Systems Science Approaches for Global Environmental Health Research: Enhancing Intervention Design and Implementation for Household Air Pollution (HAP) and Water, Sanitation, and Hygiene (WASH) Programs

Exploring the use of solid fuels for cooking and household air pollution in informal settlements through photovoice: The Fuel to Pot study in Ndirande (Malawi) and Mukuru (Kenya)

INTRODUCTION

Worldwide, 2.4 billion people rely on solid fuels such as wood or charcoal for cooking, leading to approximately 3.2 million deaths per year from illnesses attributable to household air pollution. Across Africa, household air pollution generated by solid fuel use accounts for nearly 700,000 deaths each year. Most studies to date have focused either household air pollution exposure, its impacts on particular health outcomes or on the efficacy of mitigation interventions. However, the economic, social, and cultural determinants of household air pollution in Africa are still poorly understood. The purpose of this study was to explore people's experience of using solid fuels for cooking in two informal settlements, Ndirande in Malawi and Mukuru in Kenya, and the associated harms caused by household air pollution.

METHODS

We adopted a community-based participatory method, photovoice, which was conducted with 9 participants in Ndirande and 10 participants in Mukuru. Participants took pictures reflecting their experiences and perceptions of household air pollution harms over a two-week period, and later discussed, sorted and analysed those in a series of meetings. Thematic analysis was used to analyse the data.

RESULTS

With their pictures, participants described fuel stacking and switching behaviours in their communities. They described a mix of charcoal, firewood and other biomass fuels use. They also expressed their awareness and perceptions of the harms caused by smoke when cooking. Participants explained the simple behaviours used by residents to minimize the harms of household air pollution to themselves and within their own household. Other themes explored the roles and responsibilities for procuring fuels in the home, and the stated solutions required to address the issues and manage the transition to cleaner fuels in those informal settlements.

CONCLUSION

This study highlights not only the need to understand the daily life, priorities and concerns of those who use solid fuels on informal settlements, but also the urgency to place them and their experience at the heart of the solutions that will reduce the health harms of household air pollution.

Bridges and Mechanisms: Integrating Systems Science Thinking into Implementation Research

We present a detailed argument for how to integrate, or bridge, systems science thinking and methods with implementation science. We start by showing how fundamental systems science principles of structure, dynamics, information, and utility are relevant for implementation science. Then we examine the need for implementation science to develop and apply richer theories of complex systems. This can be accomplished by emphasizing a causal mechanisms approach. Identifying causal mechanisms focuses on the "cogs and gears" of public health, clinical, and organizational interventions. A mechanisms approach focuses on how a specific strategy will produce the implementation outcome. We show how connecting systems science to implementation science opens new opportunities for examining and addressing social determinants of health and conducting equitable and ethical implementation research. Finally, we present case studies illustrating successful applications of systems science within implementation science in community health policy, tobacco control, health care access, and breast cancer screening.

Understanding the Cardiovascular and Metabolic Health Effects of Air Pollution in the Context of Cumulative Exposomic Impacts

Poor air quality accounts for more than 9 million deaths a year globally according to recent estimates. A large portion of these deaths are attributable to cardiovascular causes, with evidence indicating that air pollution may also play an important role in the genesis of key cardiometabolic risk factors. Air pollution is not experienced in isolation but is part of a complex system, influenced by a host of other external environmental exposures, and interacting with intrinsic biologic factors and susceptibility to ultimately determine cardiovascular and metabolic outcomes. Given that the same fossil fuel emission sources that cause climate change also result in air pollution, there is a need for robust approaches that can not only limit climate change but also eliminate air pollution health effects, with an emphasis of protecting the most susceptible but also targeting interventions at the most vulnerable populations. In this review, we summarize the current state of epidemiologic and mechanistic evidence underpinning the association of air pollution with cardiometabolic disease and how complex interactions with other exposures and individual characteristics may modify these associations. We identify gaps in the current literature and suggest emerging approaches for policy makers to holistically approach cardiometabolic health risk and impact assessment.

Reinforcing Feedbacks for Sustainable Implementation of Rural Drinking-Water Treatment Technology

Progress toward universal access to safe drinking water depends on rural water service delivery models that incorporate water safety management. Water supplies of all types have high rates of fecal contamination unless water safety risks are actively managed through water source protection, treatment, distribution, and storage. Recognizing the role of treatment within this broader risk-based framework, this study focuses on the implementation of passive chlorination and ultraviolet (UV) disinfection technologies in rural settings. These technologies can reduce the health risk from microbiological contaminants in drinking water; however, technology-focused treatment interventions have had limited sustainability in rural settings. This study examines the requirements for sustainable implementation of rural water treatment through qualitative content analysis of 26 key informant interviews, representing passive chlorination and UV disinfection projects in rural areas in South America, Africa, and Asia. The analysis is aligned with the RE-AIM framework and delivers insight into 18 principal enablers and barriers to rural water treatment sustainability. Analysis of the interrelationships among these factors identifies leverage points and encourages fit-for-purpose intervention design reinforced by collaboration between facilitating actors through hybrid service delivery models. Further work should prioritize health impact evidence, water quality reporting guidance, and technological capabilities that optimize trade-offs in fit-for-purpose treatment design.

Effects of Behavioral, Clinical, and Policy Interventions in Reducing Human Exposure to Bisphenols and Phthalates: A Scoping Review

BACKGROUND

There is growing interest in evidence-based interventions, programs, and policies to mitigate exposures to bisphenols and phthalates and in using implementation science frameworks to evaluate hypotheses regarding the importance of specific approaches to individual or household behavior change or institutions adopting interventions.

OBJECTIVES

This scoping review aimed to identify, categorize, and summarize the effects of behavioral, clinical, and policy interventions focused on exposure to the most widely used and studied bisphenols [bisphenol A (BPA), bisphenol S (BPS), and bisphenol F (BPF)] and phthalates with an implementation science lens.

METHODS

A comprehensive search of all individual behavior, clinical, and policy interventions to reduce exposure to bisphenols and phthalates was conducted using PubMed, Web of Science, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and Google Scholar. We included studies published between January 2000 and November 2022. Two reviewers screened references in CADIMA, then extracted data (population characteristics, intervention design, chemicals assessed, and outcomes) for studies meeting inclusion criteria for the present review.

RESULTS

A total of 58 interventions met the inclusion criteria. We classified interventions as dietary (n = 27 ), clinical (n = 13 ), policy (n = 14 ), and those falling outside of these three categories as "other" (n = 4 ). Most interventions (81%, 47/58) demonstrated a decrease in exposure to bisphenols and/or phthalates, with policy level interventions having the largest magnitude of effect.

DISCUSSION

Studies evaluating policy interventions that targeted the reduction of phthalates and BPA in goods and packaging showed widespread, long-term impact on decreasing exposure to bisphenols and phthalates. Clinical interventions removing bisphenol and phthalate materials from medical devices and equipment showed overall reductions in exposure biomarkers. Dietary interventions tended to lower exposure with the greatest magnitude of effect in trials where fresh foods were provided to participants. The lower exposure reductions observed in pragmatic nutrition education trials and the lack of diversity (sociodemographic backgrounds) present limitations for generalizability to all populations. https://doi.org/10.1289/EHP11760.

Reflective questioning to guide socially just global health reform: a narrative review and expert elicitation

Recent research has highlighted the impacts of colonialism and racism in global health, yet few studies have presented concrete steps toward addressing the problems. We conducted a narrative review to identify published evidence that documented guiding frameworks for enhancing equity and inclusion in global health research and practice (GHRP). Based on this narrative review, we developed a questionnaire with a series of reflection questions related on commonly reported challenges related to diversity, inclusion, equity, and power imbalances. To reach consensus on a set of priority questions relevant to each theme, the questionnaire was sent to a sample of 18 global health experts virtually and two rounds of iterations were conducted. Results identified eight thematic areas and 19 reflective questions that can assist global health researchers and practitioners striving to implement socially just global health reforms. Key elements identified for improving GHRP include: (1) aiming to understand the historical context and power dynamics within the areas touched by the program; (2) promoting and mobilizing local stakeholders and leadership and ensuring measures for their participation in decision-making; (3) ensuring that knowledge products are co-produced and more equitably accessible; (4) establishing a more holistic feedback and accountability system to understand needed reforms based on local perspectives; and (5) applying systems thinking to addressing challenges and encouraging approaches that can be sustained long-term. GHRP professionals should reflect more deeply on how their goals align with those of their in-country collaborators. The consistent application of reflective processes has the potential to shift GHRP towards increased equity.

Impact of technology and economic complexity on environmental pollution and economic growth in developing and developed countries: using IPAT and STIRPAT models

These days, the most serious threats to the global economy, society, and humans are climate change and global warming, mainly rooted in the sharp increase of economic activities and their concomitant greenhouse gas emissions. This paper aims to investigate how economic complexity and various sectors of the economy affect environmental and economic development. This study employs a modified IPAT and STIRPAT model to investigate the relationship of environmental pollution and economic development with economic complexity, economic structure, and technology in 21 MENA and 34 OECD countries between 1971-2017. Our findings show that economic complexity and industrialization positively affect economic growth in both groups of countries. However, economic complexity and industrialization affect environmental pollution in MENA and developing countries positively but in OECD and developed countries negatively. This relationship accepts the Environmental Kuznets Hypothesis for the nexus of economic complexity and environmental pollution. According to the findings, policymakers in developing countries should increase environmental considerations in their development planning. Also, developed countries should assist developing countries in their endeavors to decrease environmental contamination by supplying technology transfer and financial aid.

Global, regional, and national burden of preterm birth attributable to ambient and household PM2.5 from 1990 to 2019: Worsening or improving?

BACKGROUND

Maternal exposure to fine particular matter (PM_2.5) during pregnancy, including ambient and household PM_2.5, has been linked with increased risk of preterm birth (PTB). However, the global spatio-temporal distribution of PTB-related deaths and disability-adjusted life years (DALYs) attributable to PM_2.5 is not well documented. We estimated the global, regional, and national patterns and trends of PTB burden attributable to both ambient and household PM_2.5 from 1990 to 2019.

METHODS

Based on the Global Burden of Disease Study (GBD) 2019 database, we obtained the numbers of deaths and DALYs as well as age-standardized mortality rate (ASMR) and age-standardized DALY rate (ASDR) of PTB attributable to total, ambient, and household PM_2.5 by socio-demographic index (SDI) and sex during 1990-2019. The average annual percentage changes (AAPCs) were calculated to assess the temporal trends of attributable burdens.

RESULTS

In 2019, 126,752 deaths and 11.3 million DALYs related to PTB worldwide (two-thirds in Western Sub-Saharan Africa and South Asia) could be caused by excess PM_2.5 above the theoretical minimum-risk exposure level (TMREL), of which 39 % and 61 % were attributable to ambient PM_2.5 and household PM_2.5, respectively. From 1990 to 2019, the global ASMR due to ambient PM_2.5 increased slightly by 7.08 % whereas that due to household PM_2.5 decreased substantially by 58.81 %, although the latter still dominated the attributable PTB burden, especially in low and low-middle SDI regions. Similar results were also observed for ASDRs. In addition, PTB burden due to PM_2.5 was higher in male infants and in lower SDI regions.

CONCLUSIONS

Globally in 2019, PM_2.5 remains a great concern on the PTB burden, especially in Western Sub-Saharan Africa and South Asia. Between 1990 and 2019, age-standardized burden of PTB due to ambient PM_2.5 increased globally, while that due to household PM_2.5 decreased markedly but still dominated in low and low-middle SDI regions.

Effectiveness of a home-environmental intervention package and an early child development intervention on child health and development in high-altitude rural communities in the Peruvian Andes: a cluster-randomised controlled trial

BACKGROUND

Unsafe drinking water, poor sanitation and hygiene, exposure to household air pollution and low cognitive and socio-emotional stimulation are risk factors affecting children in low- and middle-income countries. We implemented an integrated home-environmental intervention package (IHIP), comprising a kitchen sink, hygiene education and a certified improved biomass cookstove, and an early child development (ECD) programme to improve children´s health and developmental outcomes in the rural high-altitude Andes of Peru.

METHODS

We conducted a one-year cluster-randomised controlled trial among 317 children < 36 months divided into 4 arms (IHIP + ECD, IHIP, ECD, and Control) and 40 clusters (10 clusters per arm). ECD status (socio-emotional, fine and gross motor, communication, cognitive skills, and an overall performance) measured with the Peruvian Infant Development Scale and the occurrence of self-reported child diarrhoea from caretakers were primary outcomes. Secondary outcomes included the occurrence of acute respiratory infections and the presence of thermo-tolerant faecal bacteria in drinking water. The trial was powered to compare each intervention against its control arm but it did not allow pairwise comparisons among the four arms. Primary analysis followed the intention-to-treat principle. For the statistical analysis, we employed generalised estimating equation models with robust standard errors and an independent correlation structure.

RESULTS

We obtained ECD information from 101 children who received the ECD intervention (individually and combined with IHIP) and 102 controls. Children who received the ECD intervention performed better in all the domains compared to controls. We found differences in the overall performance (64 vs. 39%, odd ratio (OR): 2.8; 95% confidence interval (CI): 1.6-4.9) and the cognitive domain (62 vs 46%, OR: 1.9; 95% CI: 1.1-3.5). Data analysis of child morbidity included 154 children who received the IHIP intervention (individually and combined with ECD) and 156 controls. We recorded 110,666 child-days of information on diarrhoea morbidity and observed 1.3 mean episodes per child-year in the children who received the IHIP intervention and 1.1 episodes in the controls. This corresponded to an incidence risk ratio of 1.2 (95% CI: 0.8-1.7).

CONCLUSIONS

Child stimulation improved developmental status in children, but there was no health benefit associated with the home-environmental intervention. Limited year-round access to running water at home and the possible contamination of drinking water after boiling were two potential factors linked to the lack of effect of the home-environmental intervention. Potential interactions between ECD and home-environmental interventions need to be further investigated.

TRIAL REGISTRATION

ISRCTN, ISRCTN-26548981. Registered 15 January 2018-Retrospectively registered, https://doi.org/10.1186/ISRCTN26548981 .

Malaria and Helminthic Co-Infection during Pregnancy in Sub-Saharan Africa: A Systematic Review and Meta-Analysis

Malaria and helminthic co-infection during pregnancy causes fetomaternal haemorrhage and foetal growth retardation. This study determined the pooled burden of pregnancy malaria and helminthic co-infection in sub-Saharan Africa. CINAHL, EMBASE, Google Scholar, Scopus, PubMed, and Web of Science databases were used to retrieve data from the literature, without restricting language and publication year. The Joanna Briggs Institute's critical appraisal tool for prevalence studies was used for quality assessment. STATA Version 14.0 was used to conduct the meta-analysis. The I2 statistics and Egger's test were used to test heterogeneity and publication bias. The random-effects model was used to estimate the pooled prevalence at a 95% confidence interval (CI). The review protocol has been registered in PROSPERO, with the number CRD42019144812. In total, 24 studies (n = 14,087 participants) were identified in this study. The pooled analysis revealed that 20% of pregnant women were co-infected by malaria and helminths in sub-Saharan Africa. The pooled prevalence of malaria and helminths were 33% and 35%, respectively. The most prevalent helminths were Hookworm (48%), Ascaris lumbricoides (37%), and Trichuris trichiura (15%). Significantly higher malaria and helminthic co-infection during pregnancy were observed. Health systems in sub-Saharan Africa must implement home-grown innovative solutions to underpin context-specific policies for the early initiation of effective intermittent preventive therapy.

Demonstrating a systems approach for integrating disparate data streams to inform decisions on children's environmental health

Background

The use of systems science methodologies to understand complex environmental and human health relationships is increasing. Requirements for advanced datasets, models, and expertise limit current application of these approaches by many environmental and public health practitioners.

Methods

A conceptual system-of-systems model was applied for children in North Carolina counties that includes example indicators of children’s physical environment (home age, Brownfield sites, Superfund sites), social environment (caregiver’s income, education, insurance), and health (low birthweight, asthma, blood lead levels). The web-based Toxicological Prioritization Index (ToxPi) tool was used to normalize the data, rank the resulting vulnerability index, and visualize impacts from each indicator in a county. Hierarchical clustering was used to sort the 100 North Carolina counties into groups based on similar ToxPi model results. The ToxPi charts for each county were also superimposed over a map of percentage county population under age 5 to visualize spatial distribution of vulnerability clusters across the state.

Results

Data driven clustering for this systems model suggests 5 groups of counties. One group includes 6 counties with the highest vulnerability scores showing strong influences from all three categories of indicators (social environment, physical environment, and health). A second group contains 15 counties with high vulnerability scores driven by strong influences from home age in the physical environment and poverty in the social environment. A third group is driven by data on Superfund sites in the physical environment.

Conclusions

This analysis demonstrated how systems science principles can be used to synthesize holistic insights for decision making using publicly available data and computational tools, focusing on a children’s environmental health example. Where more traditional reductionist approaches can elucidate individual relationships between environmental variables and health, the study of collective, system-wide interactions can enable insights into the factors that contribute to regional vulnerabilities and interventions that better address complex real-world conditions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-12682-3.

Systems Thinking for Effective Interventions in Global Environmental Health

Environmental health risks such as household air pollution due to burning solid fuels, inadequate water, sanitation, and hygiene, and chemical pollution disproportionately affect the poorest and most marginalized populations. While billions of dollars and countless hours of research have been applied toward addressing these issues in both development and humanitarian contexts, many interventions fail to achieve or sustain desired outcomes over time. This pattern points to the perpetuation of linear thinking, despite the complex nature of environmental health within these contexts. There is a need and an opportunity to engage in critical reflection of the dominant paradigms in the global environmental health community, including how they affect decision-making and collective learning. These paradigms should be adapted as needed toward the integration of diverse perspectives and the uptake of systems thinking. Participatory modeling, complexity-aware monitoring, and virtual simulation modeling can help achieve this. Additionally, virtual simulation modeling is relatively inexpensive and can provide a low-stakes environment for testing interventions before implementation.

Use, cost-effectiveness, and end user perspectives of a home solar lighting intervention in rural Uganda: a mixed methods, randomized controlled trial

Energy poverty is prevalent in resource-limited settings, leading households to use inefficient fuels and appliances that contribute to household air pollution. Randomized controlled trials of household energy interventions in low and middle income countries have largely focused on cooking services. Less is known about the adoption and impact of clean lighting interventions. We conducted an explanatory sequential mixed methods study as part of a randomized controlled trial of home solar lighting systems in rural Uganda in order to identify contextual factors determining the use and impact of the solar lighting intervention. We used sensors to track usage, longitudinally assessed household lighting expenditures and health-related quality of life, and performed cost-effectiveness analyses. Qualitative interviews were conducted with all 80 trial participants and coded using reflexive thematic analysis. Uptake of the intervention solar lighting system was high with daily use averaging 8.23 ± 5.30 hours per day. The intervention solar lighting system increased the EQ5D index by 0.025 [95% CI 0.002 - 0.048] and led to an average monthly reduction in household lighting costs by -1.28 [-2.52, -0.85] US dollars, with higher savings in users of fuel-based lighting. The incremental cost-effectiveness ratio for the solar lighting intervention was $2025.72 US dollars per quality adjusted life year (QALY) gained making the intervention cost-effective when benchmarked against the gross domestic product (GDP) per capita in Uganda. Thematic analysis of qualitative data from individual interviews showed that solar lighting was transformative and associated with numerous benefits that fit within a Social Determinants of Health (SDOH) framework. The benefits included improved household finances, improved educational performance of children, increased household safety, improved family and community cohesion, and improved perceived household health. Our findings suggest that household solar lighting interventions may be a cost-effective approach to improve health-related quality of life by addressing SDOH.

The Applications of Implementation Science in Water, Sanitation, and Hygiene (WASH) Research and Practice

BACKGROUND

Delivery of high quality, at-scale, and sustained services is a major challenge in the water, sanitation, and hygiene (WASH) sector, made more challenging by a dearth of evidence-based models for adaption across contexts in low- and middle-income countries.

OBJECTIVE

We aim to describe the value of implementation science (IS) for the WASH sector and provide recommendations for its application.

METHODS

We review concepts from the growing field of IS-defined as the "scientific study of methods to promote the systematic uptake of research findings and other evidence-based practices into routine practice, and hence, to improve the quality and effectiveness of health services"-and we translate their relevance to WASH research, learning, and delivery.

DISCUSSION

IS provides a suite of methods and theories to systematically develop, evaluate, and scale evidence-based interventions. Though IS thinking has been applied most notably in health services delivery in high-income countries, there have been applications in low-income settings in fields such as HIV/AIDS and nutrition. Expanding the application of IS to environmental health, specifically WASH interventions, would respond to the complexity of sustainable service delivery. WASH researchers may want to consider applying IS guidelines to their work, including adapting pragmatic research models, using established IS frameworks, and cocreating knowledge with local stakeholders. https://doi.org/10.1289/EHP7762.

Applications of Systems Science to Understand and Manage Multiple Influences within Children's Environmental Health in Least Developed Countries: A Causal Loop Diagram Approach

Least developed countries (LDCs) are home to over a billion people throughout Africa, Asia-Pacific, and the Caribbean. The people who live in LDCs represent just 13% of the global population but 40% of its growth rate. Characterised by low incomes and low education levels, high proportions of the population practising subsistence living, inadequate infrastructure, and lack of economic diversity and resilience, LDCs face serious health, environmental, social, and economic challenges. Many communities in LDCs have very limited access to adequate sanitation, safe water, and clean cooking fuel. LDCs are environmentally vulnerable; facing depletion of natural resources, the effects of unsustainable urbanization, and the impacts of climate change, leaving them unable to safeguard their children’s lifetime health and wellbeing. This paper reviews and describes the complexity of the causal relationships between children’s health and its environmental, social, and economic influences in LDCs using a causal loop diagram (CLD). The results identify some critical feedbacks between poverty, family size, population growth, children’s and adults’ health, inadequate water, sanitation and hygiene (WASH), air pollution, and education levels in LDCs and suggest leverage points for potential interventions. A CLD can also be a starting point for quantitative systems science approaches in the field, which can predict and compare the effects of interventions.

Defining and Intervening on Cumulative Environmental Neurodevelopmental Risks: Introducing a Complex Systems Approach

BACKGROUND

The combined effects of multiple environmental toxicants and social stressor exposures are widely recognized as important public health problems contributing to health inequities. However cumulative environmental health risks and impacts have received little attention from U.S. policy makers at state and federal levels to develop comprehensive strategies to reduce these exposures, mitigate cumulative risks, and prevent harm. An area for which the inherent limitations of current approaches to cumulative environmental health risks are well illustrated is children's neurodevelopment, which exhibits dynamic complexity of multiple interdependent and causally linked factors and intergenerational effects.

OBJECTIVES

We delineate how a complex systems approach, specifically system dynamics, can address shortcomings in environmental health risk assessment regarding exposures to multiple chemical and nonchemical stressors and reshape associated public policies.

DISCUSSION

Systems modeling assists in the goal of solving problems by improving the "mental models" we use to make decisions, including regulatory and policy decisions. In the context of disparities in children's cumulative exposure to neurodevelopmental stressors, we describe potential policy insights about the structure and behavior of the system and the types of system dynamics modeling that would be appropriate, from visual depiction (i.e., informal maps) to formal quantitative simulation models. A systems dynamics framework provides not only a language but also a set of methodological tools that can more easily operationalize existing multidisciplinary scientific evidence and conceptual frameworks on cumulative risks. Thus, we can arrive at more accurate diagnostic tools for children's' environmental health inequities that take into consideration the broader social and economic environment in which children live, grow, play, and learn. https://doi.org/10.1289/EHP7333.

Using Feedback to Improve Accountability in Global Environmental Health and Engineering

Engineered environmental health interventions and services in low-income and resource-limited settings-such as water supply and treatment, sanitation, and cleaner household energy services-have had a less than expected record of sustainability and have sometimes not delivered on their potential to improve health. These interventions require both effectively functioning technologies as well as supporting financial, political, and human resource systems, and may depend on user behaviors as well as professionalized service delivery to reduce harmful exposures. In this perspective, we propose that the application of smarter, more actionable monitoring and decision support systems and aligned financial incentives can enhance accountability between donors, implementers, service providers, governments, and the people who are the intended beneficiaries of development programming. Made possible in part by new measurement techniques, including emerging sensor technologies, rapid impact evaluation, citizen science, and performance-based contracting, such systems have the potential to propel the development of solutions that can work over the long-term, allowing the benefits of environmental health improvements to be sustained in settings where they are most critical by improving trust and mutual accountability among stakeholders.