Developmental toxicity of diesel exhaust: A review of studies in experimental animals

Exposure to heavy metals, antioxidant status, and the interaction of single nucleotide polymorphisms in the genes CAT rs7943316, GSTP1 rs1695, as well as GSTM1 and GSTT1 genes, among workers in occupational settings

Individuals working in diverse fields are consistently exposed to work-related pollutants that can impact their overall health. The current study investigated the presence of pollutants in seven different occupational groups and their impact on human health. Biochemical and genetic approaches were employed. Heavy metals were determined by ICP-MS technique. Oxidative stress biochemical markers and molecular analysis of the glutathione transferases gene SNPs (GSTT1, GSTM1, GSTP1), catalase (CAT, rs7943316), and superoxide dismutase (SOD, rs17880487) was carried out. The results revealed a significantly higher quantity of Cd among five occupational groups. Catalase, malonaldehyde, and glutathione was significantly dysregulated. Molecular analysis of the gene SNPs suggests a probable relationship between the antioxidants and the phenotypic expression of the CAT, GSTP1, GSTT1, and GSTM1 SNPs. It is concluded that chronic exposure to occupational contaminants like Cd affects human health through oxidative stress in association with some of their gene SNPs.

Differential impact of diesel exhaust particles on glutamatergic and dopaminergic neurons in Caenorhabditis elegans: A neurodegenerative perspective

The growing body of evidence links exposure to particulate matter pollutants with an increased risk of neurodegenerative diseases. In the present study, we investigated whether diesel exhaust particles can induce neurobehavioral alterations associated with neurodegenerative effects on glutamatergic and dopaminergic neurons in Caenorhabditis elegans (C. elegans). Exposure to DEP at concentrations of 0.167 µg/cm2 and 1.67 µg/cm2 resulted in significant developmental delays and altered locomotion behaviour. These effects were accompanied by discernible alterations in the expressions of antioxidant genes sod-3 and gst-4 observed in transgenic strains. Behaviour analysis demonstrated a significant reduction in average speed (p < 0.001), altered paths, and decreased swimming activities (p < 0.01), particularly at mid and high doses. Subsequent assessment of neurodegeneration markers in glutamatergic (DA1240) and dopaminergic (BZ555) transgenic worms revealed notable glutamatergic neuron degeneration at 0.167 μg/cm2 (∼30 % moderate, ∼20 % advanced) and 1.67 μg/cm2 (∼28 % moderate, ∼24 % advanced, p < 0.0001), while dopaminergic neurons exhibited structural deformities (∼16 %) without significant degeneration in terms of blebs and breaks. Furthermore, in silico docking simulations suggest the presence of an antagonistic competitive inhibition induced by DEP in the evaluated neuro-targets, stronger for the glutamatergic transporter than for the dopaminergic receptor from the comparative binding affinity point of view. The results underscore DEP's distinctive neurodegenerative effects and suggest a link between locomotion defects and glutamatergic neurodegeneration in C. elegans, providing insights into environmental health risks assessment.

Associations of Trimester-Specific Exposure to Perchlorate, Thiocyanate, and Nitrate with Childhood Neurodevelopment: A Birth Cohort Study in China

Studies about the impacts of maternal exposure to perchlorate, thiocyanate, and nitrate on offspring neurodevelopment are scarce. Based on a birth cohort in China, 1,028 mothers provided urine samples at three trimesters for determination of the three target analytes, and their offspring neurodevelopment was evaluated at 2 years old. Associations of maternal exposure to the three chemicals with offspring neurodevelopment were estimated using three statistical methods. Trimester-specific analyses using generalized estimating equation models showed that double increment of thiocyanate and nitrate during the first trimester was associated with 1.56 (95% CI: -2.82, -0.30) and 1.22 (-2.40, -0.03) point decreases in the offspring mental development index (MDI), respectively. Weighted quantile sum (WQS) regression analyses showed that the mixture exposure at the first and second trimesters was negatively associated with the offspring MDI (β = -2.39, 95% CI: -3.85, -0.93; β = -1.75, 95% CI: -3.04, -0.47, respectively) and thiocyanate contributed the most to the association (65.0 and 91.6%, respectively). Bayesian kernel machine regression analyses suggested an inverted U-shape relationship of maternal urinary thiocyanate with the offspring MDI. These findings suggested that prenatal exposure to the three chemicals (at current levels), especially thiocyanate and nitrate, may impair neurodevelopment. Early pregnancy seems to be the sensitive window.

Endocrine-disrupting chemicals and male reproductive health

Modifiable factors, such as environmental exposures, can impact human fertility. The objective of this review is to summarize the potential effects of exposure to important endocrine-disrupting chemicals on male reproductive health. Most experimental and animal data demonstrate strong evidence for the negative effects of exposure to phenols, phthalates, pesticides, and perfluoroalkyl and polyfluoroalkyl substances on male reproductive health. Although evidence of negative associations in humans was overall strong for phthalates and pesticides, limited and inconclusive relationships were found for the other examined chemical biomarkers. Reasons for the discrepancies in results include but are not limited to, differences in study populations, exposure concentrations, number of samples collected, sample sizes, study design, and residual confounding. Additional studies are needed, particularly for newer phenols and perfluoroalkyl and polyfluoroalkyl substances, given the scarce literature on the topic and increasing exposures over time.

Degenerative and Regenerative Actin Cytoskeleton Rearrangements, Cell Death, and Paradoxical Proliferation in the Gills of Pearl Gourami (Trichogaster leerii) Exposed to Suspended Soot Microparticles

The effect is studied of water-suspended soot microparticles on the actin cytoskeleton, apoptosis, and proliferation in the gill epithelium of pearl gourami. To this end, the fish are kept in aquariums with 0.005 g/L of soot for 5 and 14 days. Laser confocal microscopy is used to find that at the analyzed times of exposure to the pollutant zones appear in the gill epithelium, where the actin framework of adhesion belts dissociates and F-actin either forms clumps or concentrates perinuclearly. It is shown that the exposure to soot microparticles enhances apoptosis. On day 5, suppression of the proliferation of cells occurs, but the proliferation increases to the control values on day 14. Such a paradoxical increase in proliferation may be a compensatory process, maintaining the necessary level of gill function under the exposure to toxic soot. This process may occur until the gills' recovery reserve is exhausted. In general, soot microparticles cause profound changes in the actin cytoskeleton in gill cells, greatly enhance cell death, and influence cell proliferation as described. Together, these processes may cause gill dysfunction and affect the viability of fish.

Diesel exhaust particles exposure induces liver dysfunction: Exploring predictive potential of human circulating microRNAs signature relevant to liver injury risk

Diesel exhaust particles (DEP) pollution should be taken seriously because it is an extensive environmental and occupational health concern. Exploring early effect biomarkers is crucial for monitoring and managing DEP-associated health risk assessment. Here, we found that serum levels of 67 miRNAs were dysregulated in DEP exposure group. Notably, 20 miRNAs were identified as each having a significant dose-response relationship with the internal exposure level of DEP. Further, we revealed that the DEP exposure could affect the liver function of subjects and that 7 miRNAs (including the well-known liver injury indicator, miR-122-5p) could serve as the novel epigenetic-biomarkers (epi-biomarkers) to reflect the liver-specific response to the DEP exposure. Importantly, an unprecedented prediction model using these 7 miRNAs was established for the assessment of DEP-induced liver injury risk. Finally, bioinformatic analysis indicated that the unique set of miRNA panel in serum might also contribute to the molecular mechanism of DEP exposure-induced liver damage. These results broaden our understanding of the adverse health outcomes of DEP exposure. Noteworthy, we believe this study could shed light on roles and functions of epigenetic biomarkers from environmental exposure to health outcomes by revealing the full chain of exposure-miRNAs-molecular pathways-disease evidence.

Exhaust emissions of gaseous and particle size-segregated water-soluble organic compounds from diesel-biodiesel blends

This study assessed the emissions of gaseous pollutants and particle size distributed water-soluble organics (WSO) from a diesel vehicle fuelled with ultralow sulphur diesel (B0) and 10 (B10), 20 (B20), and 30% (B30) biodiesel blends in a chassis dynamometer tested under transient mode. Particulate emission sampling was carried out in an ultraviolet (UV) test chamber using a 10-stage impactor. Samples were grouped into three size fractions and analysed by gas chromatography-mass spectrometry. Increasing the biofuel ratio up to 30% in the fuel reduced WSO emissions by 20.9% in comparison with conventional diesel. Organic acids accounted for 82-89% of WSO in all tested fuels. Dicarboxylic acids were the most abundant compound class, followed by hydroxy, aromatic, and linear alkanoic acids. Correlations between compounds demonstrated that adding biodiesel to diesel fuel reduces the emissions of nitrogen oxides (NOx), benzene, toluene, ethylbenzene and xylenes (BTEX), methane (CH4), total and nonmethane hydrocarbons (THC and NMHC), and dicarboxylic and hydroxy acids, but increases emissions of carbon dioxide (CO2) and alkanoic and aromatic acids. Emissions of dicarboxylic and hydroxy acids were strongly correlated with the biodiesel content. WSO emissions of coarse and fine (1.0-10 μm) particles decreased with the increasing biofuel content in fuel blend. The total share of ultrafine (0.18-1.0 μm) and nanoparticles (< 0.18 μm) increased in WSOs emissions from B20 and B30 blends, when compared with petrodiesel. The biodiesel content also affected the chemical profile of WSO size fractions.

Recent Insights into Particulate Matter (PM2.5)-Mediated Toxicity in Humans: An Overview

Several epidemiologic and toxicological studies have commonly viewed ambient fine particulate matter (PM_2.5), defined as particles having an aerodynamic diameter of less than 2.5 µm, as a significant potential danger to human health. PM_2.5 is mostly absorbed through the respiratory system, where it can infiltrate the lung alveoli and reach the bloodstream. In the respiratory system, reactive oxygen or nitrogen species (ROS, RNS) and oxidative stress stimulate the generation of mediators of pulmonary inflammation and begin or promote numerous illnesses. According to the most recent data, fine particulate matter, or PM_2.5, is responsible for nearly 4 million deaths globally from cardiopulmonary illnesses such as heart disease, respiratory infections, chronic lung disease, cancers, preterm births, and other illnesses. There has been increased worry in recent years about the negative impacts of this worldwide danger. The causal associations between PM_2.5 and human health, the toxic effects and potential mechanisms of PM_2.5, and molecular pathways have been described in this review.

Early structural and functional changes in Baikal Sculpin gills exposed to suspended soot microparticles in experiment

The toxic influence of soot microparticles on terrestrial organisms has been well studied, although there is scarce data on how microparticles could affect hydrobionts. We performed a first-ever study of the short-term (5 days) impact of furnace soot (0.005 g/L) on the structural and functional features of gill cells in the Baikal Sculpin species Paracottus knerii, Dybowski, 1874. The soot samples used in the experiment were composed of small (10-100 nm) particles and larger (up to 20 μm) aggregates. The dominant fractions of the polycyclic aromatic hydrocarbons of these microparticles were phenanthrene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzofluoranthenes, benzopyrenes, indeno[1,2,3-c,d]pyrenes, and benzo[ghi]perylene. Trace element analysis of the soot detected the presence of C, S, Si, Al, Ca, K, Mg, P, and Fe. The gill condition was assessed with electron scanning, transmission, and laser confocal microscopy. Soot induces degenerative changes in the macrostructure and surface of secondary lamellae and increases mucus production in fish gills. A decrease in mitochondrial activity, an increase in reactive oxygen species production, and an increase in the frequency of programmed cell death in gill epithelium were observed under the influence of soot. In chloride cells, an induction of macroautophagy was detected. In general, the changes in fish gills after the short-term influence of soot microparticles indicate the stress of respiratory and osmotic regulation systems in fish. The data obtained are important for forming a coherent picture of the impact of soot on hydrobionts and for developing bioindication methods for evaluating the risks of their influence on aquatic ecosystems.

Health and the Megacity: Urban Congestion, Air Pollution, and Birth Outcomes in Brazil

We studied the health effects of economic development in heavily urbanized areas, where congestion poses a challenge to environmental conditions. We employed detailed data from air pollution and birth records around the metropolitan area of São Paulo, Brazil, between 2002 and 2009. During this period, the megacity experienced sustained growth marked by the increases in employment rates and ownership of durable goods, including automobiles. While better economic conditions are expected to improve infant health, air pollution that accompanies it is expected to do the opposite. To untangle these two effects, we focused on episodes of thermal inversion—meteorological phenomena that exogenously lock pollutants closer to the ground—to estimate the causal effects of in utero exposure to air pollution. Auxiliary results confirmed a positive relationship between thermal inversions and several air pollutants, and we ultimately found that exposure to inversion episodes during the last three months of pregnancy led to sizable reductions in birth weight and increases in the incidence of preterm births. Increased pollution exposure induced by inversions also has a significant impact over fetal survival as measured by the size of live-birth cohorts.

Air pollution and children's health-a review of adverse effects associated with prenatal exposure from fine to ultrafine particulate matter

BACKGROUND

Particulate matter (PM), a major component of ambient air pollution, accounts for a substantial burden of diseases and fatality worldwide. Maternal exposure to PM during pregnancy is particularly harmful to children's health since this is a phase of rapid human growth and development.

METHOD

In this review, we synthesize the scientific evidence on adverse health outcomes in children following prenatal exposure to the smallest toxic components, fine (PM_2.5) and ultrafine (PM_0.1) PM. We highlight the established and emerging findings from epidemiologic studies and experimental models.

RESULTS

Maternal exposure to fine and ultrafine PM directly and indirectly yields numerous adverse birth outcomes and impacts on children's respiratory systems, immune status, brain development, and cardiometabolic health. The biological mechanisms underlying adverse effects include direct placental translocation of ultrafine particles, placental and systemic maternal oxidative stress and inflammation elicited by both fine and ultrafine PM, epigenetic changes, and potential endocrine effects that influence long-term health.

CONCLUSION

Policies to reduce maternal exposure and health consequences in children should be a high priority. PM_2.5 levels are regulated, yet it is recognized that minority and low socioeconomic status groups experience disproportionate exposures. Moreover, PM_0.1 levels are not routinely measured or currently regulated. Consequently, preventive strategies that inform neighborhood/regional planning and clinical/nutritional recommendations are needed to mitigate maternal exposure and ultimately protect children's health.

Exposure to ambient particulate matter and biomass burning during pregnancy: associations with birth weight in Thailand

BACKGROUND

There is a growing evidence that exposure to ambient particulate air pollution during pregnancy is associated with adverse birth outcomes, including reduced birth weight (BW). The objective of this study was to quantify associations between BW and exposure to particulate matter (PM) and biomass burning during pregnancy in Thailand.

METHODS

We collected hourly ambient air pollutant data from ground-based monitors (PM with diameter of <10 µm [PM₁₀], Ozone [O₃], and nitrogen dioxide [NO₂]), biomass burning from satellite remote sensing data, and individual birth weight data during 2015-2018. We performed a semi-ecological analysis to evaluate the association between mean trimester exposure to air pollutants and biomass burning with BW and low-birth weight (LBW) (<2500 g), adjusting for gestation age, sex, previous pregnancies, mother's age, heat index, season, year, gaseous pollutant concentrations, and province. We examined potential effect modification of PM₁₀ and biomass burning exposures by sex.

RESULTS

There were 83,931 eligible births with a mean pregnancy PM₁₀ exposure of 39.7 µg/m³ (standard deviation [SD] = 7.7). The entire pregnancy exposure was associated with reduced BW both for PM₁₀ (-6.81 g per 10 µg/m³ increase in PM₁₀ [95% CI = -12.52 to -1.10]) and biomass burning (-6.34 g per 1 SD increase in fires/km² [95% CI = -11.35 to -1.34]) only after adjustment for NO₂. In contrast with these findings, a reduced odds ratio (OR) of LBW was associated with PM₁₀ exposure only in trimesters one and two, with no relationship across the entire pregnancy period. Associations with biomass burning were limited to increased ORs of LBW with exposure in trimester three, but only for male births.

CONCLUSION

Based on our results, we encourage further investigation of air pollution, biomass burning and BW in Thailand and other low-income and middle-income countries.

In Utero Exposure to Particulate Air Pollution during Pregnancy: Impact on Birth Weight and Health through the Life Course

In high-income countries, and increasingly in lower- and middle-income countries, chronic non-communicable diseases (NCDs) have become the primary health burden. It is possible that in utero exposure to environmental pollutants such as particulate matter (PM) may have an impact on health later in life, including the development of NCDs. Due to a lack of data on foetal growth, birth weight is often used in epidemiologic studies as a proxy to assess impacts on foetal development and adverse birth outcomes since it is commonly recorded at birth. There are no research studies with humans that directly link PM exposure in utero to birth weight (BW) and subsequently, the effects of lower BW on health outcomes in old age. It is, however, plausible that such associations exist, and it is thus important to assess the potential public health impacts of PM across the life course, and it is plausible to use birth weight as an indicator of risk. We therefore split this narrative review into two parts. In the first part, we evaluated the strength of the evidence on the impact of PM exposure during the entire pregnancy on birth weight outcomes in ten meta-analyses. In the second part, we reviewed the literature linking lower birth weight to childhood and adult chronic cardiovascular disease to explore the potential implications of PM exposure in utero on health later in life. Within the reviewed meta-studies on birth weight, there is sufficient evidence that PM pollution is associated with lower birth weight, i.e., the majority of meta-studies found statistically significant reductions in birth weight. From the second part of the review, it is evident that there is good evidence of associations between lower birth weight and subsequent cardiovascular disease risk. It is thus plausible that in utero exposure to PM is associated with lower birth weight and persisting biological changes that could be associated with adverse health effects in adulthood. Based on the reviewed evidence, however, the magnitude of later life cardiovascular health impacts from in utero exposure and its impact on BW are likely to be small compared to health effects from exposure to particulate air pollution over a whole lifetime.

Nitrophenols are negative modulators of steroidogenesis in preovulatory follicles of the hen (Gallus domesticus) ovary: An in vitro and in vivo study

This study assessed the effects of 4-nitrophenol (PNP) and 3-methyl-4-nitrophenol (PNMC) on steroidogenesis in the granulosa layers (GLs) and theca layers (TLs) of chicken preovulatory follicles in vitro and in vivo. In the in vitro experiment, three of the largest yellow preovulatory follicles (F3 < F2 < F1) were exposed to PNP or PNMC (10^-8-10^-4 M), ovine luteinising hormone (oLH; 10 ng/mL), and combinations of oLH and PNP or PNMC (10^-6 M). In the in vivo experiment, laying hens were treated for 6 days with PNP or PNMC (10 mg/kg). In vitro experiments revealed that PNP and PNMC decreased basal and oLH-stimulated P4 secretion from the GL as well as T and E2 secretion from the TLs of F3-F1 follicles. Treatment of laying hens with nitrophenols lowered plasma concentrations of luteinising hormone and all three steroids. The reduction of steroid secretion was associated with decrease in LHR, HSD3B1 and CYP19A1 mRNA expression in the GL and/or TLs of the preovulatory follicles, both in vitro and in vivo. Moreover, PNP decreased HSD3B protein expression in the GL of F2 follicles in vitro and in vivo, while PNMC diminished its expression in the GL of F1 follicles in vivo. In vitro, nitrophenols did not affect CYP19A1 protein expression; however, nitrophenols inhibited its expression in the TLs of F3 and F2 follicles in vivo. The results obtained clearly demonstrate that nitrophenols are negative modulators of steroidogenesis in chicken preovulatory follicles and, in consequence, may not only impair ovulation process, but also affect function of the hypothalamic-pituitary-ovarian axis.

Recent insights on indirect mechanisms in developmental toxicity of nanomaterials

BACKGROUND

Epidemiological and animal studies provide compelling indications that environmental and engineered nanomaterials (NMs) pose a risk for pregnancy, fetal development and offspring health later in life. Understanding the origin and mechanisms underlying NM-induced developmental toxicity will be a cornerstone in the protection of sensitive populations and the design of safe and sustainable nanotechnology applications.

MAIN BODY

Direct toxicity originating from NMs crossing the placental barrier is frequently assumed to be the key pathway in developmental toxicity. However, placental transfer of particles is often highly limited, and evidence is growing that NMs can also indirectly interfere with fetal development. Here, we outline current knowledge on potential indirect mechanisms in developmental toxicity of NMs.

SHORT CONCLUSION

Until now, research on developmental toxicity has mainly focused on the biodistribution and placental translocation of NMs to the fetus to delineate underlying processes. Systematic research addressing NM impact on maternal and placental tissues as potential contributors to mechanistic pathways in developmental toxicity is only slowly gathering momentum. So far, maternal and placental oxidative stress and inflammation, activation of placental toll-like receptors (TLRs), impairment of placental growth and secretion of placental hormones, and vascular factors have been suggested to mediate indirect developmental toxicity of NMs. Therefore, NM effects on maternal and placental tissue function ought to be comprehensively evaluated in addition to placental transfer in the design of future studies of developmental toxicity and risk assessment of NM exposure during pregnancy.

Influence of negative corona discharge on the Zeta potential of diesel particles

Electrical agglomeration as a pretreatment means can reduce the exhaust particle number concentration of diesel engine. The charge of particle is an important factor affecting the coagulation process. Therefore, an experiment was carried out to study the charging characteristic of diesel particles. Zeta potential for diesel particle was used to represent the charged state and the charge of particles could be calculated according to the value of Zeta potential. Influences of various factors on the charge of particle were investigated by changing the charged voltage, internal temperature of charging zone, and the load of engine. Experimental results show that the increase of charged voltage can improve the charge and the absolute value of diesel particles. With increase of charging zone temperature, corona inception voltage declines and the charge of particle increases. The load of engine has a positive effect on the charge of particles which reaches its peak at full load.

Effects of air pollution on the nervous system and its possible role in neurodevelopmental and neurodegenerative disorders

Recent extensive evidence indicates that air pollution, in addition to causing respiratory and cardiovascular diseases, may also negatively affect the brain and contribute to central nervous system diseases. Air pollution is comprised of ambient particulate matter (PM) of different sizes, gases, organic compounds, and metals. An important contributor to PM is represented by traffic-related air pollution, mostly ascribed to diesel exhaust (DE). Epidemiological and animal studies have shown that exposure to air pollution may be associated with multiple adverse effects on the central nervous system. In addition to a variety of behavioral abnormalities, the most prominent effects caused by air pollution are oxidative stress and neuro-inflammation, which are seen in both humans and animals, and are supported by in vitro studies. Among factors which can affect neurotoxic outcomes, age is considered most relevant. Human and animal studies suggest that air pollution may cause developmental neurotoxicity, and may contribute to the etiology of neurodevelopmental disorders, including autism spectrum disorder. In addition, air pollution exposure has been associated with increased expression of markers of neurodegenerative disease pathologies, such as alpha-synuclein or beta-amyloid, and may thus contribute to the etiopathogenesis of neurodegenerative diseases, particularly Alzheimer's disease and Parkinson's disease.

A systematic review of the health effects associated with the inhalation of particle-filtered and whole diesel exhaust

Background: Diesel exhaust is a complex mixture comprised of gases and particulate matter and is a contributor to ambient air pollution. To reduce health risks, recent changes in diesel engine technology have significantly altered the composition of diesel exhaust, primarily by lowering emissions of particulate matter. However, animal toxicological studies continue to report health effects following exposure to diesel exhaust from engines employing particulate filters. The cause of these effects remains unclear.Objective and methods: To gain an understanding of the role of both particle-filtered and whole diesel exhaust on specific health outcomes, we conducted a systematic review in which we examined animal toxicological and controlled human exposure studies that included a comparison between inhalation of particle-filtered and whole diesel exhaust on any health endpoint.Results: We identified 26 studies that met both the inclusion and study evaluation criteria. For most health outcomes, the particle filtration methods employed in the included studies did not appreciably attenuate the health effects associated with exposure to whole diesel exhaust. There were also several health endpoints for which significant effects were associated with exposure to either particle-filtered or whole diesel exhaust, but not to both.Conclusions: Overall, the results from this systematic review demonstrate that exposure to different components in diesel exhaust can have distinct and independent health effects. Thus, to better inform human health risk assessments, future studies aimed at elucidating the health effects from diesel exhaust should include exposure to both particle-filtered and whole diesel exhaust.

Nitrophenols suppress steroidogenesis in prehierarchical chicken ovarian follicles by targeting STAR, HSD3B1, and CYP19A1 and downregulating LH and estrogen receptor expression

To assess the effects of 4-nitrophenol (PNP) and 3-methyl-4-nitrophenol (PNMC) on steroidogenesis in the chicken ovary, white (WF, 1-4 mm) and yellowish (YF, 4-8 mm) prehierarchical follicles were incubated in a medium supplemented with PNP or PNMC (10^-8-10^-4 M), ovine LH (oLH; 10 ng/mL), and combinations of oLH with PNP or PNMC (10^-6 M). Testosterone (T) and estradiol (E2) concentrations in media and mRNA expression for steroidogenic proteins (STAR, HSD3B1, and CYP19A1), and LH receptors (LHR), estrogen receptor α (ESR1) and β (ESR2) in follicles were determined by RIA and real-time qPCR, respectively. PNP and PNMC decreased T and E2 secretion by the WF and YF, and oLH-stimulated T secretion from these follicles. PNP decreased basal STAR and HSD3B1 mRNA levels both in the WF and YF, and CYP19A1 mRNAs in the WF. PNP reduced oLH-affected mRNA expression of these genes in the YF. PNMC inhibited basal STAR, HSD3B1, and CYP19A1 mRNA expression in the WF, but not in the YF. PNMC reduced oLH-stimulated STAR and CYP19A1 expression in the YF and WF, respectively. PNP decreased basal mRNA expression of LHR, ESR1, and ESR2 in the WF, but it increased ESR1 and ESR2 mRNA levels in the YF. PNMC reduced both basal and oLH-affected LHR, ESR1, and ESR2 mRNA expression in the WF; however, it did not influence expression of these genes in the YF. We suggest that nitrophenols by influencing sex steroid synthesis and transcription of LH and estrogen receptors in prehierarchical ovarian follicles may impair their development and selection to the preovulatory hierarchy.

Airborne, Vehicle-Derived Fe-Bearing Nanoparticles in the Urban Environment: A Review

Airborne particulate matter poses a serious threat to human health. Exposure to nanosized (<0.1 μm), vehicle-derived particulates may be hazardous due to their bioreactivity, their ability to penetrate every organ, including the brain, and their abundance in the urban atmosphere. Fe-bearing nanoparticles (<0.1 μm) in urban environments may be especially important because of their pathogenicity and possible association with neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. This review examines current knowledge regarding the sources of vehicle-derived Fe-bearing nanoparticles, their chemical and mineralogical compositions, grain size distribution and potential hazard to human health. We focus on data reported for the following sources of Fe-bearing nanoparticles: exhaust emissions (both diesel and gasoline), brake wear, tire and road surface wear, resuspension of roadside dust, underground, train and tram emissions, and aircraft and shipping emissions. We identify limitations and gaps in existing knowledge as well as future challenges and perspectives for studies of airborne Fe-bearing nanoparticles.

Association Between Air Pollution Exposure, Cognitive and Adaptive Function, and ASD Severity Among Children with Autism Spectrum Disorder

Prenatal exposure to air pollution has been associated with autism spectrum disorder (ASD) risk but no study has examined associations with ASD severity or functioning. Cognitive ability, adaptive functioning, and ASD severity were assessed in 327 children with ASD from the Childhood Autism Risks from Genetics and the Environment study using the Mullen Scales of Early Learning (MSEL), the Vineland Adaptive Behavior Scales (VABS), and the Autism Diagnostic Observation Schedule calibrated severity score. Estimates of nitrogen dioxide (NO₂), particulate matter (PM_2.5 and PM₁₀), ozone, and near-roadway air pollution were assigned to each trimester of pregnancy and first year of life. Increasing prenatal and first year NO₂ exposures were associated with decreased MSEL and VABS scores. Increasing PM₁₀ exposure in the third trimester was paradoxically associated with improved performance on the VABS. ASD severity was not associated with air pollution exposure.

Repeated gestational exposure to diesel engine exhaust affects the fetal olfactory system and alters olfactory-based behavior in rabbit offspring

BACKGROUND

Airborne pollution, especially from diesel exhaust (DE), is known to have a negative effect on the central nervous system in exposed human populations. However, the consequences of gestational exposure to DE on the fetal brain remain poorly explored, with various effects depending on the conditions of exposure, as well as little information on early developmental stages. We investigated the short-term effects of indirect DE exposure throughout gestation on the developing brain using a rabbit model. We analyzed fetal olfactory tissues at the end of gestation and tested behaviors relevant to pups' survival at birth. Pregnant dams were exposed by nose-only inhalation to either clean air or DE with a content of particles (DEP) adjusted to 1 mg/m3 by diluting engine exhaust, for 2 h/day, 5 days/week, from gestational day 3 (GD3) to day 27 (GD27). At GD28, fetal olfactory mucosa, olfactory bulbs and whole brains were collected for anatomical and neurochemical measurements. At postnatal day 2 (PND2), pups born from another group of exposed or control female were examined for their odor-guided behavior in response to the presentation of the rabbit mammary pheromone 2-methyl-3-butyn-2-ol (2MB2).

RESULTS

At GD28, nano-sized particles were observed in cilia and cytoplasm of the olfactory sensory neurons in the olfactory mucosa and in the cytoplasm of periglomerular cells in the olfactory bulbs of exposed fetuses. Moreover, cellular and axonal hypertrophies were observed throughout olfactory tissues. Concomitantly, fetal serotoninergic and dopaminergic systems were affected in the olfactory bulbs. Moreover, the neuromodulatory homeostasis was disturbed in a sex-dependent manner in olfactory tissues. At birth, the olfactory sensitivity to 2MB2 was reduced in exposed PND2 pups.

CONCLUSION

Gestational exposure to DE alters olfactory tissues and affects monoaminergic neurotransmission in fetuses' olfactory bulbs, resulting in an alteration of olfactory-based behaviors at birth. Considering the anatomical and functional continuum between the olfactory system and other brain structures, and due to the importance of monoamine neurotransmission in the plasticity of neural circuits, such alterations could participate to disturbances in higher integrative structures, with possible long-term neurobehavioral consequences.

Neurodevelopmental toxicity induced by maternal PM2.5 exposure and protective effects of quercetin and Vitamin C

Epidemiological studies show that maternal exposure to PM_2.5 affects the neurodevelopment of the offspring, especially the neurocognitive function. However, no relevant experimental researches have been published on toxic mechanism and diet intervention. We evaluated the effects of exposure to different doses of PM_2.5 on the behavioral development of offspring via a PM_2.5 exposure model established by intratracheal instillation, explored its mechanism and the protective effects of quercetin and VC intervention, and focused on the protein expression of CREB/BDNF signaling pathway. Specifically, Exposure to PM_2.5 during gestation and lactation period caused maternal oxidative stress. Maternal exposure to PM_2.5 changed postnatal open-field behaviors in both gender, impaired spatial learning and memory in the female offspring, increased the level of IL-1β, IL-6, down-regulated p-CREB/CREB, BDNF, TrkB, p-CaMKII/CaMKII, p-CaMKIV/CaMKIV, up-regulated p-Akt/Akt and p-ERK1/2/ERK1/2 in the offspring. In addition, maternal supplementation with quercetin ameliorate the maternal oxidative stress, improved progeny inflammatory response, regulated BDNF, TrkB, p-Akt/Akt, p-ERK1/2/ERK1/2 in female offspring, regulated TrkB, p-CREB/CREB and p-Akt/Akt in male offspring. Maternal supplementation with VC increased the levels of CAT in maternal mice, up-regulated BDNF in female offspring, regulated p-CREB/CREB and p-ERK1/2/ERK1/2 in male offspring. Our findings indicate that PM2.5 exposure during pregnancy and lactation could impair behavioral development of offspring. Quercetin shows more protective effects than VC. The mechanism of neurodevelopmental toxicity induced by PM_2.5 may be related to oxidative stress, inflammatory response and modulation of the CREB/BDNF signaling pathway.

Impact of a gestational exposure to diesel exhaust on offspring gonadal development: experimental study in the rabbit

The aim of the present work was to address experimentally the possible impact of exposure to air pollution during gestation on the differentiation and function of the gonads of the offspring using a rabbit model. Rabbits were exposed daily to diluted diesel exhaust gas or filtered air from the 3rd until the 27th day of gestation, during which time germ cells migrate in genital ridges and divide, and fetal sex is determined. Offspring gonads were collected shortly before birth (28th day of gestation) or after puberty (7.5 months after birth). The structure of the gonads was analyzed by histological and immunohistological methods. Serum concentrations of testosterone and anti-Müllerian hormone were determined using ELISA. The morphology and the endocrine function of the gonads collected just at the arrest of the exposure were similar in polluted and control animals in both sexes. No differences were observed as well in gonads collected after puberty. Sperm was collected at the head of the epididymis in adults. Sperm motility and DNA fragmentation were measured. Among all parameters analyzed, only the sperm DNA fragmentation rate was increased three-fold in exposed males. Mechanisms responsible for these modifications and their physiological consequences are to be further clarified.

A Comparison of the Health Effects of Ambient Particulate Matter Air Pollution from Five Emission Sources

This article briefly reviews evidence of health effects associated with exposure to particulate matter (PM) air pollution from five common outdoor emission sources: traffic, coal-fired power stations, diesel exhaust, domestic wood combustion heaters, and crustal dust. The principal purpose of this review is to compare the evidence of health effects associated with these different sources with a view to answering the question: Is exposure to PM from some emission sources associated with worse health outcomes than exposure to PM from other sources? Answering this question will help inform development of air pollution regulations and environmental policy that maximises health benefits. Understanding the health effects of exposure to components of PM and source-specific PM are active fields of investigation. However, the different methods that have been used in epidemiological studies, along with the differences in populations, emission sources, and ambient air pollution mixtures between studies, make the comparison of results between studies problematic. While there is some evidence that PM from traffic and coal-fired power station emissions may elicit greater health effects compared to PM from other sources, overall the evidence to date does not indicate a clear ‘hierarchy’ of harmfulness for PM from different emission sources. Further investigations of the health effects of source-specific PM with more advanced approaches to exposure modeling, measurement, and statistics, are required before changing the current public health protection approach of minimising exposure to total PM mass.

Residential distance to major roadways and semen quality, sperm DNA integrity, chromosomal disomy, and serum reproductive hormones among men attending a fertility clinic

OBJECTIVE

We examined associations of residential distance to major roadways, as a proxy for traffic-related air pollution exposures, with sperm characteristics and male reproductive hormones.

DESIGN

The cohort included 797 men recruited from Massachusetts General Hospital Fertility Center between 2000 and 2015 to participate in fertility research studies.

MATERIALS AND METHODS

Men reported their residential addresses at enrollment and provided 1-6 semen samples and a blood sample during follow-up. We estimated the Euclidean distance to major roadways (e.g. interstates and highways: limited access highways, multi-lane highways (not limited access), other numbered routes, and major roads) using information from the Massachusetts Department of Geographic Information Systems. Semen parameters (1238 semen samples), sperm DNA integrity (389 semen samples), chromosomal disomy (101 semen samples), and serum reproductive hormones (405 serum samples) were assessed following standard procedures.

RESULTS

Men in this cohort were primarily Caucasian (86%), not current smokers (92%), with a college or higher education (88%), and had an average age of 36 years and BMI of 27.7 kg/m2. The median (interquartile range) residential distance to a major roadway was 111 (37, 248) meters. Residential proximity to major roadways was not associated with semen parameters, sperm DNA integrity, chromosomal disomy, or serum reproductive hormone concentrations. The adjusted percent change (95% CI) in semen quality parameters associated with a 500 m increase in residential distance to a major roadway was -1.0% (-6.3, 4.5) for semen volume, 4.3% (-5.8, 15.7) for sperm concentration, 3.1% (-7.2, 14.5) for sperm count, 1.1% (-1.2, 3.4) for % total motile sperm, and 0.1% (-0.3, 0.5) for % morphologically normal sperm. Results were consistent when we modeled the semen parameters dichotomized according to WHO 2010 reference values.

CONCLUSION

Residential distance to major roadways, as a proxy for traffic-related air pollution exposure, was not related to sperm characteristics or serum reproductive hormones among men attending a fertility clinic in Massachusetts.

Comparison of Mutagenic Activities of Various Ultra-Fine Particles

Air pollution is increasing, along with consumption of fossil fuels such as coal and diesel gas. Air pollutants are known to be a major cause of respiratory-related illness and death, however, there are few reports on the genotoxic characterization of diverse air pollutants in Korea. In this study, we investigated the mutagenic activity of various particles such as diesel exhaust particles (DEP), combustion of rice straw (RSC), pine stem (PSC), and coal (CC), tunnel dust (TD), and road side dust (RD). Ultra-fine particles (UFPs) were collected by the glass fiber filter pad. Then, we performed a chemical analysis to see each of the component features of each particulate matter. The mutagenicity of various UFPs was determined by the Ames test with four Salmonella typhimurium strains with or without metabolic activation. The optimal concentrations of UFPs were selected based on result of a concentration decision test. Moreover, in order to compare relative mutagenicity among UFPs, we selected and tested DEP as mutation reference. DEP, RSC, and PSC induced concentration-dependent increases in revertant colony numbers with TA98, TA100, and TA1537 strains in the absence and presence of metabolic activation. DEP showed the highest specific activity among the particulate matters. In this study, we conclude that DEP, RSC, PSC, and TD displayed varying degrees of mutagenicity, and these results suggest that the mutagenicity of these air pollutants is associated with the presence of polycyclic aromatic hydrocarbons (PAHs) in these particulate matters.

The reproductive toxicology of male SD rats after PM2.5 exposure mediated by the stimulation of endoplasmic reticulum stress

Evidence has shown that exposure to fine particulate matter (PM) contributed to poor semen quality in males. However, the reproductive toxicity and relevant molecular mechanisms of Particular Matter 2.5 (PM_2.5) from different seasons are not well understood. In the present work, we intend to investigate the toxic effects of PM_2.5 during summer and winter on reproductive cells and tissues and focus on endoplasmic reticulum stress (ERS) to illustrate the possible molecular mechanisms. Sprague Dawley (SD) rats were exposed to PM_2.5 from the summer season (0.2, 0.6, and 1.5 mg/kg b. w.) and winter (0.3, 1.5, and 2.7 mg/kg b. w.) through intratracheal instillation. The exposure was performed once every 3 days and continued for 2 months. Sperm and reproductive organs (testis and epididymis) were collected from the animals to conduct toxicity evaluation and mechanism analysis. The data showed that sperm relative motility rates were remarkably decreased, while sperm malformation rates were significantly increased with exposure to the summer and winter PM_2.5. In particular, the reproductive toxicity of winter PM_2.5 in the highest dose group was significantly greater than that in the other PM_2.5 exposure groups. The pathological results also showed that the rats in the winter PM_2.5 group of 2.7 mg/kg b. w. had severe testicular tissue injury, as determined by haematoxylin and eosin (HE) staining. The apoptotic results obtained by terminal dUTP nick-end labelling (TUNEL) further suggested that summer and winter PM_2.5 exposure promoted the testicular germ cell apoptosis. The reproductive toxicity of winter PM_2.5 in the testis was stronger than that of summer PM_2.5. In addition, the expressions of GRP78 and XBP-1, biomarkers of ERS, was enhanced under the conditions of PM_2.5 exposure, and ERS-mediated apoptosis through the upregulation of CHOP and Caspase-12 in the epididymis and testis was activated. In conclusion, PM_2.5 exposure induced reproductive toxicity in male SD rats by the stimulation of ERS.

Does increased traffic flow around unconventional resource development activities represent the major respiratory hazard to neighboring communities?: knowns and unknowns

PURPOSE OF REVIEW

The objective of this review is to demonstrate that the focus on air emissions causing respiratory effects and associated with gas development may be misplaced by attributing those exposures mainly to well pad activities.

RECENT FINDINGS

The most recent publications on the health effects of hydraulic fracturing operations seem to parallel findings from studies of diesel particulate exposure near roadways and the health effects associated with those exposures. It seems at least possible that some, if not all, of the respiratory effects associated with unconventional resource development may be traffic-related. Road traffic generated by hydraulic fracturing operations is one possible source of environmental impact whose significance has, until now, been largely neglected in the available literature with 4000 to 6000 vehicles visiting the well pad.

SUMMARY

Exposures from well pads diminish rapidly with distances of only a few kilometers but there is evidence showing disease risk multiple kilometers from well pads. This leaves open the possibility that the several thousand vehicle trips per well pad create traffic emissions over wide areas away from the pad. This alternative source of exposure has not previously been well studied but is being more seriously considered.

EPR Technology as Sensitive Method for Oxidative Stress Detection in Primary and Secondary Keratinocytes Induced by Two Selected Nanoparticles

Exogenous factors can cause an imbalance in the redox state of biological systems, promoting the development of oxidative stress, especially reactive oxygen species (ROS). To monitor the intensity of ROS production in secondary keratinocytes (HaCaT) by diesel exhaust particles and thermoresponsive nanogels (tNG), electron paramagnetic resonance (EPR) spectroscopy after 1 and 24 h of incubation, respectively, was applied. Their cytotoxicity was analyzed by a cell viability assay (XTT). For tNG an increase in the cell viability and ROS production of 10% was visible after 24 h, whereas 1 h showed no effect. A ten times lower concentration of diesel exhaust particles exhibited no significant toxic effects on HaCaT cells for both incubation times, thus normal adult human keratinocytes (NHK) were additionally analyzed by XTT and EPR spectroscopy. Here, after 24 h a slight increase of 18% in metabolic activity was observed. However, this effect could not be explained by the ROS formation. A slight increase in the ROS production was only visible after 1 h of incubation time for HaCaT (9%) and NHK (14%).

Developmental Neurotoxicity of Traffic-Related Air Pollution: Focus on Autism

PURPOSE OF REVIEW

Epidemiological and animal studies suggest that air pollution may negatively affect the central nervous system (CNS) and contribute to CNS diseases. Traffic-related air pollution is a major contributor to global air pollution, and diesel exhaust (DE) is its most important component.

RECENT FINDINGS

Several studies suggest that young individuals may be particularly susceptible to air pollution-induced neurotoxicity and that perinatal exposure may cause or contribute to developmental disabilities and behavioral abnormalities. In particular, a number of recent studies have found associations between exposures to traffic-related air pollution and autism spectrum disorders (ASD), which are characterized by impairment in socialization and in communication and by the presence of repetitive and unusual behaviors. The cause(s) of ASD are unknown, and while it may have a hereditary component, environmental factors are increasingly suspected as playing a pivotal role in its etiology, particularly in genetically susceptible individuals. Autistic children present higher levels of neuroinflammation and systemic inflammation, which are also hallmarks of exposure to traffic-related air pollution. Gene-environment interactions may play a relevant role in determining individual susceptibility to air pollution developmental neurotoxicity. Given the worldwide presence of elevated air pollution, studies on its effects and mechanisms on the developing brain, genetic susceptibility, role in neurodevelopmental disorders, and possible therapeutic interventions are certainly warranted.

Ecotoxicity assessment of particulate matter emitted from heavy-duty diesel-powered vehicles: influence of leaching conditions

Concerns regarding the environmental impact of diesel exhaust particulate matter (DPM) have increased in recent years. Following emission to the atmosphere, these fine materials can sorb many contaminants at their surface, which can subsequently be released, for instance, due to physicochemical environmental changes. The desorption of contaminants from particulate matter will increase the environmental pollution and can promote ecotoxicological effects. In this context, the objective of this study was to assess the aquatic ecotoxicity profile of extracts of DPM obtained at two different pH values. Thus, after collecting particulate matter from the diesel exhaust of heavy engines, extracts were obtained with pure water (at pH 2.00 and 5.00) and with a mixture of three organic solvents (dichloromethane, n-hexane, and acetone). To assess the environmental impact of DPM, the exhaust extracts were used in a battery of aquatic bioassays including key organisms of the food chain: bacteria (Aliivibrio fischeri), algae (Scenedesmus subspicatus), daphnids (Daphnia magna), and fishes (Danio rerio). The aqueous leachate at natural pH (2.0) and solvent extracts were extremely ecotoxic, while the aqueous leachate at pH = 5.0 showed the lowest ecotoxicity. The global ranking of sensitivity for the biotests tested was daphnids > algae > bacteria > fishes. Thus, the use of this bioassay battery could improve our understanding of the impact of DPM on aquatic environments, which is dependent on the pH of the leaching process.

Neurotoxicity of traffic-related air pollution

The central nervous system is emerging as an important target for adverse health effects of air pollution, where it may contribute to neurodevelopmental and neurodegenerative disorders. Air pollution comprises several components, including particulate matter (PM) and ultrafine particulate matter (UFPM), gases, organic compounds, and metals. An important source of ambient PM and UFPM is represented by traffic-related air pollution, primarily diesel exhaust (DE). Human epidemiological studies and controlled animal studies have shown that exposure to air pollution, and to traffic-related air pollution or DE in particular, may lead to neurotoxicity. In particular, air pollution is emerging as a possible etiological factor in neurodevelopmental (e.g. autism spectrum disorders) and neurodegenerative (e.g. Alzheimer's disease) disorders. The most prominent effects caused by air pollution in both humans and animals are oxidative stress and neuro-inflammation. Studies in mice acutely exposed to DE (250-300μg/m3 for 6h) have shown microglia activation, increased lipid peroxidation, and neuro-inflammation in various brain regions, particularly the hippocampus and the olfactory bulb. An impairment of adult neurogenesis was also found. In most cases, the effects of DE were more pronounced in male mice, possibly because of lower antioxidant abilities due to lower expression of paraoxonase 2.

Outdoor air pollution and sperm quality

Exposure to air pollution has been clearly associated with a range of adverse health effects, including reproductive toxicity, but its effects on male semen quality are still unclear. We performed a systematic review (up to June 2016) to assess the impact of air pollutants on sperm quality. We included 17 semi-ecological, panel, and cohort studies, assessing outdoor air pollutants, such as PM2.5, PM10, NOx, SO2, and O3, and their effects on DNA fragmentation, sperm count, sperm motility, and sperm morphology. Thirteen studies assessed air pollution exposure measured environmentally, and six used biomarkers of air pollution exposure (two did both). We rated the studies using the Newcastle-Ottawa Scale and assessed with the exposure method. Taking into account these factors and the number of studies finding significant results (positive or negative), the evidence supporting an effect of air pollution on DNA fragmentation is weak but suggestive, on sperm motility is limited and probably inexistent, on lower sperm count is inconclusive, and on sperm morphology is very suggestive. Because of the diversity of air pollutants and sperm parameters, and the studies' designs, we were unable to perform a meta-analysis. In summary, most studies concluded that outdoor air pollution affects at least one of the four semen quality parameters included in the review. However, results lack consistency, and furthermore, studies were not comparable. Studies using standardized air pollution and semen measures are required to obtain more reliable conclusions.

PROSPERO REGISTRATION NUMBER

CRD42015007175.

Maternal exposure to diluted diesel engine exhaust alters placental function and induces intergenerational effects in rabbits

BACKGROUND

Airborne pollution is a rising concern in urban areas. Epidemiological studies in humans and animal experiments using rodent models indicate that gestational exposure to airborne pollution, in particular diesel engine exhaust (DE), reduces birth weight, but effects depend on exposure duration, gestational window and nanoparticle (NP) concentration. Our aim was to evaluate the effects of gestational exposure to diluted DE on feto-placental development in a rabbit model. Pregnant females were exposed to diluted (1 mg/m(3)), filtered DE (NP diameter ≈ 69 nm) or clean air (controls) for 2 h/day, 5 days/week by nose-only exposure (total exposure: 20 days in a 31-day gestation).

RESULTS

DE exposure induced early signs of growth retardation at mid gestation with decreased head length (p = 0.04) and umbilical pulse (p = 0.018). Near term, fetal head length (p = 0.029) and plasma insulin and IGF1 concentrations (p = 0.05 and p = 0.019) were reduced. Placental function was also affected, with reduced placental efficiency (fetal/placental weight) (p = 0.049), decreased placental blood flow (p = 0.009) and fetal vessel volume (p = 0.002). Non-aggregated and "fingerprint" NP were observed at various locations, in maternal blood space, in trophoblastic cells and in the fetal blood, demonstrating transplacental transfer. Adult female offspring were bred with control males. Although fetoplacental biometry was not affected near term, second generation fetal metabolism was modified by grand-dam exposure with decreased plasma cholesterol (p = 0.008) and increased triglyceride concentrations (p = 0.015).

CONCLUSIONS

Repeated daily gestational exposure to DE at levels close to urban pollution can affect feto-placental development in the first and second generation.

Environmental factors, epigenetics, and developmental origin of reproductive disorders

Sex-specific differentiation, development, and function of the reproductive system are largely dependent on steroid hormones. For this reason, developmental exposure to estrogenic and anti-androgenic endocrine disrupting chemicals (EDCs) is associated with reproductive dysfunction in adulthood. Human data in support of "Developmental Origins of Health and Disease" (DOHaD) comes from multigenerational studies on offspring of diethylstilbestrol-exposed mothers/grandmothers. Animal data indicate that ovarian reserve, female cycling, adult uterine abnormalities, sperm quality, prostate disease, and mating behavior are susceptible to DOHaD effects induced by EDCs such as bisphenol A, genistein, diethylstilbestrol, p,p'-dichlorodiphenyl-dichloroethylene, phthalates, and polyaromatic hydrocarbons. Mechanisms underlying these EDC effects include direct mimicry of sex steroids or morphogens and interference with epigenomic sculpting during cell and tissue differentiation. Exposure to EDCs is associated with abnormal DNA methylation and other epigenetic modifications, as well as altered expression of genes important for development and function of reproductive tissues. Here we review the literature exploring the connections between developmental exposure to EDCs and adult reproductive dysfunction, and the mechanisms underlying these effects.

Association between prenatal exposure to ambient diesel particulate matter and perchloroethylene with children's 3rd grade standardized test scores

The objective of this research was to determine if prenatal exposure to two common urban air pollutants, diesel and perchloroethylene, affects children's 3rd grade standardized test scores in mathematics and English language arts (ELA). Exposure estimates consisted of annual average ambient concentrations of diesel particulate matter and perchloroethylene obtained from the Environmental Protection Agency's 1996 National Air Toxics Assessment for the residential census tract at birth. Outcome data consisted of linked birth and educational records for 201,559 singleton, non-anomalous children born between 1994 and 1998 who attended New York City public schools. Quantile regression models were used to estimate the effects of these exposures on multiple points within the continuous distribution of standardized test scores. Modified Poisson regression models were used to calculate risk ratios (RR) and 95% confidence intervals (CI) of failing to meet curricula standards, an indicator derived from test scores. Models were adjusted for a number of maternal, neighborhood and childhood factors. Results showed that math scores were approximately 6% of a standard deviation lower for children exposed to the highest levels of both pollutants as compared to children with low levels of both pollutants. Children exposed to high levels of both pollutants also had the largest risk of failing to meet math test standards when compared to children with low levels of exposure to the pollutants (RR 1.10 95%CI 1.07,1.12 RR high perchloroethylene only 1.03 95%CI 1.00,1.06; RR high diesel PM only 1.02 95%CI 0.99,1.06). There was no association observed between exposure to the pollutants and failing to meet ELA standards. This study provides preliminary evidence of associations between prenatal exposure to urban air pollutants and lower academic outcomes. Additionally, these findings suggest that individual pollutants may additively impact health and point to the need to study the collective effects of air pollutant mixtures.

KEY WORDS

air toxics, academic outcomes, urban health, tetrachloroethylene, air pollutant mixtures.

Genotoxicity assessment of particulate matter emitted from heavy-duty diesel-powered vehicles using the in vivo Vicia faba L. micronucleus test

Diesel exhaust particulate matter (PM) can have an impact on the environment due to its chemical constitution. A large number of substances such as organic compounds, sulfates, nitrogen derivatives and metals are adsorbed to the particles and desorption of these contaminants could promote genotoxic effects. The objective of this study was to assess the in vivo genotoxicity profile of diesel exhaust PM from heavy-duty engines. Extracts were obtained through leaching with pure water and chemical extraction using three organic solvents (dichloromethane, hexane, and acetone). The in vivo Vicia faba micronucleus test (ISO 29200 protocol) was used to assess the environmental impact of the samples collected from diesel exhaust PM. The solid diesel PM (soot) dissolved in water, and the different extracts, showed positive results for micronucleus formation. After the addition of EDTA, the aqueous extracts did not show a genotoxic effect. The absence of metals in the organic solvent extract indicated that organic compounds also had a genotoxic effect, which was not observed for a similar sample cleaned in a C18 column. Thus, considering the ecological importance of higher plants in relation to ecosystems (in contrast to Salmonella spp., which are commonly used in mutagenicity studies), the Vicia micronucleus test was demonstrated to be appropriate for complementing prokaryotic or in vitro tests on diesel exhaust particulate matter included in risk assessments.

Characterization of the chemical composition of PM2.5 emitted from on-road China III and China IV diesel trucks in Beijing, China

The composition of diesel exhaust fine particulate matter (PM2.5) is of growing interest because of its impacts on health and climatic factors and its application in source apportionment and aerosol modeling. We characterized the detailed chemical composition of the PM2.5, including the organic carbon (OC), elemental carbon (EC), water-soluble ions (WSIs), and elemental contents, emitted from China III and China IV diesel trucks (nine each) based on real-world measurements in Beijing using a portable emissions measurement system (PEMS). Carbonaceous compounds were the dominant components (totaling approximately 87%) of the PM2.5, similar to the results (greater than 80% of the PM2.5) of our previous study of on-road China III diesel trucks. In general, the amounts of individual component groups (carbonaceous compounds, WSIs, and elements) and PM2.5 emissions for China IV diesel trucks were lower than those of China III diesel trucks of the same size, except for the WSIs and elements for the light- and medium-duty diesel trucks. The EC/OC mass ratios were strongly dependent on the emission standards, and the ratios of China IV diesel trucks were higher than those of China III diesel trucks of the same size. The chemical species in the PM2.5 were significantly affected by the driving conditions. Overall, the emission factors (EFs) of the PM2.5 and OC under non-highway (NHW) driving conditions were higher than those under highway (HW) driving conditions, and the EC/OC mass ratios presented an increasing trend, with decreasing OC/PM2.5 and increasing EC/PM2.5 from NHW to HW driving conditions; similar trends were reported in our previous study. In addition, Pearson's correlation coefficients among the PM2.5 species were analyzed to determine the relationships among the various chemical components.

Associations between Prenatal Exposure to Black Carbon and Memory Domains in Urban Children: Modification by Sex and Prenatal Stress

Background

Whether fetal neurodevelopment is disrupted by traffic-related air pollution is uncertain. Animal studies suggest that chemical and non-chemical stressors interact to impact neurodevelopment, and that this association is further modified by sex.

Objectives

To examine associations between prenatal traffic-related black carbon exposure, prenatal stress, and sex with children’s memory and learning.

Methods

Analyses included N = 258 mother-child dyads enrolled in a Boston, Massachusetts pregnancy cohort. Black carbon exposure was estimated using a validated spatiotemporal land-use regression model. Prenatal stress was measured using the Crisis in Family Systems-Revised survey of negative life events. The Wide Range Assessment of Memory and Learning (WRAML2) was administered at age 6 years; outcomes included the General Memory Index and its component indices [Verbal, Visual, and Attention Concentration]. Relationships between black carbon and WRAML2 index scores were examined using multivariable-adjusted linear regression including effect modification by stress and sex.

Results

Mothers were primarily minorities (60% Hispanic, 26% Black); 67% had ≤12 years of education. The main effect for black carbon was not significant for any WRAML2 index; however, in stratified analyses, among boys with high exposure to prenatal stress, Attention Concentration Index scores were on average 9.5 points lower for those with high compared to low prenatal black carbon exposure (P_{3-way interaction} = 0.04).

Conclusion

The associations between prenatal exposure to black carbon and stress with children’s memory scores were stronger in boys than in girls. Studies assessing complex interactions may more fully characterize health risks and, in particular, identify vulnerable subgroups.

A perspective on the developmental toxicity of inhaled nanoparticles

This paper aimed to clarify whether maternal inhalation of engineered nanoparticles (NP) may constitute a hazard to pregnancy and fetal development, primarily based on experimental animal studies of NP and air pollution particles. Overall, it is plausible that NP may translocate from the respiratory tract to the placenta and fetus, but also that adverse effects may occur secondarily to maternal inflammatory responses. The limited database describes several organ systems in the offspring to be potentially sensitive to maternal inhalation of particles, but large uncertainties exist about the implications for embryo-fetal development and health later in life. Clearly, the potential for hazard remains to be characterized. Considering the increased production and application of nanomaterials and related consumer products a testing strategy for NP should be established. Due to large gaps in data, significant amounts of groundwork are warranted for a testing strategy to be established on a sound scientific basis.

Effect of carbon black nanomaterial on biological membranes revealed by shape of human erythrocytes, platelets and phospholipid vesicles

BACKGROUND

We studied the effect of carbon black (CB) agglomerated nanomaterial on biological membranes as revealed by shapes of human erythrocytes, platelets and giant phospholipid vesicles. Diluted human blood was incubated with CB nanomaterial and observed by different microscopic techniques. Giant unilamellar phospholipid vesicles (GUVs) created by electroformation were incubated with CB nanomaterial and observed by optical microscopy. Populations of erythrocytes and GUVs were analyzed: the effect of CB nanomaterial was assessed by the average number and distribution of erythrocyte shape types (discocytes, echinocytes, stomatocytes) and of vesicles in test suspensions, with respect to control suspensions. Ensembles of representative images were created and analyzed using computer aided image processing and statistical methods. In a population study, blood of 14 healthy human donors was incubated with CB nanomaterial. Blood cell parameters (concentration of different cell types, their volumes and distributions) were assessed.

RESULTS

We found that CB nanomaterial formed micrometer-sized agglomerates in citrated and phosphate buffered saline, in diluted blood and in blood plasma. These agglomerates interacted with erythrocyte membranes but did not affect erythrocyte shape locally or globally. CB nanomaterial agglomerates were found to mediate attractive interaction between blood cells and to present seeds for formation of agglomerate - blood cells complexes. Distortion of disc shape of resting platelets due to incubation with CB nanomaterial was not observed. CB nanomaterial induced bursting of GUVs while the shape of the remaining vesicles was on the average more elongated than in control suspension, indicating indirect osmotic effects of CB nanomaterial.

CONCLUSIONS

CB nanomaterial interacts with membranes of blood cells but does not have a direct effect on local or global membrane shape in physiological in vitro conditions. Blood cells and GUVs are convenient and ethically acceptable methods for the study of effects of various substances on biological membranes and therefrom derived effects on organisms.

Diesel exhaust particle exposure in vitro impacts T lymphocyte phenotype and function

Background

Diesel exhaust particles (DEP) are major constituents of ambient air pollution and their adverse health effect is an area of intensive investigations. With respect to the immune system, DEP have attracted significant research attention as a factor that could influence allergic diseases interfering with cytokine production and chemokine expression. With this exception, scant data are available on the impact of DEP on lymphocyte homeostasis. Here, the effects of nanoparticles from Euro 4 (E4) and Euro 5 (E5) light duty diesel engines on the phenotype and function of T lymphocytes from healthy donors were evaluated.

Methods

T lymphocytes were isolated from peripheral blood obtained from healthy volunteers and subsequently stimulated with different concentration (from 0.15 to 60 μg/ml) and at different time points (from 24 h to 9 days) of either E4 or E5 particles. Immunological parameters, including apoptosis, autophagy, proliferation levels, mitochondrial function, expression of activation markers and cytokine production were evaluated by cellular and molecular analyses.

Results

DEP exposure caused a pronounced autophagic-lysosomal blockade, thus interfering with a key mechanism involved in the maintaining of T cell homeostasis. Moreover, DEP decreased mitochondrial membrane potential but, unexpectedly, this effect did not result in changes of the apoptosis and/or necrosis levels, as well as of intracellular content of adenosine triphosphate (ATP). Finally, a down-regulation of the expression of the alpha chain of the interleukin (IL)-2 receptor (i.e., the CD25 molecule) as well as an abnormal Th1 cytokine expression profile (i.e., a decrease of IL-2 and interferon (IFN)-γ production) were observed after DEP exposure. No differences between the two compounds were detected in all studied parameters.

Conclusions

Overall, our data identify functional and phenotypic T lymphocyte parameters as relevant targets for DEP cytotoxicity, whose impairment could be detrimental, at least in the long run, for human health, favouring the development or the progression of diseases such as autoimmunity and cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-014-0074-0) contains supplementary material, which is available to authorized users.