Health Effects Of Long-term Exposure Research Articles

Systematic review on health effects of long-term exposure to UFP

Systematic review on health effects of long-term exposure to UFP

Assessing Adverse Health Effects of Long-Term Exposure to Low Levels of Ambient Air Pollution: The HEI Experience and What's Next?

Although concentrations of ambient air pollution continue to decline in high-income regions, epidemiological studies document adverse health effects at levels below current standards in many countries. The Health Effects Institute (HEI) recently completed a comprehensive research initiative to investigate the health effects of long-term exposure to low levels of air pollution in the United States (U.S.), Canada, and Europe. We provide an overview and synthesis of the results of this initiative along with other key research, the strengths and limitations of the research, and remaining research needs. The three studies funded through the HEI initiative estimated the effects of long-term ambient exposure to fine particulate matter (PM2.5), nitrogen dioxide, ozone, and other pollutants on a broad range of health outcomes, including cause-specific mortality and cardiovascular and respiratory morbidity. To ensure high quality research and comparability across studies, HEI worked actively with the study teams and engaged independent expert panels for project oversight and review. All three studies documented positive associations between mortality and exposure to PM2.5 below the U.S. National Ambient Air Quality Standards and current and proposed European Union limit values. Furthermore, the studies observed nonthreshold linear (U.S.), or supra-linear (Canada and Europe) exposure-response functions for PM2.5 and mortality. Heterogeneity was found in both the magnitude and shape of this association within and across studies. Strengths of the studies included the large populations (7-69 million), state-of-the-art exposure assessment methods, and thorough statistical analyses that applied novel methods. Future work is needed to better understand potential sources of heterogeneity in the findings across studies and regions. Other areas of future work include the changing and evolving nature of PM components and sources, including wildfires, and the role of indoor environments. This research initiative provided important new evidence of the adverse effects of long-term exposures to low levels of air pollution at and below current standards, suggesting that further reductions could yield larger benefits than previously anticipated.

Exposure to Neighborhood Greenness and Hypertension Incidence in Adults: A Longitudinal Cohort Study in Taiwan.

There are few studies on the health effects of long-term exposure to neighborhood greenness in a longitudinal setting, especially in Asian countries with high population densities. This study investigates the association between long-term exposure to neighborhood greenness and hypertension among adults in Taiwan. We selected 125,537 participants ( of age) without hypertension from Taiwan who had joined the standard medical examination program between 2001 and 2016. Neighborhood greenness was estimated using the normalized difference vegetation index (NDVI), derived from satellite images at a resolution of . The 2-y average NDVI value within a circular buffer around participants' residences was calculated. A time-varying Cox regression model was used to investigate the association between neighborhood greenness and incident hypertension. Mediation analyses were performed to examine whether the association was explained by air pollution, leisure-time physical exercise, or body mass index (BMI). Compared with living in areas within the first quartile of neighborhood greenness, living in areas within the second, third, and fourth quartiles of neighborhood greenness was found to be associated with a lower risk of hypertension, with hazard ratios (HRs) and 95% confidence intervals (CIs) of 0.95 (95% CI: 0.91, 1.00), 0.95 (95% CI: 0.90, 0.99), and 0.93 (95% CI: 0.88, 0.97), respectively. Each 0.1-unit increase in the NDVI was associated with a 24% lower risk of developing hypertension (0.76; 95% CI: 0.66, 0.87), with this associations being stronger among males and those with higher education levels. This association was slightly mediated by BMI but not by air pollution or leisure-time physical exercise. Our findings suggest the protective effects of neighborhood greenness on hypertension development, especially in males and well-educated individuals. Our results reinforced the importance of neighborhood greenness for supporting health. https://doi.org/10.1289/EHP13071.

New sensitive LC-MS/MS method for the simultaneous determination of 13 phenolic and carboxylic acid pesticide biomarkers in human urine, including dicamba

The commercialization in 2016 of genetically engineered seeds tolerant to dicamba and/or 2,4-dichlorophenoxyacetic acid (2,4-D) has caused a rapid increase in the use of these herbicides. New questions about the reproductive and chronic health effects of long-term exposure to these herbicides have been raised. To assess exposure to dicamba and other pesticides of interest in the Heartland Study, a birth cohort study based in the United States, a new analytical method was needed. The present study describes the development and validation of this new solid phase extraction and liquid chromatography-tandem mass spectrometry method that detects simultaneously 13 pesticides or their metabolites in 250 μL of urine. More specifically, the method allows the analysis of dicamba, 2,4-D and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), which are herbicides, of malathion dicarboxylic acid (MDA), para-nitrophenol (PNP), 3,5,6-trichloro-2-pyridinol (TCPy), 2-diethylamino-6-methylpyrimidin-4-ol (DEAMPY) and 2-isopropyl-6-methyl-4-pyrimidinol (IMPY), which are metabolites of organophosphate insecticides, and finally of cis-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis-DCCA), trans-3-(2,2-Dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (trans-DCCA), 3-Phenoxybenzoic acid (3-PBA), 4-Fluoro-3-phenoxybenzoic acid (4-F-3-PBA) and cis-3-(2,2-Dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis-DBCA), which are metabolites of synthetic pyrethroids insecticides. The method was validated under ISO/IEC 17025 guidance. The limit of detection (LOD) in urine samples was 0.10 μg/L for dicamba, while the LOD for other analytes ranged between 0.0038 μg/L and 0.091 μg/L. Accuracy was evaluated by analyzing samples from two External Quality Assessment Schemes, namely G-EQUAS and OSEQAS. Preliminary results obtained following the analysis of 91 urine samples taken from pregnant women enrolled in the Heartland Study are presented here. This method is suitable for human biomonitoring studies.

Assessing Adverse Health Effects of Long-Term Exposure to Low Levels of Ambient Air Pollution: What’s Next?

Assessing Adverse Health Effects of Long-Term Exposure to Low Levels of Ambient Air Pollution: What’s Next?

Long-term exposure to outdoor air pollution and asthma in low-and middle-income countries: A systematic reviewprotocol.

Several epidemiological studies have examined the risk of asthma and respiratory diseases in association with long-term exposure to outdoor air pollution. However, little is known regarding the adverse effects of long-term exposure to outdoor air pollution on the development of these outcomes in low- and middle-income countries (LMICs). Our study aims to investigate the association between long-term exposure to outdoor air pollution and asthma and respiratory diseases in LMICs through a systematic review with meta-analysis. This systematic review and meta-analysis will follow the PRISMA (Preferred Reporting for Systematic Reviews and Meta-Analyses) checklist and flowchart guidelines. The inclusion criteria that will be used in our study are 1) Original research articles with full text in English; 2) Studies including adult humans; 3) Studies with long-term air pollution assessment in LMICs, air pollutants including nitrogen oxide (NO2), sulfur oxide (SO2), particulate matter (PM2.5 and PM10), carbon monoxide (CO) and ozone (O3); 4) cohort and cross-sectional studies; 5) Studies reporting associations between air pollution and asthma and respiratory symptoms. A comprehensive search strategy will be used to identify studies published up till August 2022 and indexed in Embase, Medline, and Web of Science. Three reviewers will independently screen records retrieved from the database searches. Where there are enough studies with similar exposure and outcomes, we will calculate, and report pooled effect estimates using meta-analysis. PROSPERO CRD42022311326. Findings from the health effects of long-term exposure to outdoor air pollution may be of importance for policymakers. This review will also identify any gaps in the current literature on this topic in LMICs and provide direction for future research.

Concentrations of Tetrabromobisphenol-A and hexabromocyclododecane in Thai child daycare centre dust and the exposure risk for young children

Children spend one-third of their day in child daycare centres, where they may be exposed to toxic chemicals, such as tetrabromobisphenol-A (TBBPA) and hexabromocyclododecane (HBCDD), from indoor dust. However, studies on the exposure of TBBPA and HBCDD in schools remain scarce, especially in Thailand, where no such study has yet been reported. Therefore, in this study, we collected dust samples from 20 child daycare centres in Thailand and analysed them for flame retardants, TBBPA and HBCDD. TBBPA was detected in all samples with a median concentration of 35 ng g−1 (range, 14–5017.7 ng g−1). The median level of HBCDD was lower than the quantitation limit (LOQ) with <LOQ to 86.6 ng g−1 of dust sample. The electronic density score was calculated from the number of electronic appliances divided by each sampled surface floor area that revealed an abundance of TBBPA in the dust in rooms with many electronic items. The use of electronic devices, especially printers, that were found to be related to the high TBBPA concentration in the room, should be minimised in child daycare centres. The children's exposure to these chemicals from dust was estimated for dust ingestion and dermal absorption. The combined exposure was lower than the established reference dose value, and the hazard quotient for children via these two pathways were ranged 0.7 × 10−6 – 2.7 × 10−4 for TBBPA and 1.8 × 10−5 – 4.9 × 10−5 for HBCDD, which did not exceed 1.0. Although there is uncertainty regarding the potential health effects of long-term exposure to these substances, it is undeniable that child daycare centres represent a source of exposure to these substances for children. Further investigation of other intake routes of several flame retardants in child daycare centres and identification of the sources of these substances is warranted to decrease children's health risks from exposure to these harmful substances in child daycare centres.

Clean air in Europe for all: A call for more ambitious action.

Clean air in Europe for all: A call for more ambitious action.

Comparison of traditional Cox regression and causal modeling to investigate the association between long-term air pollution exposure and natural-cause mortality within European cohorts

Most studies investigating the health effects of long-term exposure to air pollution used traditional regression models, although causal inference approaches have been proposed as alternative. However, few studies have applied causal models and comparisons with traditional methods are sparse. We therefore compared the associations between natural-cause mortality and exposure to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) using traditional Cox and causal models in a large multicenter cohort setting. We analysed data from eight well-characterized cohorts (pooled cohort) and seven administrative cohorts from eleven European countries. Annual mean PM2.5 and NO2 from Europe-wide models were assigned to baseline residential addresses and dichotomized at selected cut-off values (PM2.5: 10, 12, 15 μg/m³; NO2: 20, 40 μg/m³). For each pollutant, we estimated the propensity score as the conditional likelihood of exposure given available covariates, and derived corresponding inverse-probability weights (IPW). We applied Cox proportional hazards models i) adjusting for all covariates (“traditional Cox”) and ii) weighting by IPW (“causal model”). Of 325,367 and 28,063,809 participants in the pooled and administrative cohorts, 47,131 and 3,580,264 died from natural causes, respectively. For PM2.5 above vs. below 12 μg/m³, the hazard ratios (HRs) of natural-cause mortality were 1.17 (95% CI 1.13–1.21) and 1.15 (1.11–1.19) for the traditional and causal models in the pooled cohort, and 1.03 (1.01–1.06) and 1.02 (0.97–1.09) in the administrative cohorts. For NO2 above vs below 20 μg/m³, the HRs were 1.12 (1.09–1.14) and 1.07 (1.05–1.09) for the pooled and 1.06 (95% CI 1.03–1.08) and 1.05 (1.02–1.07) for the administrative cohorts. In conclusion, we observed mostly consistent associations between long-term air pollution exposure and natural-cause mortality with both approaches, though estimates partly differed in individual cohorts with no systematic pattern. The application of multiple modelling methods might help to improve causal inference.299 of 300 words.

Serum lead, mercury, manganese, and copper and DNA methylation age among adults in Detroit, Michigan.

Although the effects of lead, mercury, manganese, and copper on individual disease processes are well understood, estimating the health effects of long-term exposure to these metals at the low concentrations often observed in the general population is difficult. In addition, the health effects of joint exposure to multiple metals are difficult to estimate. Biological aging refers to the integrative progression of multiple physiologic and molecular changes that make individuals more at risk of disease. Biomarkers of biological aging may be useful to estimate the population-level effects of metal exposure prior to the development of disease in the population. We used data from 290 participants in the Detroit Neighborhood Health Study to estimate the effect of serum lead, mercury, manganese, and copper on three DNA methylation-based biomarkers of biological aging (Horvath Age, PhenoAge, and GrimAge). We used mixed models and Bayesian kernel machine regression and controlled for participant sex, race, ethnicity, cigarette use, income, educational attainment, and block group poverty. We observed consistently positive estimates of the effects between lead and GrimAge acceleration and mercury and PhenoAge acceleration. In contrast, we observed consistently negative associations between manganese and PhenoAge acceleration and mercury and Horvath Age acceleration. We also observed curvilinear relationships between copper and both PhenoAge and GrimAge acceleration. Increasing total exposure to the observed mixture of metals was associated with increased PhenoAge and GrimAge acceleration and decreased Horvath Age acceleration. These findings indicate that an increase in serum lead or mercury from the 25th to 75th percentile is associated with a ∼0.25-year increase in two epigenetic markers of all-cause mortality in a population of adults in Detroit, Michigan. While few of the findings were statistically significant, their consistency and novelty warrant interest.

Health effects of long-term exposure to ultrafine particles around Schiphol airport

Background and aim: Studies have shown elevated concentrations of ultrafine particles (UFP) near airports. Little is known about the health effects of UFP, in particular from aviation (UFP-aviation). We evaluated the health effects of long-term exposure to UFP-aviation around Schiphol Airport, The Netherlands. Methods: We investigated a wide range of health outcomes, by linking modelled annual average residential concentrations of UFP-aviation to individual data from existing health registries and surveys. We conducted two longitudinal cohort studies, on mortality and incidence of medication use, and a cross-sectional study using survey data on self-reported health and lifestyle factors. The cohort studies included all residents of 31 municipalities in a 45x50 km area around Schiphol Airport (~1.3 million adults). Survey data was available for 90,880 adults. Effect estimates were adjusted for individual and neighborhood-level covariates and expressed per 3500 pts/cm3 (~p5-p95 increment across the three studies). We performed a number of sensitivity analyses to evaluate the robustness of the results, including adjustment for co-pollutants and noise. The combination of different databases and designs allowed us to evaluate consistency of the findings both within and across studies. Results: We found no clear or consistent associations between UFP-aviation and health outcomes related to general health, respiratory health, neurodegenerative disease, or mental health. For cardiovascular health, we found robust positive associations with incidence of medication use for heart disease [HR 1.03 (95%CI 1.00-1.05)] and mortality for arrhythmia [HR 1.08 (95%CI 0.98-1.02)], but not for incidence of medication use for hypertension or (total or other subclasses of) cardiovascular mortality. In the survey data, we found robust significant associations with prevalence of hypertension and self-reported heart attack and consistently elevated (non-significant) associations with self-reported stroke. Conclusions: Exposure to UFP from aviation around Schiphol Airport was associated with cardiovascular health outcomes. Keywords: ultrafine particles, aviation, air pollution, mortality, morbidity

The health impacts of Indonesian peatland fires

BackgroundIndonesian peatlands have been drained for agricultural development for several decades. This development has made a major contribution to economic development. At the same time, peatland drainage is causing significant air pollution resulting from peatland fires. Peatland fires occur every year, even though their extent is much larger in dry (El Niño) years. We examine the health effects of long-term exposure to fine particles (PM2.5) from all types of peatland fires (including the burning of above and below ground biomass) in Sumatra and Kalimantan, where most peatland fires in Indonesia take place.MethodsWe derive PM2.5 concentrations from satellite imagery calibrated and validated with Indonesian Government data on air pollution, and link increases in these concentrations to peatland fires, as observed in satellite imagery. Subsequently, we apply available epidemiological studies to relate PM2.5 exposure to a range of health outcomes. The model utilizes the age distribution and disease prevalence of the impacted population.ResultsWe find that PM2.5 air pollution from peatland fires, causes, on average, around 33,100 adults and 2900 infants to die prematurely each year from air pollution. In addition, peatland fires cause on average around 4390 additional hospitalizations related to respiratory diseases, 635,000 severe cases of asthma in children, and 8.9 million lost workdays. The majority of these impacts occur in Sumatra because of its much higher population density compared to Kalimantan. A main source of uncertainty is in the Concentration Response Functions (CRFs) that we use, with different CRFs leading to annual premature adult mortality ranging from 19,900 to 64,800 deaths. Currently, the population of both regions is relatively young. With aging of the population over time, vulnerabilities to air pollution and health effects from peatland fires will increase.ConclusionsPeatland fire health impacts provide a further argument to combat fires in peatlands, and gradually transition to peatland management models that do not require drainage and are therefore not prone to fire risks.

Biological effects of inhaled crude oil vapor V. Altered biogenic amine neurotransmitters and neural protein expression

Workers in the oil and gas industry are at risk for exposure to a number of physical and chemical hazards at the workplace. Chemical hazard risks include inhalation of crude oil or its volatile components. While several studies have investigated the neurotoxic effects of volatile hydrocarbons, in general, there is a paucity of studies assessing the neurotoxicity of crude oil vapor (COV). Consequent to the 2010 Deepwater Horizon (DWH) oil spill, there is growing concern about the short- and long-term health effects of exposure to COV. NIOSH surveys suggested that the DWH oil spill cleanup workers experienced neurological symptoms, including depression and mood disorders, but the health effects apart from oil dispersants were difficult to discern. To investigate the potential neurological risks of COV, male Sprague-Dawley rats were exposed by whole-body inhalation to COV (300 ppm; Macondo surrogate crude oil) following an acute (6 h/d × 1 d) or sub-chronic (6 h/d × 4 d/wk. × 4 wks) exposure regimen. At 1, 28 or 90 d post-exposure, norepinephrine (NE), epinephrine (EPI), dopamine (DA) and serotonin (5-HT) were evaluated as neurotransmitter imbalances are associated with psychosocial-, motor- and cognitive- disorders. Sub-chronic COV exposure caused significant reductions in NE, EPI and DA in the dopaminergic brain regions, striatum (STR) and midbrain (MB), and a large increase in 5-HT in the STR. Further, sub-chronic exposure to COV caused upregulation of synaptic and Parkinson's disease-related proteins in the STR and MB. Whether such effects will lead to neurodegenerative outcomes remain to be investigated.

Establishing the National Institute for Research in Environmental Health, India.

ProblemMultiple environmental health issues resulting from pollution and climate change threaten public health in India.ApproachThe Government of India recognized the need for a permanent environmental health research institute; the Indian Council of Medical Research therefore established the National Institute for Research in Environmental Health in Bhopal in 2010. Scientists at the institute assessed the multiple long-term health effects of exposure to methyl isocyanate, and are now conducting research on a wide array of locally relevant environmental health issues.Local settingThe Union Carbide India Limited pesticide factory in Bhopal was the site of a methyl isocyanate gas leak in 1984, which affected half a million people. The Indian Council of Medical Research set up a coordinating unit in the immediate aftermath, which was upgraded to the Bhopal Gas Disaster Research Centre in 1986 and then the Centre for Rehabilitation Studies in 1995.Relevant changesScientists at the institute undertake environmental monitoring and health risk assessment studies among communities located near polluted areas, such as industrial areas. They are also assessing the training needs of practising physicians, with the aim of developing a curated curriculum to meet the deficiencies in environmental health education in the country.Lessons learntEnvironmental legislation was introduced in the wake of the disaster and a research institute in environmental health was established. Researchers at the institute have recognized the importance of engaging communities in environmental health research, as well as knowledge dissemination to relevant stakeholders.

Frailty Risk in Older Adults Associated With Long-Term Exposure to Ambient PM2.5 in 6 Middle-Income Countries.

BackgroundA series of studies have explored the health effects of long-term exposure to ambient PM2.5 among older adults. However, few studies have investigated the adverse effect of long-term exposure to ambient PM2.5 on frailty, and the results are inconclusive. This study sought to investigate the associations between long-term exposure to ambient PM2.5 and frailty in 6 low- and middle-income countries.MethodsWe included an analytical sample of 34 138 individuals aged 50 and older from the Study on global AGEing and adult health Wave 1 (2007/2010). Air pollution estimates were generated using a standard methodology derived from Moderate Resolution Imaging Spectroradiometer observations and Multiangle Imaging Spectroradiometer instruments from the Terra satellite, along with simulations from the GEOS-Chem chemical transport model. A 3-level hierarchical logistic model was used to evaluate the association between frailty index and long-term PM2.5 exposure at 3 levels (individual, province, and country).ResultsIn rural areas, each 10 μg/m3 increase in ambient PM2.5 was associated with a 30% increase in the odds of frailty (OR = 1.30, 95% CI: 1.21–1.39) after adjusting for various potential confounding factors. The gender-stratified analysis showed that the association seemed to be slightly stronger in men (OR = 1.31, 95% CI: 1.18–1.46) than in women (OR = 1.21, 95% CI: 1.07–1.36) in rural areas.ConclusionIn a large sample of community-based older adults from 6 middle-income countries, we found evidence that long-term PM2.5 exposure was associated with frailty in rural areas.

Long-term exposure to black carbon and mortality: A 28-year follow-up of the GAZEL cohort.

The current evidence on health effects of long-term exposure to outdoor airborne black carbon (BC) exposure remains scarce. To examine the association between long-term exposure to BC and mortality in a large population-based French cohort, with 28years of follow-up. Data from the GAZEL cohort were collected between 1989 and 2017. Land use regression model with temporal extrapolation wa used to estimate yearly BC and PM2.5 exposure at the residential addresses from 1989 until censoring for 19,906 participants. Time-varying Cox models with attained age as time-scale was used to estimate the associations between BC and all-cause and cardiovascular mortality, after adjusting for individual and area-level covariates. To handle confounding by PM2.5, we used the residual of BC regressed on PM2.5 as an alternate exposure variable. For all-cause mortality, we also examined effect modification by sex, smoking status, BMI and fruit/vegetable intake. The median of 20-year moving average of BC exposure was 2.02 10-5/m in study population. We found significant associations between BC exposure and all-cause mortality (n=2357) using both 20-year moving average of BC and residual of BC, with corresponding hazard ratios (HR) of 1.14 (95%CI: 1.07-1.22) and 1.17 (95%CI: 1.10-1.24) for an inter-quartile range (IQR) increase (0.86 10-5/m for BC and 0.57 10-5/m for residual of BC). We found a similar association between BC and cardiovascular mortality (n=277) with a HR of 1.15 (95%CI: 0.95-1.38). The dose-response relationship between BC and all-cause mortality was monotonic but nonlinear with a steeper slope at high BC levels. In addition, the effect of BC was higher among never-smokers and among those having fruit/vegetables less than twice a week. There was a positive association between long-term exposure to BC and increased mortality risk, reinforcing the emerging evidence that BC is a harmful component of PM2.5.

Monte Carlo Simulation-Based Calculations of Complex DNA Damage for Incidents of Environmental Ionizing Radiation Exposure

In this paper, we present a useful Monte Carlo (MC)-based methodology that can be utilized to calculate the absorbed dose and the initial levels of complex DNA damage (such as double strand breaks-DSBs) in the case of an environmental ionizing radiation (IR) exposure incident (REI) i.e., a nuclear accident. Our objective is to assess the doses and complex DNA damage by isolating only one component of the total radiation released in the environment after a REI that will affect the health of the exposed individual. More specifically, the radiation emitted by radionuclide 137Cs in the ground (under the individual’s feet). We use a merging of the Monte Carlo N-Particle Transport code (MCNP) with the Monte Carlo Damage Simulation (MCDS) code. The DNA lesions have been estimated through simulations for different surface activities of a 137Cs ground-based γ radiation source. The energy spectrum of the emitted secondary electrons and the absorbed dose in typical mammalian cells have been calculated using the MCNP code, and then these data are used as an input in the MCDS code for the estimation of critical DNA damage levels and types. As a realistic application, the calculated dose is also used to assess the Excess Lifetime Cancer Risk (ELCR) for eight hypothetical individuals, living in different zones around the Chernobyl Nuclear Power Plant, exposed to different time periods at the days of the accident in 1986. We conclude that any exposition of an individual in the near zone of Chernobyl increases the risk of cancer at a moderate to high grade, connected also with the induction of complex DNA damage by radiation. Generally, our methodology has proven to be useful for assessing γ rays-induced complex DNA damage levels of the exposed population, in the case of a REI and for better understanding the long-term health effects of exposure of the population to IR.

Systematic Methods to Select and Review Epidemiological Literature on the Health Effects of Long-term Exposure to TRAP

BACKGROUND AND AIM: The health effects of traffic-related air pollution (TRAP) continue to be of important public health interest. Following its well-cited 2010 critical review, HEI appointed a new expert Panel to review the literature on the health effects of long-term exposure to TRAP. METHODS: The Panel followed a systematic protocol they published in Prospero to search the literature, assess study quality, summarize results, and reach conclusions about the body of evidence. An extensive search was conducted of literature published between January 1980 and July 2019 on selected health outcomes (all-cause and cause-specific mortality, respiratory effects, cardiometabolic effects, and adverse birth outcomes). The Panel considered studies both within and outside the near-road environment because traffic contributes to ambient air pollution at neighborhood and urban scales. They developed a framework of exposure to TRAP to guide transparent selection and evaluation of epidemiological studies. Criteria including the pollutant considered, spatial scale, and exposure assessment methods were used to identify studies in which the exposure contrasts were related primarily to traffic emissions. RESULTS:Meta-analyses were performed in cases where three or more studies were identified for the same exposure and health outcome. Conclusions were based on a modified US National Toxicology Program’s Office of Health Assessment and Translation (OHAT) approach and a narrative assessment. The two approaches were considered equally valuable in the Special Report, reflecting the complex issues in determining the level of confidence. CONCLUSIONS:The review is now well underway, and the methods along with lessons learned during their application will be presented. The systematic review will undergo peer-review, and publication is aimed for late 2021. The new review will be an authoritative update of HEI’s most-cited report for use by researchers and policymakers. KEYWORDS: traffic-related air pollution, systematic review, birth outcomes, cardiometabolic effects, respiratory effects, mortality

Results of an HEI Systematic Review on the Health Effects of Long-term Exposure to Traffic-Related Air Pollution

BACKGROUND AND AIM: After a broad search, the HEI Panel on the Health Effects of Long–Term Exposure to Traffic–Related Air Pollution (TRAP) identified 1100 studies relevant for further screening, 352 of which met the inclusion criteria and are considered in the systematic review. Respiratory effects in children (N=117) and birth outcomes (N=86) were the most common outcomes published in the literature. Slightly fewer studies investigated cardiometabolic effects (N=57), respiratory effects in adults (N=50), and mortality (N=48). METHODS: The systematic review is undergoing independent peer-review and publication is aimed for late 2021. RESULTS:The Panel’s initial findings were for a moderate to high level of confidence in an association between exposure to TRAP with term low birth weight. They also reported a moderate or high level of confidence in an association between exposure to TRAP and asthma onset in children and adults, and occurrence of acute respiratory infections in children. Furthermore, they found moderate evidence for an association between exposure to TRAP and ischemic heart disease, stroke, and diabetes mellitus. The overall confidence in an association between TRAP exposure and mortality was high for all-cause, circulatory, ischemic heart disease mortality; moderate to high for lung cancer mortality; and moderate for respiratory mortality. For the other health outcomes assessed, the confidence was very low or low for an association with TRAP, and the evaluation was often limited by the small numbers of studies. CONCLUSIONS:In light of the large number of people exposed to TRAP – both in and beyond the near–road environment, the Panel concluded that the moderate to high confidence in an association between long-term exposure to TRAP and various adverse health effects indicates that exposures to TRAP are an important public health concern and deserve continued targeted policy and broader public focus. KEYWORDS: traffic-related air pollution, systematic review, birth outcomes, cardiometabolic effects, respiratory effects, mortality

Knowledge on adverse effects of traffic-related air pollution: have we filled the gap? What more do we need to know?

BACKGROUND AND AIM: The Health Effects Institute has conducted a systematic review on the health effects of long-term exposure to traffic-related air pollution (TRAP) and selected adverse health outcomes, with an expert Panel. The findings have provided a moderate or high level of confidence in the presence of an association between long-term exposure to TRAP and various adverse health effects. Although the evidence is already compelling for some of the outcomes investigated, a number of future research opportunities emerged from the results of this report. METHODS: Critical evaluation of research needs. RESULTS:NO2 was the TRAP exposure indicator used most often in the review. There remains a need to gain a better understanding of whether the epidemiological associations found for TRAP are due to direct effects of NO2, or to another component of TRAP, or to the broader mixture of correlated components indicative of TRAP. There is a need for additional epidemiological studies on an array of traffic pollutants including UFP and non-tailpipe PM indicators, because there were few studies and there are good reasons to suspect they might be health relevant beyond what is already known. Studies have been conducted on populations residing in a wide range of countries, though the majority were done in Europe and North America. Hence there is a need for more health studies in areas outside North America and Europe. Additional studies should evaluate the role of spatially correlated factors that may either confound and/or modify the health effects of TRAP, most notably traffic noise, and factors related to the built environment, such as presence of green space. Finally, various suggestions to improve methods in study design, analysis and evidence synthesis were identified. CONCLUSIONS:The systematic review helped to identify several important areas for future research. KEYWORDS: Systematic review, traffic-related air pollution, cardiovascular effects, respiratory effects, mortality