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1.
Is Air Pollution Associated with Increased Risk of Dementia? A Meta-Analysis of Epidemiological Research.
Dhiman, V, Trushna, T, Raj, D, Tiwari, RR
Neurology India. 2022;70(3):1004-1019
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Several studies have indicated that there may be a link between exposure to air pollution and the development of dementia. This study aimed to perform a systematic review and meta-analysis to determine the risk of developing dementia, cognitive decline, and/or Alzheimer’s disease (AD) following air pollution exposure. The results showed that exposure to small particulate matter (less than 2.5 micro m) was a risk factor for the development of dementia, AD and dementia caused by blockages in the blood vessels leading to the brain. Exposure to ozone was a risk factor for AD. Carbon monoxide, large particulate matter (10 micro m and less), nitrogen dioxide, nitrous oxides, and sulphur dioxide exposure was not a risk factor for any dementia related diseases. It was concluded that exposure to certain types of pollution may be detrimental to brain health and further research is required in developing countries, where pollution exposure can be particularly high. This study could be used by health care professionals to make informed decisions on the control of air pollution in those who are at risk of developing dementia or who are already suffering from this disease. The introduction of plants and air purifiers may be of benefit to those who are vulnerable.
Abstract
BACKGROUND There are prevailing inconsistencies in epidemiological research about air pollution being a risk factor for dementia. OBJECTIVE We performed meta-analyses to calculate the pooled estimates of the risk of developing dementia due to air pollution exposure. METHODS AND MATERIALS We performed a systematic search in PubMed, Google Scholar, The Cochrane Library, and J-GATEPLUS databases for peer-reviewed epidemiological studies reporting the risk of developing all-cause dementia, cognitive decline, Alzheimer's disease (AD), and vascular dementia (VaD) due to exposure to particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5) and less than 10 μm (PM10), ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), nitrogen oxides (NOX) and sulfur dioxide (SO2) from the beginning until December 2020. Meta-analysis was performed by adopting the random-effects model using Meta-XL. RESULTS In all-cause dementia, the pooled hazard ratio (HR) for PM2.5 and NO2 exposure was 1.03 [(95%CI: 1.01-1.06; I2 = 99% (P < 0.001)] and 1.00 [(95%CI: 1.00-1.01; I2 = 96% (P < 0.001)], respectively. The pooled HR for NOX was 1.00 [(95%CI: 1.00-1.01; I2 = 61% (P = 0.05)]. In AD, the pooled HRs for PM2.5 and O3 was 1.08 (95%CI: 1.01-1.15; I2 = 99% (P < 0.001)]) and 1.02 (95%CI: 0.96-1.08; I2 = 100% (P < 0.001)], respectively. In VaD, the pooled HR for PM2.5 exposure was 1.03 (95%CI: 1.01-1.06; I2 = 91% (P < 0.001)]. In NO2/NOX, the results were found to be equivocal. Meta-analysis could not be performed in cognitive decline because of wide variations in assessments methods. CONCLUSIONS The present study showed exposure to PM2.5 as a risk factor for all-cause dementia, AD, and VaD and exposure to O3 as a possible risk factor for AD. These findings can be used for policy measures and further research.
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Association between pesticide exposure and colorectal cancer risk and incidence: A systematic review.
Matich, EK, Laryea, JA, Seely, KA, Stahr, S, Su, LJ, Hsu, PC
Ecotoxicology and environmental safety. 2021;219:112327
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Pesticides that are applied to farms or yards can remain in the environment for longer than intended. The aim of this study was to investigate the association between human pesticide exposure and colorectal cancer (CRC) risk and incidence. This study is a systematic review of 139 studies (qualitative analysis). This review showed that there are similar numbers of significant positive and inverse associations between pesticide exposure and colon cancer, rectal cancer, or CRC risk. However, certain pesticides are of high concern in relation to these types of cancers. Authors conclude that further biological sample measurement studies are needed to determine the amount of time the pesticides or their metabolites remain in the environment or bio specimen from the population.
Abstract
BACKGROUND Studies investigating the association between pesticide exposure and colorectal cancer (CRC) risk have been inconclusive. OBJECTIVES Investigate the association between pesticide exposure and CRC risk through a systematic literature review. METHODS CRC has the fourth-highest rate of cancer-caused death in the US after lung cancer, breast cancer in women, and prostate cancer in men. Here we have conducted a systematic literature search on studies examining the association between any pesticide exposure and CRC risk using PubMed, MEDLINE via EBSCO host, and Embase according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. RESULTS Following the review, 139 articles were included for qualitative evaluation. Study participants were farmers, pesticide applicators, pesticide manufacturers, spouses of pesticide applicators, farm residents, Korean veterans of the Vietnam War, rural communities, and those who consumed food with pesticide residues. The studies' results were split between those with significant positive (39 significant results) and inverse (41 significant results) associations when comparing pesticide exposure and CRC risk. DISCUSSION From our literature review, we have identified a similar number of significant positive and inverse associations of pesticide exposure with CRC risk and therefore cannot conclude whether pesticide exposure has a positive or inverse association with CRC risk overall. However, certain pesticides such as terbufos, dicamba, trifluralin, S-ethyl dipropylthiocarbamate (EPTC), imazethapyr, chlorpyrifos, carbaryl, pendimethalin, and acetochlor are of great concern not only for their associated elevated risk of CRC, but also for the current legal usage in the United States (US). Aldicarb and dieldrin are of moderate concern for the positive associations with CRC risk, and also for the illegal usage or the detection on imported food products even though they have been banned in the US. Pesticides can linger in the soil, water, and air for weeks to years and, therefore, can lead to exposure to farmers, manufacturing workers, and those living in rural communities near these farms and factories. Approximately 60 million people in the US live in rural areas and all of the CRC mortality hotspots are within the rural communities. The CRC mortality rate is still increasing in the rural regions despite the overall decreasing of incidence and mortality of CRC elsewhere. Therefore, the results from this study on the relationship between pesticide exposure and CRC risk will help us to understand CRC health disparities.
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Presence of positive skin prick tests to inhalant allergens and markers of T2 inflammation in subjects with chronic spontaneous urticaria (CSU): a systematic literature review.
Wong, MM, Keith, PK
Allergy, asthma, and clinical immunology : official journal of the Canadian Society of Allergy and Clinical Immunology. 2020;16:72
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Urticaria is an immune driven skin reaction, which manifests as hives and swelling and results in significantly decreased quality of life in those who suffer from it. The causes are currently unknown, however airborne substances such as house dust mites and plant pollen may play a role in its development. This systematic review and meta-analysis of 18 studies aimed to determine the role of airborne allergens in the development of chronic spontaneous urticaria (CSU). The results showed that individuals with CSU were more likely to have a sensitivity to airborne allergens and that house dust mites were a leading cause of sensitivity. It was concluded that airborne associated sensitivity is of importance to the development of CSU. This study could be used by healthcare professionals to understand that airborne allergens may be a cause of CSU and that house dust mites may be involved in its development. It is important to determine the cause and eliminate it, to increase the chances of successful treatment.
Abstract
BACKGROUND Current guidelines do not recommend performing aeroallergen skin prick testing (SPT) in chronic spontaneous urticaria (CSU). OBJECTIVE The objective of this review was to investigate the presence of aeroallergen sensitization and markers of T2 inflammation in subjects with CSU. METHODS Systematic literature reviews to identify all studies that evaluated the presence of T2 markers of allergic inflammation in CSU subjects were performed. RESULTS In 16 studies that assessed the prevalence of positive SPT to multiple aeroallergens in CSU, 38.5% of CSU subjects had positive SPT. In three controlled studies, 34.2% of CSU subjects had positive SPT to multiple aeroallergens, compared to 13.6% of controls (p = 0.047). In 18 studies that assessed the prevalence of house dust mite (HDM) positive SPT in CSU, 27.5% of CSU subjects had positive SPT. In three controlled studies, 27.5% of CSU subjects had positive SPT to HDM, compared to 2.1% of controls (p = 0.047). Overall, CSU subjects were 3.1 times more likely to be aeroallergen-sensitized (95% CI 1.7-5.8, p = 0.0002) and 6.1 times more likely to be HDM-sensitized (95% CI 3.7-9.9, p < 0.00001) than controls. Mean total serum IgE (tIgE) levels were 238 kU/L and median tIgE levels were 164 kU/L, which was greater than the upper 90th percentile of normal (< 137 kU/L). Compared to healthy controls, CSU subjects were 6.5 times more likely to have IgG autoantibody against FcεR1α (p = 0.001), 2.4 times more likely to have IgG anti-IgE antibody (p = 0.03) and 5 times more likely to have anti-thyroid peroxidase (anti-TPO) antibody (p = 0.02). When corticosteroids were withheld for ≥ 28 days, mean blood eosinophil percentage was elevated at 5.9% (normal < 4%), but other studies reporting absolute count found the mean was in the normal range, 239 × 10 6 / L (normal < 400 × 10 6 / L). CONCLUSION Increased aeroallergen sensitization, tIgE, autoantibodies and blood eosinophil percentage in the CSU subjects indicates the possible importance of T2 inflammation in the pathogenesis of CSU. Further studies may be warranted to determine if specific allergen avoidance, desensitization or improvement in the mucosal allergic inflammation present in asthma and/or rhinitis has any benefit in the management of CSU.
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Respiratory and Allergic Effects in Children Exposed to Pesticides-A Systematic Review.
Buralli, RJ, Dultra, AF, Ribeiro, H
International journal of environmental research and public health. 2020;17(8)
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Agricultural pesticides are harmful chemicals used to protect plants from pests and diseases. There has been previous research showing a link between pesticide usage and respiratory symptoms, asthma, allergies, and lung function irregularities in children. To evaluate the relationship between pesticide usage and allergic and respiratory effects in children, 21 studies were included in this systematic review. This systematic review reports an association between multiple sources of pesticide exposure during fetal and early development and respiratory symptoms and allergies among children. Compared to high-income countries, children in the middle- and low-income countries were exposed to multiple pesticide sources. As current scientific evidence is sparse, more research is needed to determine the causal relationship between pesticides and respiratory and allergic symptoms in children. Robust research in low- and middle-income countries is necessary. Healthcare professionals can use the results of this study to understand the harmful effects of pesticide exposure in children and to take clinical decisions to reduce the exposure and its effects.
Abstract
Pesticide exposure may affect children's respiratory and allergic health, although results from epidemiological studies have not reached consensus. This review aims to analyze the scientific evidence on respiratory and allergic effects of exposure to agricultural pesticides in children aged up to 12 years old. The databases PubMed, Web of Science, Scielo, and Lilacs were screened to select articles published in English, Spanish, or Portuguese, and 21 articles were included in this review. Most investigations were conducted in North America (mostly in the United States), while no studies conducted in Latin America or Africa were found, despite their intensive use of pesticides. Children are exposed to pesticides through multiple pathways from the prenatal period throughout later developmental stages and may experience several respiratory effects. Most studies (79%) found positive associations with pesticide exposure and children's respiratory and allergic effects such as asthma, wheezing, coughs, acute respiratory infections, hay fever, rhinitis, eczema, chronic phlegm, and lung function impairments. Contrastingly, 21% of the studies found no associations between pesticide exposure and children's respiratory health. The vast differences among the characteristics of the studies hamper any comparison of the results. Exposure to pesticides may have several impacts on childhood respiratory health. More studies must be conducted, especially in low- and middle-income countries, preferably with comparable research protocols adapted to local realities. Efforts should be made to develop comprehensive risk mitigation strategies and behavioral interventions to reduce children's exposure to pesticides used in agriculture and respiratory health effects, and to ensure healthy childhood growth.
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Occupational Exposures and Neurodegenerative Diseases-A Systematic Literature Review and Meta-Analyses.
Gunnarsson, LG, Bodin, L
International journal of environmental research and public health. 2019;16(3)
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Parkinson’s disease, amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease are the most common neurodegenerative disorders. They primarily affect ageing individuals and are characterized by a steady progressive course because of increasing loss of specific neurons in the brain. The aim of this study was to assess neurodegenerative diseases in relation to main occupational exposures and investigate the possibility of publication bias. This study is a systematic review and meta-analysis of sixteen studies. Results show that exposure to pesticides brought about at least 50% increased risk for contracting the neurodegenerative diseases Parkinson’s disease, Alzheimer’s, or ALS. Exposure to lead involved at least a significant risk for ALS and Parkinson’s disease while non-lead exposures did not seem to involve risk. Furthermore, occupational exposure to electromagnetic fields may increase by 10% the risk for ALS and Alzheimer’s disease.
Abstract
Objectives: To carry out an integrated and stratified meta-analysis on occupational exposure to electromagnetic fields (EMFs), metals and pesticides and its effects on amyotrophic lateral sclerosis (ALS) and Parkinson's and Alzheimer's disease, and investigate the possibility of publication bias. Methods: In the current study, we updated our recently published meta-analyses on occupational exposures in relation to ALS, Alzheimer's and Parkinson's disease. Based on 66 original publications of good scientific epidemiological standard, according to the Meta-analysis of Observational Studies in Epidemiology (MOOSE) and the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) guidelines, we analysed subgroups by carrying out stratified meta-analyses on publication year, statistical precision of the relative risk (RR) estimates, inspection of the funnel plots and test of bias. Results: Based on 19 studies the weighted RR for occupational exposure to EMFs was 1.26 (95% confidence interval (CI) 1.07⁻1.50) for ALS, 1.33 (95% CI 1.07⁻1.64) for Alzheimer's disease and 1.02 (95% CI 0.83⁻1.26) for Parkinson's disease. Thirty-one studies concerned occupational exposure to pesticides and the weighted RR was 1.35 (95% CI 1.02⁻1.79) for ALS, 1.50 (95% CI 0.98⁻2.29) for Alzheimer's disease and 1.66 (95% CI 1.42⁻1.94) for Parkinson's disease. Finally, 14 studies concerned occupational exposure to metals and only exposure to lead (five studies) involved an elevated risk for ALS or Parkinson's disease and the weighted RR was 1.57 (95% CI 1.11⁻2.20). The weighted RR for all the non-lead exposures was 0.97 (95% CI 0.88⁻1.06). Conclusions: Exposure to pesticides increased the risk of getting the mentioned neurodegenerative diseases by at least 50%. Exposure to lead was only studied for ALS and Parkinson's disease and involved 50% increased risk. Occupational exposure to EMFs seemed to involve some 10% increase in risk for ALS and Alzheimer's disease only.
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Environmental Factors and the Risk of Brain Tumours in Young People: A Systematic Review.
Zumel-Marne, A, Castano-Vinyals, G, Kundi, M, Alguacil, J, Cardis, E
Neuroepidemiology. 2019;53(3-4):121-141
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Brain tumours (BT) are the second most common cancer type in children and young adults. The aim of this study was to review and summarize the scientific literature about exposure to environmental factors and BT risk. This study is a systematic review of 70 articles of which 69% (n = 49) had >200 cases recruited. Results indicate a possible association between exposure to heavy metals, passive smoking, water and air pollutants, use of pesticides and living on a farm with farm animals, meat consumption during preconception, pregnancy or early infancy and an increased risk of BT in children and young adults. Authors conclude that larger scale studies with better exposure assessment are needed to evaluate possible associations between environmental risk factors and BT in young people.
Abstract
BACKGROUND Brain tumours (BT) are one of the most frequent tumour types in young people, although little is known about their risk factors. OBJECTIVE The objective of the current work was to review and summarize the scientific literature concerning exposure to environmental factors and BT risk in young people (<25 years old). METHODS PUBMED, Embase, Cochrane Library, Scopus, IME-Biomedina (bibliographic database of Consejo Superior de Investigaciones Científicas) and Web of science databases were searched. A score to assess the quality of the methodological information was created. RESULTS Some possible associations between BT risk in young people were reported for cadmium, consumption of well water, presence of nitrate or nitrate-nitrogen in tap water, mother's passive smoking, air pollution, parental handling of pesticides at home and/or professional pesticide treatment within houses, living on a farm and/or with farm animals, some parental occupations and high amount of meat consumption. CONCLUSIONS Although many of the studies reviewed suggest associations between the environmental exposures and BT in children and young adults, at present no reliable conclusion can be drawn as most results are based on small number of cases and exposure assessment is limited. Large-scale studies with better exposure assessment are needed to shed light on these possible associations, especially on exposure to heavy metals, tab water consumption, pesticides and parental smoking.
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Swimming pool exposure is associated with autonomic changes and increased airway reactivity to a beta-2 agonist in school aged children: A cross-sectional survey.
Cavaleiro Rufo, J, Paciência, I, Silva, D, Martins, C, Madureira, J, Oliveira Fernandes, E, Padrão, P, Moreira, P, Delgado, L, Moreira, A
PloS one. 2018;13(3):e0193848
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Studies have shown an association between swimming in chemically-treated pools and a higher risk of asthma in children, although the mechanism is not fully understood. This study aimed to investigate how swimming pool attendance influences lung and nervous system function in school-aged children. Around 800 children were classified as current swimmers (CS), past swimmers (PS) or non-swimmers (NS). The children underwent several tests to determine their lung function and allergic response to common allergens. Parasympathetic nervous system function was tested by measuring the speed at which their pupils constricted in response to light. The current swimmers group had significantly lower pupil constriction speeds compared to PS and NS, suggesting a poorer functioning of the autonomic nervous system, possibly due to inflammation resulting from swimming pool chemical exposure. CS experienced greater constriction of the airways compared to NS. A non-significant trend for a higher risk of asthma, atopic eczema and rhinitis, was observed in swimmers. The authors concluded that swimming pool attendance appears to be associated with autonomic nervous system changes and increased baseline airway smooth muscle constriction even in children without asthma.
Abstract
BACKGROUND Endurance swimming exercises coupled to disinfection by-products exposure has been associated with increased airways dysfunction and neurogenic inflammation in elite swimmers. However, the impact of swimming pool exposure at a recreational level on autonomic activity has never been explored. Therefore, this study aimed to investigate how swimming pool attendance is influencing lung and autonomic function in school-aged children. METHODS A total of 858 children enrolled a cross sectional survey. Spirometry and airway reversibility to beta-2 agonist, skin-prick-tests and exhaled nitric oxide measurements were performed. Pupillometry was used to evaluate autonomic nervous function. Children were classified as current swimmers (CS), past swimmers (PS) and non-swimmers (NS), according to the amount of swimming practice. RESULTS Current swimmers group had significantly lower maximum and average pupil constriction velocities when compared to both PS and NS groups (3.8 and 5.1 vs 3.9 and 5.3 vs 4.0 and 5.4 mm/s, p = 0.03 and p = 0.01, respectively). Moreover, affinity to the beta-2 agonist and levels of exhaled nitric oxide were significantly higher in CS when compared to NS (70 vs 60 mL and 12 vs 10 ppb, p<0.01 and p = 0.03, respectively). A non-significant trend for a higher risk of asthma, atopic eczema and allergic rhinitis was found with more years of swimming practice, particularly in atopic individuals (β = 1.12, 1.40 and 1.31, respectively). After case-case analysis, it was possible to observe that results were not influenced by the inclusion of individuals with asthma. CONCLUSIONS Concluding, swimming pool attendance appears to be associated with autonomic changes and increased baseline airway smooth muscle constriction even in children without asthma.
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Comparison of Oropharyngeal Microbiota from Children with Asthma and Cystic Fibrosis.
Boutin, S, Depner, M, Stahl, M, Graeber, SY, Dittrich, SA, Legatzki, A, von Mutius, E, Mall, M, Dalpke, AH
Mediators of inflammation. 2017;2017:5047403
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The lungs are under constant exposure to microorganisms contained in inhaled air and the upper respiratory tract. In healthy subjects, the lower airways are colonized by bacteria. Changes in the microbiome are found in several lung diseases associated with chronic airway inflammation including chronic obstructive pulmonary disease, asthma and cystic fibrosis. The aim of the study was to find out whether the throat microbiota of children with asthma and cystic fibrosis differ from healthy children. Another aim was to find out whether the throat microbiota of children with asthma differ from those with cystic fibrosis. The study compared the throat microbiota of healthy school-aged children with that of age-matched children with asthma and cystic fibrosis. Results indicate that the microbiota of cystic fibrosis, asthmatic, and healthy children show high levels of similarities with a strong core microbiota. The cystic fibrosis group show a decrease in both diversity and total bacterial load in the throat in comparison to asthmatic and control children. The cystic fibrosis group also showed a significant increase in typical pathogens in the throat. Based on the results, the authors conclude that the three patient groups had a core microbiome and a host regulation that favours the growth of commensals.
Abstract
A genuine microbiota resides in the lungs which emanates from the colonization by the oropharyngeal microbiota. Changes in the oropharyngeal microbiota might be the source of dysbiosis observed in the lower airways in patients suffering from asthma or cystic fibrosis (CF). To examine this hypothesis, we compared the throat microbiota from healthy children (n = 62) and that from children with asthma (n = 27) and CF (n = 57) aged 6 to 12 years using 16S rRNA amplicon sequencing. Our results show high levels of similarities between healthy controls and children with asthma and CF revealing the existence of a core microbiome represented by Prevotella, Streptococcus, Neisseria, Veillonella, and Haemophilus. However, in CF, the global diversity, the bacterial load, and abundances of 53 OTUs were significantly reduced, whereas abundances of 6 OTUs representing opportunistic pathogens such as Pseudomonas, Staphylococcus, and Streptococcus were increased compared to those in healthy controls controls and asthmatics. Our data reveal a core microbiome in the throat of healthy children that persists in asthma and CF indicating shared host regulation favoring growth of commensals. Furthermore, we provide evidence for dysbiosis with a decrease in diversity and biomass associated with the presence of known pathogens consistent with impaired host defense in children with CF.