A study on the effect of phthalate esters and their metabolites on idiopathic infertile males

Phthalate esters in dusts from different indoor and outdoor microenvironment and potential human health risk: A case study in Beijing

Phthalate esters (PAEs) are widely used plasticizers that can easily migrate from plastic products, thereby presenting potential health risks through exposure. While PAE concentrations in dust have received increasing attention, there is still a lack of comprehensive understanding regarding their environmental distribution, composition profiles, and associated human exposure risks in Beijing. This study investigated the presence of seven PAEs in 124 dust samples collected from eight indoor and four outdoor microenvironment types across the Beijing metropolitan area. The PAEs were detected universally in all samples, with di(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP) and di-iso-butyl phthalate (DIBP) as the predominant compounds, accounting for 91.78%-99.91% and 91.22%-99.76% of total PAE concentrations (Σ7PAEs) in indoor and outdoor dust, respectively. Indoor dust exhibited significantly higher Σ7PAEs (range: 45.33-1212.41 μg/g, mean: 130.61 μg/g) compared to outdoor dust (range: 2.10-5.41 μg/g, mean: 3.38 μg/g). Among indoor microenvironments, taxis had the highest Σ7PAEs (mean: 1250.59 μg/g), followed by private cars, print shops, residences, furniture shops, shopping malls, dormitories and offices. Outdoor Σ7PAEs levels decreased in the order of roads, residential areas, green belts, and parks. Estimated daily exposure doses through dust ingestion were significantly higher than those from dermal absorption and inhalation for five occupational groups (taxi drivers, print shop workers, road workers, office workers, jobless people), indicating dust ingestion as the primary exposure route, with DEHP and DBP as the main contributors. While current exposure levels may not present significant non-cancer risks based on hazard quotient and hazard index estimations, it's noteworthy that DEHP may pose a carcinogenic risk to taxi drivers. Potential risks cannot be overlooked considering the absence of toxicity thresholds, additional exposure pathways, and possible cocktail effects from coexisting pollutants.

Evaluation of the endocrine disrupting potential of Di-isononyl phthalate

Low molecular weight ortho-phthalate compounds have been implicated in disruption of androgen pathways when exposure occurs during the masculinization programming window. Di-isononyl phthalate (DINP) is a high molecular weight phthalate and a high production volume chemical. To understand the potential for DINP and its metabolites to disrupt endocrine pathways, a weight of evidence assessment was conducted according to the European Chemicals Agency (ECHA)/ European Food Safety Authority (EFSA) Endocrine Disruptor Guidance (2018). Toxicological data related to estrogen (E), androgen (A), thyroid (T), or steroidogenesis (S) pathways was assessed. Literature searches returned 110 articles from which data were extracted and assessed in conjunction with 105 high-throughput assays. An in-silico assessment of the EATS activity for DINP metabolites also was conducted. Based on the available evidence, DINP did not elicit thyroid- or estrogen-related apical outcomes in vivo. There were no studies evaluating thyroid hormone levels in vivo which, according to the ECHA/EFSA guidance, constitutes a data gap and prevents a conclusion being drawn on the T-pathway. The E, A, and S-pathways were sufficiently assessed to conclude on the endocrine disrupting potential of DINP. Based on the lack of apical outcomes, DINP did not disrupt the E-pathway. For the A and S-pathways, there was limited evidence to support adverse apical outcomes, so a mode of action assessment using a structured adverse outcome pathway (AOP) framework was performed. No biologically plausible link could be established between the key events in the hypothesized AOP that lead to adverse outcomes. Further, no dose or temporal concordance for A- and S-mediated findings were identified. Therefore, DINP does not meet the ECHA/EFSA criteria to be considered an endocrine disruptor.

BPA and low-Se exacerbate apoptosis and mitophagy in chicken pancreatic cells by regulating the PTEN/PI3K/AKT/mTOR pathway

INTRODUCTION

Bisphenol A (BPA) is a widespread environmental pollutant which has serious toxic effects on organisms. One of the crucial trace elements is selenium (Se), whose shortage can harm biological tissues and enhance the toxicity of contaminants, in which apoptosis and autophagy are core events.

OBJECTIVES

An in vivo model was established to investigate the effects of BPA and low-Se on chicken pancreatic tissue, and identify the possible potential molecular mechanism.

METHODS

A total of 80 1-day-old broiler chickens (Xinghua Chicken Farm, Harbin, China) were stochastically divided into 4 groups (n = 20/group): Control group, BPA group, low-Se group, and low-Se + BPA group. Pancreatic tissue was collected at day 42 to detect changes in markers.

RESULTS

First, the data showed that BPA and low-Se exposure gave rose to structural abnormalities in pancreatic tissue, oxidative stress, mitochondrial dysfunction and homeostasis imbalance, apoptosis and mitophagy. In addition, the co-exposure of BPA and low-Se caused the most serious damage to pancreatic tissue. In terms of mechanism, it was found that apoptosis and mitophagy induced by BPA and low-Se were related to the activation of PTEN/PI3K/AKT/mTOR pathway.

CONCLUSION

In summary, the study found that BPA and low-Se exacerbated mitochondria damage, apoptosis and mitophagy by regulating the PTEN/PI3K/AKT/mTOR pathway.

The threat of microplastics and microbial degradation potential; a current perspective

Microplastics in marine environments come from various sources, and over the years, their buildup in marine environments suggests an inevitable need for the safe mitigation of plastic pollution. Microplastics are one of the chief and hazardous components of marine pollution, as they are transferred through the food chain to different trophic levels, affecting living organisms. They are also a source of transfer for pathogenic organisms. Upon transfer to humans, several toxic effects can occur. This review aims to assess the accumulation of microplastics in marine environments globally, the threat posed to humans, and the biodegradation potential of bacteria and fungi for future mitigation strategies. The versatility of bacteria and fungi in the biodegradation of different types of plastics has been discussed, with a focus on the microbial majority that has been cultivated in labs from the marine environment. We also propose that the exploration of yet-to-be-cultivated microbial majority can be a way forward for employing future strategies to mitigate microplastics.

Environmental pollutant Di-(2-ethylhexyl) phthalate induces asthenozoospermia: new insights from network toxicology

The global decline in sperm quality in men is closely associated with environmental exposure to the plasticizer Di-(2-ethylhexyl) phthalate (DEHP), but the molecular mechanisms underlying its induction of asthenozoospermia (AZS) remain incompletely understood. By integrating the toxicological targets of DEHP and differential genes in AZS patients, and combining machine learning, molecular docking, and dynamics simulations, this study successfully identified hub genes and signaling pathways induced by DEHP in AZS, aiming to provide new strategies for the prevention and treatment of this disease. A total of 26 toxicological targets were identified, with FGFR1, MMP7, and ST14 clearly defined as playing crucial regulatory roles in DEHP-induced AZS. This study also reveals that DEHP may induce reproductive system inflammation, affecting the proliferation and survival of reproductive cells, and subsequently impacting sperm vitality, possibly through regulating the mTORC1 pathway, TNF-α signaling via the NF-κB pathway, and MYC targets v1 pathway. Furthermore, changes in the immune microenvironment revealed the significant impact of immune status on testicular function. In conclusion, this study provides important scientific evidence for understanding the molecular mechanisms of AZS and developing prevention and treatment strategies based on toxicological targets.

Antioxidants in mitigating phthalate-induced male reproductive toxicity: A comprehensive review

Phthalates, widely used as plasticizers, have been increasingly linked to male reproductive toxicity through mechanisms including oxidative stress, endocrine disruption, inflammation, and apoptosis. This comprehensive review evaluates the protective role of various antioxidants in mitigating the detrimental effects of phthalates such as di-(2-ethylhexyl) phthalate (DEHP), di-butyl phthalate (DBP), mono-(2-ethylhexyl) phthalate (MEHP), and monobutyl phthalate (MBP) on male reproductive health. Antioxidants such as lycopene, ellagic acid, genistein, and selenium compounds exhibit significant efficacy in counteracting phthalate-induced damage by neutralizing reactive oxygen species (ROS), enhancing endogenous antioxidant defenses, reducing inflammatory responses, and preventing apoptosis. Lycopene demonstrates broad-spectrum protective effects, particularly through its high ROS-scavenging capacity and ability to preserve mitochondrial function. Ellagic acid effectively ameliorates oxidative stress and inflammation, while genistein enhances the Nrf2 pathway and restores hormonal balance, offering robust protection against reproductive toxicity. Selenium compounds improve antioxidant enzyme activities, providing essential support against oxidative damage. These findings underscore the potential of antioxidants as therapeutic agents against phthalate-induced male reproductive dysfunction. Future research should focus on optimizing antioxidant combinations, understanding dose-response relationships, and assessing long-term efficacy and safety to develop effective interventions for safeguarding male reproductive health.

Di-n-butyl phthalate induces toxicity in male fetal mouse testicular development by regulating the MAPK signaling pathway

"White pollution" has a significant impact on male reproduction. Di-n-butyl phthalate (DBP) is one of the most important factors in this type of pollution. Currently, research from international sources has demonstrated the significant reproductive toxicity of DBP. However, most of these studies have focused mainly on hormones expression at the protein and mRNA levels and the specific molecular targets of DBP and its mechanisms of action remain unclear. In this study, we established a Sprague Dawley pregnant mouse model exposed to DBP, and all male offspring were immediately euthanized at birth and bilateral testes were collected. We found through transcriptome sequencing that cell apoptosis and MAPK signaling pathway are the main potential pathways for DBP induced reproductive toxicity. Molecular biology analyses revealed a significant increase in the protein levels of JNK1(MAPK8) and BAX, as well as a significant increase in the BAX/BCL2 ratio after DBP exposure. Therefore, we propose that DBP induces reproductive toxicity by regulating JNK1 expression to activate the MAPK signaling pathway and induce reproductive cell apoptosis. In conclusion, our study provides the first evidence that the MAPK signaling pathway is involved in DBP-induced reproductive toxicity and highlights the importance of JNK1 as a potential target of DBP in inducing reproductive toxicity.

Isomers are more likely to cause collapse of Daphnia magna populations than Di-(2-ethylhexyl) phthalate (DEHP)

Di-(2-ethylhexyl) phthalate (DEHP) is the most commonly used phthalate and is ubiquitous in surface water. Based on its well-established toxicological profile, many countries and regions have adopted specific environmental quality standard (EQS) for DEHP. In China, the EQS value for DEHP is 8 μg/L. However, information on isomers structurally similar to DEHP is limited. Among the isomers of DEHP, di-isooctyl phthalate (DIOP) and di-n-octyl phthalate (DnOP) have received limited attention. The goal of this paper was to study effects and toxic potencies of DEHP, DIOP, and DnOP to individuals and predict effects on populations of female Daphnia magna (cladoceran crustacea) in media containing environmentally relevant concentrations of single PAEs for three consecutive generations (21 days for every generation). Exposure to all three PAEs resulted in reduced survival and reproduction and cause collapse of populations at the highest concentrations. DnOP was the most potent for causing adverse effects followed by DIOP, while DEHP was the least potent. 8 μg DnOP/L were found to reduce the population size by 37 % in the F2 generation. These findings demonstrate that PAE isomers other than DEHP can cause adverse effects.

Toxicity assessment of microplastic (MPs); a threat to the ecosystem

Plastic is now considered part and parcel of daily life due to its extensive usage. Microplastic (MP) pollution is becoming a growing worry and has been ranked as the second most critical scientific problem in the realm of ecology and the environment. Microplastics are smaller in size than the plastic and are more harmful to biotic and as well as abiotic environments. The toxicity of microplastic depends upon its shape and size and increases with an increase in its adsorption capacity and their toxicity. The reason behind their harmful nature is their small size and their large surface area-to-volume ratio. Microplastic can get inside fruits, vegetables, seeds, roots, culms, and leaves. Hence microplastic enters into the food chain. There are different entry points for microplastic to enter into the food chain. Such sources can include polluted food, beverages, spices, plastic toys, and household (packing, cooking, etc.). The concentration of microplastic in terrestrial environments is increasing day by day. Microplastic causes the destruction of soil structure; destroys soil microbiota, cause depletion of nutrients in the soil, and their absorption by plants decreases plant growth. Apart from other environmental problems caused by microplastic, human health is also badly affected by microplastic pollution present in the terrestrial environment. The presence of microplastics in the human body has been confirmed. Microplastic enters into the body of humans in different possible ways. According to their way of entering the body, microplastics cause different diseases in humans. MPs also cause negative effects on the human endocrine system. At the ecosystem level, the impacts of microplastic are interconnected and can disrupt ecological processes. Although recently different papers have been published on several aspects of the microplastic present in the terrestrial environment but there is no complete overview that focus on the interrelationship of MPs in plants, and soil and their effect on higher animals like a human. This review provides a completely detailed overview of existing knowledge about sources, occurrences, transport, and effects of microplastic on the food chain and soil quality and their ecotoxicological effects on plants and humans.

Do phthalates and their metabolites cause poor semen quality? A systematic review and meta-analysis of epidemiological studies on risk of decline in sperm quality

A systematic review and meta-analysis were conducted to understand the association of phthalates and their metabolites with sperm quality in humans. By June 30, 2022, relevant literature on the effects of phthalates and their metabolites on sperm quality were searched and collected using three English-language databases including PubMed, EMbase, and Web of Science. Two researchers independently screened literature, extracted data, and assessed risk of bias. Stata 11 and RevMan 5.3 were used to conduct meta-analysis, test publication bias, and sensitivity analysis. A total of 12 literature were included for meta-analysis, excluding literature with different effect sizes. The results of meta-analysis indicated that monobutyl phthalate (MBP) and monobenzyl phthalate (MBzP) in urine were negatively correlated with semen concentration, and the results were statistically significant (MBP, pooled odds ratio (OR), 95% confidence interval (CI): 2.186 (1.471, 3.248), P < 0.05) and (MBzP, pooled OR (95%CI): 1.882 (1.471, 3.248), P < 0.05). Furthermore, the level of Di-(2-ethylhexyl) phthalate (DEHP) in semen was negatively correlated with semen concentration and the combined effect size was (pooled correlation coefficients (r) (95%CI): -0.225 (-0.319, -0.192), P < 0.05). However, the associations between MBP and MBzP with sperm motility and sperm morphology were not statistically significant (P > 0.05). And there was also no significant correlation between monoethyl phthalate (MEP), monomethyl phthalate (MMP), and mono-2-ethylhexyl phthalate (MEHP) and semen parameters, including semen concentration, sperm motility, and sperm morphology (P > 0.05). In summary, this current study provides moderate-certainty evidence for the data demonstrated that is a negative correlation between urine MBP levels, urine MBzP levels, and semen DEHP levels with semen concentration. In the future, more longitudinal cohort studies are needed to help elucidate the overall association.

Phthalate toxicity mechanisms: An update

Phthalates are one of the most widely used plasticizers in polymer products, and they are increasingly being exposed to people all over the world, generating health concerns. Phthalates are often used as excipients in controlled-release capsules and enteric coatings, and patients taking these drugs may be at risk. In both animals and human, phthalates are mainly responsible for testicular dysfunction, ovarian toxicity, reduction in steroidogenesis. In this regard, for a better understanding of the health concerns corresponding to phthalates and their metabolites, still more research is required. Significantly, multifarious forms of phthalates and their biomedical effects are need to be beneficial to investigate in the various tissues or organs. Based on these investigations, researchers can decipher their toxicity concerns and related mechanisms in the body after phthalate's exposure. This review summarizes the chemical interactions, mechanisms, and their biomedical applications of phthalates in animals and human.

Food and human safety: the impact of microplastics

Plastic waste pollution is one of the biggest problems in the world today. The amount of plastic in the environment continues to increase, and human exposure to microplastic (MP) has become a reality. This subject has attracted the attention of the whole world. The MP problem has also been noticed by the scientific community. The term microplastic is mostly used to define synthetic material with a high polymer content that can have a size range from 0.1 to 5000 µm. This paper aims to characterize the routes of exposure to MP, define its pollution sources, and identify food types contaminated with plastics. This review addresses the current state of knowledge on this type of particles, with particular emphasis on their influence on human health. Adverse effects of MP depend on routes and sources of exposure. The most common route of exposure is believed to be the gastrointestinal tract. Sources of MP include fish, shellfish, water as well as tea, beer, wine, energy drinks, soft drinks, milk, salt, sugar, honey, poultry meat, fruits, and vegetables. Studies have shown that particles of PET, PE, PP, PS, PVC, PA, and PC are the most frequently found in food.

Female Reproductive Health and Exposure to Phthalates and Bisphenol A: A Cross Sectional Study

The xenoestrogenicity of some plasticisers (phthalates and bisphenol A) is documented in the literature and may pose a risk to female reproductive health. The aim of this study was to assess exposure to six phthalates. This was achieved by measuring their respective metabolites (mono-ethylphthalate (MEP); mono-n-butylphthalate (MnBP); mono-n-ottylphthalate (MnOP); and monobenzylphthalate (MBzP)), as well as the sum of two of the diethyl-hexyl phthalate metabolites-(∑DEHP) and bisphenol A (BPA) in a female population with infertility problems, and by conducting a correlation analysis between infertility factors, work activities, and lifestyle habits, in order to formulate a causal hypothesis. A cross-sectional epidemiological study was carried out and women under 43 years of age were recruited from an assisted reproduction technology (ART) center; the sample of 186 women was given a specific questionnaire and a spot urine sample was collected. Phthalate metabolites and urinary BPA were analyzed by HPLC/MS/MS. The results showed significantly higher mean values for MEP in women with recurrent pregnancy loss (RPL) (820.5 ± 1929.5 µg/g of creatinine) and idiopathic infertility (230.0 ± 794.2 µg/g of creatinine) than in women with other infertility factors (76.9 ± 171.8 µg/g of creatinine). Similarly, for MnOP levels, women with idiopathic infertility (2.95 ± 3.44 µg/g of creatinine) showed significantly higher values than women with the other infertility factors taken together (1.35 ± 2.05 µg/g of creatinine). Women with tubal factors of infertility, RPL, and endocrine dysfunctions show higher values of DEHP (p = 0.032). Considering occupations, women working in commerce showed more than twice as much urinary BPA levels (1.10 ± 0.48 µg/g of creatinine) compared to women working in other industries (0.45 ± 0.35 µg/g of creatinine). The presence of significantly higher values of certain phthalates, DEHP in particular, especially in women with RPL and idiopathic infertility, suggests a possible involvement of these compounds as competing factors in reproductive issues. The study of sources of exposure suggested that the working activity in trade, as a casher in particular, represents a major one for BPA (p = 0.015).

Stereological analysis and transcriptome profiling of testicular injury induced by di-(2-ethylhexyl) phthalate in prepubertal rats

Di-(2-ethylhexyl) phthalate (DEHP) is the most common phthalate that can affect the male reproductive system. DEHP exposure at the prepubertal stage could lead to the injury of immature testes, but the mechanism has not been fully clarified. In the present study, we elucidated the possible underlying mechanism of DEHP-induced prepubertal testicular injury through stereological analysis and transcriptome profiling. Compared with the control group, the DEHP-treated rats had lower body weight gain and decreased testicular weight and organ coefficient. Moreover, lower serum levels of testosterone and LH were observed in the DEHP group, in contrast to the increased FSH level. Additionally, the serum level of estradiol had no significant difference after DEHP exposure. Stereological analysis showed significant reduction in volumes of most testicular structures, especially in the seminiferous tubule and seminiferous epithelium, along with a vast decrease of spermatogenic cells and obvious structural damages with substantial pathological signs (germ cracks, cytoplasmic vacuolization, sloughing, multinucleated giant cell formation, chromatolysis desquamation and dissolution, pyknosis of nuclei) in the seminiferous tubule upon DEHP exposure at the prepubertal stage. Furthermore, transcriptome profiling identified 5548 differentially expressed genes (DEGs) upon DEHP exposure. Pathway enrichment analysis revealed several crucial signaling pathways related to retinol metabolism, oxidative phosphorylation, steroid hormone biosynthesis, and cell adhesion molecules (CAMs). In addition, seven DEGs selected from RNA-seq data were validated by quantitative real-time polymerase chain reaction (qRT-PCR), and the results showed the same trends as the RNA-seq results. In conclusion, the above findings provide basic morphological data and lay a foundation for systematic research on transcriptome profiling in prepubertal testicular injury induced by DEHP.

The effects of the phthalate DiNP on reproduction†

Di-isononyl phthalate (DiNP) is a high molecular weight, general purpose, plasticizer used primarily in the manufacture of polymers and consumer products. It can be metabolized rapidly and does not bioaccumulate. The primary metabolite of DiNP is monoisononyl-phthalate (MiNP) and the secondary metabolites include three oxidative derivatives of DiNP, which have been identified mainly in urine: mono-oxoisononyl phthalate (MOINP or oxo-MiNP), mono-carboxyisooctyl phthalate (MCIOP, MCOP or cx-MiNP), and mono-hydroxyisononyl phthalate (MHINP or OH-MiNP). The secondary metabolites are very sensitive biomarkers of DiNP exposure while primary metabolites are not. As the usage of DiNP worldwide increases, studies evaluating its potential reproductive toxicity are becoming more prevalent in the literature. In studies on female animals, the researchers found that the exposure to DiNP appears to induce negative effects on ovarian function and fertility in animal models. Whether or not DiNP has direct effects on the uterus is still controversial, and the effects on human reproduction require much more research. Studies on males indicate that DiNP exposure has disruptive effects on male reproduction and fertility. Occupational studies also indicate that the exposure to DiNP might induce negative effects on male reproduction, but larger cohort studies are needed to confirm this. This review presents an overview of the literature regarding the reproductive effects of exposure to DiNP.