Developmental exposure to polycyclic aromatic hydrocarbons (PAHs): Focus on benzo[a]pyrene neurotoxicity

Ambient polycyclic aromatic hydrocarbons and cardiovascular disease in China

Polycyclic aromatic hydrocarbons (PAHs) are a prominent category of ambient air pollutants worldwide, but our understanding of their potential health effects at ambient concentrations is severely limited. Our goal was to investigate the relation between ambient PAHs and daily hospitalizations for cardiovascular disease and explore its potential mechanism. This research included both observational and experimental studies. For population-based study, we collected data on daily hospitalizations for cardiovascular events in 184 major Chinese cities, which cover a population of 280 million individuals, for period of 2014-2017. We utilized a time-series quasi-Poisson regression model to assess the city-specific relations between PAHs and hospitalizations, and then employed a random-effects meta-analysis to aggregate the effect estimates across the cities. We also employed meta-regression models and stratified analyses to explore possible effect modifiers. For animal study, mice were exposed to varying doses of PAHs via tracheal instillation to evaluate the cardiac damage induced by PAHs. Potential mechanisms were elucidated through transcriptomic and proteomic sequencing. On the national scale, each interquartile range (IQR) increase in PAHs concentrations at 0-7 days was related to a 5.18 % (3.27 %-7.12 %) increase in hospital admissions for cardiovascular disease, 5.72 % (3.83 %-7.65 %) for ischemic heart disease, and 6.08 % (3.37 %-8.87 %) for ischemic stroke. The cardiovascular impacts of PAHs remained even after controlling for PM2.5. The associations were more pronounced in cities with lower socioeconomic level, or higher temperatures and relative humidity, as well as in subpopulations with elder age (P < 0.05). We also found consistent associations between each of the seven individual PAHs and cardiovascular outcomes. In animal models, PAHs exposure induces cardiac injury via inflammation and oxidative stress, potentially linked to the PI3K/AKT and MAPK signaling pathways. This nationwide study indicated that ambient PAHs could represent a distinct risk factor for cardiovascular disease. They may contribute to cardiac damage through the regulation of inflammation and oxidative stress.

A gold-silver nanostar 2D array composite structure for rapid SERS determination of PAHs

This study developed a portable multi-ring aromatic hydrocarbon (PAH) detection tool using a dual-metal surface-enhanced Raman scattering (SERS) substrate. Gold-silver nanostars (AuNS@Ag) were synthesized by a secondary seed-mediated growth method and assembled into a two-dimensional array by a liquid-phase interface self-assembly method, uniformly deposited on a silicon wafer. The PAHs in water samples were identified using a portable Raman spectrometer. The SERS detection platform has high sensitivity and stability, and can detect pyrene and phenanthrene with concentrations of 10-8 M and 0.5 × 10-8 M, respectively. The stable dual-metal nanomaterial AuNS@Ag 2D array has potential application prospects and can be used for environmental monitoring.

Impact of Benzo(a)pyrene and Pyrene Exposure on Activating Autophagy and Correlation with Endoplasmic Reticulum Stress in Human Astrocytes

Benzo(a)pyrene (B(a)P) and pyrene, the most prominent subtypes of polycyclic aromatic hydrocarbons (PAHs), contaminate environments as organic pollutants. They adversely affect body systems, including degeneration of the central nervous system. This study investigated the in vitro toxic effects of B(a)P and pyrene on proliferation, endoplasmic reticulum (ER) stress induction, and autophagy in human astrocytes using U-87 MG human astrocytoma cells as a model. Both B(a)P and pyrene were toxic to U-87 MG cells in a concentration-dependent manner. Astrocytic proliferation was interfered with, enhancing S-phase cell cycle arrest. B(a)P promoted the presence of autophagic vesicles and the expression of autophagic markers LC3, beclin-1, and p62, suggesting activated autophagy. B(a)P enhanced the expression of ER stress markers BiP, PERK, and IRE1. ER stress appeared to be correlated with autophagy induction, as demonstrated by experiments using chloroquine, an autophagy inhibitor. Pyrene enhanced the expression of autophagic markers and ER stress primarily via PERK activation, although autophagic vesicles were not observed. The study demonstrates that B(a)P enhances ER stress-mediated autophagy more evidently than pyrene and affected toxicity to astrocytes. These results provide a basis for understanding the toxic effects of the main PAH substances affecting astrocytes.

Seasonal variations, source apportionment, and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in sediments from Klip River, Johannesburg, South Africa

The widespread occurrence of polycyclic aromatic hydrocarbons (PAHs) in water bodies is a significant cause of concern due to their persistence and toxicity. This study aimed at assessing the qualitative and quantitative profile of 16 EPA PAHs present in sediment collected from nine sites along the Klip River, Johannesburg, South Africa. The target compounds were extracted from sediment by microwave-assisted extraction (MAE). The extraction method accuracy was evaluated by analyzing certified reference material of sediment (CRM-104). The total concentration of PAHs detected in sediment samples ranged from 1.46 to 7.41 mg/kg. High molecular weight (HMW) PAHs were found to be in higher concentrations for both low flow (24.5 mg/kg) and high flow (19.4 mg/kg) seasons compared to the lower molecular weight (LMW) PAHs, which had 11.1 mg/kg for low flow and 5.63 mg/kg for high flow seasons. For identification of source of PAHs in sediments, the diagnostic ratio was employed, which revealed the PAHs were from petrogenic and pyrogenic sources. Toxicity test using zebrafish embryo development test (ZFET) resulted in high mortality, low hatch rate, and high malformations, which indicated the contamination of sediments from the Klip River. These findings suggest that exposure to this water system poses risks to the environment, aquatic life, and humans who depend on it.

Adverse neurodevelopment in children associated with prenatal exposure to fine particulate matter (PM2.5) - Possible roles of polycyclic aromatic hydrocarbons (PAHs) and mechanisms involved

Prenatal exposure to ambient fine particles (PM2.5) and polycyclic aromatic hydrocarbons (PAHs) has been associated with adverse birth outcomes including neurodevelopmental effects with cognitive and/or behavioral implications in early childhood. As a background we first briefly summarize human studies on PM2.5 and PAHs associated with adverse birth outcomes and modified neurodevelopment. Next, we add more specific information from animal studies and in vitro studies and elucidate possible biological mechanisms. More specifically we focus on the potential role of PAHs attached to PM2.5 and explore whether effects of these compounds may arise from disturbance of placental function or more directly by interfering with neurodevelopmental processes in the fetal brain. Possible molecular initiating events (MIEs) include interactions with cellular receptors such as the aryl hydrocarbon receptor (AhR), beta-adrenergic receptors (βAR) and transient receptor potential (TRP)-channels resulting in altered gene expression. MIE linked to the binding of PAHs to cytochrome P450 (CYP) enzymes and formation of reactive electrophilic metabolites are likely less important. The experimental animal and in vitro studies support the epidemiological findings and suggest steps involved in mechanistic pathways explaining the associations. An overall evaluation of the doses/concentrations used in experimental studies combined with the mechanistic understanding further supports the hypothesis that prenatal PAHs exposure may cause adverse outcomes (AOs) linked to human neurodevelopment. Several MIEs will likely occur simultaneously in various cells/tissues involving several key events (KEs) which relative importance will depend on dose, time, tissue, genetics, other environmental factors, and neurodevelopmental endpoint in study.

Benzo[a]pyrene exposure induces anxiety-like behaviors in the mice through brain metabolic alterations

The deleterious health impacts of polycyclic aromatic hydrocarbons (PAHs) on the population have been extensively substantiated and acknowledged. Mounting evidence underscores that PAH exposure is closely linked to an elevated risk of mental disorders, particularly in populations experiencing occupational and high-level exposure. In this study, we aimed to investigate the mechanisms underlying anxiety-like behaviors induced by different dosages of PAHs, with a concentrated focus on brain region-specific metabolic alterations in mice using various metabolomics approaches. Male C57BL/6 mice were exposed to benzo[a]pyrene (B[a]P), a typical PAH, through gavage at occupational exposure and EPA toxicologically relevant dosages (2.0 and 20.0 mg/kg/day) for 21 days, respectively. Behavioral assessments revealed that occupational exposure to B[a]P induced anxiety-like behaviors in C57BL/6 mice. Meanwhile, elevated serum norepinephrine and corticotropin-releasing hormone further confirmed the anxiety-inducing effects of B[a]P exposure. Metabolomics analysis uncovered dysregulation across various metabolic pathways following B[a]P exposure, encompassing brain neurotransmitter, organic acid, amino acid, lipid, fatty acid, and cholesterol. Anxiety levels and lipid metabolic abnormalities were notably exacerbated at the higher dosage, despite being only a 10-fold increase. Of particular significance, a decrease in lysophosphatidic acid (LPA) and lysophosphatidylserine (LPS) emerged as pivotal indicators of B[a]P neurotoxicity. Spatial-resolved metabolomics further demonstrated distinctive lipid and metabolite profiles across different brain subregions after exposure to B[a]P. Remarkably, alterations were specifically observed in the anxiety-related brain regions, such as the hippocampus, cortex, white matter, and thalamus, varying with exposure dosages. These findings underscore the significance of brain metabolic abnormalities in the development of mental disorders triggered by B[a]P exposure and highlight the need for establishing precise exposure limits of B[a]P to safeguard public mental health.

Un-avoided polycyclic aromatic hydrocarbons exposure on human and animals: current detoxication strategies and future prospects

Polycyclic aromatic hydrocarbons (PAHs) are a class of ubiquitous organic compounds mainly produced during the incomplete combustion or pyrolysis of organic materials. Multiple studies have acknowledged PAHs as human carcinogen, which necessitates its detoxication from human and animals. Great and continuous efforts have been made to alleviate the adverse effects of PAHs to human and animals. This study summarizes plenty of techniques, including herbal extraction, phytochemicals, commercial agent and microbes, coupled with some optimized strategies, have utilized for the detoxication of PAHs, which also have limitations. Augmenting the delivery systems of phytochemicals for the improvement of sustained release property and enhancement of the bioavailability, introducing newly screened microbes for PAHs detoxication via biodegrading, as well as engineering microbes for the production of phytochemicals and degradation enzymes are the three future aspects needed to be considered in-depth.

PAHs as environmental pollutants and their neurotoxic effects

Polycyclic aromatic hydrocarbons (PAHs), which are widely present in incompletely combusted air particulate matter <2.5 μm (PM2.5), tobacco and other organic materials, can enter the human body through various routes and are a class of environmental pollutants with neurotoxic effects. PAHs exposure can lead to abnormal development of the nervous system and neurobehavioral abnormalities in animals, including adverse effects on the nervous system of children and adults, such as a reduced learning ability, intellectual decline, and neural tube defects. After PAHs enter cells of the nervous system, they eventually lead to nervous system damage through mechanisms such as oxidative stress, DNA methylation and demethylation, and mitochondrial autophagy, potentially leading to a series of nervous system diseases, such as Alzheimer's disease. Therefore, preventing and treating neurological diseases caused by PAHs exposure are particularly important. From the perspective of the in vitro and in vivo effects of PAHs exposure, as well as its effects on human neurodevelopment, this paper reviews the toxic mechanisms of action of PAHs and the corresponding prevention and treatment methods to provide a relevant theoretical basis for preventing the neurotoxicity caused by PAHs, thereby reducing the incidence of diseases related to the nervous system and protecting human health.

Ferroptosis implication in environmental-induced neurotoxicity

Neurotoxicity, stemming from exposure to various chemical, biological, and physical agents, poses a substantial threat to the intricate network of the human nervous system. This article explores the implications of ferroptosis, a regulated form of programmed cell death characterized by iron-dependent lipid peroxidation, in environmental-induced neurotoxicity. While apoptosis has historically been recognized as a primary mechanism in neurotoxic events, recent evidence suggests the involvement of additional pathways, including ferroptosis. The study aims to conduct a comprehensive review of the existing literature on ferroptosis induced by environmental neurotoxicity across diverse agents such as natural toxins, insecticides, particulate matter, acrylamide, nanoparticles, plastic materials, metal overload, viral infections, anesthetics, chemotherapy, and radiation. The primary objective is to elucidate the diverse mechanisms through which these agents trigger ferroptosis, leading to neuronal cell death. Furthermore, the article explores potential preventive or therapeutic strategies that could mitigate ferroptosis, offering insights into protective measures against neurological damage induced by environmental stressors. This comprehensive review contributes to our evolving understanding of neurotoxicological processes, highlighting ferroptosis as a significant contributor to neuronal cell demise induced by environmental exposures. The insights gained from this study may pave the way for the development of targeted interventions to protect against ferroptosis-mediated neurotoxicity and ultimately safeguard public health.

Presence of polycyclic aromatic hydrocarbons and persistent organochlorine pollutants in human Milk: Evaluating their levels, association with Total antioxidant capacity, and risk assessment

Breastfeeding provides numerous health benefits for both infants and mothers, promoting optimal growth and development while offering protection against various illnesses and diseases. This study investigated the levels of polychlorinated biphenyls (PCB), organochlorine pesticides (OCP) and polycyclic aromatic hydrocarbons (PAH) in human milk sampled in Zadar (Croatia). The primary objectives were twofold: firstly, to evaluate the individual impact of each compound on the total antioxidant capacity (TAC) value, and secondly, to assess associated health risks. Notably, this study presents pioneering and preliminary insights into PAH levels in Croatian human milk, contributing to the limited research on PAH in breast milk worldwide. PCB and OCP levels in Croatian human milk were found to be relatively lower compared to worldwide data. Conversely, PAH levels were comparatively higher, albeit with lower detection frequencies. A negative correlation was established between organic contaminant levels and antioxidative capacity, suggesting a potential link between higher antioxidative potential and lower organic contaminant levels. Diagnostic ratio pointed towards traffic emissions as the primary source of the detected PAH. The presence of PAH suggests potential health risk, underscoring the need for further in-depth investigation.

Polycyclic Aromatic Hydrocarbons' Impact on Crops and Occurrence, Sources, and Detection Methods in Food: A Review

Polycyclic aromatic hydrocarbons (PAHs) represent a category of persistent organic pollutants that pose a global concern in the realm of food safety due to their recognized carcinogenic properties in humans. Food can be contaminated with PAHs that are present in water, air, or soil, or during food processing and cooking. The wide and varied sources of PAHs contribute to their persistent contamination of food, leading to their accumulation within these products. As a result, monitoring of the levels of PAHs in food is necessary to guarantee the safety of food products as well as the public health. This review paper attempts to give its readers an overview of the impact of PAHs on crops, their occurrence and sources, and the methodologies employed for the sample preparation and detection of PAHs in food. In addition, possible directions for future research are proposed. The objective is to provide references for the monitoring, prevention, and in-depth exploration of PAHs in food.

Seasonal variation in urinary PAH metabolite levels and associations with neonatal birth outcomes

Previous studies have demonstrated that exposure to polycyclic aromatic hydrocarbons (PAHs) can affect maternal and infant health. However, the conclusions regarding the effects of seasonal PAH exposure on maternal and infant health have been inconsistent. To further elucidate this issue, this study included data from 2282 mother-infant pairs in the Zuni birth cohort. The objective was to investigate the association between maternal late-pregnancy urinary PAH metabolite concentrations and neonatal birth outcomes during the heating and non-heating seasons. The results demonstrated that PAH exposure in Zunyi was primarily dominated by 2-OHNAP and 1-OHNAP and that the concentrations of PAH metabolites were significantly higher during the heating season. Furthermore, PAH metabolite exposure was found to affect neonatal birth weight, birth length, and parity index with seasonal differences. Further dose-effect analyses revealed nonlinear relationships and seasonal differences between PAH metabolites and neonatal birth weight, birth length, and parity index. Bayesian kernel mechanism regression modeling demonstrated that the inverted U-shaped relationship between PAH metabolites and neonatal birth weight and parity index was exclusive to the heating season. Consequently, it can be posited that maternal exposure to PAH metabolites during late pregnancy exerts a detrimental influence on neonatal growth and development, which is further compounded by the use of heating fuels. This highlights the necessity to either control or alter the use of heating fuels during pregnancy.

Spatiotemporal Gradients of PAH Concentrations in Greek Cities and Associated Exposure Impacts

To study the spatiotemporal variability of particle-bound polycyclic aromatic hydrocarbons (PAHs) and assess their carcinogenic potential in six contrasting urban environments in Greece, a total of 305 filter samples were collected and analyzed. Sampling sites included a variety of urban background, traffic (Athens, Ioannina and Heraklion), rural (Xanthi) and near-port locations (Piraeus and Volos). When considering the sum of 16 U.S. EPA priority PAHs, as well as that of the six EU-proposed members, average concentrations observed across locations during summer varied moderately (0.4-2.2 ng m-3) and independently of the population of each site, with the highest values observed in the areas of Piraeus and Volos that are affected by port and industrial activities. Winter levels were significantly higher and more spatially variable compared to summer, with the seasonal enhancement ranging from 7 times in Piraeus to 98 times in Ioannina, indicating the large impact of PAH emissions from residential wood burning. Regarding benzo(a)pyrene (BaP), an IARC Group 1 carcinogen and the only EU-regulated PAH, the winter/summer ratios were 24-33 in Athens, Volos, Heraklion and Xanthi; 60 in Piraeus; and 480 in Ioannina, which is afflicted by severe wood-burning pollution events. An excellent correlation was observed between organic carbon (OC) and benzo(a)pyrene (BaP) during the cold period at all urban sites (r2 > 0.8) with stable BaP/OC slopes (0.09-0.14 × 10-3), highlighting the potential use of OC as a proxy for the estimation of BaP in winter conditions. The identified spatiotemporal contrasts, which were explored for the first time for PAHs at such a scale in the Eastern Mediterranean, provide important insights into sources and controlling atmospheric conditions and reveal large deviations in exposure risks among cities that raise the issue of environmental injustice on a national level.

Exploring the Impact of Naphthalene (Polycyclic Aromatic Hydrocarbons) on Anabas testudineus (Bloch) through Dose-Specific Bioenzymological Analysis

This study addresses the increasing concern about naphthalene, a polycyclic aromatic hydrocarbon (PAH), highlighting its growing threats to the environment and aquatic life. The research examines its impact on Anabas testudineus (Bloch) through a detailed dose-specific bioenzymological analysis. Experimental fish groups were exposed to T1 (0.71 mg/L) and T2 (1.42 mg/L) naphthalene concentrations, representing 25 and 50% of the LC50 value, respectively, over a 1-21 day period. Following the experiment, water samples underwent physicochemical analysis, while fish tissues were examined for diverse bioenzymological parameters. Among these parameters, aspirate aminotransferase (AST) and alanine aminotransferase (ALT) serve as crucial indicators for monitoring the physiological status of fish and addressing pollution induced by PAHs, especially naphthalene. Statistical significance was observed in morpho-pathological changes and erythrocyte alterations, particularly the presence of tear-drop appearance (Tr) positively interacting with swelled cells (Sc), vacuolated cells (Va), and sickle cells (Sk) (P < 0.05). These findings highlight tear-drop appearance (Tr) as a significant biomarker in response to naphthalene exposure. The observed changes in A. testudineus tissue bioenzymology, apoptosis, and erythrocytic alterations were exposure and dose-dependent. The research highlights the significance of overseeing and controlling PAH concentrations in aquatic ecosystems to ensure the well-being of A. testudineus (Bloch).

Environmental impact and human health effects of polycyclic aromatic hydrocarbons and remedial strategies: A detailed review

Polycyclic Aromatic Hydrocarbons (PAHs) profoundly impact public and environmental health. Gaining a comprehensive understanding of their intricate functions, exposure pathways, and potential health implications is imperative to implement remedial strategies and legislation effectively. This review seeks to explore PAH mobility, direct exposure pathways, and cutting-edge bioremediation technologies essential for combating the pervasive contamination of environments by PAHs, thereby expanding our foundational knowledge. PAHs, characterised by their toxicity and possession of two or more aromatic rings, exhibit diverse configurations. Their lipophilicity and remarkable persistence contribute to their widespread prevalence as hazardous environmental contaminants and byproducts. Primary sources of PAHs include contaminated food, water, and soil, which enter the human body through inhalation, ingestion, and dermal exposure. While short-term consequences encompass eye irritation, nausea, and vomiting, long-term exposure poses risks of kidney and liver damage, difficulty breathing, and asthma-like symptoms. Notably, cities with elevated PAH levels may witness exacerbation of bronchial asthma and chronic obstructive pulmonary disease (COPD). Bioremediation techniques utilising microorganisms emerge as a promising avenue to mitigate PAH-related health risks by facilitating the breakdown of these compounds in polluted environments. Furthermore, this review delves into the global concern of antimicrobial resistance associated with PAHs, highlighting its implications. The environmental effects and applications of genetically altered microbes in addressing this challenge warrant further exploration, emphasising the dynamic nature of ongoing research in this field.

Evaluation of exposure to multiple organic pollutants in riparian communities of the Brazilian Amazon: Screening levels and potential health risks

Organic pollutants are widely distributed in the environment. Due to their physical and chemical characteristics, they tend to be biomagnified in food chains, mainly in aquatic organisms. Therefore, food consumption is a significant route of lifelong exposure. Although the Amazon River basin contains the highest freshwater biodiversity on Earth, there is scarce literature focusing on the levels of organic pollutants in the local population. The present study was aimed at assessing the levels of several environmental pollutants (polycyclic aromatic hydrocarbons, bisphenols, parabens, and benzophenones) in urine samples from riverside communities along the Tapajós and Amazon Rivers in the Brazilian Amazon region. The results show a 100 % detection of naphthalene metabolites (namely, 1-hydroxy-naphthalene (1OH-NAP), 2-hydroxy-naphthalene (2OH-NAP)), with the highest levels belonging to benzylparaben (BzP) (17.3 ng/mL). Gender-specific analysis revealed that women had significantly higher levels of certain PAH metabolites (i.e., 1OH-NAP and 2-hydroxy-fluorene (2OH-FLU)) than men. In turn, most of the evaluated compounds were higher in urine samples from people living near the Amazon River, which presents increased traffic of boats and ships than the Tapajós River. On the other hand, the human health risk assessment suggested that all communities are at risk of suffering non-carcinogenic effects from exposure to PAHs. At the same time, they are also at risk of carcinogenic effects from exposure to benzo[a]pyrene metabolites. Thus, further studies are needed in order to evaluate the potential health effects of exposure to a mixture of these organic pollutants and other contaminants present in the area, such as mercury.