Maternal mechanisms in air pollution exposure-related adverse pregnancy outcomes: A systematic review

Air pollution exposure is linked to various adverse health effects including cardiopulmonary, neurological and reproductive outcomes. Susceptible populations such as pregnant women and infants can be affected to a greater extent compared to healthy individuals. Thus, understanding air pollutant exposure-related toxicity pathways in pregnancy can provide information on developmental origin of health and diseases in both mothers and infants. The objective of this literature review was to explore maternal mechanisms underlying the association between air pollutant exposures and adverse maternal/infant health effects. A total of 209 articles published from 1996 until November 2024 were retrieved using PubMed, Scopus and Web of Science using relevant search terms (e.g. "Air Pollution" AND "Maternal" AND "Infant" AND "Health" AND "Biomarker"). After screening and removal of articles based on exclusion criteria, 36 observational studies were included for the final analysis. There were relatively fewer articles on air pollution exposure-related adverse maternal health effects compared to air-pollution-related adverse infant health effects. Of these articles selected for the final review, 32 studies compared the effects of particulate matter (PM), PM2.5, few on other (gaseous) pollutants and one study on effects of mixtures of air pollutants. Adverse maternal health effects included hypertensive disorders, gestational diabetes mellitus (GDM) and clinically recognized early pregnancy loss, while adverse infant health effects ranged from low birth weight, preterm birth, changes in fetal heart rate, crown rump length and fetal hyperinsulinism. Moreover, oxidative stress, inflammatory responses, endothelial and metabolic dysfunction were some of the mechanisms implicated in air pollution exposure-related adverse birth outcomes. These findings warrant further validation work and identification of maternal mechanism(s) constituting the causal pathway.

Investigation of size-segregated particulate matter and carbonaceous components in Phnom Penh, Cambodia

This study investigated the size-segregated carbonaceous components of particulate matter (PM), including ultrafine particles (UFP or PM0.1), across three distinct urban settings in Phnom Penh, Cambodia: an educational site (University of Health Sciences, UHS), an institutional site (Ministry of Environment, MoE), and a residential area near a landfill. A cascade impactor-type sampler equipped with an inertial filter was used to collect size-segregated particles down to UFPs. Carbonaceous species, including organic carbon (OC) and elemental carbon (EC), were analyzed using a thermal/optical carbon analyzer to determine their composition and ratios. The results indicated no significant differences in mass concentration between weekdays and weekends at all sites; however, PM profiles varied across the location. The UHS site displayed higher EC levels in UFP, with concentrations suggesting significant local vehicular emissions, underscored by a lower OC/EC ratio (2.39 ± 1.13) compared to other sites. In contrast, the landfill site exhibited higher OC components in finer particles, suggesting emissions from organic sources such as waste burning and cooking activities, evidenced by higher OC/EC ratios across all particle sizes (e.g., OC/EC ratio in UFP at 3.78 ± 0.98). The MoE site presented a balanced profile with moderate levels of both OC and EC, influenced by its proximity to natural dispersion factors like the Tonle Sap River. Additionally, air mass backward trajectory analysis integrated with hotspot data indicated transboundary influences, particularly from agricultural burning in surrounding provinces, including Vietnam. Therefore, both local and transboundary emissions influenced the PM levels in Phnom Penh city.

Possible relationship between respiratory diseases and urinary concentrations of polycyclic aromatic hydrocarbon metabolites - a pilot study

This study investigates the potential relationship between exposure to polycyclic aromatic hydrocarbons (PAHs), specifically monohydroxylated metabolites (OH-PAHs), in urine, and the prevalence of respiratory diseases in 2-year-old children residing in two locations within the Czech Republic - České Budějovice (control location) and the historically contaminated mining district of Most. Despite current air quality and lifestyle similarities between the two cities, our research aims to uncover potential long-term health effects, building upon previous data indicating distinctive patterns in the Most population. A total of 248 urine samples were analysed for the presence of 11 OH-PAHs. Employing liquid-liquid extraction with ethyl acetate and clean-up through dispersive solid-phase extraction, instrumental analysis was conducted using ultra-high performance liquid chromatography coupled with tandem mass spectrometry. The incidence of respiratory diseases was assessed through questionnaires administered by paediatricians. The concentrations of OH-PAHs were elevated in urine samples from 2-year-olds in Most compared to those from České Budějovice. The incidence of respiratory diseases showed statistically significant higher levels of OH-PAHs in children from Most, together with a higher incidence of influenza. This association underlines the impact of environmental PAH exposure on children's respiratory health. It suggests that elevated urinary OH-PAH levels indicate an increased risk of developing respiratory diseases in the affected population. Further studies are needed to clarify the possible long-term health effects and to contribute to sound public health strategies.

Impact of Air Pollution on the Health of the Population in Parts of the Czech Republic

Thirty years ago, Northern Bohemia in the Czech Republic was one of the most air polluted areas in Europe. After political changes, the Czech government put forward a research program to determine if air pollution is really affecting human health. This program, later called the "Teplice Program", was initiated in collaboration with scientists from the United States Environmental Protection Agency (US EPA). This cooperation made possible the use of methods on the contemporary level. The very high concentrations of sulphur dioxide (SO2), particulate matter of 10 micrometers or less (PM10), and polycyclic aromatic hydrocarbons (PAHs) present in the air showed, for the first time, the impact of air pollutants on the health of the population in mining districts: adverse pregnancy outcomes, the impact of air pollution on sperm morphology, learning disabilities in children, and respiratory morbidity in preschool children. A surprising result came from the distribution of the sources of pollution: 70% of PM10 pollution came from local heating and not from power plants as expected. Thanks to this result, the Czech government supported changes in local heating from brown coal to natural gas. This change substantially decreased SO2 and PM10 pollution and affected mortality, especially cardiovascular mortality.

Estimation of human exposure to polycyclic aromatic hydrocarbons (PAHs) based on the dietary and outdoor atmospheric monitoring in the Czech Republic

In everyday life, humans can be exposed to various chemicals including ubiquitous polycyclic aromatic hydrocarbons (PAHs) mostly through food consumption and/or inhalation. In the presented study, we evaluated PAH concentrations in duplicate samples (n = 251). Concurrently, the outdoor concentrations of PM2.5-bound PAHs in filters (n = 179) were also monitored. The daily exposure to PAHs was subsequently estimated for the risk group of pregnant women living in two different cities (Most city and Ceske Budejovice city) in the Czech Republic. This is the first unique study in Europe to evaluate human daily exposure to 20 PAHs both from inhalation (outdoor air) and dietary intake. For the analysis of samples collected during the years 2016/2017, a gas chromatography coupled to tandem mass spectrometry was applied. Focusing on the diet samples, a slightly higher sum of detected PAHs was measured in duplicates obtained from the mothers living in the Most city (0.115-186 ng g^-1) compared to the Ceske Budejovice city (0.115-97.1 ng g^-1). This could be due to a higher occurrence of major analytes (pyrene, phenanthrene and fluoranthene) and the different composition of daily diet. The values of toxic and most often detected substance, namely benzo[a]pyrene (BaP), were also higher by 35% in the Most city. Regarding the outdoor air contamination (only particulate phase - PM2.5 was assessed), here the opposite situation was observed, relatively higher amounts of all PAHs were monitored in the Ceske Budejovice city (median: 2.22 ng m^-3) than in the Most city (median: 1.07 ng m^-3). These higher PAH concentrations in the Ceske Budejovice city are probably caused by more intense traffic, higher population and also by the occurrence of old-fashioned heating plant. Depending on a seasonal variability, especially during the cold season, the concentrations of BaP exceeded the European average emission limit (1 ng m^-3) by 1.5-6 times. This highest inhalation exposure to all PAHs was observed in February. However, the dietary intake still represents the dominant contributor (>90%) to the total PAH exposure.

Greater susceptibility of girls to airborne Benzo[a]pyrene for obesity-associated childhood asthma

BACKGROUND

Sexually dimorphic risk of obesity-associated asthma is posited to accelerate around puberty. Yet, the role of air pollution on the lean and obese asthmatic children has never been examined.

OBJECTIVE

To compare whether a unit exposure to airborne benzo[a]pyrene (B[a]P) is associated with altered risks of asthma across the overweight/obese (OV/OB) control, lean asthmatic, and OV/OB asthmatic children, respectively, compared to the lean controls, before and after adjusting for oxidant stress markers (i.e. 15‑F2t‑IsoP, 8‑oxo‑dG, and Carbonyl).

METHODS

Asthmatic and healthy control children, recruited from polluted urban and rural areas, were matched to ambient concentration of B[a]P. A unit increase in B[a]P and multinomial logistic regression on OV/OB control, lean asthmatic, and OV/OB asthma were compared across the sex- and age-groups.

RESULTS

The median B[a]P was associated with a linear increase among the female children, according to OV/OB and asthma, respectively, and together, compared to the lean control girls (p = 0.001). While B[a]P was associated with positive relationship with 15‑F2t‑IsoP level among the OV/OB boys, the same exposure-outcome association was inverse among the OV/OB girls. One natural log-unit increase in ambient B[a]P was associated with 10.5-times greater odds (95% CI, 2.6-39.6; p = 0.001) the adolescent OV/OB boys, compared to the unit odds among the lean controls. In contrast, the adolescent OV/OB girls were associated with highest adjusted odds of the asthma (aOR = 15.4; 95% CI, 2.9-29.1; p < 0.001) compared to the lean control girls. An adjustment for 15‑F2t‑IsoP, and Carbonyls was associated with greater odds of asthma per unit exposure for the adolescent OV/OB girls (aOR = 16.2; 95% CI, 1.4-181.8; p = 0.024).

CONCLUSIONS

B[a]P exposure was associated with a leap in the odds of asthma among the OV/OB adolescents, particularly the girls, after adjusting for 15‑F2t‑IsoP and Carbonyls.