultrastructural observation of testicular germ cells showed that the edges of the nuclear membranes were indistinct, and the mitochondria were severely damaged with the cristae disrupted, decreased or even disappeared in MPEs group. Immunohistochemistry and Western blot analysis showed that testicular CYP11A1, CYP17A1 and 17β-HSD were up-regulated, while StAR, PIWIL1 and PIWIL2 were down-regulated in MPEs group (P < 0.05); However, the alterations of these parameters were restored in MPEs+Que group. The results indicated MPEs disturbed steroid hormone metabolism, and caused male reproductive injuries; whereas, Que could inhibit MPEs' male reproductive toxicity, which might relate to the restored regulation of steroid hormone metabolism.

Development and validation of an improved QuEChERS method for the extraction of semi-volatile organic compounds (SVOCs) from complex soils

In order to achieve rapid, sensitive, and high-throughput determination of typical semi-volatile organic compounds (SVOCs) in soil samples, a method for the rapid determination of 63 SVOCs in soil was developed by optimizing and improving the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) extraction technique in conjunction with gas chromatography-mass spectrometry (GC-MS) analysis. A small amount of soil sample (5.0 g) was vortexed with 10 mL of a mixture of acetone and n-hexane (V/V = 1 : 1) for 2 min, followed by rapid vortex purification and centrifugation using a mixture of copper powder and octadecylsilane (C18) dispersant. The resulting supernatant was then purified through a 0.22 μm filter membrane. The results showed that the 63 SVOCs exhibited good linear relationships within the concentration range of 100-5000 μg L-1, with correlation coefficients (R2) above 0.99. The method detection limit (MDL = 3.3 Sy/m) was lower than 0.050 mg kg-1. At a spike concentration of 1 mg kg-1, the recovery rates of the 63 SVOCs were almost above 70% (n = 7). Compared with the rapid solvent extraction (ASE) method specified in US EPA 3545 standard, this method reduced the organic solvent usage by 14 times and significantly shortened the operation time. Furthermore, this method did not involve any transfer or concentration steps of the extractant during the experimental process, reducing the exposure time of toxic compounds and providing support for the principles of green analytical chemistry. Moreover, in the detection of most compounds in the same batch of contaminated soil, the extraction results obtained by QuEChERS were superior to those obtained by the ASE method, providing evidence for the practical application of this method. This method is rapid, simple, accurate, requires a small sample volume, and causes minimal environmental pollution. It provides a high-throughput detection method for the rapid screening of SVOCs in soil.

National-scale urinary phthalate metabolites in the general urban residents involving 26 provincial capital cities in China and the influencing factors as well as non-carcinogenic risks

Phthalates (PAEs) are widely used in daily products but can cause a variety of adverse effects in humans. Few studies have been carried out on human internal exposure levels of PAEs on a large-scale, especially in developing countries. In the present study, 1161 urine samples collected from residents of 26 provincial capitals in China were analyzed for nine phthalate metabolites (mPAEs). The chemicals were widely detected, and the median specific gravity adjusted urinary concentration of Σ₉mPAEs was 278 μg/L. Di-(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) were the main parent PAEs that the residents were exposed to. Demographic characteristics, such as age and educational level, were significantly associated with PAE exposure. Children and the elderly had higher mPAE levels. Subjects with lower educational levels were more frequently exposed to DnBP and DEHP. However, mono-ethyl phthalate showed the opposite trend, i.e., higher concentrations in subjects aged 18-59 years and with higher educational levels. Geographic differences were detected at the national scale. Residents in northeastern and western China had higher levels of mPAEs than those in central China, most likely because of different industrial usage of the chemicals and different living habits and living conditions of the residents. Health risk assessment showed that hazard indices of PAEs ranged from 0.07 to 9.34, with 20.0% of the subjects being concern for potential non-carcinogenic risk as assessed by Monte Carlo simulation. DEHP and DnBP were the primary contributors, representing 96.7% of total risk. This first large-scale study on PAE human internal exposure in China provides useful information on residents' health in a developing country, which could be used for chemical management and health protection.

Maternal DBP exposure promotes synaptic formation in offspring by activating astrocytes via the AKT/NF-κB/IL-6/JAK2/STAT3 signaling pathway

It has been demonstrated that activated astrocytes in the hypothalamus could disrupt GnRH secretion in offspring after maternal di-n-butyl phthalate (DBP) exposure, indicating that the effect of DBP on astrocyte activation and crosstalk between astrocytes and neurons is still worthy of further investigation. In this study, pregnant mice were intragastrically administered DBP dissolved in corn oil from gestational days (GD) 12.5-21.5. Maternal DBP exposure resulted in hippocampal astrocyte activation, abnormal synaptic formation, and reduced autonomic and exploratory behavior in offspring on postnatal day (PND) 22. Further studies identified that mono-n-butyl phthalate (MBP) induced astrocyte activation and proliferation by activating the AKT/NF-κB/IL-6/JAK2/STAT3 signaling pathway. Moreover, upregulated thrombospondin 1 (TSP1) in activated astrocytes regulated synaptic-related protein expression. This study highlights the neurotoxicity of maternal DBP exposure to offspring, which provides new insights into identifying potential molecular targets for the treatment of diseases related to neurological development disorders in children.

The Effect of Di (2-Ethylhexyl) Phthalate on Hair Trace Mineral Levels in Rats

We studied the effect of di (2-ethylhexyl) phthalate (DEHP) on rat hair deposition of Iron (Fe), Copper (Cu), Manganese (Mn), and Zinc (Zn). Four groups, each of eight of female Wistar rats weighing 250-300 g, were randomly distributed to (1) control (corn oil-based diet), (2) DEHP 20 (20 mg DEHP per kg body weight (bw), (3) DEHP 100 (100mg DEHP kg/bw, and (4) DEHP 500 (500 mg DEHP kg/bw). The diets were fed daily for 14 days by gastric gavage before the rats were sacrificed. Hair content of Fe, Cu, Mn, and Zn was analyzed with atomic absorption spectrophotometry. There were no significant effect of DEHP on hair Fe content. However, hair Cu, Mn, and Zn were increased after DEHP 20 exposure (p<0.001). After administering DEHP 100 and DEHP 500, both Mn and Zn were decreased (p<0.001), respectively. Hair deposition of Cu, Mn, and Zn was affected by DEHP.

Phthalate metabolites: Characterization, toxicities, global distribution, and exposure assessment

Phthalates are plasticizers in various products and regarded as endocrine disruptors due to their anti-androgen effects. Environmental occurrence and toxicities of parent phthalates have been widely reported, while the current state of knowledge on their metabolites is rarely summarized. Based on the available literature, the present review mainly aims to 1) characterize the potential metabolites of phthalates (mPAEs) using the pharmacokinetics evidences acquired via animal or human models; 2) examine the molecular and cellular mechanism involved in toxicity for mPAEs; 3) investigate the exposure levels of mPAEs in different human specimens (e.g., urine, blood, seminal fluid, breast milk, amniotic fluid and others) across the globe; 4) discuss the models and related parameters for phthalate exposure assessment. We suggest there is subtle difference in toxic mechanisms for mPAEs compared to their parent phthalates due to their alternative chemical structures. Human monitoring studies performed in Asia, America and Europe have provided the population exposure baseline levels for typical phthalates in different regions. Urine is the preferred matrix than other specimens for phthalate exposure study. Among ten urinary mPAEs, the largest proportions of di-(2-ethylhexyl) phthalate (DEHP) metabolites (40%), monoethyl phthalate (mEP) (43%) and DEHP metabolites/mEP (both 29%) were observed in Asia, America and Europe respectively, and mono-5-carboxy-2-ethypentyl phthalate was the most abundant compounds among DEHP metabolites. Daily intakes of phthalates can be accurately calculated via urinary mPAEs if the proper exposure parameters were determined. Further work should focus on combining epidemiological and biological evidences to establish links between phthalates exposure and biological phenotypes. More accurate molar fractions (F_UE) of the urinary excreted monoester related to the ingested diesters should be collected in epidemiological or pharmacokinetic studies for different population.

A fluorinated chitosan-based QuEChERS method for simultaneous determination of 20 organophosphorus pesticide residues in ginseng using GC-MS/MS

In this study, a new fluorinated methacrylamide (MACF) was synthesized and evaluated as an adsorbent in the dispersive solid-phase extraction for the effective determination and extraction of 20 organophosphorus pesticides (OPPs) from ginseng samples using the QuEChERS (quick, easy, cheap, effective, rugged, safe) method coupled with GC-MS/MS. The properties of MACF were characterized using Fourier-transform infrared spectroscopy, elemental analysis, and high-resolution ¹⁹ F NMR. MACF, chitosan, primary and secondary amine, octadecylsilane, graphitized carbon black, Z-Sep, Z-Sep⁺ , and EMR-Lipid were compared in terms of extraction efficiency. The best results were obtained when MACF was used. Matrix-matched calibration was employed for quantification. All the OPPs exhibited good linearity (r²  > 0.9969) with the concentration at their respective concentration ranges. The limits of detection were 1.5-3.0 μg/kg, and the limits of quantification were 5.0-10.0 μg/kg. The trueness of the 20 pesticides at four spiked levels ranged from 86.1 to 111.1%, and the relative standard deviation was less than 11.3%. The modified QuEChERS method using MACF as the adsorbent was sensitive, reliable, and cost-effective and could be used for the determination of 20 OPP residues in ginseng.

A critical review on human internal exposure of phthalate metabolites and the associated health risks

Phthalates (PAEs) are popular synthetic chemicals used as plasticizers and solvents for various products, such as polyvinyl chloride or personal care products. Human exposure to PAEs is associated with various diseases, resulting in PAE biomonitoring in humans. Inhalation, dietary ingestion, and dermal absorption are the major human exposure routes. However, estimating the actual exposure dose of PAEs via an external route is difficult. As a result, estimation by internal exposure has become the popular analytical methods to determine the concentrations of phthalate metabolites (mPAEs) in human matrices (such as urine, serum, breast milk, hair, and nails). The various exposure sources and patterns result in different composition profiles of PAEs in biomatrices, which vary from country to country. Nevertheless, the mPAEs of diethyl phthalate (DEP), di-n-butyl phthalate (DnBP), di-iso-butyl phthalate (DiBP), and di-(2-ethylhexyl) phthalate (DEHP) are predominant in the urine. These mPAEs have greater potential health risks for humans. Children have been observed to exhibit higher exposure risks to several mPAEs than adults. Besides age, other influencing factors for phthalate exposure are gender, jobs, and residential areas. Although many studies have reported biological monitoring of PAEs, only a few reviews that adequately summarized the reports are available. The current review appraised available studies on mPAE quantitation in human biomatrices and estimated the dose and health risks of phthalate exposure. While some countries lack biomonitoring data, some countries' data do not reflect the current PAE exposure. Thence, future studies should involve frequent PAE biomonitoring to accurately estimate human exposure to PAEs, which will contribute to health risk assessments of human exposure to PAEs. Such would aid the formulation of corresponding regulations and restrictions by the government.

Evaluation of the Occurrence of Phthalates in Plastic Materials Used in Food Packaging

Phthalates are multifunctional synthetic chemicals found in a wide array of consumer and industrial products, mainly used to improve the mechanical properties of plastics, giving them flexibility and softness. In the European Union, phthalates are prohibited at levels greater than 0.1% by weight in most food packaging. In the current study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) was optimized, through the multivariate optimization process, and validated to evaluate the occurrence of four common phthalates, di-iso-butyl phthalate (DIBP), butyl-benzyl phthalate (BBP), di-n-octyl phthalate (DOP), and 2,2,4,4-tetrabromodiphenyl (BDE), in different food packaging. The best extraction efficiency was achieved using the polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber at 80 °C for 30 min. The validated method showed good linearity, precision (RSD < 13%), and recoveries (90.2 to 111%). The limit of detection (LOD) and of quantification (LOQ) ranged from 0.03 to 0.08 µg/L and from 0.10 to 0.24 µg/L, respectively. On average, the phthalates concentration varied largely among the assayed food packaging. DIBP was the most predominant phthalate in terms of occurrence (71.4% of analyzed simples) and concentration (from 3.61 to 10.7 μg/L). BBP was quantified in only one sample and BDE was detected in trace amounts (<LOQ) in only two samples.