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Human Reproduction Update Jan 2023Air pollution is both a sensory blight and a threat to human health. Inhaled environmental pollutants can be naturally occurring or human-made, and include...
BACKGROUND
Air pollution is both a sensory blight and a threat to human health. Inhaled environmental pollutants can be naturally occurring or human-made, and include traffic-related air pollution (TRAP), ozone, particulate matter (PM) and volatile organic compounds, among other substances, including those from secondhand smoking. Studies of air pollution on reproductive and endocrine systems have reported associations of TRAP, secondhand smoke (SHS), organic solvents and biomass fueled-cooking with adverse birth outcomes. While some evidence suggests that air pollution contributes to infertility, the extant literature is mixed, and varying effects of pollutants have been reported.
OBJECTIVE AND RATIONALE
Although some reviews have studied the association between common outdoor air pollutants and time to pregnancy (TTP), there are no comprehensive reviews that also include exposure to indoor inhaled pollutants, such as airborne occupational toxicants and SHS. The current systematic review summarizes the strength of evidence for associations of outdoor air pollution, SHS and indoor inhaled air pollution with couple fecundability and identifies gaps and limitations in the literature to inform policy decisions and future research.
SEARCH METHODS
We performed an electronic search of six databases for original research articles in English published since 1990 on TTP or fecundability and a number of chemicals in the context of air pollution, inhalation and aerosolization. Standardized forms for screening, data extraction and study quality were developed using DistillerSR software and completed in duplicate. We used the Newcastle-Ottawa Scale to assess risk of bias and devised additional quality metrics based on specific methodological features of both air pollution and fecundability studies.
OUTCOMES
The search returned 5200 articles, 4994 of which were excluded at the level of title and abstract screening. After full-text screening, 35 papers remained for data extraction and synthesis. An additional 3 papers were identified independently that fit criteria, and 5 papers involving multiple routes of exposure were removed, yielding 33 articles from 28 studies for analysis. There were 8 papers that examined outdoor air quality, while 6 papers examined SHS exposure and 19 papers examined indoor air quality. The results indicated an association between outdoor air pollution and reduced fecundability, including TRAP and specifically nitrogen oxides and PM with a diameter of ≤2.5 µm, as well as exposure to SHS and formaldehyde. However, exposure windows differed greatly between studies as did the method of exposure assessment. There was little evidence that exposure to volatile solvents is associated with reduced fecundability.
WIDER IMPLICATIONS
The evidence suggests that exposure to outdoor air pollutants, SHS and some occupational inhaled pollutants may reduce fecundability. Future studies of SHS should use indoor air monitors and biomarkers to improve exposure assessment. Air monitors that capture real-time exposure can provide valuable insight about the role of indoor air pollution and are helpful in assessing the short-term acute effects of pollutants on TTP.
Topics: Pregnancy; Female; Humans; Air Pollution; Air Pollutants; Tobacco Smoke Pollution; Particulate Matter; Fertility; Environmental Pollutants
PubMed: 35894871
DOI: 10.1093/humupd/dmac029 -
Environment International Sep 2020Air pollution is a leading cause of mortality and morbidity worldwide. Short-term exposure (from one hour to days) to selected air pollutants has been associated with... (Meta-Analysis)
Meta-Analysis
Short-term exposure to particulate matter (PM and PM), nitrogen dioxide (NO), and ozone (O) and all-cause and cause-specific mortality: Systematic review and meta-analysis.
BACKGROUND
Air pollution is a leading cause of mortality and morbidity worldwide. Short-term exposure (from one hour to days) to selected air pollutants has been associated with human mortality. This systematic review was conducted to analyse the evidence on the effects of short-term exposure to particulate matter with aerodynamic diameters less or equal than 10 and 2.5 µm (PM PM), nitrogen dioxide (NO), and ozone (O), on all-cause mortality, and PM and PM on cardiovascular, respiratory, and cerebrovascular mortality.
METHODS
We included studies on human populations exposed to outdoor air pollution from any source, excluding occupational exposures. Relative risks (RRs) per 10 µg/m increase in air pollutants concentrations were used as the effect estimates. Heterogeneity between studies was assessed using 80% prediction intervals. Risk of bias (RoB) in individual studies was analysed using a new domain-based assessment tool, developed by a working group convened by the World Health Organization and designed specifically to evaluate RoB within eligible air pollution studies included in systematic reviews. We conducted subgroup and sensitivity analyses by age, sex, continent, study design, single or multicity studies, time lag, and RoB. The certainty of evidence was assessed for each exposure-outcome combination. The protocol for this review was registered with PROSPERO (CRD42018087749).
RESULTS
We included 196 articles in quantitative analysis. All combinations of pollutants and all-cause and cause-specific mortality were positively associated in the main analysis, and in a wide range of sensitivity analyses. The only exception was NO, but when considering a 1-hour maximum exposure. We found positive associations between pollutants and all-cause mortality for PM (RR: 1.0041; 95% CI: 1.0034-1.0049), PM (RR: 1.0065; 95% CI: 1.0044-1.0086), NO (24-hour average) (RR: 1.0072; 95% CI: 1.0059-1.0085), and O (RR: 1.0043; 95% CI: 1.0034-1.0052). PM and PM were also positively associated with cardiovascular, respiratory, and cerebrovascular mortality. We found some degree of heterogeneity between studies in three exposure-outcome combinations, and this heterogeneity could not be explained after subgroup analysis. RoB was low or moderate in the majority of articles. The certainty of evidence was judged as high in 10 out of 11 combinations, and moderate in one combination.
CONCLUSIONS
This study found evidence of a positive association between short-term exposure to PM, PM, NO, and O and all-cause mortality, and between PM and PM and cardiovascular, respiratory and cerebrovascular mortality. These results were robust through several sensitivity analyses. In general, the level of evidence was high, meaning that we can be confident in the associations found in this study.
Topics: Air Pollutants; Air Pollution; Cause of Death; Environmental Exposure; Humans; Nitrogen Dioxide; Ozone; Particulate Matter; Time Factors
PubMed: 32590284
DOI: 10.1016/j.envint.2020.105876 -
Journal of Environmental Sciences... Apr 2023Air pollution has previously been linked to several adverse health outcomes, but the potential association between air pollution and liver cancer remains unclear. We... (Review)
Review
Air pollution has previously been linked to several adverse health outcomes, but the potential association between air pollution and liver cancer remains unclear. We searched PubMed, EMBASE, and Web of Science from inception to 10 October 2021, and manually reviewed the references of relevant papers to further identify any related literature investigating possible associations between air pollution and liver cancer. Risk estimates values were represented by statistical associations based on quantitative analyses. A total of 13 cohort studies obtained from 11 articles were included, with 10,961,717 participants. PM was the most frequently examined pollutant (included in 11 studies), followed by NO and NO (included in 6 studies), and fewer studies focused on other pollutants (PM, PM, PM, O, and BC). In all the 16 associations for liver cancer mortality, 14 associations reported the effect of PM on liver cancer mortality. Eight associations on PM were significant, showing a suggestive association between PM and liver cancer mortality. Among 24 associations shown by risk estimates for liver cancer incidence, most associations were not statistically significant. For other air pollutants, no positive associations were presented in these studies. PM was the most frequently examined pollutant, followed by NO and NO, and fewer studies focused on other pollutants. PM was associated with liver cancer mortality, but there was no association for other air pollutants. Future research should use advanced statistical methods to further assess the impact of multiple air pollutants on liver cancer in the changing socio-environmental context.
Topics: Humans; Air Pollution; Air Pollutants; Liver Neoplasms; Environmental Pollutants
PubMed: 36503807
DOI: 10.1016/j.jes.2022.05.037 -
Ecotoxicology and Environmental Safety Apr 2023We aimed to evaluate the relationship between the composition of particulate matter (PM) and gestational diabetes mellitus (GDM) by a comprehensively review of... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
We aimed to evaluate the relationship between the composition of particulate matter (PM) and gestational diabetes mellitus (GDM) by a comprehensively review of epidemiological studies.
METHODS
We systematically identified cohort studies related to air pollution and GDM risk before February 8, 2023 from six databases (PubMed, Embase, Web of Science Core Collection, China National Knowledge Infrastructure, Wanfang Data Knowledge Service Platform and Chongqing VIP Chinese Science and Technology Periodical databases). We calculated the relative risk (RR) and its 95% confidence intervals (CIs) to assess the overall effect by using a random effects model.
RESULTS
This meta-analysis of 31 eligible cohort studies showed that exposure to PM, PM, SO, and NO was associated with a significantly increased risk of GDM, especially in preconception and first trimester. Analysis of the components of PM found that the risk of GDM was strongly linked to black carbon (BC) and nitrates (NO). Specifically, BC exposure in the second trimester and NO exposure in the first trimester elevated the risk of GDM, with the RR of 1.128 (1.032-1.231) and 1.128 (1.032-1.231), respectively. The stratified analysis showed stronger correlations of GDM risk with higher levels of pollutants in Asia, except for PM and BC, which suggested that the specific composition of particulate pollutants had a greater effect on the exposure-outcome association than the concentration.
CONCLUSIONS
Our study found that ambient air pollutant is a critical factor for GDM and further studies on specific particulate matter components should be considered in the future.
Topics: Pregnancy; Female; Humans; Diabetes, Gestational; Air Pollution; Air Pollutants; Particulate Matter; Cohort Studies; Environmental Exposure
PubMed: 36934545
DOI: 10.1016/j.ecoenv.2023.114802 -
The Science of the Total Environment Dec 2023Growing studies have focused on the effects of ambient air pollution on thyroid hormones (THs), but the results were controversial. Therefore, a systematic review and... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Growing studies have focused on the effects of ambient air pollution on thyroid hormones (THs), but the results were controversial. Therefore, a systematic review and meta-analysis was conducted by pooling current evidence on this association.
METHODS
Four databases were searched for studies examining the associations of particulate matter [diameter ≤10 μm (PM) or ≤2.5 μm (PM)] and gaseous [sulfur dioxide (SO), nitrogen dioxide (NO), ozone (O), carbon monoxide (CO)] pollutants with THs levels. Random effects models were used to pool the changes in THs levels with increasing air pollutant concentrations. Subgroup analyses were constructed by region, design, sample size, pollutant concentrations, evaluated methods, and potential risk exposure windows.
RESULTS
A total of 14 studies covering 357,226 participants were included in this meta-analysis. The pooled results showed significant associations of exposure to PM, PM, NO, SO, and CO with decreases in free thyroxine (FT4) with percent changes (PC) ranging from -0.593 % to -3.925 %. PM, NO, and CO were negatively associated with levels of FT4/FT3 (PC: from -0.604 % to -2.975 %). In addition, results showed significant associations of PM with hypothyroxinemia and high thyroid-stimulating hormone (TSH). Subgroup analyses indicated that PM and NO were significantly associated with FT4 in studies of Chinese, and similar significant findings were found in studies of PM and FT4/FT3 in areas with higher concentrations of air pollutants and larger samples. PM exposure in the first trimester was found to be associated with lower FT4 levels in pregnant women.
CONCLUSION
Our findings suggest that exposure to air pollution is associated with changes in THs levels. Enhanced management of highly polluted areas, identification of harmful components and sources of PM, and protection from harmful exposures in early pregnancy may be of great public health importance for the population's thyroid function.
Topics: Female; Humans; Pregnancy; Nitrogen Dioxide; Thyroid Gland; Environmental Exposure; Air Pollution; Air Pollutants; Particulate Matter; Ozone; Sulfur Dioxide; Thyroid Hormones; Environmental Pollutants
PubMed: 37660827
DOI: 10.1016/j.scitotenv.2023.166780 -
Reviews on Environmental Health Dec 2021Some studies have shown that environmental risk factors, including air pollution, might be related to the incidence or recurrence of multiple sclerosis (MS). This... (Review)
Review
OBJECTIVES
Some studies have shown that environmental risk factors, including air pollution, might be related to the incidence or recurrence of multiple sclerosis (MS). This systematic review was conducted to investigate the relation between air pollution and MS.
METHODS
A systematic search was conducted in PubMed, Scopus, Science Direct, Embase, and Web of Science; until January 2020 with no restrictions. The search strategy was conducted with air pollution key words such as CO, PM, PM, SO, and NO, for exposure and the key word "Multiple sclerosis" as the outcome.
RESULTS
Eventually, after applying the inclusion and exclusion criteria, 17 articles were included. The methodologies and outcomes reported were heterogeneous and different metrics had been used in the results; therefore conducting a meta-analysis was not possible. Eight studies had analyzed the relation between particulate matter (PM) and the prevalence or relapse of MS and had observed a significant relation. NO and NOx were associated with recurrence or prevalence of MS in three studies. But, in three cohort studies, no association was observed between air pollution and recurrence or occurrence of MS.
CONCLUSIONS
The results of this systematic review show that outdoor air pollution, especially PM and nitrogen oxides might be related to the prevalence or relapse of MS.
Topics: Air Pollutants; Air Pollution; Environmental Exposure; Humans; Multiple Sclerosis; Particulate Matter
PubMed: 34821118
DOI: 10.1515/reveh-2020-0079 -
European Journal of Epidemiology Apr 2014The present systematic review and metaanalysis of published observational studies was conducted to assess the health effects of exposure to air pollution on diabetes... (Meta-Analysis)
Meta-Analysis Review
The present systematic review and metaanalysis of published observational studies was conducted to assess the health effects of exposure to air pollution on diabetes risk. Online databases were searched through January 2013, and the reference lists of pertinent articles reporting observational studies in humans were examined. Pooled relative risks and 95 % confidence intervals were calculated with a random-effects model. Exposure to air pollution was associated with slight increase in risk of diabetes and susceptibility of people with diabetes to air pollution. These results were consistent between time-series, case-crossover and cohort studies and between studies conducted in North America and Europe. The association between exposure to air pollution and diabetes was stronger for gaseous pollutants than for particulate matter. Our metaanalysis suggests that exposure to air pollution may be a risk factor for diabetes and increase susceptibility of people with diabetes to air pollution.
Topics: Air Pollutants; Air Pollution; Diabetes Mellitus; Environmental Exposure; Humans; Risk Factors
PubMed: 24791705
DOI: 10.1007/s10654-014-9907-2 -
Environmental Pollution (Barking, Essex... Jun 2021Despite the widely-known effects of air pollution, pollutants exposure surrounding pregnancy and the risk for autism spectrum disorder (ASD) in newborns remains... (Meta-Analysis)
Meta-Analysis Review
Despite the widely-known effects of air pollution, pollutants exposure surrounding pregnancy and the risk for autism spectrum disorder (ASD) in newborns remains controversial. The purpose of our study was to carry out a systematic review and meta-analyses of the risk of ASD in newborns following air pollution exposure during the perinatal period (preconception to second year of life). The PubMed, Cochrane Library, Embase and ScienceDirect databases were searched for articles, published up to July 2020, with the keywords "air pollution" and "autism". Three models were used for each meta-analysis: a global model based on all risks listed in included articles, a pessimistic model based on less favorable data only, and an optimistic model based on the most favorable data only. 28 studies corresponding to a total of 758 997 newborns were included (47190 ASD and 703980 controls). Maternal exposure to all pollutants was associated with an increased risk of ASD in newborns by 3.9% using the global model and by 12.3% using the optimistic model, while the pessimistic model found no change. Each increase of 5 μg/m in particulate matter <2.5 μm (PM2.5) was associated with an increased risk of ASD in newborns, regardless of the model used (global +7%, pessimistic +5%, optimistic +15%). This risk increased during preconception (global +17%), during pregnancy (global +5%, and optimistic +16%), and during the postnatal period (global +11% and optimistic +16%). Evidence levels were poor for other pollutants (PM10, NOx, O3, metals, solvents, styrene, PAHs, pesticides). PM2.5 was associated with a greater risk than PM10 (coefficient 0.20, 95CI -0.02 to 0.42), NOx (0.29, 0.08 to 0.50) or solvents (0.24, 0.04 to 0.44). All models revealed that exposure to pollutants, notably PM2.5 during pregnancy, was associated with an increased risk of ASD in newborns. Pregnancy and postnatal periods seem to be the most at-risk periods.
Topics: Air Pollutants; Air Pollution; Autism Spectrum Disorder; Environmental Exposure; Female; Humans; Infant, Newborn; Maternal Exposure; Particulate Matter; Pregnancy
PubMed: 33714060
DOI: 10.1016/j.envpol.2021.116856 -
Environmental Research May 2021Air pollution is a major public health threat. The present study is the first systematic review (SR) to determine the association of exposure to air pollution and... (Review)
Review
Air pollution is a major public health threat. The present study is the first systematic review (SR) to determine the association of exposure to air pollution and Multiple Sclerosis (MS) Progression. A Literature search was carried out using relevant keywords within several international databases. A comprehensive literature search was carried out systematically and yielded 24 eligible studies concerning the relationship of exposure to air pollution including criteria air pollutants such as particulate matter, NOx and SOx, CO, traffic noise, etc. and MS disease. The results of the included studies reveal that there was a significant relationship between exposure to air pollution and MS development and progression. Although the effect of air pollution in the pathogenesis of MS is notfully known, according to the results of the included studies exposure to polluted air can stimulate several mechanisms that act as risk factors for developing MS and for having disease relapses or neurological disability. The major potential mechanism is Dysimmune inflammatory responses subsequent oxidative stress (OS), which leads to neuroinflammation and breakdown of the normal balance between immunity and self-tolerance. Air pollutants induce and sustain chemical reactions that produce reactive oxygen species (ROSs) and nitrogen reactive species (RNSs) which can initiate inflammatory cascades via the redox-sensitive mitogen-activated protein kinase (MAPK) and NF-κB that recruit and activate neutrophils, monocytes, and dendritic cells that stimulate the adaptive immune responses such as Th1 and Th17 inflammatory responses. The uncontrolled inflammatory responses following these events cause cell death and the release of self-antigens capable of stimulating the production of auto-aggressive T-cells via enhancing antigen presentation and facilitate entry of these cells to the central nervous system. Thus, oxidative stress is the culprit in the systemic inflammation and immune imbalance development and progression, powerful risk factors in MS.
Topics: Air Pollutants; Air Pollution; Central Nervous System; Environmental Exposure; Humans; Multiple Sclerosis; Particulate Matter
PubMed: 33129851
DOI: 10.1016/j.envres.2020.110386 -
Neuroscience and Biobehavioral Reviews May 2022Early life exposure to air pollution has been associated with neurodevelopmental disorders. Emerging evidence are highlighting a possible impact of air pollution on... (Review)
Review
Early life exposure to air pollution has been associated with neurodevelopmental disorders. Emerging evidence are highlighting a possible impact of air pollution on typically developing children. Thirty papers were included in this review to systematically evaluate the association between air pollutants exposure in prenatal and/or postnatal periods and specific neurodevelopmental skills (i.e. intellective functioning, memory and learning, attention and executive functions, verbal language, numeric ability and motor and/or sensorimotor functions) in preschool- and school-age children. Detrimental effects of air pollutants on children's neurodevelopmental skills were observed, although they do not show clinically relevant performance deficits. The most affected domains were global intellective functioning and attention/executive functions. The pollutants that seem to represent the greatest risk are PM2.5, NO₂ and PAHs. Prenatal exposure is primarily associated with child neurodevelopment at pre-school and school ages. Early exposure to air pollutants is related to adverse neurodevelopmental outcomes in the general population of children. Further research is needed to support stronger conclusions.
Topics: Air Pollutants; Air Pollution; Child; Child, Preschool; Environmental Exposure; Female; Humans; Neurodevelopmental Disorders; Particulate Matter; Pregnancy
PubMed: 35331818
DOI: 10.1016/j.neubiorev.2022.104623