Biological effects and dose-response assessment of diesel exhaust particles on in vitro early embryo development in mice

Exposure to mixtures of PM2.5 components and term premature rupture of membranes: a case-crossover study in Shijiazhuang, China

This study aims to explore the acute effects of short-term exposure to PM2.5 components and their mixture on PROM. Counts of hospital admissions due to PROM were collected at the Fourth Hospital of Shijiazhuang. The associations between the PROM and PM2.5 components was examined using a time-stratified case-crossover approach. The overall effects of components on TPROM were examined using the BKMR. During the study period 30,709 cases of PROMwere identified. The relative risks and the 95% CI of TPROM were 1.013 (1.002, 1.028) and 1.015 (1.003, 1.028) associated with per interquartile range increase in nitrate and ammonium ion on the current day and they were 1.007 (1.001, 1.013) and 1.003 (1.000, 1.005) on the previous day. The results from the BKMR models showed a higher risk of TPROM was associated with exposure to mixtures, in which, nitrate and organic matter were the main contributors to the overall effect.

Impact of Climate Change on Reproductive Health and Pregnancy Outcomes: A Systematic Review

Climate change has emerged as a significant global health challenge, with growing evidence linking environmental factors to adverse reproductive health outcomes. The primary objective of this review is to assess the effects of climate change-driven environmental factors, such as air pollution and temperature extremes, on reproductive health outcomes, including fertility rates, miscarriage, preterm birth, and congenital anomalies. A comprehensive search of PubMed, Google Scholar, and Web of Science was conducted until July 2024. Studies included in the review were observational, experimental, and randomized controlled trials that reported quantitative data on reproductive outcomes in relation to climate-related environmental exposures. A total of 49 studies were selected for qualitative synthesis. The review found that increased exposure to particulate matter (PM2.5), extreme temperatures, and proximity to traffic were consistently associated with reduced fertility, increased risks of miscarriage, preterm birth, and low birth weight. Adverse effects were particularly pronounced among vulnerable populations, such as pregnant women of lower socioeconomic status and those living in disaster-prone areas. The studies also highlighted potential transgenerational effects, with prenatal exposure to environmental stressors influencing the long-term health of offspring. The findings underscore the urgent need for public health interventions and policies to mitigate environmental exposures that negatively impact reproductive health. Future research should focus on longitudinal and interventional studies to establish causal relationships and inform effective public health strategies.

Exposure to urban ambient particles (PM2.5) before pregnancy affects the expression of endometrial receptive markers to embryo implantation in mice: Preliminary results

Air pollution (AP) is one of the main recent concerns in reproductive healthy due to its potential to promote negative outcomes during pregnancy and male and female fertility. Several studies have demonstrated that AP exposure has been linked to increased embryonic implantation failures, alterations in embryonic, fetal and placental development. For a well-succeeded implantation, both competent blastocyst and receptive endometrium are required. Based on the lack of data about the effect of AP in endometrial receptivity, this study aimed to evaluate he particulate matter (PM) exposure impact on uterine receptive markers in mice and associate the alterations to increased implantation failures due to AP. For this study, ten dams per group were exposed for 39 days to either filter (F) or polluted air (CAP). At fourth gestational day (GD4), females were euthanized. Morphological, ultrastructural, immunohistochemical and molecular analysis of uterine and ovarian samples were performed. CAP-exposed females presented a reduced number of corpus luteum; glands and epithelial cells were increased with pinopodes formation impairment. Immunohistochemistry analysis revealed decreased LIF protein levels. These preliminary data suggests that PM exposure may exert negative effects on endometrial receptivity by affecting crucial parameters to embryonic implantation as uterine morphological differentiation, corpus luteum quantity and LIF expression during implantation window.

The relationship between maternal exposure to ambient air pollutants and premature rupture of membranes: A systematic review and meta-analysis

Air pollution is an environmental stimulus that may predispose pregnant women to preterm rapture of membrane (PROM). However, the relationship of maternal exposure to air pollutants and PROM is still unclear. To investigate the relationship between the long-term and short-term maternal exposure to air pollution and PROM. We searched all studies published in PubMed, Embase and Web of Science up to February 2024. The studies provided quantitative effect estimates with 95% confidence intervals, for the impact of short-term (<30 days) or long-term (≥30 days) maternal exposure to air pollutants on PROM, preterm PROM (PPROM) or term PROM (TPROM). The odds ratio (OR), risk ratio (RR), or hazard ratio (HR), with 95% confidence intervals was extracted, and RR or HR were deemed as OR because of the low prevalence of PROM. Fixed- or random-effects meta-analyses performed. In total, 17 relevant studies were included. Maternal exposure to PM2.5 in the second trimester increases the risk of PROM (pooled OR = 1.15, 95%CI: 1.05-1.26). Maternal exposure to PM10, NO2, NO, CO and SO2 during pregnancy and short-term maternal exposure to PM2.5, NO2, SO2 and O3 also associate with PROM occurrence. The results of the study show that both long-term maternal exposure in the second or third trimester and short-term maternal exposure to ambient air pollution can increase the risk of PROM.

Epithelial MAPK signaling directs endothelial NRF2 signaling and IL-8 secretion in a tri-culture model of the alveolar-microvascular interface following diesel exhaust particulate (DEP) exposure

BACKGROUND

Particulate matter 2.5 (PM2.5) deposition in the lung's alveolar capillary region (ACR) is significantly associated with respiratory disease development, yet the molecular mechanisms are not completely understood. Adverse responses that promote respiratory disease development involve orchestrated, intercellular signaling between multiple cell types within the ACR. We investigated the molecular mechanisms elicited in response to PM2.5 deposition in the ACR, in an in vitro model that enables intercellular communication between multiple resident cell types of the ACR.

METHODS

An in vitro, tri-culture model of the ACR, incorporating alveolar-like epithelial cells (NCI-H441), pulmonary fibroblasts (IMR90), and pulmonary microvascular endothelial cells (HULEC) was developed to investigate cell type-specific molecular responses to a PM2.5 exposure in an in-vivo-like model. This tri-culture in vitro model was termed the alveolar capillary region exposure (ACRE) model. Alveolar epithelial cells in the ACRE model were exposed to a suspension of diesel exhaust particulates (DEP) (20 µg/cm2) with an average diameter of 2.5 µm. Alveolar epithelial barrier formation, and transcriptional and protein expression alterations in the directly exposed alveolar epithelial and the underlying endothelial cells were investigated over a 24 h DEP exposure.

RESULTS

Alveolar epithelial barrier formation was not perturbed by the 24 h DEP exposure. Despite no alteration in barrier formation, we demonstrate that alveolar epithelial DEP exposure induces transcriptional and protein changes in both the alveolar epithelial cells and the underlying microvascular endothelial cells. Specifically, we show that the underlying microvascular endothelial cells develop redox dysfunction and increase proinflammatory cytokine secretion. Furthermore, we demonstrate that alveolar epithelial MAPK signaling modulates the activation of NRF2 and IL-8 secretion in the underlying microvascular endothelial cells.

CONCLUSIONS

Endothelial redox dysfunction and increased proinflammatory cytokine secretion are two common events in respiratory disease development. These findings highlight new, cell-type specific roles of the alveolar epithelium and microvascular endothelium in the ACR in respiratory disease development following PM2.5 exposure. Ultimately, these data expand our current understanding of respiratory disease development following particle exposures and illustrate the utility of multicellular in vitro systems for investigating respiratory tract health.

PFOS and F-53B disrupted inner cell mass development in mouse preimplantation embryo

Perfluorooctane sulfonic acid (PFOS) is a perfluoroalkyl and polyfluoroalkyl substance (PFAS) widely used in daily life. As its toxicity was confirmed, it has been gradually substituted by F-53B (chlorinated polyfluoroalkyl sulfonates, Cl-PFESAs) in China. PFOS exposure during prenatal development may hinder the development of preimplantation embryos, as indicated by recent epidemiological research and in vivo assays. However, the embryotoxicity data for F-53B are scarce. Furthermore, knowledge about the toxicity of F-53B and PFOS exposure to internal follicular fluid concentrations on early preimplantation embryo development remains limited. In this study, internal exposure concentrations of PFOS (10 nM) and F-53B (2 nM) in human follicular fluid were chosen to study the effects of PFAS on early mouse preimplantation embryo development. We found that both PFOS and F-53B treated zygotes exhibited higher ROS activity in 8-cell embryos but not in 2-cell stage embryos. PFOS and F-53B significantly affected the proportion and aggregation of the inner cell mass (ICM) in the blastocyst, but not the total cell number. Mouse embryonic stem cells (mESCs, isolated from the ICM) and embryoid body (EB) assays were employed to assess the toxicity of PFOS and F-53B on the development and differentiation of embryonic pluripotent cells. These results suggested that mESCs exhibited more DNA damage and abnormal germ layer differentiation after brief exposure to PFOS or F-53B. Finally, RNA-sequencing revealed that PFOS and F-53B exposure affected mESCs biosynthetic processes and chromatin-nucleosome assembly. Our results indicate that F-53B has potential risks as an alternative to PFOS, which disrupts ICM development and differentiation.

A systematic review of evidence for maternal preconception exposure to outdoor air pollution on Children's health

The preconception period is a critical window for gametogenesis, therefore preconception exposure to air pollutants may have long-term effects on children. We systematically reviewed epidemiological evidence concerning the effects of preconception ambient air pollution exposure on children's health outcomes and identified research gaps for future investigations. We searched PubMed and Web of Science from journal inception up to October 2022 based on an established protocol (PROSPERO: CRD42022277608). We then identified 162 articles based on searching strategy, 22 of which met the inclusion criteria. Studies covered a wide range of health outcomes including birth defects, preterm birth, birthweight, respiratory outcomes, and developmental outcomes. Findings suggested that exposure to outdoor air pollutants during maternal preconception period were associated with various health outcomes, of which birth defects has the most consistent findings. A meta-analysis revealed that during 3-month preconception period, a 10 μg/m3 increase in PM10 and PM2.5 was associated with relative risk (RR) of birth defects of 1.06 (95% confidence interval (CI): 1.00, 1.02) and 1.14 (95% CI: 0.82, 1.59), respectively. Preterm birth, low birthweight, and autism have also been associated with maternal preconception exposure to PM2.5, PM10, O3 and SO2. However, the significance of associations and effect sizes varied substantially across studies, partly due to the heterogeneity in exposure and outcome assessments. Future studies should use more accurate exposure assessment methods to obtain individual-level exposures with high temporal resolution. This will allow the exploration of which specific time window (weeks or months) during the preconception period has the strongest effect. In future epidemiologic studies, integrating pathophysiologic biomarkers relevant to clinical outcomes may help improve the causal inference of associations between preconception exposure and health outcomes suggested by the current limited literature. Additionally, potential effects of paternal preconception exposure need to be studied.

Systematic review of climate change effects on reproductive health

Climate change is a major risk factor for overall health, including reproductive health, and well-being. Increasing temperatures, due mostly to increased greenhouse gases trapping excess heat in the atmosphere, result in erratic weather patterns, wildfires, displacement of large communities, and stagnant water resulting in vector-borne diseases that, together, have set the stage for new and devastating health threats across the globe. These conditions disproportionately affect disadvantaged and vulnerable populations, including women, pregnant persons, young children, the elderly, and the disabled. This review reports on the evidence for the adverse impacts of air pollution, wildfires, heat stress, floods, toxic chemicals, and vector-borne diseases on male and female fertility, the developing fetus, and obstetric outcomes. Reproductive health care providers are uniquely positioned and have an unprecedented opportunity to educate patients and policy makers about mitigating the impact of climate change to assure reproductive health in this and future generations.

Associations between ambient air pollution and IVF outcomes in a heavily polluted city in China

RESEARCH QUESTION

Is air pollution related to IVF outcomes in a heavily polluted city in China?

DESIGN

A retrospective cohort study of 8628 fresh, autologous IVF cycles was conducted for the first time at the Reproductive Medicine Center of The Third Affiliated Hospital of Zhengzhou University between May 2014 and December 2018 (oocyte retrieval date). The exposure was divided into four periods (gonadotrophin injection to oocyte retrieval [P1], oocyte retrieval to embryo transfer [P2], 1 day after embryo transfer to embryo transfer +14 days [P3] and gonadotrophin injection to embryo transfer +14 days [P4]) and four levels (Q1-Q4 according to their 25th, 50th and 75th percentiles).

RESULTS

An interquartile range increase (Q2 versus Q1) in particulate matter ≤10 µm (PM10) during P3 and P4 and sulphur dioxide (SO₂) during P3 significantly decreased the clinical pregnancy rate (adjusted odds ratio [aOR] 0.81, 95% confidence interval [CI] 0.71-0.92 for PM10 of P3; aOR 0.87, 95% CI 0.76-1.00 for PM10 of P4; aOR 0.82, 95% CI 0.73-0.93 for SO₂ of P3). In addition, PM10 was associated with an increased biochemical pregnancy rate (Q3 versus Q1: aOR 1.55, 95% CI 1.09-2.19 for PM10 of P1) and decreased live birth rate (Q2 versus Q1: aOR 0.88, 95% CI 0.77-0.99 for PM10 of P3). The multivariate regression results were consistent with that of multiple treatments propensity score method (PSM) for SO₂ pollutants in P3 and PM10 pollutants in P4.

CONCLUSION

From the early follicular stage to the pregnancy test period, high concentrations of PM10 and SO₂ may have a negative impact on IVF treatment outcomes in the study area.

Maternal proximity to Central Appalachia surface mining and birth outcomes

Supplemental Digital Content is available in the text.

Maternal residency in Central Appalachia counties with coal production has been previously associated with increased rates of low birth weight (LBW). To refine the relationship between surface mining and birth outcomes, this study employs finer spatiotemporal estimates of exposure.

Prenatal exposure to fine particles, premature rupture of membranes and gestational age: A prospective cohort study

BACKGROUND

The associations between maternal exposure to fine particles with aerodynamic diameter ≤ 2.5 μm (PM_2.5) and gestational age as well as premature rupture of membranes (PROM) remain unclear. Few studies have focused on preconception exposure and components of fine particles in China.

METHODS

A total of 1715 pregnant women were enrolled at hospitals affiliated with Nanjing Medical University from 2014 to 2015. Personal exposure to PM_2.5 was estimated from preconception to the first trimester. Gestational age and PROM were investigated to explore their associations with PM_2.5 and its components.

RESULTS

From 12 weeks before conception to the end of the first trimester, the gestational age was reduced by 0.89 days (95% CI: -1.37, -0.40) per 10 μg/m³ increment in PM_2.5 exposure. After the exposure period was separated into two groups, PM_2.5 exposure reduced the gestational age by 0.35 days (95% CI: -0.59, -0.11) in the 12 weeks before pregnancy. With maternal exposure to PM_2.5 early in the first trimester, gestational age was reduced by 0.62 days (95% CI: -1.09, -0.14). After mediation analysis, we found that PROM mediated the association between PM_2.5 and gestational age from preconception to the first trimester. Components analysis indicated that exposure to black carbon, organic matter, and nitrate increased the risk of PROM and decreased gestational age.

CONCLUSION

Exposure to PM_2.5 as well as some components of PM_2.5 before and during early pregnancy was associated with PROM and gestational age. PROM might be a potential mediator in associations between PM_2.5 as well as various components and gestational age.

Effects of fine particulate matter (PM2.5) on ovarian function and embryo quality in mice

Fine particulate matter (PM_2.5) has an adverse effect on reproductive function, in particular causing reduced male reproductive function, but relatively few studies have directly targeted its effects on female reproduction. To investigate the effects of PM_2.5 exposure on female reproduction, we exposed female mice to PM_2.5 by intratracheal instillation for 28 days, and evaluated apoptosis of ovarian granulosa cells and oocytes and the quality embryos after insemination. Our results showed increased numbers of apoptotic granulosa cells and oocytes after exposure to elevated concentrations of PM_2.5, which had adverse effects on female fertility via compromising embryo development and quality. We conclude that PM_2.5 induced apoptosis of ovarian granulosa cells and oocytes leading to disrupted embryo development and female fertility in mice.

Time-Varying Exposure to Air Pollution and Outcomes of in Vitro Fertilization among Couples from a Fertility Clinic

BACKGROUND

A few studies suggest that air pollution may decrease fertility, but prospective studies and examinations of windows of susceptibility remain unclear.

OBJECTIVE

We aimed to examine the association between time-varying exposure to nitrogen dioxide ([Formula: see text]), ozone ([Formula: see text]), fine particulate matter [Formula: see text] ([Formula: see text]), and black carbon (BC) on in vitro fertilization (IVF) outcomes.

METHODS

We included 345 women (522 IVF cycles) for the [Formula: see text], [Formula: see text], and [Formula: see text] analyses and 339 women (512 IVF cycles) for the BC analysis enrolled in a prospective cohort at a Boston fertility center (2004–2015). We used validated spatiotemporal models to estimate daily residential exposure to [Formula: see text], [Formula: see text], [Formula: see text], and BC. Multivariable discrete time Cox proportional hazards models with four periods [ovarian stimulation (OS), oocyte retrieval to embryo transfer (ET), ET to implantation, implantation to live birth] estimated odds ratios (OR) and 95% confidence intervals (CI) of failing at IVF. Time-dependent interactions were used to identify vulnerable periods.

RESULTS

An interquartile range (IQR) increase in [Formula: see text], [Formula: see text], and BC throughout the IVF cycle was associated with an elevated odds of failing at IVF prior to live birth ([Formula: see text], 95% CI: 0.95, 1.23 for [Formula: see text]; [Formula: see text], 95% CI: 0.88, 1.28 for [Formula: see text]; and [Formula: see text], 95% CI: 0.96, 1.41 for BC). This relationship significantly varied across the IVF cycle such that the association with higher exposure to air pollution during OS was strongest for early IVF failures. An IQR increase in [Formula: see text], [Formula: see text], and BC exposure during OS was associated with 1.42 (95% CI: 1.20, 1.69), 1.26 (95% CI: 0.96, 1.67), and 1.23 (95% CI: 0.96, 1.59) times the odds of failing prior to oocyte retrieval, and 1.32 (95% CI: 1.13, 1.54), 1.27 (95% CI: 0.98, 1.65), and 1.32 (95% CI: 1.10, 1.59) times the odds of failing prior to ET.

CONCLUSION

Increased exposure to traffic-related pollutants was associated with higher odds of early IVF failure. https://doi.org/10.1289/EHP4601.

Impact of ambient PM2.5 on adverse birth outcome and potential molecular mechanism

PM_2.5 (particulate matter ≤2.5 µm in aerodynamic diameter) refers to atmospheric particulate matter (PM) with an aerodynamic diameter of equal and less than 2.5 µm that tends to be suspended for long periods of time and travel over long distances in both outdoor and indoor atmospheres. PM_2.5, along with the toxic compounds attached on it, may cause a wide range of disorders. The fetus is considered to be highly susceptible to a variety of toxicants including atmospheric pollutants such as PM_2.5 through prenatal exposure. To better understand the relationship between maternal exposure to PM_2.5 and adverse birth outcomes for reproduction and fetus development, we studied the published data on this issue including case-control studies, cohort studies and meta-analyses studies, and summarized the basic impact of ambient particulate matter on adverse birth outcomes. Research evidence indicates that PM_2.5 has a potential to induce low birth weight (LBW), preterm birth (PTB), and stillbirth. A further in-depth analysis shows that oxidative stress, DNA methylation, mitochondrial DNA (mtDNA) content alteration, and endocrine disruptions may all play an important role in PM_2.5 induced adverse effects to pregnant women and fetuses. In addition, PM_2.5 exposure can cause male reproductive toxicity, leading to associated adverse pregnancy outcomes.

Live-Birth Bias and Observed Associations Between Air Pollution and Autism

A recent analysis found that exposure to air pollution during specific weeks of pregnancy was negatively associated with risk of autism spectrum disorder (ASD) when mutually adjusted for postnatal air-pollution exposure. In this commentary, we describe 2 possible selection-bias processes that might lead to such results, both related to live-birth bias (i.e., the inevitable restriction of the analyzed sample to live births). The first mechanism is described using a directed acyclic graph and relates to the chance of live birth being a common consequence of both exposure to air pollution and another risk factor of ASD. The second mechanism involves preferential depletion of fetuses susceptible to ASD in the higher air-pollution exposure group. We further discuss the assumptions underlying these processes and their causal structures, their plausibility, and other studies where similar phenomena might have occurred.

Residential proximity to major roadways and traffic in relation to outcomes of in vitro fertilization

BACKGROUND

Emerging data from animal and human studies suggest that traffic-related air pollution adversely affects early pregnancy outcomes; however evidence is limited.

OBJECTIVE

We examined whether residential proximity to major roadways and traffic, as proxies for traffic-related air pollution, are associated with in vitro fertilization (IVF) outcomes.

METHODS

This analysis included 423 women enrolled in the Environment and Reproductive Health (EARTH) Study, a prospective cohort study, who underwent 726 IVF cycles (2004-2017). Using geocoded residential addresses collected at study entry, we calculated the distance to nearest major roadway and the traffic density within a 100 m radius. IVF outcomes were abstracted from electronic medical records. We used multivariable generalized linear mixed models to evaluate the associations between residential proximity to major roadways and traffic density and IVF outcomes adjusting for maternal age, body mass index, race, education level, smoking status, and census tract median income.

RESULTS

Closer residential proximity to major roadways was statistically significantly associated with lower probability of implantation and live birth following IVF. The adjusted percentage of IVF cycles resulting in live birth for women living ≥400 m from a major roadway was 46% (95% CI 36, 56%) compared to 33% (95% CI 26, 40%) for women living <50 m (p-for-comparison, 0.04). Of the intermediate outcomes, there were suggestive associations between living closer to major roadways and slightly higher estradiol trigger concentrations (p-trend = 0.16) and lower endometrial thickness (p-trend = 0.06). Near-residence traffic density was not associated with outcomes of IVF.

CONCLUSION

Closer residential proximity to major roadways was related to reduced likelihood of live birth following IVF.

Effects of diesel exhaust-derived secondary organic aerosol (SOA) on oocytes: Potential risks to meiotic maturation

Particulate air pollution (PM 2.5) is a worldwide concern. Growing epidemiological evidence has shown pathophysiological effects of PM 2.5, not only on cardiovascular system but also on reproductive performance. The composition and physicochemical properties of PM 2.5 vary depending on the emission sources, climate conditions, and complex chemical reactions in the air. These factors make it difficult to understand the cause and mechanistic details of the adverse health effects of PM 2.5. Here, we show potential impacts of PM 2.5 on oocyte maturation in mice by utilizing diesel exhaust-derived secondary organic aerosol (SOA), a major component of urban PM 2.5. We found that the SOA destabilized microtubules of mouse oocytes and p-benzoquinone is one of the candidates for the microtubule-destabilizing compounds. We propose that some biologically reactive components of PM 2.5 should be prioritized for the regulation of atmospheric quality.

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.

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.

Maternal exposure to ambient PM2.5 exaggerates fetal cardiovascular maldevelopment induced by homocysteine in rats

Maternal exposure to airborne particulate matter with aerodynamic diameter <2.5 µm (PM_2.5 ) during pregnancy and lactation periods is associated with filial congenital cardiovascular diseases. This study aimed to investigate the toxic effects of maternal exposure to ambient levels of PM_2.5 on filial cardiovascular maldevelopment induced by homocysteine. Using a 2 × 2 factorial design, rats were randomized into four groups and were exposed to ambient PM_2.5 or filtered air (FA) throughout the pregnancy and lactation periods coupled with the administration of either homocysteine (HCY) or normal saline (NS) daily from gestation days 8-10. Morphological changes in the heart, myocardial apoptosis, expressions of cardiac progenitor transcriptional factors, and levels of cytokines were investigated in the offspring. The apoptosis-like changes in the myocardium were seen in the FA plus HCY-treated group and more obviously in the PM_2.5 plus HCY-treated group, which was in accordance with an increased myocardial apoptosis rate in the two groups. PM_2.5 exposure resulted in significantly decreased Nkx2-5 protein level and GATA4 and Nkx2-5 mRNA expressions, and significantly increased TNF-α and IL-1β levels. There were significant interactions between PM_2.5 exposure and HCY-treatment that PM_2.5 exposure reduced Nkx2-5 protein levels and GATA4 and Nkx2-5 mRNA expressions in the HCY-treated groups. These results suggest that maternal exposure to PM_2.5 , even at the ambient levels in urban regions in China, exaggerates filial cardiovascular maldevelopment induced by HCY in a murine model, exacerbating structural abnormalities in the filial cardiac tissue, which is possibly associated with oxidative stress and reduced GATA4 and Nkx2-5 transcription factor expressions. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 877-889, 2017.

The Associations Between Air Pollution and Adverse Pregnancy Outcomes in China

Research on the potential impact of air pollution on the human's health has increased rapidly in recent years. Several studies have suggested that exposure to air pollutants during period of pregnancy which is a crucial time point of mother-fetus development may have long-term and serious impact on adverse pregnancy outcomes. There is lack of review to evaluate the existed epidemiologic evidence on the associations between air pollutants and adverse pregnancy outcomes in China, so we conducted a review to explore the current epidemiological evidence on the effects of air pollutants to pregnancy outcomes and possible mechanisms during the pregnancy process. We used keywords to systematically search all the English and Chinese literatures on studies that were conducted in China. Exposure to air pollutants during pregnancy had shown there were harmful effects for different birth outcomes: preterm birth, low birth weight, stillbirth, birth defects, infertility, and macrosomia fetus. Results on the effects of air pollutants on adverse pregnancy outcomes are small and inconsistent because they vary in their design and methodology. The existed available evidence is compatible with either a small negative effect of air pollutants on pregnancy outcomes or with no effect; therefore, further studies are needed to confirm and quantify the possible associations and potential biologic mechanisms between air pollutants and pregnancy outcomes.

PM2.5 induces embryonic growth retardation: Potential involvement of ROS-MAPKs-apoptosis and G0/G1 arrest pathways

Airborne fine particulate matter (PM_2.5 ) is an "invisible killer" to human health. There is increasing evidence revealing the adverse effects of PM_2.5 on the early embryonic development and pregnancy outcome, but the molecular mechanism underlying PM_2.5 -induced embryotoxicity is largely unknown. Previous studies have documented that exposure to PM triggers ROS generation, leads to subsequent activation of MAPKs signaling, and results in corresponding cell biological changes including enhanced apoptosis and altered cell cycle in the cardiopulmonary system. Here, we investigated whether ROS-MAPKs-apoptosis/cell cycle arrest pathways play an important role in PM_2.5 -induced embryotoxicity using the rat whole embryo culture system. The results showed that PM_2.5 treatment led to embryonic growth retardation at concentrations of 50 μg/ml and above, as evidenced by the reduced yolk sac diameter, crown-rump length, head length and somite number. PM_2.5 -induced embryonic growth retardation was accompanied by cell apoptosis and G0/G1 phase arrest. Furthermore, ROS generation and subsequent activation of JNK and ERK might be involved in PM_2.5 -induced apoptosis and G0/G1 phase arrest by downregulating Bcl-2/Bax protein ratio and upregulating p15^INK4B , p16^INK4A , and p21^WAF1/CIP1 transcription level. In conclusion, our results indicate that ROS-JNK/ERK-apoptosis and G0/G1 arrest pathways are involved in PM_2.5 -induced embryotoxicity, which not only provides insights into the molecular mechanism of PM_2.5 -induced embryotoxicity, but also may help to identify specific interventions to improve adverse pregnancy outcomes of PM_2.5 . © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 2028-2044, 2016.

Outdoor air pollution and human infertility: a systematic review

Air pollution is a current research priority because of its adverse effects on human health, including on fertility. However, the mechanisms through which air pollution impairs fertility remain unclear. In this article, we perform a systematic review to evaluate currently available evidence on the impact of air pollution on fertility in humans. Several studies have assessed the impact of air pollutants on the general population, and have found reduced fertility rates and increased risk of miscarriage. In subfertile patients, women exposed to higher concentrations of air pollutants while undergoing IVF showed lower live birth rates and higher rates of miscarriage. After exposure to similar levels of air pollutants, comparable results have been found regardless of the mode of conception (IVF versus spontaneous conception), suggesting that infertile women are not more susceptible to the effects of pollutants than the general population. In addition, previous studies have not observed impaired embryo quality after exposure to air pollution, although evidence for this question is sparse.

Stress exposure during the preimplantation period affects blastocyst lineages and offspring development

We found retardation of preimplantation embryo growth after exposure to maternal restraint stress during the preimplantation period in our previous study. In the present study, we evaluated the impact of preimplantation maternal restraint stress on the distribution of inner cell mass (ICM) and trophectoderm (TE) cells in mouse blastocysts, and its possible effect on physiological development of offspring. We exposed spontaneously ovulating female mice to restraint stress for 30 min three times a day during the preimplantation period, and this treatment caused a significant increase in blood serum corticosterone concentration. Microscopic evaluation of embryos showed that restraint stress significantly decreased cell counts per blastocyst. Comparing the effect of restraint stress on the two blastocyst cell lineages, we found that the reduction in TE cells was more substantial than the reduction in ICM cells, which resulted in an increased ICM/TE ratio in blastocysts isolated from stressed dams compared with controls. Restraint stress reduced the number of implantation sites in uteri, significantly delayed eye opening in delivered mice, and altered their behavior in terms of two parameters (scratching on the base of an open field test apparatus, time spent in central zone) as well. Moreover, prenatally stressed offspring had significantly lower body weights and in 5-week old females delivered from stressed dams, fat deposits were significantly lower. Our results indicate that exposure to stress during very early pregnancy can have a negative impact on embryonic development with consequences reaching into postnatal life.

Impact of air pollution on fertility: a systematic review

Air pollution has gained considerable interest because of the multiple adverse effects reported on human health, although its impact on fertility remains unclear. A systematic search was performed to evaluate the impact of air pollutants on fertility. Controlled trials and observational studies assessing animal model and epidemiological model were included. Occupational exposure and semen quality studies were not considered. Outcomes of interest included live birth, miscarriage, clinical pregnancy, implantation, and embryo quality. Ten studies were included and divided into two groups: animal studies and human epidemiological studies including the general population as well as women undergoing in vitro fertilization and embryo transfer (IVF/ET). Results from this systematic review suggest a significant impact of air pollution on miscarriage and clinical pregnancy rates in the general population, whereas among subfertile patients certain air pollutants seem to exert a greater impact on fertility outcomes, including miscarriage and live birth rates. Besides, studies in mammals observed a clear detrimental effect on fertility outcomes associated to air pollutants at high concentration. The lack of prospective studies evaluating the effect of air pollution exposure in terms of live birth constitutes an important limitation in this review. Thus, further studies are needed to confirm these findings.

Air pollution and preterm premature rupture of membranes: a spatiotemporal analysis

Preterm premature rupture of membranes (PROM) is the leading identifiable predisposing factor for preterm birth. Although maternal exposure to air pollution can potentially have an impact on preterm PROM, there is no available evidence on such an impact. In this study, based on 5,555 singleton births occurring in Barcelona, Spain (2002-2005), we investigated the associations of maternal exposure to nitrogen dioxide, nitrogen oxides, and particulate matter with aerodynamic diameters of ≤2.5 µm (PM2.5), 2.5 µm-10 µm, and ≤10 µm and PM2.5 light absorption with preterm PROM and gestational age at the rupture of membranes (ROM). We utilized temporally adjusted land-use regression models to predict pollutant levels at each subject's home address during each week of her pregnancy. We conducted matched (according to the length of exposure) case-control analyses to estimate the preterm PROM risk associated with 1 interquartile-range increase in exposure levels during the entire pregnancy and during the last 3 months prior to ROM. We found an increase in preterm PROM risk of up to 50% (95% confidence interval: 4, 116) and a 1.3-day (95% confidence interval: -1.9, -0.6) reduction in gestational age at ROM associated with PM2.5 absorbance, nitrogen dioxide exposure, and nitrogen oxide exposure during the entire pregnancy and the last 3 months prior to ROM.

Intrauterine exposure to diesel exhaust diminishes adult ovarian reserve

OBJECTIVE

To analyze ovarian and uterine morphologic changes resulting from intrauterine and postnatal exposure to diesel exhaust.

DESIGN

Crossover study. Experimental groups: intrauterine and postnatal clean air exposure; intrauterine exposure to diesel only; postnatal exposure to diesel only; and intrauterine and postnatal exposure to diesel.

SETTING

Laboratory of Experimental Air Pollution.

ANIMAL(S)

Swiss mice.

INTERVENTION(S)

Mice exposed to diesel exhaust with doses that correspond to the daily average PM₂.₅ levels (fine particles in the ambient air 2.5 μm or less in size) reported by the World Health Organization.

MAIN OUTCOME MEASURE(S)

Morphometric analyses of the ovaries and uterus were performed to define the relative area occupied by follicles, corpus luteum, and stroma and the proportionate area of glands, epithelial layer, and stroma within the uterine endometrium.

RESULT(S)

A significant reduction in the proportion of primordial follicles was observed in intrauterine-exposed animals, those exposed during the postnatal period, and in animals exposed during both phases. Primary follicle proportion was reduced in animals exposed during pregnancy. No significant changes were detected in uterine morphology.

CONCLUSION(S)

Intrauterine exposure to acceptable levels of diesel exhaust compromises the reproductive potential of female mice, diminishing ovarian reserve when sexual maturity is achieved. This effect could increase the risk of premature menopause. The findings raise concern about current environmental guidelines for diesel exposure, warranting more careful examination of this issue in humans by regulatory authorities.

Toxicological properties of emission particles from heavy duty engines powered by conventional and bio-based diesel fuels and compressed natural gas

Background

One of the major areas for increasing the use of renewable energy is in traffic fuels e.g. bio-based fuels in diesel engines especially in commuter traffic. Exhaust emissions from fossil diesel fuelled engines are known to cause adverse effects on human health, but there is very limited information available on how the new renewable fuels may change the harmfulness of the emissions, especially particles (PM). We evaluated the PM emissions from a heavy-duty EURO IV diesel engine powered by three different fuels; the toxicological properties of the emitted PM were investigated. Conventional diesel fuel (EN590) and two biodiesels were used − rapeseed methyl ester (RME, EN14214) and hydrotreated vegetable oil (HVO) either as such or as 30% blends with EN590. EN590 and 100% HVO were also operated with or without an oxidative catalyst (DOC + POC). A bus powered by compressed natural gas (CNG) was included for comparison with the liquid fuels. However, the results from CNG powered bus cannot be directly compared to the other situations in this study.

Results

High volume PM samples were collected on PTFE filters from a constant volume dilution tunnel. The PM mass emission with HVO was smaller and with RME larger than that with EN590, but both biofuels produced lower PAH contents in emission PM. The DOC + POC catalyst greatly reduced the PM emission and PAH content in PM with both HVO and EN590. Dose-dependent TNFα and MIP-2 responses to all PM samples were mostly at the low or moderate level after 24-hour exposure in a mouse macrophage cell line RAW 264.7. Emission PM from situations with the smallest mass emissions (HVO + cat and CNG) displayed the strongest potency in MIP-2 production. The catalyst slightly decreased the PM-induced TNFα responses and somewhat increased the MIP-2 responses with HVO fuel. Emission PM with EN590 and with 30% HVO blended in EN590 induced the strongest genotoxic responses, which were significantly greater than those with EN590 + cat or 100% HVO. The emission PM sample from the CNG bus possessed the weakest genotoxic potency but had the strongest oxidative potency of all the fuel and catalyst combinations. The use of 100% HVO fuel had slightly weaker and 100% RME somewhat stronger emission PM induced ROS production, when compared to EN590.

Conclusions

The harmfulness of the exhaust emissions from vehicle engines cannot be determined merely on basis of the emitted PM mass. The study conditions and the engine type significantly affect the toxicity of the emitted particles. The selected fuels and DOC + POC catalyst affected the PM emission from the heavy EURO IV engine both qualitative and quantitative ways, which influenced their toxicological characteristics. The plain HVO fuel performed very well in emission reduction and in lowering the overall toxicity of emitted PM, but the 30% blend of HVO in EN590 was no better in this respect than the plain EN590. The HVO with a DOC + POC catalyst in the EURO IV engine, performed best with regard to changes in exhaust emissions. However some of the toxicological parameters were significantly increased even with these low emissions.

Alleviative effect of quercetin on germ cells intoxicated by 3-methyl-4-nitrophenol from diesel exhaust particles

As a component of diesel exhaust particles, 3-methyl-4-nitrophenol (4-nitro-m-cresol, PNMC) is also a metabolite of the insecticide fenitrothion and imposes hazardous effects on human health. In the present study, the alleviative effect of a common antioxidant flavonoid quercetin on mouse germ cells intoxicated by PNMC was investigated. Results showed that a single intraperitoneal injection of PNMC at 100 mg/kg induced severe testicular damage after one week. PNMC-treated mice showed a significant loss of germ cells (approximate 40% loss of round germ cells). PNMC caused an increase of hydroxyl radical and hydrogen peroxide production and lipid peroxidation, as well as a decrease in glutathione level, superoxide dismutase and glutathione peroxidase activities. Furthermore, treatment of PNMC increased expression of the pro-apoptotic protein Bax and decreased expression of the anti-apoptotic protein Bcl-XL in germ cells. In addition, testicular caspase-3 activity was significantly up-regulated and germ cell apoptosis was significantly increased in the PNMC-treated mice. In contrast, combined administration of quercetin at 75 mg/kg significantly attenuated PNMC-induced testicular toxicity. These results indicate that the antioxidant quercetin displays a remarkable protective effect on PNMC-induced oxidative damage in mouse testes and may represent an efficient supplement to attenuate reproductive toxicity by environmental toxicants to ensure healthy sperm production.

Effect of diesel exhaust particles on human middle ear epithelial cells

OBJECTIVE

In the present study, we investigate whether diesel exhaust particles (DEPs) cause cytotoxicity and induce inflammation or increase the expression of mucin in immortalized human middle ear epithelial cell lines (HMEECs). Several publications have shown an association between traffic-related air pollutants and otitis media. Additionally, DEP have been shown to cause inflammation and an allergic response in the airways.

METHODS

Cell viability following DEP treatment was investigated in HMEECs using the MTT assay. We measured the expression of the inflammatory cytokines TNF-α and COX-2 and the mucin genes MUC5AC and MUC5B using semiquantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting.

RESULTS

Cell viability tests showed that exposure to more than 80 μg/mL of DEP caused a decrease in cell viability. DEP exposure also increased the expression of MUC5AC, but did not induce the expression of MUC5B in HMEECs.

CONCLUSION

DEP decreased cell viability, induced an inflammatory response, and increased mucin gene expression in HMEECs. These findings support the hypothesis that environmental diesel exposure is a risk factor for otitis media.