Long-term exposure to particulate matter and roadway proximity with age at natural menopause in the Nurses' Health Study II Cohort

Is air pollution a risk factor for early menopause?

BACKGROUND

Ambient air pollution is a serious public health issue that may influence reproductive health, including fertility and menopause onset in women worldwide. Thus, understanding the risk factors associated with early menopause is crucial to inform women about potential health risks and guide public health interventions.

METHODS

We collected data from KHANES (The Korea National Health and Nutrition Examination Survey) at the Korean Center for Disease Control and Prevention, Ministry of Health and Welfare between 2010 and 2020. These data were linked with summary pollution data from AiMS-CREATE (AI-Machine Learning and Statistics Collaborative Research Ensemble for Air Pollution, Temperature, and All Types of Environmental Exposures) from 2002 to 2020. These summary data encapsulate the monthly average air pollution predictions for 226 si-gun-gu (cities, counties, and districts) in Korea. A total of 8506 participants who had experienced menopause (early menopause: 40-44 years, N = 341; normal menopause: ≥ 45 years, N = 8165) between 2002 and 2020 were included in the analysis. We employed survey logistic regression analyses to determine the associations between ambient air pollution and menopause after adjusting for covariates.

RESULTS

An association was observed between particulate matter 2.5 (PM2.5) and early menopause (adjusted survey logistic regression (aOR): 1.26, 95% confidence interval (CI): 1.21-1.31), between particulate matter 10 (PM10) and early menopause (aOR: 1.17, 95% CI: 1.14-1.20).

CONCLUSION

Our findings suggest that exposure to ambient air pollution may contribute to the onset of menopause, emphasizing the importance of addressing air quality as a public health priority. This study highlights the need for further research to explore the underlying mechanisms and long-term health impacts of environmental factors associated with early menopause.

Circulating Interleukin-6 Mediates PM2.5-Induced Ovarian Injury by Suppressing the PPARγ Pathway

Exposure to airborne fine particulate matter (PM2.5) is strongly associated with poor fertility and ovarian damage. However, the mechanism underlying this remains largely unclear. Here, we found that PM2.5 markedly impaired murine ovarian reserve, decreased hormone levels, and aggravated ovarian inflammation. Circulating interleukin-6 (IL-6) was elevated in PM2.5-exposed mice and was further confirmed to mediate this damage by IL-6 recombinant protein intervention. PM2.5 exposure led to increased alveolar macrophage infiltration in the lungs. However, alveolar macrophage clearance with clodronate liposomes could not fully reverse the elevated IL-6 levels and ovarian injury, suggesting that alveolar macrophages were probably not the only source of circulating IL-6. Further experiments indicated that IL-6 mainly targeted ovarian theca-interstitial cells and impaired testosterone synthesis via suppressing the peroxisome proliferator-activated receptor γ (PPARγ) pathway. In addition, apoptosis of granulosa cells and restriction of follicular growth were observed in co-cultures with IL-6-treated theca-interstitial cells, which could be further reversed by the PPARγ agonist. Moreover, IL-6-neutralizing antibodies ameliorated PM2.5-induced ovarian damage. Notably, increased levels of circulating IL-6 were observed in premature ovarian aging patients and were inversely associated with their ovarian function. In summary, our findings offer a mechanistic explanation for PM2.5-induced ovarian dysfunction and verify IL-6 as a biomarker and potential therapeutic target.

Fine particulate matter and ovarian health: A review of emerging risks

Fine particulate matter (PM2.5) pollution has raised significant public concerns, especially for vulnerable populations. Studies have indicated the association between PM2.5 and ovarian disorders, although the mechanisms underlying the effects have not yet been fully elucidated. In this review, we elucidated three main conditions pertaining to ovarian function that may result from exposure to PM2.5: diminished ovarian reserve, polycystic ovary syndrome, and infertility. Specific effects of ovarian disorders caused by PM2.5 are discussed, including reactive oxygen species, apoptosis, DNA damage, and inflammation.

Physical activity and menopausal symptoms: evaluating the contribution of obesity, fitness, and ambient air pollution status

OBJECTIVE

The menopausal transition is accompanied by transient symptoms that have been linked to subclinical cardiovascular disease (CVD); CVD has also been linked to air pollution. Physical activity (PA) reduces CVD, improves body composition, and can reduce menopausal symptoms. The purpose of this study was to assess the links between PA and menopausal symptoms and whether obesity, fitness, and air pollution status play a role in this relationship.

METHODS

Women (40-60 y; N = 243; mean [SD] age, 47.8 [5.6] y) from areas with high versus low air pollution enrolled in the Healthy Aging in Industrial Environment Program 4 prospective cohort study completed psychological, cardiorespiratory fitness, body composition, and menopausal status screening followed by a 14-day prospective assessment of menopausal symptoms (Menopause Rating Scale) using a mobile application. Daily PA was assessed objectively across 14 days via Fitbit Charge 3 monitor. General linear mixed models were conducted and controlled for age, menopausal status, day in the study, wear time, and neuroticism.

RESULTS

Peri/postmenopausal women ( β = 0.43, P < 0.001) and those residing in a high-air-pollution environment ( β = 0.45, P < 0.05) reported more somatovegetative symptoms. Hot flashes alone were associated with peri/postmenopausal status ( β = 0.45, P < 0.001), and for women residing in a high-air-pollution environment, lower reporting of hot flashes was observed on days when a woman was more physically active than usual ( β = -0.15, P < 0.001). No associations were found for cardiorespiratory fitness and visceral fat with any of the symptoms.

CONCLUSIONS

PA may enhance resilience to hot flashes, especially when residing in high-air-pollution environments where we also observed higher reporting of somatovegetative menopausal symptoms.

Reduction of ovarian reserves and activation of necroptosis to in vivo air pollution exposures

We investigated the association between air pollution and changes in ovarian follicles, anti-mullerian hormone (AMH) levels, the occurrence of necroptosis cell death by activation of receptor-interacting protein kinase 3 (RIPK3) and, the activation of mixed lineage kinase domain-like (MLKL) proteins. Forty-two female Wistar rats were divided into three groups of 14 each, which were exposed to real-ambient air, filtered air and purified air (control) in two periods of 3 and 5 months. The results showed that the number of ovarian follicles decreased in the group exposed to real-ambient air versus the control group (P < 0.0001). The trend of age-related AMH changes with respect to exposure to air pollutants was affected and its levels decreased after 3 months of exposure. The MLKL increased in the group exposed to the real-ambient air compared to the control group (P = 0.033). Apparently long-term exposure to air pollution can reduce ovarian reserves.

Source attribution of carbonaceous fraction of particulate matter in the urban atmosphere based on chemical and carbon isotope composition

Air quality is of large concern in the city of Krakow, southern Poland. A comprehensive study was launched by us in which two PM fractions (PM1 and PM10) were sampled during 1-year campaign, lasting from April 21, 2018 to March 19, 2019. A suite of modern analytical methods was used to characterize the chemical composition of the collected samples. The contents of 14 sugars, sugar alcohols and anhydrosugars, 16 polycyclic aromatic hydrocarbons, selected metals and non-metals and ions were analyzed, in addition to organic and elemental carbon content. The carbon isotope composition in both analysed PM fractions, combined with an isotope-mass balance method, allowed to distinguish three main components of carbonaceous emissions in the city: (1) emissions related to combustion of hard coal, (2) emissions related to road transport, and (3) biogenic emissions. The heating season emissions from coal combustion had the biggest contribution to the reservoir of carbonaceous aerosols in the PM10 fraction (44%) and, together with the biogenic emission, they were the biggest contributors to the PM1 fraction (41% and 44%, respectively). In the non-heating season, the dominant source of carbon in PM10 and PM1 fraction were the biogenic emissions (48 and 54%, respectively).

Pollution and endometriosis: A deep dive into the environmental impacts on women's health

BACKGROUND

The interaction between pollution and endometriosis is a pressing issue that demands immediate attention. The impact of pollution, particularly air and water pollution, or occupational hazards, on hormonal disruption and the initiation of endometriosis remains a major issue.

OBJECTIVES

This narrative review aims to delve into the intricate connection between pollution and endometriosis, shedding light on how environmental factors contribute to the onset and severity of this disease and, thus, the possible public health policy implications.

DISCUSSION

Endocrine-disrupting chemicals (EDCs) in pollutants dysregulate the hormonal balance, contributing to the progression of this major gynaecological disorder. Air pollution, specifically PM2.5 and PAHs, has been associated with an increased risk of endometriosis by enhancing chronic inflammation, oxidative stress, and hormonal imbalances. Chemical contaminants in water and work exposures, including heavy metals, dioxins, and PCBs, disrupt the hormonal regulation and potentially contribute to endometriosis. Mitigating the environmental impact of pollution is required to safeguard women's reproductive health. This requires a comprehensive approach involving stringent environmental regulations, sustainable practices, responsible waste management, research and innovation, public awareness, and collaboration among stakeholders.

CONCLUSION

Public health policies have a major role in addressing the interaction between pollution and endometriosis in a long-term commitment.

Obstetric and psychiatric history as predictors for psychosomatic symptoms among Korean perimenopausal women

OBJECTIVES

Menopause presents various physical and psychological disturbances for women and comes at a high financial cost. Therefore, this study aimed to identify factors influencing menopause symptoms.

STUDY DESIGN

Data of Korean perimenopausal women aged 40-60 (n = 1060; mean age, 46.03 ± 4.08) were collected by a research company. Participants were classified into a "functional" group (n = 716) or a "dysfunctional" group (n = 344) according to the severity of their perimenopausal psychosomatic symptoms. To investigate the association of obstetric and psychiatric history with membership of the "dysfunctional" group, a hierarchical logistic regression analysis was conducted.

RESULTS

The outcomes of all three hierarchical logistic regression models presented significant overall model fit. Among the independent variables, family history of menopausal symptoms, menarcheal age, number of pregnancies, history of postpartum depression, postpartum psychosis, and other psychiatric disorders were positively associated with being in the "dysfunctional" group, whereas age and number of deliveries were negatively associated with being in the "dysfunctional" group.

CONCLUSION

A short reproductive period and short exposure to estrogen due to late menarche and early menopausal transition may be related to severe perimenopausal symptoms. The relationship between the history of postpartum mental illness and severe perimenopausal symptoms may be associated with heightened sensitivity to hormonal triggers when a woman is exposed to fluctuating ovarian sex steroid levels. The relationship between parity or gravidity and the severity of menopausal symptoms in Korean women differed from that in studies conducted in other countries, possibly due to the low birth rate in Korea.

Long-term exposure to air pollution and anti-mullerian hormone rate of decline: a population-based cohort study in Tehran, Iran

Anti-mullerian hormone (AMH) concentration is a marker of ovarian reserve that decreases with age. However, a decrease in AMH may occur more rapidly under the influence of environmental factors. The present study investigated the association between long-term exposure to ambient air pollutants with serum concentrations of AMH and the AMH rate of decline. This study included 806 women with median age of 43 years (interquartile range: 38-48) participating in the Tehran Lipid and Glucose Study (TLGS) that were followed from 2005 to 2017. The AMH concentration and the demographic, anthropometric, and personal health parameters of the study participants were obtained from the TLGS cohort database. Air pollutant data were collected from the monitoring stations and the individual exposures were estimated by previously developed land use regression (LUR) models. Multiple linear regression analysis was used to estimate linear relationships between the air pollutant exposures and serum concentration of AMH and with the AMH declination rate. The results show no statistically significant associations between exposures to any of the air pollutants (including PM10, PM2.5, SO2, NO, NO2, NOX, and benzene, toluene, ethylbenzene, p-xylene, m-xylene, o-xylene (BTEX), and total BTEX) with serum concentration of AMH. Compared to the first tertile, no statistically significant associations were observed between the second or third tertiles of air pollutants, with the AMH rate of decline. In this study, we did not find significant association between air pollution and AMH in middle age women in Tehran, Iran. Future work may study such associations in younger women.

Environmental Exposures and Anti-Müllerian Hormone: A Mixture Analysis in the Nurses' Health Study II

BACKGROUND

Previous studies have linked environmental exposures with anti-Müllerian hormone (AMH), a marker of ovarian reserve. However, associations with multiple environment factors has to our knowledge not been addressed.

METHODS

We included a total of 2,447 premenopausal women in the Nurses' Health Study II (NHSII) who provided blood samples during 1996-1999. We selected environmental exposures linked previously with reproductive outcomes that had measurement data available in NHSII, including greenness, particulate matter, noise, outdoor light at night, ultraviolet radiation, and six hazardous air pollutants (1,3-butadiene, benzene, diesel particulate matter, formaldehyde, methylene chloride, and tetrachloroethylene). For these, we calculated cumulative averages from enrollment (1989) to blood draw and estimated associations with AMH in adjusted single-exposure models, principal component analysis (PCA), and hierarchical Bayesian kernel machine regression (BKMR).

RESULTS

Single-exposure models showed negative associations of AMH with benzene (percentage reduction in AMH per interquartile range [IQR] increase = 5.5%, 95% confidence interval [CI] = 1.0, 9.8) and formaldehyde (6.1%, 95% CI = 1.6, 10). PCA identified four major exposure patterns but only one with high exposure to air pollutants and light at night was associated with lower AMH. Hierarchical BKMR pointed to benzene, formaldehyde, and greenness and suggested an inverse joint association with AMH (percentage reduction comparing all exposures at the 75th percentile to median = 8.2%, 95% CI = 0.7, 15.1). Observed associations were mainly among women above age 40.

CONCLUSIONS

We found exposure to benzene and formaldehyde to be consistently associated with lower AMH levels. The associations among older women are consistent with the hypothesis that environmental exposures accelerate reproductive aging.

Outdoor air pollution and anti-Müllerian hormone concentrations in the Sister Study

BACKGROUND

Anti-Müllerian hormone (AMH) concentrations are a marker of ovarian reserve and are indicative of a woman's reproductive lifespan. Exposure to tobacco smoke has been associated with lower AMH concentrations; however, less is known about the association between ambient air pollution and ovarian reserve.

METHODS

For 883 premenopausal Sister Study participants recruited between 2003 and 2009 in the United States, adult residential annual average concentrations of PM2.5, PM10, and NO2 were estimated using validated universal kriging models incorporating land-use regression. We estimated the distance in meters to the nearest major road for both adult enrollment and childhood residences. Serum AMH was measured using an ultrasensitive ELISA assay. Samples with AMH concentrations below the detection limit were analyzed using a picoAMH ELISA assay. Multivariable-adjusted linear regression was used to estimate the percent change in AMH in relation to ambient residential air pollution, categorized in quartiles and per interquartile range increase, and distance to a major roadway.

RESULTS

Overall, we observed little to no evidence of associations between AMH and air pollution concentrations or proximity to roadways. Women in the highest quartile of NO2 exposure, a traffic-related pollutant, had higher estimated AMH concentrations (Q4 vs. Q1, 42.9%; 95% CI = -3.4, 111.4) compared with the lowest quartile. However, lower mean AMH concentrations were observed for women living closer to a major roadway (<50 m to nearest roadway vs. ≥200 m = -32.9%; 95% CI = -56.1, 2.6).

CONCLUSIONS

We saw little consistent evidence to support an association between outdoor air pollution and diminished ovarian reserve in US women ages 35-54.