Prenatal exposure to long-term heat stress and stillbirth in Ghana: A within-space time-series analysis.

INTRODUCTION: Few studies examined the association between prenatal long-term ambient temperature exposure and stillbirth and fewer still from developing countries. Rather than ambient temperature, we used a human thermophysiological index, Universal Thermal Climate Index (UTCI) to investigate the role of long-term heat stress exposure on stillbirth in Ghana. METHODS: District-level monthly UTCI was linked with 90,532 stillbirths of 5,961,328 births across all 260 local districts between 1st January 2012 and 31st December 2020. A within-space time-series design was applied with distributed lag nonlinear models and conditional quasi-Poisson regression. RESULTS: The mean (28.5 ± 2.1 °C) and median UTCI (28.8 °C) indicated moderate heat stress. The Relative Risks (RRs) and 95% Confidence Intervals (CIs) for exposure to lower-moderate heat (1st to 25th percentiles of UTCI) and strong heat (99th percentile) stresses showed lower risks, relative to the median UTCI. The higher-moderate heat stress exposures (75th and 90th percentiles) showed greater risks which increased with the duration of heat stress exposures and were stronger in the 90th percentile. The risk ranged from 2% (RR = 1.02, 95% CI 0.99, 1.05) to 18% (RR = 1.18, 95% CI 1.02, 1.36) for the 90th percentile, relative to the median UTCI. Assuming causality, 19 (95% CI 3, 37) and 27 (95% CI 3, 54) excess stillbirths per 10,000 births were attributable to long-term exposure to the 90th percentile relative to median UTCI for the past six and nine months, respectively. Districts with low population density, low gross domestic product, and low air pollution which collectively defined rural districts were at higher risk as compared to those in the high level (urban districts). DISCUSSION: Maternal exposure to long-term heat stress was associated with a greater risk of stillbirth. Climate change-resilient interventional measures to reduce maternal exposure to heat stress, particularly in rural areas may help lower the risk of stillbirth.

Children with nut allergies have impaired gene expression of Toll-like receptors pathway.

BACKGROUND: Trends in food allergies prompted investigation into the underlying mechanisms. Genetic and epigenetic factors are of high interest, and, in particular, the interplay between genes relating to immune factors directly and indirectly involved in food allergy pathogenesis. We sought to determine potential links between gene expression and epigenetic factors relating to Toll-like receptor (TLR) pathways and childhood food allergies. METHODS: In a cross-sectional study, samples from 80 children with and without food allergies were analysed for gene expression, DNA methylation and a range of immune factors relating to TLR pathways. TLR2, TLR4, CD14, IL5, IL13 and vitamin D were explored. RESULTS: The importance of these immune factors appeared to vary between the different types of food allergies. Expression of TLR2 (P < .001), TLR4 (P = .014) and CD14 (P = .028) varied significantly between children with no food allergy, allergy to nuts and peanuts, and allergy to eggs. DNA methylation in the promoter regions of these genes had a significant association with gene expression. These trends persisted when subjects were stratified by nut allergy vs no nut allergy. Furthermore, TLR2 (P = .001) and CD14 (P = .007) expressions were significantly lower in children with food allergies when compared to those without. CONCLUSION: Gene expression of TLR pathway genes was directly related to food allergy type, and DNA methylation had an indirect effect. TLR2 pathways are of significant interest in nut allergies.

Occupational exposures to agricultural dust by Western Australian wheat-belt farmers during seeding operations.

Agricultural operations routinely expose farm workers to high levels of soil dust and other airborne particulate matter that have been linked to adverse health outcomes. The main objective of this study was to investigate exposure to agricultural dust during seeding operations of Western Australian farm workers. Twenty-one wheat-belt farms were recruited to participate in the study. Data were collected over the 6-week seeding period of April-June 2014. Each farm was visited once, and workers were asked to complete a workplace survey that asked questions related to minimizing exposure to agricultural dusts and occupational health and safety issues on their farm. Farmers were also asked to simultaneously participate in monitoring of personal exposure to inhalable or respirable dust along with real-time monitoring for particulate air pollution in their tractor cabin. Sampling was undertaken for 4 hr. The results showed that, on average, Western Australian farmers were exposed to personal respirable dust concentrations above the Australian Institute of Occupational Hygienists recommended guideline values, with some farmers being exposed to concentrations up to seven times higher than the value for respirable dusts. In comparison, in-cabin dust concentrations were lower, although some individual tractors recorded intermittently higher levels, which might be attributed to the type of work activity or process being undertaken. Remaining in tractor cabins with closed doors and windows with properly maintained seals might minimize the infiltration of hazardous dusts and may provide some protection from dust exposures. Future research should focus on educating and providing farm owners and workers with more information on adopting work processes and procedures related to minimizing harmful exposures to agricultural dusts.

Development of a model for particulate matter pollution in Australia with implications for other satellite-based models.

Estimating exposure to particulate matter (PM10) air pollution concentrations in Australia is challenging due to relatively few monitoring sites relative to the geographic distribution of the population. We modelled daily ground-level PM10 concentrations for the period 2006-2011 for Australia using linear mixed models with satellite remote-sensed AOD, land-use and geographical variables as predictors. The variation in daily PM10 explained by the model was 51% for Australia overall, and ranged from 51% for Tasmania to 78% for South Australia. Cross-validation indicated that the models were most suitable for prediction in New South Wales and Victoria and least suitable for prediction in Western Australia, the Australian Capital Territory and Tasmania. Most of the variation in PM10 concentrations was explained by temporal rather than spatial variation. The inclusion of AOD and other predictors did not substantially improve model performance. Temporal models were sufficient to account for daily PM10 variation recorded by statutory monitors.

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.

Critical Windows of Maternal Exposure to Biothermal Stress and Birth Weight for Gestational Age in Western Australia.

BACKGROUND: There is limited and inconsistent evidence on the risk of ambient temperature on small for gestational age (SGA) and there are no known related studies for large for gestational age (LGA). In addition, previous studies used temperature rather than a biothermal metric. OBJECTIVES: Our aim was to examine the associations and critical susceptible windows of maternal exposure to a biothermal metric [Universal Thermal Climate Index (UTCI)] and the hazards of SGA and LGA. METHODS: We linked 385,337 singleton term births between 1 January 2000 and 31 December 2015 in Western Australia to daily spatiotemporal UTCI. Distributed lag nonlinear models with Cox regression and multiple models were used to investigate maternal exposure to UTCI from 12 weeks preconception to birth and the adjusted hazard ratios (HRs) of SGA and LGA. RESULTS: Relative to the median exposure, weekly and monthly specific exposures showed potential critical windows of susceptibility for SGA and LGA at extreme exposures, especially during late gestational periods. Monthly exposure showed strong positive associations from the 6th to the 10th gestational months with the highest hazard of 13% for SGA (HR=1.13; 95% CI: 1.10, 1.14) and 7% for LGA (HR=1.07; 95% CI: 1.03, 1.11) at the 10th month for the 1st UTCI centile. Entire pregnancy exposures showed the strongest hazards of 11% for SGA (HR=1.11; 95% CI: 1.04, 1.18) and 3% for LGA (HR=1.03; 95% CI: 0.95, 1.11) at the 99th UTCI centile. By trimesters, the highest hazards were found during the second and first trimesters for SGA and LGA, respectively, at the 99th UTCI centile. Based on estimated interaction effects, male births, mothers who were non-Caucasian, smokers, ≥35 years of age, and rural residents were most vulnerable. CONCLUSIONS: Both weekly and monthly specific extreme biothermal stress exposures showed potential critical susceptible windows of SGA and LGA during late gestational periods with disproportionate sociodemographic vulnerabilities. https://doi.org/10.1289/EHP12660.

Maternal acute thermophysiological stress and stillbirth in Western Australia, 2000-2015: A space-time-stratified case-crossover analysis.

BACKGROUND: The extreme thermal environment driven by climate change disrupts thermoregulation in pregnant women and may threaten the survival of the developing fetus. OBJECTIVES: To investigate the acute effect of maternal exposure to thermophysiological stress (measured with Universal Thermal Climate Index, UTCI) on the risk of stillbirth and modification of this effect by sociodemographic disparities. METHODS: We conducted a space-time-stratified case-crossover analysis of daily UTCI and 2835 singleton stillbirths between 1st January 2000 and 31st December 2015 across multiple small areas in Western Australia. Distributed lag non-linear models were combined with conditional quasi-Poisson regression to investigate the effects of the UTCI exposure from the preceding 6 days to the day of stillbirth. We also explored effect modification by fetal and maternal sociodemographic factors. RESULTS: The median UTCI was 13.9 °C (representing no thermal stress) while the 1st and 99th percentiles were 0.7 °C (slight cold stress) and 31.7 °C (moderate heat stress), respectively. Relative to median UTCI, we found positive associations between acute maternal cold and heat stresses and higher risks of stillbirth, increasing with the intensity and duration of the thermal stress episodes. The cumulative risk from the preceding 6 days to the day of stillbirth was stronger in the 99th percentile (RR = 1.19, 95% CI: 1.17, 1.21) than the 1st percentile (RR = 1.14, 95% CI: 1.12, 1.15), relative to the median UTCI. The risks were disproportionately higher in term and male stillborn fetuses, smoking, unmarried, ≤19 years old, non-Caucasian, and low socioeconomic status mothers. DISCUSSION: Acute maternal exposure to both cold and heat stresses may contribute to the risk of stillbirth and be exacerbated by sociodemographic disparities. The findings suggest public health attention, especially for the identified higher-risk groups. Future studies should consider the use of a human thermophysiological index, rather than surrogates such as ambient temperature.

Prenatal acute thermophysiological stress and spontaneous preterm birth in Western Australia, 2000-2015: A space-time-stratified case-crossover analysis.

Epidemiologic evidence on acute heat and cold stress and preterm birth (PTB) is inconsistent and based on ambient temperature rather than a thermophysiological index. The aim of this study was to use a spatiotemporal thermophysiological index (Universal Thermal Climate Index, UTCI) to investigate prenatal acute heat and cold stress exposures and spontaneous PTB. We conducted a space-time-stratified case-crossover analysis of 15,576 singleton live births with spontaneous PTB between January 1, 2000 and December 31, 2015 in Western Australia. The association between UTCI and spontaneous PTB was examined with distributed lag nonlinear models and conditional quasi-Poisson regression. Relative to the median UTCI, there was negligible evidence for associations at the lower range of exposures (1st to 25th percentiles). We found positive associations in the 95th and 99th percentiles, which increased with increasing days of heat stress in the first week of delivery. The relative risk (RR) and 95% confidence interval (CI) for the immediate (delivery day) and cumulative short-term (up to six preceding days) exposures to heat stress (99th percentile, 31.2 °C) relative to no thermal stress (median UTCI, 13.8 °C) were 1.01 (95% CI: 1.01, 1.02) and 1.05 (95% CI: 1.04, 1.06), respectively. Elevated effect estimates for heat stress were observed for the transition season, the year 2005-2009, male infants, women who smoked, unmarried, ≤ 19 years old, non-Caucasians, and high socioeconomic status. Effect estimates for cold stress (1st percentile, 0.7 °C) were highest in the transition season, during 2005-2009, and for married, non-Caucasian, and high socioeconomic status women. Acute heat stress was associated with an elevated risk of spontaneous PTB with sociodemographic vulnerability. Cold stress was associated with risk in a few vulnerable subgroups. Awareness and mitigation strategies such as hydration, reducing outdoor activities, affordable heating and cooling systems, and climate change governance may be beneficial. Further studies with the UTCI are required.

Prenatal exposure to ambient air pollution and adverse birth outcomes: An umbrella review of 36 systematic reviews and meta-analyses.

Multiple systematic reviews and meta-analyses linked prenatal exposure to ambient air pollutants to adverse birth outcomes with mixed findings, including results indicating positive, negative, and null associations across the pregnancy periods. The objective of this study was to systematically summarise systematic reviews and meta-analyses on air pollutants and birth outcomes to assess the overall epidemiological evidence. Systematic reviews with/without meta-analyses on the association between air pollutants (NO2, CO, O3, SO2, PM2.5, and PM10) and birth outcomes (preterm birth; stillbirth; spontaneous abortion; birth weight; low birth weight, LBW; small-for-gestational-age) up to March 30, 2022 were included. We searched PubMed, CINAHL, Scopus, Medline, Embase, and the Web of Science Core Collection, systematic reviews repositories, grey literature databases, internet search engines, and references of included studies. The consistency in the directions of the effect estimates was classified as more consistent positive or negative, less consistent positive or negative, unclear, and consistently null. Next, the confidence in the direction was rated as either convincing, probable, limited-suggestive, or limited non-conclusive evidence. Final synthesis included 36 systematic reviews (21 with and 15 without meta-analyses) that contained 295 distinct primary studies. PM2.5 showed more consistent positive associations than other pollutants. The positive exposure-outcome associations based on the entire pregnancy period were more consistent than trimester-specific exposure averages. For whole pregnancy exposure, a more consistent positive association was found for PM2.5 and birth weight reductions, particulate matter and spontaneous abortion, and SO2 and LBW. Other exposure-outcome associations mostly showed less consistent positive associations and few unclear directions of associations. Almost all associations showed probable evidence. The available evidence indicates plausible causal effects of criteria air pollutants on birth outcomes. To strengthen the evidence, more high-quality studies are required, particularly from understudied settings, such as low-and-middle-income countries. However, the current evidence may warrant the adoption of the precautionary principle.

Ambient Air Pollution, Extreme Temperatures and Birth Outcomes: A Protocol for an Umbrella Review, Systematic Review and Meta-Analysis.

Prenatal exposure to ambient air pollution and extreme temperatures are among the major risk factors of adverse birth outcomes and with potential long-term effects during the life course. Although low- and middle-income countries (LMICs) are most vulnerable, there is limited synthesis of evidence in such settings. This document describes a protocol for both an umbrella review (Systematic Review 1) and a focused systematic review and meta-analysis of studies from LMICs (Systematic Review 2). We will search from start date of each database to present, six major academic databases (PubMed, CINAHL, Scopus, MEDLINE/Ovid, EMBASE/Ovid and Web of Science Core Collection), systematic reviews repositories and references of eligible studies. Additional searches in grey literature will also be conducted. Eligibility criteria include studies of pregnant women exposed to ambient air pollutants and/or extreme temperatures during pregnancy with and without adverse birth outcomes. The umbrella review (Systematic Review 1) will include only previous systematic reviews while Systematic Review 2 will include quantitative observational studies in LMICs. Searches will be restricted to English language using comprehensive search terms to consecutively screen the titles, abstracts and full-texts to select eligible studies. Two independent authors will conduct the study screening and selection, risk of bias assessment and data extraction using JBI SUMARI web-based software. Narrative and semi-quantitative syntheses will be employed for the Systematic Review 1. For Systematic Review 2, we will perform meta-analysis with two alternative meta-analytical methods (quality effect and inverse variance heterogeneity) as well as the classic random effect model. If meta-analysis is infeasible, narrative synthesis will be presented. Confidence in cumulative evidence and the strength of the evidence will be assessed. This protocol is registered with PROSPERO (CRD42020200387).

Agricultural Dust Exposures and Health and Safety Practices among Western Australian Wheatbelt Farmers during Harvest.

BACKGROUND: Agricultural farmworkers are routinely exposed to high levels of airborne dust particles that have been linked to adverse health outcomes. METHODS: This study measured personal and environmental exposures to dust particulates by farmworkers during harvesting activities. Farmers completed a workplace survey with regards to their health and safety awareness and practices and researchers observed general farm safety practices on selected farms using a checklist. RESULTS: In this study, farmers were noted to commonly work extended hours and shifts during harvest due to rigid timing deadlines. Results showed that 40% of farmers were exposed to concentrations of inhalable particles greater than SafeWork Australia's workplace exposure standards for grain dusts, assuming a 16 h working day over 5 shifts. Twenty-two percent were exposed to concentrations that were above the adjusted standard for 12 h shifts. Survey results showed that three-quarters of farm owners provided new workers with some type of induction related to farm safety, however this was mostly undertaken in an arbitrary manner. Despite noting that farming was a dusty occupation and reporting to use protective measures to reduce harmful dust exposures, no workers were observed to wear respiratory protection when working outside of the protection of a vehicle cabin. CONCLUSION: This study identified substantial gaps in health and safety knowledge among farm managers and workers, and improved education and training are highly recommended.

Applications of low-cost sensing technologies for air quality monitoring and exposure assessment: How far have they gone?

Over the past decade, a range of sensor technologies became available on the market, enabling a revolutionary shift in air pollution monitoring and assessment. With their cost of up to three orders of magnitude lower than standard/reference instruments, many avenues for applications have opened up. In particular, broader participation in air quality discussion and utilisation of information on air pollution by communities has become possible. However, many questions have been also asked about the actual benefits of these technologies. To address this issue, we conducted a comprehensive literature search including both the scientific and grey literature. We focused upon two questions: (1) Are these technologies fit for the various purposes envisaged? and (2) How far have these technologies and their applications progressed to provide answers and solutions? Regarding the former, we concluded that there is no clear answer to the question, due to a lack of: sensor/monitor manufacturers' quantitative specifications of performance, consensus regarding recommended end-use and associated minimal performance targets of these technologies, and the ability of the prospective users to formulate the requirements for their applications, or conditions of the intended use. Numerous studies have assessed and reported sensor/monitor performance under a range of specific conditions, and in many cases the performance was concluded to be satisfactory. The specific use cases for sensors/monitors included outdoor in a stationary mode, outdoor in a mobile mode, indoor environments and personal monitoring. Under certain conditions of application, project goals, and monitoring environments, some sensors/monitors were fit for a specific purpose. Based on analysis of 17 large projects, which reached applied outcome stage, and typically conducted by consortia of organizations, we observed that a sizable fraction of them (~ 30%) were commercial and/or crowd-funded. This fact by itself signals a paradigm change in air quality monitoring, which previously had been primarily implemented by government organizations. An additional paradigm-shift indicator is the growing use of machine learning or other advanced data processing approaches to improve sensor/monitor agreement with reference monitors. There is still some way to go in enhancing application of the technologies for source apportionment, which is of particular necessity and urgency in developing countries. Also, there has been somewhat less progress in wide-scale monitoring of personal exposures. However, it can be argued that with a significant future expansion of monitoring networks, including indoor environments, there may be less need for wearable or portable sensors/monitors to assess personal exposure. Traditional personal monitoring would still be valuable where spatial variability of pollutants of interest is at a finer resolution than the monitoring network can resolve.

The association between ambient air pollution and selected adverse pregnancy outcomes in China: A systematic review.

The association between exposure to ambient air pollution and respiratory or cardiovascular endpoints is well-established. An increasing number of studies have shown that this exposure is also associated with adverse pregnancy outcomes. However, the majority of research has been undertaken in high-income western countries, with relatively lower levels of exposure. There is now a sufficient number of studies to warrant an assessment of effects in China, a relatively higher exposure setting. We conducted a systematic review of 25 studies examining the association between ambient air pollution exposure and adverse pregnancy outcomes (lower birth weight, preterm birth, mortality, and congenital anomaly) in China, published between 1980 and 2015. The results indicated that sulphur dioxide (SO2) was more consistently associated with lower birth weight and preterm birth, and that coarse particulate matter (PM10) was associated with congenital anomaly, notably cardiovascular defects.