Reviews in environmental health: How systematic are they?

Factors influencing the effectiveness of nature-based interventions (NBIs) aimed at improving mental health and wellbeing: An umbrella review

Several systematic reviews support nature-based interventions (NBIs) as a mechanism of enhancing mental health and wellbeing. However, the available evidence for the effectiveness of these interventions is fragmentary and mixed. The heterogeneity of existing evidence and significant fragmentation of knowledge within the field make it difficult to draw firm conclusions regarding the effectiveness of NBIs. This can only limit the development of interventions to support personal and planetary wellbeing, potentially resulting in ineffective and ill-targeted investment decisions. These concerns have hindered the translation of research evidence into practice and guidelines are urgently required to assist researchers, practitioners and policymakers in developing interventions to promote environmental stewardship and meet the health needs of diverse communities. A higher-order or meta-level synthesis is required to make sense of this evidence. This umbrella review synthesises evidence on the barriers and enablers to nature-based interventions through a summative review of existing published systematic reviews and meta-analyses. A systematic search in PsycINFO, PubMed, Greenfile, Web of Science, Embase, Scopus, Academic Search Complete (EBSCO), Environment Complete (EBSCO), Cochrane Library, CINAHL, Health Policy Reference Centre and Google Scholar was performed. This is a mixed method review, and systematic reviews with both quantitative and qualitative data synthesis were included. 64 systematic reviews were included in the synthesis. The descriptive data, extracted from each study, forms an overview of the characteristics of available evidence on nature-based interventions. A narrative synthesis is used to present the potential factors influencing the outcomes of NBIs. The risk of bias of the systematic reviews was assessed using a 16-item Assessment of Multiple Systematic Reviews 2 (AMSTAR2) checklist. Directions for future research, potential quality needs and recommendations for future research, policymaking, and practice are discusssed.

Effects of air pollution on the development and progression of digestive diseases: an umbrella review of systematic reviews and meta-analyses

Air pollution, especially particulate matter (PM), is one of the most common risk factors for global burden of disease. However, its effect on the risk of digestive diseases is unclear. Herein, we attempt to explore this issue by reviewing the existing evidence from published meta-analyses. We conducted a systematic literature search to identify all relevant meta-analyses regarding the association of air pollution with digestive diseases, and summarize their major findings. We assessed the methodological quality and evidence quality of the included meta-analyses using the AMSTAR-2 and GRADE tools, respectively, and the overlap of primary studies was assessed by the GROOVE tool. Nine meta-analyses were included in our analysis, containing 43 primary studies with high overlap. In the included meta-analyses, the methodological quality was from critically low to moderate, and the evidence quality was from very low to moderate. The exposure was primarily PM2.5. Seven, four, and one meta-analysis investigated the effect of air pollution on liver diseases, gastrointestinal diseases, and pancreatic diseases, respectively. PM2.5 exposure was significantly associated with liver dysfunction, chronic liver diseases, liver cancer, and colorectal cancer, but not oesophagus cancer, gastric cancer, or pancreatic cancer. Based on very low to moderate quality evidence from meta-analyses, PM2.5 exposure may contribute to the development of some digestive diseases, especially liver diseases.

Viral respiratory infections and air pollution: A review focused on research in Poland

The COVID-19 pandemic has reinforced an interest in the relationship between air pollution and respiratory viral infections, indicating that their burden can be increased under poor air quality. This paper reviews the pathways through which air pollutants can enhance susceptibility to such infections and aggravate their clinical course and outcome. It also summarizes the research exploring the links between various viral infections and exposure to solid and gaseous pollution in Poland, a region characterized by poor air quality, especially during a heating season. The majority of studies focused on concentrations of particulate matter (PM; 86.7%); the other pollutants, i.e., BaP, benzene, CO, NOx, O3, and SO2, were studied less often and sometimes only in the context of a particular infection type. Most research concerned COVID-19, showing that elevated levels of PM and NO2 correlated with higher morbidity and mortality, while increased PM2.5 and benzo[a]pyrene levels were related to worse clinical course and outcome in hospitalized, regardless of age and dominant SARS-CoV-2 variant. PM10 and PM2.5 levels were also associated with the incidence of influenza-like illness and, along with NO2 concentrations, with a higher rate of children's hospitalizations due to lower respiratory tract RSV infections. Higher levels of air pollutants also increased hospitalization due to bronchitis (PM, NOx, and O3) and emergency department admission due to viral croup (PM10, PM2.5, NOx, CO, and benzene). Although the conducted studies imply only correlations and have other limitations, as discussed in the present paper, it appears that improving air quality through reducing combustion processes in energy production in Poland should be perceived as a part of multilayered protection measures against respiratory viral infections, decreasing the healthcare costs of COVID-19, lower tract RSV infections, influenza, and other respiratory viral diseases prevalent between autumn and early spring, in addition to other health and climate benefits.

Systems for rating bodies of evidence used in systematic reviews of air pollution exposure and reproductive and children's health: a methodological survey

BACKGROUND

Translating findings from systematic reviews assessing associations between environmental exposures and reproductive and children's health into policy recommendations requires valid and transparent evidence grading.

METHODS

We aimed to evaluate systems for grading bodies of evidence used in systematic reviews of environmental exposures and reproductive/ children's health outcomes, by conducting a methodological survey of air pollution research, comprising a comprehensive search for and assessment of all relevant systematic reviews. To evaluate the frameworks used for rating the internal validity of primary studies and for grading bodies of evidence (multiple studies), we considered whether and how specific criteria or domains were operationalized to address reproductive/children's environmental health, e.g., whether the timing of exposure assessment was evaluated with regard to vulnerable developmental stages.

RESULTS

Eighteen out of 177 (9.8%) systematic reviews used formal systems for rating the body of evidence; 15 distinct internal validity assessment tools for primary studies, and nine different grading systems for bodies of evidence were used, with multiple modifications applied to the cited approaches. The Newcastle Ottawa Scale (NOS) and the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) framework, neither developed specifically for this field, were the most commonly used approaches for rating individual studies and bodies of evidence, respectively. Overall, the identified approaches were highly heterogeneous in both their comprehensiveness and their applicability to reproductive/children's environmental health research.

CONCLUSION

Establishing the wider use of more appropriate evidence grading methods is instrumental both for strengthening systematic review methodologies, and for the effective development and implementation of environmental public health policies, particularly for protecting pregnant persons and children.

Maternal exposure to ambient air temperature and adverse birth outcomes: An umbrella review of systematic reviews and meta-analyses

BACKGROUND

Multiple systematic reviews on prenatal ambient temperature and adverse birth outcomes exist, but the overall epidemiological evidence and the appropriate metric for thermal stress remain unclear. An umbrella review was performed to summarise and appraise the evidence with recommendations.

METHODS

Systematic reviews and meta-analyses on the associations between ambient temperature and adverse birth outcomes (preterm birth, stillbirth, birth weight, low birth weight, and small for gestational age) up to December 20, 2023, were synthesised according to a published protocol. Databases PubMed, CINAHL, Scopus, MEDLINE/Ovid, EMBASE/Ovid, Web of Science Core Collection, systematic reviews repositories, electronic grey literature, and references were searched. Risk of bias was assessed using Joanna Briggs Institute's critical appraisal tool.

RESULTS

Eleven systematic reviews, including two meta-analyses, were included. This comprised 90 distinct observational studies that employed multiple temperature assessment metrics with a very high overlap of primary studies. Primary studies were mostly from the United States while both Africa and South Asia contributed only three studies. A majority (7 out of 11) of the systematic reviews were rated as moderate risk of bias. All systematic reviews indicated that maternal exposures to both extremely high and low temperatures, particularly during late gestation are associated with increased risks of preterm birth, stillbirth, and reduced fetal growth. However, due to great differences in the exposure assessments, high heterogeneity, imprecision, and methodological limitations of the included systematic reviews, the overall epidemiological evidence was classified as probable evidence of causation. No study assessed biothermal metrics for thermal stress.

CONCLUSIONS

Despite the notable methodological differences, prenatal exposure to extreme ambient temperatures, particularly during late pregnancy, was associated with adverse birth outcomes. Adhering to the appropriate systematic review guidelines for environmental health research, incorporating biothermal metrics into exposure assessment, evidence from broader geodemographic settings, and interventions are recommended in future studies.

A plausibility database summarizing the level of evidence regarding the hazards induced by the exposome on children health

Childhood diseases correspond to major public health issues. A large number of studies using different approaches provide evidence regarding effects of environmental exposures, encompassed in the exposome, on children's health. We aimed to summarize the overall level of evidence (LoE) from all streams of evidence regarding exposome effects on child health. For 88 selected chemical and urban factors, we retrieved the conclusions of agency reports or literature reviews published between 2015 and 2021 regarding effects on child health, including cardiovascular, metabolic, neurodevelopmental, respiratory and other health outcomes. Adapted versions of PRISMA flowchart and AMSTAR-2 tool were used to select and assess the quality of the systematic reviews retrieved from PubMed and SCOPUS databases. For each factor-outcome pair, conclusions in three streams of evidence (epidemiological, toxicological and mechanistic, the latter corresponding to in vitro and in silico approaches) were translated into stream-specific LoEs and then combined into an overall LoE ranging from "very unlikely" to "very likely". The 88 environmental factors were implied in 611 factor-outcome pairs. Forty-four pairs (7%), corresponding to 16 factors, had a very likely overall LoE (≥80%); 127 pairs (21%), corresponding to 49 factors, had a likely or more overall LoE (≥60%). For 81 pairs (13%), no evidence was available in agency reports or published reviews, while for 275 pairs (45%), corresponding to 68 factors, the overall LoE was very unlikely (<20%). Exposure factors with the greatest number of associated health outcomes with a high overall LoE were HCB, PCBs, temperature (8 outcomes), PFOA (7 outcomes), PFOS, cotinine (6 outcomes), arsenic, lead (5 outcomes), bisphenols A and S, PFNA and PM2.5 (4 outcomes), DDT, DDE and DDD, PFHxA, PFDA, green space, UV radiation (3 outcomes). We developed an approach to extract and summarize the existing evidence about effects of environmental factors on health. The plausibility database built for children's health can be used to identify research gaps, conduct quantitative risk assessment studies. It could be expanded to consider a larger fraction of the exposome and other age groups and should be updated on a regular basis.

Prenatal exposure to ambient air pollutants and congenital heart defects: An umbrella review

BACKGROUND

Prenatal exposure to ambient air pollutants has been linked to congenital heart defects (CHD), but findings of existing systematic reviews have been mixed.

OBJECTIVE

To assess the epidemiological evidence on associations between prenatal exposure to ambient air pollutants and CHD subtypes, based on a systematic overview of reviews ("umbrella review").

METHODS

We conducted a systematic search for reviews assessing associations between prenatal exposure to criteria air pollutants and CHD. The risk of bias was evaluated using the Risk of Bias in Systematic Reviews (ROBIS) tool. The certainty of the systematic review findings was graded using the Navigation Guide methodology.

RESULTS

We identified eleven systematic reviews, including eight with meta-analyses, assessing in total 35 primary studies of prenatal exposure to criteria air pollutants and various CHD subtypes. The certainty of the findings of four meta-analyses indicating an increased risk for coarctation of the aorta associated with nitrogen dioxide exposure was rated as moderate. The certainty of findings indicating positive, inverse, or null associations for other pollutant-subtype combinations was rated as very low to low, based on low precision and high statistical heterogeneity of summary odds ratios (SOR), substantial inconsistencies between review findings, and methodological limitations of the systematic reviews.

DISCUSSION

The inconsistent findings and high statistical heterogeneity of many SOR of the included systematic reviews may partly be traced to differences in methodological approaches, and the risk of bias across included reviews (e.g., inclusion criteria, systematic search strategies, synthesis methods) and primary studies (e.g., exposure assessment, diagnostic criteria). Adherence to appropriate systematic review guidelines for environmental health research, as well as rigorous evaluation of risk of bias in primary studies, are essential for future risk assessments and policy-making. Still, our findings suggest that prenatal exposure to ambient air pollutants may increase risks for at least some CHD subtypes.

Conducting evaluations of evidence that are transparent, timely and can lead to health-protective actions

BACKGROUND

In February 2021, over one hundred scientists and policy experts participated in a web-based Workshop to discuss the ways that divergent evaluations of evidence and scientific uncertainties are used to delay timely protection of human health and the environment from exposures to hazardous agents. The Workshop arose from a previous workshop organized by the European Environment Agency (EEA) in 2008 and which also drew on case studies from the EEA reports on 'Late Lessons from Early Warnings' (2001, 2013). These reports documented dozens of hazardous agents including many chemicals, for which risk reduction measures were delayed for decades after scientists and others had issued early and later warnings about the harm likely to be caused by those agents.

RESULTS

Workshop participants used recent case studies including Perfluorooctanoic acid (PFOA), Extremely Low Frequency - Electrical Magnetic Fields (ELF-EMF fields), glyphosate, and Bisphenol A (BPA) to explore myriad reasons for divergent outcomes of evaluations, which has led to delayed and inadequate protection of the public's health. Strategies to overcome these barriers must, therefore, at a minimum include approaches that 1) Make better use of existing data and information, 2) Ensure timeliness, 3) Increase transparency, consistency and minimize bias in evidence evaluations, and 4) Minimize the influence of financial conflicts of interest.

CONCLUSION

The recommendations should enhance the production of "actionable evidence," that is, reliable evaluations of the scientific evidence to support timely actions to protect health and environments from exposures to hazardous agents. The recommendations are applicable to policy and regulatory settings at the local, state, federal and international levels.

Improving the quality of toxicology and environmental health systematic reviews: What journal editors can do

Systematic reviews are fast increasing in prevalence in the toxicology and environmental health literature. However, how well these complex research projects are being conducted and reported is unclear. Since editors have an essential role in ensuring the scientific quality of manuscripts being published in their journals, a workshop was convened where editors, systematic review practitioners, and research quality control experts could discuss what editors can do to ensure the systematic reviews they publish are of sufficient scientific quality. Interventions were explored along four themes: setting standards; reviewing protocols; optimizing editorial workflows; and measuring the effectiveness of editorial interventions. In total, 58 editorial interventions were proposed. Of these, 26 were shortlisted for being potentially effective, and 5 were prioritized as short-term actions that editors could relatively easily take to improve the quality of published systematic reviews. Recent progress in improving systematic reviews is summarized, and outstanding challenges to further progress are highlighted.