Antiandrogenic activity of extracts of diesel exhaust particles emitted from diesel-engine truck under different engine loads and speeds

Ambient black carbon particles in human ovarian tissue and follicular fluid

Evidence indicates a link between exposure to ambient air pollution and decreased female fertility. The ability of air pollution particles to reach human ovarian tissue and follicles containing the oocytes in various maturation stages has not been studied before. Particulate translocation might be an essential step in explaining reproductive toxicity and assessing associated risks. Here, we analysed the presence of ambient black carbon particles in (i) follicular fluid samples collected during ovum pick-up from 20 women who underwent assisted reproductive technology treatment and (ii) adult human ovarian tissue from 5 individuals. Follicular fluid and ovarian tissue samples were screened for the presence of black carbon particles from ambient air pollution using white light generation by carbonaceous particles under femtosecond pulsed laser illumination. We detected black carbon particles in all follicular fluid (n = 20) and ovarian tissue (n = 5) samples. Black carbon particles from ambient air pollution can reach the ovaries and follicular fluid, directly exposing the ovarian reserve and maturing oocytes. Considering the known link between air pollution and decreased fertility, the impact of such exposure on oocyte quality, ovarian ageing and fertility needs to be clarified urgently.

Effects of Ambient Air Pollution on Precocious Puberty: A Case-Crossover Analysis in Nanjing, China

BACKGROUND

Ambient air pollution is closely related to a variety of health outcomes. Few studies have focused on the correlations between air pollution exposure and children's sexual development. In this study, we investigated the potential effects of exposure to air pollution on precocious puberty among children using real-world evidence.

METHODS

We conducted a case-crossover study (n = 2201) to investigate the effect of ambient air pollution exposure on precocious puberty from January 2016 to December 2021. Average exposure levels of PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃ before diagnosis were calculated by using the inverse distance weighting (IDW) method. Distributed lag nonlinear model (DLNM) was used to assess the effect of air pollutants exposure on precocious puberty.

RESULTS

The mean age of the children who were diagnosed with precocious puberty was 7.47 ± 1.24 years. The average concentration of PM_2.5 and PM₁₀ were 38.81 ± 26.36 μg/m³ and 69.77 ± 41.07 μg/m³, respectively. We found that exposure to high concentrations of PM_2.5 and PM₁₀ might increase the risk of precocious puberty using the DLNM model adjusted for the age, SO₂, NO₂, CO, and O₃ levels. The strongest effects of the PM_2.5 and PM₁₀ on precocious puberty were observed in lag 27 (OR = 1.72, 95% CI: 1.01-2.92) and lag 16 (OR = 1.95, 95% CI: 1.33-2.85), respectively.

CONCLUSION

Our findings supported that short-term exposure to air pollution was the risk factor for precocious puberty. Every effort should be made to protect children from air pollution.

Antiandrogenic and Estrogenic Activity Evaluation of Oxygenated and Nitrated Polycyclic Aromatic Hydrocarbons Using Chemically Activated Luciferase Expression Assays

To establish the risk of the endocrine disrupting activity of polycyclic aromatic compounds, especially oxygenated and nitrated polycyclic aromatic hydrocarbons (oxy-PAHs and nitro-PAHs, respectively), antiandrogenic and estrogenic activities were determined using chemically activated luciferase expression (CALUX) assays with human osteoblast sarcoma cells. A total of 27 compounds including 9 oxy-PAHs (polycyclic aromatic ketones and quinones) and 8 nitro-PAHs was studied. The oxy-PAHs of 7H-benz[de]anthracen-7-one (BAO), 11H-benzo[a]fluoren-11-one (B[a]FO), 11H-benzo[b]fluoren-11-one (B[b]FO), and phenanthrenequinone (PhQ) exhibited significantly the potent inhibition of AR activation. All nitro-PAHs exhibited high antiandrogenic activities (especially high for 3-nitrofluoranthene (3-NFA) and 3-nitro-7H-benz[de]anthracen-7-one (3-NBAO)), and the AR inhibition was confirmed as noncompetitive for 3-NFA, 3-NBAO, and 1,3-dinitropyrene (1,3-DNPy). Antiandrogenic activity of 3-NFA demonstrated characteristically a U-shaped dose-response curve; however, the absence of fluorescence effect on the activity was confirmed. The prominent estrogenic activity dependent on dose-response curve was confirmed for 2 oxy-PAHs (i.e., B[a]FO and B[b]FO). Elucidating the role of AR and ER on the effects of polycyclic aromatic compounds (e.g., oxy- and nitro-PAHs) to endocrine dysfunctions in mammals and aquatic organisms remains a challenge.

Sub-toxic events induced by truck speed-facilitated PM2.5 and its counteraction by epigallocatechin-3-gallate in A549 human lung cells

To distinguish the influences of fuel type and truck speed on chemical composition and sub-toxic effects of particulates (PM2.5) from engine emissions, biomarkers-interleukin-6 (IL-6), cytochrome P450 (CYP) 1A1, heme oxygenase (HO)-1, and NADPH-quinone oxidoreductase (NQO)-1-were studied in A549 human lung cells. Fuel type and truck speed preferentially affected the quantity and ion/polycyclic aromatic hydrocarbon (PAH) composition of PM2.5, respectively. Under idling operation, phenanthrene was the most abundant PAH. At high speed, more than 50% of the PAHs had high molecular weight (HMW), of which benzo[a]pyrene (B[a]P), benzo[ghi]perylene (B[ghi]P), and indeno[1,2,3-cd]pyrene (I[cd]P) were the main PAHs. B[a]P, B[ghi]P, and I[cd]P caused potent induction of IL-6, CYP1A1, and NQO-1, whereas phenanthrene mildly induced CYP1A1. Based on the PAH-mediated induction, the predicted increases in biomarkers were positively correlated with the measured increases. HMW-PAHs contribute to the biomarker induction by PM2.5, at high speed, which was reduced by co-exposure to epigallocatechin-3-gallate.

Association between short-term exposure to particulate matter air pollution and outcomes of assisted reproduction technology in Lombardy, Italy: A retrospective cohort study

The harmful effect of polluted air on spontaneous fertility has been consistently reported. However, the specific pollutants involved in determining this effect are still to be clarified. The study of Assisted Reproductive Technology (ART) populations is particularly helpful in this context since it allows to monitor the key events of the reproductive process. We analyzed the medical records of 2122 patients who underwent fresh or frozen ART cycles during 2014-2017 in the Lombardy region, north-west Italy. Each subject was assigned the daily PM₁₀ estimates concentration, at the municipality of residence, during the induction of multiple follicular growth. A multivariable linear regression model with a repeated-measures design was used to estimate the association between short-term exposure to PM₁₀ and ART outcomes, A reduction in the number of retrieved oocytes in association with 10 μg/m³ increment of the pollutant estimated at 13-14 days before oocyte retrieval (Day 0) and a decrease in the percentage of metaphase II oocytes for 1-week and 2-weeks mean exposure before day 0 were observed. For cumulative pregnancies, a significant lag time change effect for PM₁₀ exposure (Day -9-0) has been detected, by means of multivariable logistic regression models. An increase in PM₁₀ exposure was associated with a decrease in clinical and ongoing pregnancies while a decrease in PM₁₀ exposure was associated with a significant increase in pregnancy rates. In a population living in a highly polluted area in Italy, we added suggestive evidence of a negative association between ART outcomes and PM₁₀ exposure after controlling for known risk factors for ART success rate.

Periconceptional exposure to air pollution and congenital hypospadias among full-term infants

BACKGROUND

Evidence regarding whether prenatal exposure to air pollution increases the risk of hypospadias remains limited. The aim of the study is to evaluate the association between exposure to ambient air pollution during early pregnancy and the incidence of hypospadias.

METHODS

We conducted a 1:10 case-control study using the Taiwanese Birth Registry database. Male full-term infants reported to have hypospadias were defined as cases, and controls were randomly selected from male full-term infants without any congenital anomaly. The monthly average of ambient air pollutants, including PM₁₀, PM_2.5, PM_2.5-10, NO₂, NOx, O₃, and O₃ 8-h maximum, from 3 months before conception to 6 months post conception was retrieved from air quality monitoring stations and interpolated to the level of township using the kriging method. Multivariable logistic regression models were utilized to evaluate the associations.

RESULTS

A total of 200 hypospadias cases, with 2000 healthy controls sampled, were reported during 2007-2014. The results revealed that PM_2.5 exposure during the first 3 months after conception (odds ratio [OR] = 1.29, 95% confidence interval [CI]: 1.01-1.65, per interquartile range [IQR] = 15.6 μg/m³) and O₃ exposure during the first month after conception (OR = 1.40, 95% CI: 1.08-1.82, per IQR = 8.0 ppb) were associated with a higher incidence of hypospadias.

CONCLUSIONS

The results of the study suggest that early gestational exposure to ambient air pollution increases the risk of hypospadias among full-term infants.

Modulation of endocrine nuclear receptor activities by polyaromatic compounds present in fractionated extracts of diesel exhaust particles

Organic pollutants associated with diesel exhaust particles (DEP), such as polycyclic aromatic hydrocarbons (PAHs) and their derivatives, may negatively impact human health. However, a comprehensive overview of their effects on endocrine nuclear receptor activities is still missing. Here, we evaluated the effects of extracts and chromatographic fractions (fractionated according to increasing polarity) of two standard reference materials derived from distinct types of diesel engines (SRM 2975, SRM 1650b), on activation of androgen receptor (AR), estrogen receptor alpha (ERα), peroxisome proliferator-activated receptor γ (PPARγ), glucocorticoid receptor (GR) and thyroid receptor α (TRα), using human cell-based reporter gene assays. Neither DEP standard modulated AR or GR activities. Crude extracts and fractions of SRM 1650b and SRM 2975 suppressed ERα-mediated activity in the ER-CALUX™ assay; however, this effect could be partly linked to their cytotoxicity in this cell line. We observed that only SRM 2975 extract and its fractions were partial PPARγ inducers, while SRM 1650b extract was not active towards this receptor. Importantly, we found that both extracts and polar fractions of SRM activated TRα and significantly potentiated the activity of endogenous TRα ligand, triiodothyronine. Based on a detailed chemical analysis of both extracts and their polar fractions, we identified several oxygenated PAH derivatives, that were present at relatively high levels in the analyzed DEP standards, including 3-nitrobenzanthrone (3-NBA), anthracene-9,10-dione, phenanthrene-9,10-dione, 9H-fluoren-9-one or benzo[a]anthracene-7,12-dione, to activate TRα activity. Nevertheless, these compounds provided only a minor contribution to the overall TRα activity identified in polar fractions. This suggests that yet unidentified polar polyaromatic compounds associated with DEP may, apart from their known impact on the aryl hydrocarbon receptor or steroid signaling, deregulate activities of additional nuclear receptors, in particular of TRα. This illustrates the need to better characterize endocrine disrupting activities of DEP.

Transcriptomic analysis reveals dose-dependent modes of action of benzo(a)pyrene in polar cod (Boreogadus saida)

Polar cod (Boreogadus saida) has been used as a model Arctic species for hazard assessment of environmental stressors such as polycyclic aromatic hydrocarbons (PAHs). However, most of the PAH studies using polar cod rely on targeted biomarker-based analysis thus may not adequately address the complexity of the toxic mechanisms of the stressors. The present study was performed to develop a broad-content transcriptomic platform for polar cod and apply it for understanding the toxic mechanisms of a model PAH, benzo(a)pyrene (BaP). Hepatic transcriptional analysis using a combination of high-density polar cod oligonucleotide microarray and quantitative real-time RT-PCR was conducted to characterize the stress responses in polar cod after 14d repeated dietary exposure to 0.4 (Low) and 20.3 μg/g fish/feeding (High) BaP doses. Bile metabolic analysis was performed to identify the storage of a key BaP hepatic biotransformation product, 3-hydroxybenzo(a)pyrene (3-OH-BaP). The results clearly showed that 3-OH-BaP was detected in the bile of polar cod after both Low and High BaP exposure. Dose-dependent hepatic stress responses were identified, with Low BaP suppressing genes involved in the defense mechanisms and High BaP inducing genes associated with these pathways. The results suggested that activation of the aryl hydrocarbon receptor signaling, induction of oxidative stress, DNA damage and apoptosis were the common modes of action (MoA) of BaP between polar cod or other vertebrates, whereas induction of protein degradation and disturbance of mitochondrial functions were proposed as novel MoAs. Furthermore, conceptual toxicity pathways were proposed for BaP-mediated effects in Arctic fish. The present study has for the first time reported a transcriptome-wide analysis using a polar cod-specific microarray and suggested novel MoAs of BaP. The analytical tools, bioinformatics solutions and mechanistic knowledge generated by this study may facilitate mechanistically-based hazard assessment of environmental stressors in the Arctic using this important fish as a model species.

Air pollution and female fertility: a systematic review of literature

Air pollution is a cause of concern for human health. For instance, it is associated with an increased risk for cancer, cardiovascular and respiratory disorders. In vitro and in vivo studies suggested that air pollutants could act as endocrine disruptors, promote oxidative stress and exert genotoxic effect. Whether air pollution affects female infertility is under debate. The aim of the present study was to conduct a systematic review of studies that evaluated the impact of air pollution on female infertility. We systematically searched the MEDLINE (PubMed) and SCOPUS databases to identify all relevant studies published before October 2017. No time or language restrictions were adopted, and queries were limited to human studies. We also hand-searched the reference lists of relevant studies to ensure we did not miss pertinent studies. The risk of bias and quality assessment of the studies identified were performed using the Newcastle-Ottawa Scale. Primary outcomes were conception rate after spontaneous intercourse and live birth rate after in vitro fertilization (IVF) procedures. Secondary outcomes were first trimester miscarriage, stillbirths, infertility, number of oocytes and embryo retrieved. Eleven articles were included in the analysis. We found that in the IVF population, nitrogen dioxide and ozone were associated with a reduced live birth rate while particulate matter of 10 mm was associated with increased miscarriage. Furthermore, in the general population, particulate matter of 2.5 mm and between 2.5 and 10 mm were associated with reduced fecundability, whereas sulfur dioxide_, carbon monoxide and nitrogen dioxide might promote miscarriage and stillbirths. The main limitation of our findigns resides in the fact that the desegn of studies included are observational and retrospective. Furthermore, there was a wide heterogenity among studies. Although larger trials are required before drawing definitive conclusions, it seems that air pollution could represent a matter of concern for female infertility.

Does air pollution play a role in infertility?: a systematic review

BACKGROUND

Air pollution is involved in many pathologies. These pollutants act through several mechanisms that can affect numerous physiological functions, including reproduction: as endocrine disruptors or reactive oxygen species inducers, and through the formation of DNA adducts and/or epigenetic modifications. We conducted a systematic review of the published literature on the impact of air pollution on reproductive function. Eligible studies were selected from an electronic literature search from the PUBMED database from January 2000 to February 2016 and associated references in published studies. Search terms included (1) ovary or follicle or oocyte or testis or testicular or sperm or spermatozoa or fertility or infertility and (2) air quality or O3 or NO2 or PM2.5 or diesel or SO2 or traffic or PM10 or air pollution or air pollutants. The literature search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We have included the human and animal studies corresponding to the search terms and published in English. We have excluded articles whose results did not concern fertility or gamete function and those focused on cancer or allergy. We have also excluded genetic, auto-immune or iatrogenic causes of reduced reproduction function from our analysis. Finally, we have excluded animal data that does not concern mammals and studies based on results from in vitro culture. Data have been grouped according to the studied pollutants in order to synthetize their impact on fertility and the molecular pathways involved.

CONCLUSION

Both animal and human epidemiological studies support the idea that air pollutants cause defects during gametogenesis leading to a drop in reproductive capacities in exposed populations. Air quality has an impact on overall health as well as on the reproductive function, so increased awareness of environmental protection issues is needed among the general public and the authorities.

Effect on the H19 gene methylation of sperm and organs of offspring after chlorpyrifos-methyl exposure during organogenesis period

To elucidate the effect on the H19 gene methylation of sperm and organs in offspring by chlorpyrifos-methyl (CPM) exposure during organogenesis period, CPM was administered at doses of 4 (CPM4), 20 (CPM20), and 100 (CPM100) mg/kg bw/day from 7 days post coitum (d.p.c.) to 17 d.p.c. after mating CAST/Ei (♂) and B6 (♀). Anogenital distance (AGD) was measured at postnatal day (PND) 21. Clinical signs, body weights, feed and water consumption, organs weights, serum hormone values, and H19 methylation level of organ and sperm were measured at PND63. Body weights were significantly lower than control until PND6. AGD was significantly decreased in the CPM100 group in males and increased in the CPM20 group in females. The absolute weights of the thymus and epididymis were significantly increased for males in all of CPM treatment groups. In the CPM20 group, absolute weights of liver, kidney, heart, lung, spleen, prostate gland, and testes were significantly increased. Testosterone concentrations in serum were significantly increased by CPM treatment in males. H19 methylation level of liver and thymus showed decreased pattern in a dose-dependent manner in males. The levels of H19 methylation in sperm were 73.76 ± 7.16% (Control), 57.84 ± 12.94% (CPM4), 64.24 ± 3.79% (CPM20), and 64.24 ± 3.79% (CPM100). Conclusively, CPM exposure during organogenesis period can disrupt H19 methylation in sperm, liver, and thymus and disturb the early development of offspring.

Toxic Identification and Evaluation of Androgen Receptor Antagonistic Activities in Acid-Treated Liver Extracts of High-Trophic Level Wild Animals from Japan

Sulfuric acid-treated liver extracts of representative high-trophic level Japanese animals were analyzed by toxic identification and evaluation (TIE) with chemically activated luciferase expression (CALUX) and chemical analysis to elucidate androgen receptor (AR) antagonistic activities and potential contributions of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). The activities were detected in striped dolphins (n = 5), Stejneger's beaked whales (n = 6), golden eagle (n = 1), and Steller's sea eagle (n = 1) with CALUX-flutamide equivalents (FluEQs) as follow: 38 (20-52), 47 (21-96), 5.0, and 80 μg FluEQ/g-lipid, respectively. The AR antagonism was detected in limited number of specimens at lower levels for finless porpoise, raccoon dog, and common cormorant. Theoretical activities (Theo-FluEQs) were calculated using the concentration of OCPs and PCBs and their IC25-based relative potency (REP) values. These total contribution to CALUX-FluEQ was 126%, 84%, 53%, 55%, and 44% for striped dolphin, Steller's sea eagle, Stejneger's beaked whale, finless porpoise, and golden eagle, respectively, and the main contributor was p,p'-DDE. However, most of the activities for raccoon dog (7.6%) and common cormorant (17%) could not be explained by OCPs and PCBs. This suggests other unknown compounds could function as AR antagonists in these terrestrial species.

Characterizations of organic compounds in diesel exhaust particulates

To characterize how the speed and load of a medium-duty diesel engine affected the organic compounds in diesel particle matter (PM) below 1 μm, four driving conditions were examined. At all four driving conditions, concentration of identifiable organic compounds in PM ultrafine (34-94 nm) and accumulation (94-1000 nm) modes ranged from 2.9 to 5.7 μg/m(3) and 9.5 to 16.4 μg/m(3), respectively. As a function of driving conditions, the non-oxygen-containing organics exhibited a reversed concentration trend to the oxygen-containing organics. The identified organic compounds were classified into eleven classes: alkanes, alkenes, alkynes, aromatic hydrocarbons, carboxylic acids, esters, ketones, alcohols, ethers, nitrogen-containing compounds, and sulfur-containing compounds. At all driving conditions, alkane class consistently showed the highest concentration (8.3 to 18.0 μg/m(3)) followed by carboxylic acid, esters, ketones and alcohols. Twelve polycyclic aromatic hydrocarbons (PAHs) were identified with a total concentration ranging from 37.9 to 174.8 ng/m(3). In addition, nine nitrogen-containing polycyclic aromatic compounds (NPACs) were identified with a total concentration ranging from 7.0 to 10.3 ng/m(3). The most abundant PAH (phenanthrene) and NPACs (7,8-benzoquinoline and 3-nitrophenanthrene) comprise a similar molecular (3 aromatic-ring) structure under the highest engine speed and engine load.

Effects of motor vehicle exhaust on male reproductive function and associated proteins

Air pollution is consistently associated with various diseases and subsequent death among children, adult, and elderly people worldwide. Motor vehicle exhaust contributes to a large proportion of the air pollution present. The motor vehicle exhaust systems emit a variety of toxic components, including carbon monoxide, nitrogen oxides, volatile organic compounds, ozone, particulate matter, and polycyclic aromatic hydrocarbons. Several epidemiological studies and laboratory studies have demonstrated that these components are potentially mutagenic, carcinogenic, and endocrine disrupting agents. However, their impact on male reproductive function and associated proteins is not very clear. Therefore, a comprehensive review on the effects of motor vehicle exhaust on male reproductive function and associated proteins is needed to better understand the risks of exhaust exposure for men. We found that motor vehicle exhaust can cause harmful effects on male reproductive functions by altering organ weights, reducing the spermatozoa qualities, and inducing oxidative stress. Remarkably, motor vehicle exhaust exposure causes significant changes in the expression patterns of proteins that are key components involved in spermatogenesis and testosterone synthesis. In conclusion, this review helps to describe the risks of vehicle exhaust exposure and its relationship to potential adverse effects on the male reproduction system.

Biological effects of polycyclic aromatic hydrocarbon derivatives

Polycyclic aromatic hydrocarbons (PAHs) are included in various environmental pollutants such as airborne particles and have been reported to induce a variety of toxic effects. On the other hand, PAH derivatives are generated from PAHs both through chemical reaction in the atmosphere and metabolism in the body.PAH derivatives have become known for their specific toxicities such as estrogenic/antiestrogenic activities and oxidative stress, and correlations between the toxicities and structures of PAH derivatives have been shown in recent studies. These studies are indispensable for demonstrating the health effects of PAH derivatives, since they would contribute to the comprehensive toxicity prediction of many kinds of PAH derivatives.

Follicle-stimulating hormone levels in female workers exposed to urban pollutants

The aim of this study was to evaluate if there were alterations in FSH plasma levels in female outdoor workers (traffic policewomen and drivers) exposed to chemical urban stressors vs. control group. After excluding subjects with main confounding factors, traffic policewomen, drivers and indoor workers were matched by age, working life, socioeconomic status, marital status, menstrual cycle day, age of menarche, habitual consumption of Italian coffee and soy. A total of 129 female subjects were included in the study: some 63 workers studied during proliferative phase and 66 during secretory phase of menstrual cycle. Proliferative phase of menstrual cycle: FSH mean values were significantly higher in traffic policewomen compared to controls (p < 0.05). Results suggest that in outdoor workers exposed to urban chemical stressors there are alterations in FSH levels; therefore FSH may be used as an early biological marker, valuable for the group, used in occupational set.

Diesel exhaust particulate extracts inhibit transcription of nuclear respiratory factor-1 and cell viability in human umbilical vein endothelial cells

Endothelial dysfunction precedes cardiovascular disease and is accompanied by mitochondrial dysfunction. Here we tested the hypothesis that diesel exhaust particulate extracts (DEPEs), prepared from a truck run at different speeds and engine loads, would inhibit genomic estrogen receptor activation of nuclear respiratory factor-1 (NRF-1) transcription in human umbilical vein endothelial cells (HUVECs). Additionally, we examined how DEPEs affect NRF-1-regulated TFAM expression and, in turn, Tfam-regulated mtDNA-encoded cytochrome c oxidase subunit I (COI, MTCO1) and NADH dehydrogenase subunit I (NDI) expression as well as cell proliferation and viability. We report that 17β-estradiol (E(2)), 4-hydroxytamoxifen (4-OHT), and raloxifene increased NRF-1 transcription in HUVECs in an ER-dependent manner. DEPEs inhibited NRF-1 transcription, and this suppression was not ablated by concomitant treatment with E(2), 4-OHT, or raloxifene, indicating that the effect was not due to inhibition of ER activity. While E(2) increased HUVEC proliferation and viability, DEPEs inhibited viability but not proliferation. Resveratrol increased NRF-1 transcription in an ER-dependent manner in HUVECs, and ablated DEPE inhibition of basal NRF-1 expression. Given that NRF-1 is a key nuclear transcription factor regulating genes involved in mitochondrial activity and biogenesis, these data suggest that DEPEs may adversely affect mitochondrial function leading to endothelial dysfunction and resveratrol may block these effects.

In utero exposure to a low concentration of diesel exhaust affects spontaneous locomotor activity and monoaminergic system in male mice

BACKGROUND

Epidemiological studies have suggested that suspended particulate matter (SPM) causes detrimental health effects such as respiratory and cardiovascular diseases, and that diesel exhaust particles from automobiles is a major contributor to SPM. It has been reported that neonatal and adult exposure to diesel exhaust damages the central nervous system (CNS) and induces behavioral alteration. Recently, we have focused on the effects of prenatal exposure to diesel exhaust on the CNS. In this study, we examined the effects of prenatal exposure to low concentration of diesel exhaust on behaviour and the monoaminergic neuron system. Spontaneous locomotor activity (SLA) and monoamine levels in the CNS were assessed.

METHODS

Mice were exposed prenatally to a low concentration of diesel exhaust (171 microg DEP/m(3)) for 8 hours/day on gestational days 2-16. SLA was assessed for 3 days in 4-week-old mice by analysis of the release of temperature-associated infrared rays. At 5 weeks of age, the mice were sacrificed and the brains were used for analysis by high-performance liquid chromatography (HPLC).

RESULTS AND DISCUSSION

Mice exposed to a low concentration of diesel exhaust showed decreased SLA in the first 60 minutes of exposure. Over the entire test period, the mice exposed prenatally to diesel exhaust showed decreased daily SLA compared to that in control mice, and the SLA in each 3 hour period was decreased when the lights were turned on. Neurotransmitter levels, including dopamine and noradrenaline, were increased in the prefrontal cortex (PFC) in the exposure group compared to the control group. The metabolites of dopamine and noradrenaline also increased in the PFC. Neurotransmitter turnover, an index of neuronal activity, of dopamine and noradrenaline was decreased in various regions of the CNS, including the striatum, in the exposure group. The serum corticosterone level was not different between groups. The data suggest that decreased SLA in mice exposed prenatally to diesel exhaust is due to facilitated release of dopamine in the PFC.

CONCLUSIONS

These results indicate that exposure of mice in utero to a low concentration of diesel exhaust decreases SLA and alters the neurochemical monoamine metabolism of several regions of the brain.

Dioxin-like and endocrine disruptive activity of traffic-contaminated soil samples

Pollution of surface soils by traffic, especially along major highways, can be a significant issue. Numerous studies have demonstrated traffic to be an important source of particulate matter and gas-phase organic air pollutants that produce many types of deleterious effects. This article brings original information about the presence of contaminants with specific mechanisms of action in traffic-influenced soils as determined by bioanalytical approaches and instrumental analyses. The initial phase of the study aimed to compare contamination of soils near highways with those from reference localities, whereas the second phase of the study investigated the influence of traffic pollution in soils at various distances from highways. For the reference areas, forest soils contained greater concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQs; 483 to 2094 pg/g) than did arable soils (96 to 478 pg/g), which represent the relevant reference for the studied soils along highways. The total concentration of TCDD-EQs determined in the in vitro transactivation assay ranged from 225 to 27,700 pg/g in traffic-affected soils. The greatest concentration of TCDD-EQs among the studied sites was observed in soils collected near highway D1, which is the primary thoroughfare in the Czech Republic. The concentrations of TCDD-EQs in roadside soils were the greatest and decreased with increased distance from highways, and this spatial distribution corresponded with the levels of polycyclic aromatic hydrocarbons (PAHs). Soils collected 100 m away from highways in most cases contained concentrations of TCDD-EQs similar to background values. Most TCDD-EQ presence was caused by nonpersistent compounds in soils, with a significant contribution from PAHs as well as other unknown nonpersistent chemicals. Extracts from most soils collected near highways exhibited antiestrogenic and in some cases antiandrogenic activities; for several sites the activity was also detected in soils farther from highways. The presence of TCDD-EQs and antihormonal activity in highway-affected soils points to traffic as a source of polluting compounds having specific effects.

Endocrine disruptive effect of 3-methyl-4-nitrophenol isolated from diesel exhaust particles in Hershberger assay using castrated immature rats

To examine the endocrine disruptive effects of 3-methyl-4-nitrophenol (4-nitro-m-cresol; PNMC) in diesel exhaust particles (DEP), the rat Hershberger assay was carried out using castrated immature rats. Castrated 28-d-old immature male rats were implanted with a 5-mm-long silastic tube containing crystalline testosterone and injected with PNMC subcutaneously at doses 1, 10, or 100 mg/kg for 5 consecutive d. The weights of the livers significantly decreased in the 10 and 100 mg/kg PNMC treatment groups as compared with the control group. The weights of the seminal vesicles significantly increased in the 10 mg/kg PNMC treatment group as compared with the control group. The weights of the Cowper's glands were significantly increased in 1 mg/kg PNMC treatment group compared with the control group. The concentrations of plasma testosterone significantly increased in the 10 and 100 mg/kg PNMC treatment groups, indicating that PNMC induced accumulation of bioactive testosterone released from the implanted tube in circulation. Plasma follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels significantly decreased under all the doses in the PNMC treatment groups, indicating that PNMC acts on the hypothalamus-pituitary axis.

Aryl hydrocarbon receptor and estrogen receptor ligand activity of organic extracts from road dust and diesel exhaust particulates

A wide variety of contaminants derived from diesel and gasoline engines, tire, asphalt, and natural organic compounds is found in road dust. Polycyclic aromatic compounds (PACs) are the important toxic targets among various contents in road dust and diesel exhaust particulates (DEPs), and endocrine-disrupting activity of PACs was suggested. In the present study, aryl hydrocarbon receptor (AhR) ligand activity was confirmed in the extract of both road dust and DEPs. In the separation of the extracts for both road dust and DEPs with reversed-phase HPLC, it was found that polar fractions contributed to significant AhR ligand activity in both a mouse hepatoma (H1L1) cell system and a yeast system. Furthermore, the contribution of these polar fractions was higher in DEPs than in road dust, probably because of the greater concentration of oxy-PAHs in DEPs than in road dust. The contribution of contaminants associated with the polar region to AhR ligand activity was also evident following the separation of road dust with normal-phase HPLC. Additionally, remarkable estrogen receptor (ER) ligand activity was detected in the highly polar region separated with normal-phase HPLC. It is suggested that many unknown AhR or ER ligand active compounds are contained in the polar region.

Analytical method for determination of dinitropyrenes using gas chromatography–high-resolution mass spectrometry

A gas chromatography-high-resolution mass spectrometry method has been developed for the determination of dinitropyrenes (DNPs). DNPs were reduced to the corresponding diaminopyrenes with sodium hydrosulfide, and the reduced DNPs were derivatized with N-methyl-bis(trifluoroacetamide). The sensitivity of this method was up to 10 times that of high-performance liquid chromatography with fluorescence detection. The detection limits for 1,3-, 1,6-, and 1,8-DNPs were in the 0.90-1.1 pg range. The concentrations were corrected with a correction factor determined from the recovery of an internal standard. The recovery of deuterium-labeled 6-nitrochrysene was at least 87%. This new method was utilized for quantitative determination of DNPs in Standard Reference Material (SRM) 1975 available from the US National Institute of Standards and Technology. Three DNP isomers were measured in SRM 1975 at 0.571-1.59 microg/g.

Estrogenic and anti-androgenic activities of 4-nitrophenol in diesel exhaust particles

A 4-nitrophenol (PNP) isolated from diesel exhaust particles (DEP) has been identified as a vasodilator. PNP is also a known degradation product of the insecticide parathion. We used uterotrophic and Hershberger assays to study the estrogenic and anti-androgenic activities of PNP in-vivo. In ovariectomized immature female rats injected subcutaneously with 1, 10, or 100 mg/kg PNP daily for 7 days, significant (P<0.05) increases in uterine weight were seen in only those receiving 10 or 100 mg/kg PNP. Furthermore, in castrated immature male rats implanted with a silastic tube (length, 5 mm) containing crystalline testosterone and injected subcutaneously with 0.01, 0.1, or 1 mg/kg PNP daily for 5 days, those receiving the doses of 0.1 mg/kg showed significant (P<0.05) weight decreases in seminal vesicles, ventral prostate, levator ani plus bulbocavernosus muscles, and glans penis. Plasma FSH and LH levels did not change in female rats but were significantly (P<0.05) increased in male rats treated with 0.1 mg/kg PNP. These results clearly demonstrated that PNP has estrogenic and anti-androgenic activities in-vivo. Our results therefore suggest that diesel exhaust emissions and the degradation of parathion can lead to accumulation of PNP in air, water, and soil and thus could have serious deleterious effects on wildlife and human health.

Simultaneous determination of urinary hydroxylated metabolites of naphthalene, fluorene, phenanthrene, fluoranthene and pyrene as multiple biomarkers of exposure to polycyclic aromatic hydrocarbons

A method is presented for determining monohydroxy polycyclic aromatic hydrocarbons (OHPAHs) having 2-, 3- and 4-rings in human urine by using high-performance liquid chromatography with fluorescence detection. A urine sample containing conjugates of OHPAHs was hydrolysed in the presence of beta-glucuronidase/aryl sulfatase and the solution was cleaned up with a solid-phase extraction (C(18) and silica). Eight OHPAHs, namely 1- and 2-hydroxynaphthalenes, 2-hydroxyfluorene, 2-, 3- and 4-hydroxyphenanthrenes, 3-hydroxyfluoranthene and 1-hydroxypyrene, were separated and 1- and 9-hydroxyphenanthrenes co-eluted on an alkylamide-type reversed-phase column with fluorimetric detection. The urinary concentrations of OHPAHs were quantified by using deuterated 1-hydoxypyrene as an internal standard. The method showed good repeatability for inter- and intra-day precisions as well as good linearity of calibration curves (r (2) ranged from 0.996 to 0.999). The limits of detection (S/N=3) were in the range from 2.3 fmol to 2.2 pmol per injection. This method was successfully applied to urine samples from non-smoking taxi drivers, traffic policemen and rural villagers of Chiang Mai, Thailand. The results showed higher urinary concentrations of OHPAHs in rural villagers, consistent with higher respiratory exposure to PAHs.

Anti-androgenic activity of 3-methyl-4-nitrophenol in diesel exhaust particles

In our continuing studies on nitrophenol derivatives as vasodilators in diesel exhaust particles, we have reported that nitrophenols in diesel exhaust particles possess not only vasodilatory activity but also estrogenic activity in vitro and in vivo, as well as anti-androgenic activity in vitro. Our efforts here were focused on the in vitro and in vivo anti-androgenic activity of 3-methyl-4-nitrophenol (4-nitro-m-cresol; PNMC), known a degradation product of the insecticide fenitrothion, in diesel exhaust particles. We investigated its anti-androgenic activity using an in vitro recombinant yeast screen and in vivo Hershberger assays. Recombinant yeast screen assay showed that PNMC possesses anti-androgenic activity at low concentrations. Furthermore, castrated 28-day-old immature male rats each implanted with a 5-mm-long silastic tube containing crystalline testosterone and injected with PNMC subcutaneously at doses from as low as 0.01 and 0.1 mg/kg up to 1 mg/kg for 5 consecutive days showed significantly decreased weights of the seminal vesicles, ventral prostate, and glans penis. Plasma follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were significantly increased in the 0.1 mg/kg PNMC treatment group. Our results demonstrate that PNMC in diesel exhaust particles clearly has anti-androgenic activity both in vitro and in vivo and can therefore be considered as an endocrine-disrupting chemical.

Bisphenol A in ambient air particulates responsible for the proliferation of MCF-7 human breast cancer cells and Its concentration changes over 6 months

To survey the estrogenic activity of the organic extracts from particulate matter of urban ambient outdoor air, samples were collected on glass fiber filters using a high-volume air sampler on the rooftop of our institute for 6 months (six filters/month). After extracting the organic materials and separating them into three fractions, i.e., acidic, neutral, and basic, we applied a cell-growth assay using MCF-7 human breast cancer cells to the original extract and the extracts of the fractions. Only the extract in the acidic fraction showed cell proliferation activity in a dose-response manner. To survey the chemical(s) responsible for the activity, a gas chromatography/mass spectrometry (GC/MS) analysis was conducted after silylating the extract. The presence of bisphenol A (BPA) was confirmed, because the retention times and the MS fragment patterns between the silylated derivative of a component in the sample and that of BPA itself were the same. By using a GC/MS-SIM (selective ion monitoring) technique, the average value was found to be 0.51 ng/m(3) of air (range: 0.02 approximately 1.92 ng/m(3) of air). The trend of the residual levels in air particulates showed seasonal variation, increasing from autumn to winter and decreasing from winter to spring. The only exception was that the value in January was lower than those in December and February. Considering the content of BPA in the extract of the acidic fraction and the strength of the activities with the extract and BPA itself, the estrogenic activity due to BPA in the fraction seemed to decrease. In spite of this decline, the possibility remains that the estrogenic activity mainly originated from BPA.