Neurobehavioral performance of PAH exposure in male coal miners in Shanxi, China: a cross-sectional 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.

Independent and joint associations between urinary polycyclic aromatic hydrocarbon metabolites and cognitive function in older adults in the United States

Background

Polycyclic aromatic hydrocarbons (PAHs), as organic pollutants widely present in daily environments, have been shown by existing epidemiological studies to be significantly associated with deficits in learning and memory functions in children and adults. However, the association between exposure to PAHs and cognitive function in older adults remains unclear. Additionally, existing related studies have only assessed the association between individual PAH exposures and cognitive assessments, overlooking the risks posed by mixed exposures. This study aims to use three statistical models to investigate the individual and overall effects of mixed PAH exposures on the cognition of older adults in the United States.

Methods

The study cohort was obtained from the NHANES database, which included individuals aged 60 and older from 2011 to 2014. Weighted generalized linear models (GLM), weighted quantile sum (WQS) models, and Bayesian kernel machine regression (BKMR) models were utilized to evaluate the connections between urinary PAH metabolites and the standardized Z-scores of four cognitive tests: Immediate Recall Test (IRT), Delayed Recall Test (DRT), Animal Fluency Test (AFT), and Digit Symbol Substitution Test (DSST).

Results

Our analysis involved 899 individuals aged 60 and above. In the fully adjusted GLM, 2-hydroxynaphthalene (2-OHNa), 3-hydroxyfluorene (3-OHFlu), and 2-hydroxyfluorene (2-OHFlu) demonstrated negative associations with DSST Z-scores. In the WQS model, six urinary PAH metabolites were negatively linked to AFT Z-scores (β (95% confidence intervals [CI]): -0.120 (-0.208, -0.033), p = 0.007) and DSST Z-scores (β (95% CI): -0.182 (-0.262, -0.103), p < 0.001). In both assessments, 2-OHNa exerted the greatest influence among the urinary PAH metabolites. In the BKMR model, there was an overall negative correlation between urinary PAH metabolites and AFT and DSST Z-scores when the concentration was within the 25th to 75th percentile, where 2-OHNa dominated the main effect of the mixture. The WQS and BKMR models were adjusted for all covariates.

Conclusion

Increased concentrations of urinary PAH metabolites are associated with cognitive decline in older adults, mainly on language ability, executive function, sustained attention, working memory, and information processing speed, with 2-OHNa playing a major effect.

Effects of Polycyclic Aromatic Hydrocarbon Exposure and Telomere Length and their Interaction on Blood Lipids in Coal Miners

OBJECTIVE

This study aimed to investigate the effects of polycyclic aromatic hydrocarbon (PAH) exposure and telomere length on lipids in coal miners.

METHODS

Basic personal information of 637 coal miners was collected by questionnaire survey. Logistic regression, the Bayesian kernel machine regression model, and weighted quantile sum regression were used to analyze the effects of PAH metabolites and telomere length and their interactions on blood lipids.

RESULTS

High exposure to 9-hydroxyphenanthrene (OR = 1.586, 95% CI: 1.011-2.487) and telomere shortening (OR = 1.413, 95% CI: 1.005-1.985) were associated with dyslipidemia. Weighted quantile sum results showed that 9-hydroxyphenanthrene accounted for the largest proportion of dyslipidemia (weight = 0.66). The interaction results showed that high 9-hydroxyphenanthrene exposure and short telomeres were risk factors for dyslipidemia in coal miners (OR = 2.085, 95% CI: 1.121-3.879). Conclusions: Our findings suggest that 9-hydroxyphenanthrene and shorter telomeres are risk factors for dyslipidemia, and their interaction increases the risk of dyslipidemia.

Coking-Produced Aromatic Compounds in Urine of Exposed and Nonexposed Populations: Exposure Levels, Source Identification, and Model-Based Health Implications

Coking contamination in China is complex and poses potential health risks to humans. In this study, we collected urine samples from coking plant workers, nearby residents, and control individuals to analyze 25 coking-produced aromatic compounds (ACs), including metabolites of polycyclic aromatic hydrocarbons (PAHs) and their derivatives, chlorophenols, and nitrophenols. The median concentration of total ACs in urine of workers was 102 μg·g-1 creatinine, significantly higher than that in the other two groups. Hydroxy-PAHs and hydroxy hetero-PAHs were the dominant ACs. Workers directly exposed from coking industrial processes, i.e., coking, coal preparation, and chemical production processes, showed higher concentrations of hydroxy-PAHs and hydroxy hetero-PAHs (excluding 5-hydroxyisoquinoline), while those from indirect exposure workshops had higher levels of other ACs, indicating different sources in the coking plant. The AC mixture in workers demonstrated positive effects on DNA damage and lipid peroxidation with 5-hydroxyisoquinoline and 3-hydroxycarbazole playing a significant role using a quantile g-computation model. Monte Carlo simulation revealed that coking contamination elevated the carcinogenic risk for exposed workers by 5-fold compared to controls with pyrene, pentachlorophenol, and carbazole contributing the most, and workers from coking process are at the highest risk. This study enhances understanding of coking-produced AC levels and provides valuable insights into coking contamination control.

Association of polycyclic aromatic hydrocarbons exposure with child neurodevelopment and adult emotional disorders: A meta-analysis study

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) have been demonstrated to be neurotoxic.

OBJECTIVES

To summarize the existing epidemiological studies to quantify the effects of PAHs exposure on child neurodevelopment and adult emotional disorders.

DATA SOURCES AND STUDY ELIGIBILITY CRITERIA

We conducted a systematic literature search for studies of child neurodevelopment and adult emotional disorders published in English up to April 2022 in the databases of PubMed, Web of Science and Embase using combinations of MeSH terms and Entry terms, and the articles were filtered out according to data availability. A variety of common PAHs were included in the meta-analysis: 1-hydroxynaphthalene, 2-hydroxynaphthalene, 2-hydroxyfluorene, 3-hydroxyfluorene, 9-hydroxyfluorene, 1-hydroxyphenanthrene, 2-hydroxyphenanthrene, 3-hydroxyphenanthrene, 4-hydroxyphenanthrene, 9-hydroxyphenanthrene, 1-hydroxypyrene and benzoapyrene (BaP).

STUDY EVALUATION AND SYNTHESIS METHODS

We extracted the content of each article, summarized its design characteristics and performed quality evaluation. We combined the odds ratio (OR) available in various studies to obtain the risk of PAHs exposure and adaptive, language, social, attention, motor skills and child depression/anxiety in children ≤ 15 years old. In addition, we also conducted a meta-analysis on the relationship between PAHs exposure and the risk of depression in adults.

RESULTS

We included a total of 16 epidemiological studies (4 cross-sectional studies and 12 cohort studies). The sample size of all included studies ranged from 110 to 9625. Prenatal exposure to PAHs was found to be associated with increased risk of social behavior (OR = 1.60, 95% CI: 1.00-2.54), attention (OR = 2.99, 95% CI: 1.48-6.02), motor skill problems (OR = 1.91, 95% CI: 1.27-2.86) and any adverse neurodevelopmental outcome in children (OR = 2.10, 95% CI: 1.69-2.62). In addition, we found that PAHs exposure could increase the risk of adult depression, with 2-hydroxyfluorene exposure showing the highest combined OR (OR = 1.48, 95% CI: 1.10-2.00).

CONCLUSIONS

The results suggested that PAHs exposure are associated with increased risk of child neurodevelopment and adult depression. The neurotoxic effects of PAHs exposure in human being should be paid more attention. The results suggested that PAHs exposure are associated with increased risk of child neurodevelopment and adult depression. The neurotoxic effects of PAHs exposure in human being should be paid more attention. Steps should be taken to enhance the biomonitoring of PAHs and to reduce the exposure in general population.

Polycyclic aromatic hydrocarbons exposure was associated with microRNA differential expression and neurotransmitter changes: a cross-sectional study in coal miners

Exposure to polycyclic aromatic hydrocarbons (PAHs) may cause neurobehavioral changes. This study aimed to explore the underlying mechanism of PAH neurotoxicity in coal miners. Urinary PAH metabolites, neurotransmitters, and oxidative stress biomarkers of 652 coal miners were examined. Subjects were divided into high and low-exposure groups based on the median of total urinary PAH metabolites. Differentially expressed miRNAs were screened from 5 samples in the low-exposure group (≤ 4.88 μmol/mol Cr) and 5 samples in the high-exposure group (> 4.88 μmol/mol Cr) using microarray technology, followed by bioinformatics analysis of the potential molecular functions of miRNA target genes. Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) was used to validate differentially expressed miRNAs. Restricted cubic splines (RCS) were applied to assess the possible dose-response relationships. Compared to the low PAH exposure group, the high-exposure group had higher levels of 5-hydroxytryptamine (5-HT), epinephrine (E), and acetylcholine (ACh), and lower levels of acetylcholinesterase (AChE). 1-OHP had a dose-response relationship with malondialdehyde (MDA), dopamine (DA), 5-HT, and AChE (P for overall associations < 0.05). There were 19 differentially expressed microRNAs in microarray analysis, significantly enriched in the cell membrane, molecular binding to regulate transcription, and several signaling pathways such as PI3K-Akt. And in the validation stage, miR-885-5p, miR-20a-5p, and let-7i-3p showed differences in the low and high-exposure groups (P < 0.05). Changes in neurotransmitters and microRNA expression levels among the coal miners were associated with PAH exposure. Their biological functions are mainly related to the transcriptional regulation of nervous system diseases or signaling pathways of disorders. These findings provide new insights for future research of PAH neurotoxicity.

Developing a profile of urinary PAH metabolites among Chinese populations in the 2010s

Polycyclic aromatic hydrocarbons (PAHs) pose significant health risks. However, no nationwide cohort has been established to consistently record biomonitoring data on PAH exposure in the Chinese population. Biomonitoring data from 56 published studies were combined in this study to develop a profile of urinary PAH metabolites among Chinese population in the 2010s. The stacked column charts described the composition profiles of hydroxylated PAHs (OH-PAHs) in general, special, and occupational populations. Hydroxynaphthalene (OH-Nap) and hydroxyfluorene (OH-Flu) accounted for more than half of the urinary OH-PAH in general and special populations. The urine of the occupational populations contained a significant amount of hydroxyphenanthrene (OH-Phe) and 1-hydroxypyrene (1-OHPyr). Furthermore, this study analyzed the distribution profiles of non-occupationally exposed populations, such as spatial distribution, age distribution, and trends over time. The population of the Southern region had higher urinary OH-PAH concentrations than the population of the Northern region. Adults (45-55 years old) had the highest level of internal PAH exposure. Between 2010 and 2018, the overall trend of urinary OH-PAHs in Chinese general populations decreased. The cumulative distribution function (CDF) revealed that 1-OHNap and 1-OHPyr were better at distinguishing internal PAH exposure among different populations. The sum of OH-Flu and OH-Phe in urine can be used to assess the impact of indoor and outdoor environments on human exposure to PAHs. Our findings suggest that more emphasis should be placed on collecting biomonitoring data for adults of all ages (particularly in the Northern region) and vulnerable populations. In conclusion, this study advocates for the establishment of a nationwide cohort study of Chinese populations as soon as possible in the future to evaluate the Chinese population's exposure to environmental contaminants.

Polycyclic aromatic hydrocarbons (PAHs): Updated aspects of their determination, kinetics in the human body, and toxicity

Polycyclic aromatic hydrocarbons (PAHs) are legacy pollutants of considerable public health concern. Polycyclic aromatic hydrocarbons arise from natural and anthropogenic sources and are ubiquitously present in the environment. Several PAHs are highly toxic to humans with associated carcinogenic and mutagenic properties. Further, more severe harmful effects on human- and environmental health have been attributed to the presence of high molecular weight (HMW) PAHs, that is PAHs with molecular mass greater than 300 Da. However, more research has been conducted using low molecular weight (LMW) PAHs). In addition, no HMW PAHs are on the priority pollutants list of the United States Environmental Protection Agency (US EPA), which is limited to only 16 PAHs. However, limited analytical methodologies for separating and determining HMW PAHs and their potential isomers and lack of readily available commercial standards make research with these compounds challenging. Since most of the PAH kinetic data originate from animal studies, our understanding of the effects of PAHs on humans is still minimal. In addition, current knowledge of toxic effects after exposure to PAHs may be underrepresented since most investigations focused on exposure to a single PAH. Currently, information on PAH mixtures is limited. Thus, this review aims to critically assess the current knowledge of PAH chemical properties, their kinetic disposition, and toxicity to humans. Further, future research needs to improve and provide the missing information and minimize PAH exposure to humans.

Association between fetal exposure to polycyclic aromatic hydrocarbons and low birth weight: a case-control study in Shenzhen, China

The potential hazards of polycyclic aromatic hydrocarbons (PAHs) on fetus development have raised widespread concerns in recent years, although current epidemiological findings are conflicting. The aim of this case-control study was to investigate the relationship between PAH concentrations in maternal serum and low birth weight (LBW). A questionnaire survey was conducted among 144 (72 pairs) neonates with normal or LBW and their mothers at four different hospitals in Shenzhen, China. Peripheral blood from primiparas and umbilical cord blood from neonates were collected. Concentrations of PAHs were determined by gas chromatography-mass spectrometry. The detection frequencies of PAHs were relatively higher in the peripheral blood samples, while levels of low molecular weight PAHs were greater than high molecular weight PAHs in both peripheral and umbilical cord blood samples. Phenanthrene was frequently detected in blood samples from the case and control groups. Logistic regression analysis showed that acenaphthene in peripheral blood was positively associated with LBW (p < 0.05). This study found a relationship between exposure to certain PAHs and LBW, although future studies are needed to confirm these results.

Exposure to polycyclic aromatic hydrocarbons and the associations with oxidative stress in waste incineration plant workers from South China

Waste incineration is one of the most common emission sources of polycyclic aromatic hydrocarbons (PAHs), causing potential occupational exposure in waste incineration workers. However, relative investigations among waste incineration plant workers are still very limited, particularly in China. Therefore, we collected urine specimens from 77 workers in a waste incineration plant as the exposed group, and 101 residents as the control group in Shenzhen, China. Nine mono-hydroxylated PAH metabolites (OH-PAHs) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) were measured, and their internal relationships were explored. The urinary levels of most OH-PAHs and 8-OHdG in the exposed group exhibited high levels versus another group (p < 0.05). We found negative associations between OH-PAHs and 8-OHdG in the control group (p < 0.05), while most of OH-PAHs were not associated with 8-OHdG in the exposed group, which indicated that the exposure to waste incineration could enlarge the level of individual oxidative stress damage. Nevertheless, PAHs were less likely to trigger obvious health risks in exposed workers through estimation of human intake and exposure risks. This study provides a reference for occupational PAH exposure and strengthen the need of health monitoring among incineration workers.

Neurotoxicity of Polycyclic Aromatic Hydrocarbons: A Systematic Mapping and Review of Neuropathological Mechanisms

Several studies present the neurotoxic effects of polycyclic aromatic hydrocarbons (PAHs), a class of environmental pollutants capable of causing neurological deficits. However, a collective review approach to this research topic is scarce. This study presents the effect of PAHs on the central nervous system using a bibliometric approach. The neuropathological mechanisms of PAHs are also highlighted. Published articles were searched for in the Scopus and Web of Science databases from January 1979 to December 2020 using the keywords 'polycyclic aromatic hydrocarbons' and 'neurotoxicity'. The total number of documents retrieved from both databases was 338. Duplicated documents (80) were excluded and 258 articles were used for the final analysis. Our findings revealed that there has been a significant increase in research outputs on this topic in the last ten years. The countries with the highest scientific productivity in this area are USA, China, France and Italy. The result also showed that, in the past few years, global scientific output in research relating to PAH neurotoxicity focused on neurodegeneration, cholinergic function, neurodevelopmental toxicity, behavioural studies, oxidative stress, neuroprotection and therapeutic intervention using different experimental models, including zebrafish, neuronal cell lines, Caenorhabditis elegans and rats. Recent studies also revealed the neuroprotective roles of some natural products against PAH-induced neurotoxicity. However, more investigation involving clinical trials is required to emphasize the observed neurotoxic effects.

Polymorphisms in DNA Repair and Xenobiotic Biotransformation Enzyme Genes and Lung Cancer Risk in Coal Mine Workers

Background: Currently coal mining employs over 7 million miners globally. This occupational setting is associated with exposure to dust particles, heavy metals, polycyclic aromatic hydrocarbons and radioactive radon, significantly increasing the risk of lung cancer (LC). The susceptibility for LC is modified by genetic variations in xenobiotic detoxification and DNA repair capacity. The aim of this study was to investigate the association between GSTM1 (deletion), APEX1 (rs1130409), XPD (rs13181) and NBS1 (rs1805794) gene polymorphisms and LC risk in patients who worked in coal mines. Methods: The study included 639 residents of the coal region of Western Siberia (Kemerovo region, Russia): 395 underground miners and 244 healthy men who do not work in industrial enterprises. Genotyping was performed using real-time and allele-specific PCR. Results: The results show that polymorphisms of APEX1 (recessive model: OR_adj = 1.87; CI 95%: 1.01–3.48) and XPD (log additive model: OR_adj = 2.25; CI 95%: 1.59–3.19) genes were associated with increased LC risk. GSTM1 large deletion l was linked with decreased risk of LC formation (OR_adj = 0.59, CI 95%: 0.36–0.98). The multifactor dimensionality reduction method for 3-loci model of gene–gene interactions showed that the GSTM1 (large deletion)—APEX1 (rs1130409)—XPD (rs13181) model was related with a risk of LC development. Conclusions: The results of this study highlight an association between gene polymorphism combinations and LC risks in coal mine workers.

The relationship between urine polycyclic aromatic hydrocarbons and depressive symptoms in American adults

BACKGROUND

Studies have shown that Polycyclic aromatic hydrocarbons (PAHs) were neurotoxic, and PAHs exposure may be related to depressive symptoms. Thus, we conducted this study for further explorations.

METHODS

Data from the National Health and Nutrition Examination Survey (NHANES) database of the 2005-2014 cycles were used. The independent variables were urine PAHs metabolites, including 1-hydroxynaphthalene (1-NAP), 2-hydroxynaphthalene (2-NAP), 3-hydroxyfluorene (3-FLU), 2-hydroxyfluorene (2-FLU), 1-hydroxyphenanthrene (1-PHE), and 1-hydroxypyrene (1-PYR). The dependent variable was depressive symptoms according to the Patient Health Questionnaire (PHQ)-9. Multivariate logistic regression analyses and the restricted cubic splines were used in the analyses.

RESULTS

A total of 7647 adults aged 20 or above were included in the analyses. In the Crude model and Model 1 (adjusted for age and gender), compared with quartile (Q) 1, the risk of depressive symptoms increased in Q4 for all the six PAHs metabolites. However, in Model 2, after adjusted for more covariates, the results were no more significant. In the stratified analysis by gender, in Model 2, the weighted OR (95% CIs) of depressive symptoms were 2.78(1.04,7.38), 3.17(1.23,8.18) for 1-NAP, 2-NAP in Q4 for females, respectively. Besides, a non-linear dose-response relationship was found between 1-NAP, 2-NAP, and depressive symptoms in females, too.

LIMITATIONS

Cross-sectional study could not infer causality.

CONCLUSIONS

Our study found a positive association between urine PAHs and depressive symptoms in females, and more studies are needed to explore the relationships between PAHs exposure and depressive symptoms in the general adult populations.

A review of human and animals exposure to polycyclic aromatic hydrocarbons: Health risk and adverse effects, photo-induced toxicity and regulating effect of microplastics

Polycyclic aromatic hydrocarbons (PAHs) are one of the most widely distributed persistent organic pollutants (POPs) in the environmental media. PAHs have been widely concerned due to their significant health risk and adverse effects to human and animals. Currently, the main sources of PAHs in the environment are the incomplete combustion of fossil fuels, as well as municipal waste incineration and agricultural non-surface source emissions. In this work, the scope of our attention includes 16 typical PAHs themselves without involving their metabolites and industrial by-products. Exposure of human and animals to PAHs can lead to a variety of adverse effects, including carcinogenicity and teratogenicity, genotoxicity, reproductive- and endocrine-disrupting effects, immunotoxicity and neurotoxicity, the type and severity of which depend on a variety of factors. On the other hand, the regulatory effect of microplastics (MPs) on the bio-toxicity and bioaccumulation capacity of PAHs has now gradually attracted attention. We critically reviewed the adsorption capacity and mechanisms of MPs on PAHs as well as the effects of MPs on PAHs toxicity, thus highlighting the importance of paying attention to the joint bio-toxicity caused by PAHs-MPs interactions. In addition, due to the extensive nature of the common exposure pathway of PAHs and ultraviolet ray, an accurate understanding of biological processes exposed to both PAHs and UV light is necessary to develop effective protective strategies. Finally, based on the above critical review, we highlighted the research gaps and pointed out the priority of further studies.