Exposure to ambient air pollution and prenatal and early childhood health effects

Ambient air pollution and birth defects in brisbane, australia

Background

Birth defects are a major public health concern as they are the leading cause of neonatal and infant mortality. Observational studies have linked environmental pollution to adverse birth outcomes, including congenital anomalies. This study examined potential associations between ambient air pollution and congenital heart defects and cleft lip or palate among births in Brisbane, Australia (1998–2004).

Methods

Ambient air pollution levels were averaged over weeks 3–8 of pregnancy among 150,308 births. Using a case–control design, we used conditional logistic regression and matched cases to 5 controls. Analyses were conducted using all births, and then births where the mother resided within 6 and 12 kilometers of an ambient air quality monitor.

Findings

When analyzing all births there was no indication that ambient air pollution in Brisbane was associated with a higher risk of cardiac defects. Among births where the mother resided within 6 kilometers of an ambient air quality monitor, a 5 ppb increase in O₃ was associated with an increased risk of pulmonary artery and valve defects (OR 2.96, 95% CI: 1.34, 7.52) while a 0.6 ppb increase in SO₂ was associated with an increased risk of aortic artery and valve defects (OR 10.76, 95% CI: 1.50, 179.8). For oral cleft defects among all births, the only adverse association was between SO₂ and cleft lip with or without cleft palate (OR 1.27, 95% CI: 1.01, 1.62). However, various significant inverse associations were also found between air pollutants and birth defects.

Conclusions

This study found mixed results and it is difficult to conclude whether ambient air pollution in Brisbane has an adverse association with the birth defects examined. Studies using more detailed estimates of air pollution exposure are needed.

Ambient air pollution and cardiovascular malformations in Atlanta, Georgia, 1986-2003

Associations between ambient air pollution levels during weeks 3-7 of pregnancy and risks of cardiovascular malformations were investigated among the cohort of pregnancies reaching at least 20 weeks' gestation that were conceived during January 1, 1986-March 12, 2003, in Atlanta, Georgia. Surveillance records obtained from the Metropolitan Atlanta Congenital Defects Program, which conducts active, population-based surveillance on this cohort, were reviewed to classify cardiovascular malformations. Ambient 8-hour maximum ozone and 24-hour average carbon monoxide, nitrogen dioxide, particulate matter with an average aerodynamic diameter of <10 microm (PM(10)), and sulfur dioxide measurements were obtained from centrally located stationary monitors. Temporal associations between these pollutants and daily risks of secundum atrial septal defect, aortic coarctation, hypoplastic left heart syndrome, patent ductus arteriosus, valvar pulmonary stenosis, tetralogy of Fallot, transposition of the great arteries, muscular ventricular septal defect, perimembranous ventricular septal defect, conotruncal defects, left ventricular outflow tract defect, and right ventricular outflow defect were modeled by using Poisson generalized linear models. A statistically significant association was observed between PM(10) and patent ductus arteriosus (for an interquartile range increase in PM(10) levels, risk ratio = 1.60, 95% confidence interval: 1.11, 2.31). Of the 60 associations examined in the primary analysis, no other significant associations were observed.

Methodological issues in studies of air pollution and reproductive health

In the past decade there have been an increasing number of scientific studies describing possible effects of air pollution on perinatal health. These papers have mostly focused on commonly monitored air pollutants, primarily ozone (O(3)), particulate matter (PM), sulfur dioxide (SO(2)), carbon monoxide (CO), and nitrogen dioxide (NO(2)), and various indices of perinatal health, including fetal growth, pregnancy duration, and infant mortality. While most published studies have found some marker of air pollution related to some types of perinatal outcomes, variability exists in the nature of the pollutants and outcomes associated. Synthesis of the findings has been difficult for various reasons, including differences in study design and analysis. A workshop was held in September 2007 to discuss methodological differences in the published studies as a basis for understanding differences in study findings and to identify priorities for future research, including novel approaches for existing data. Four broad topic areas were considered: confounding and effect modification, spatial and temporal exposure variations, vulnerable windows of exposure, and multiple pollutants. Here we present a synopsis of the methodological issues and challenges in each area and make recommendations for future study. Two key recommendations include: (1) parallel analyses of existing data sets using a standardized methodological approach to disentangle true differences in associations from methodological differences among studies; and (2) identification of animal studies to inform important mechanistic research gaps. This work is of critical public health importance because of widespread exposure and because perinatal outcomes are important markers of future child and adult health.

Preterm birth after the Utah Valley Steel Mill closure: a natural experiment

BACKGROUND

: Prior studies have linked the Utah Valley Steel Mill closure that took place between August 1986 and September 1987 to improvements in several health outcomes. So-called natural experiments ease concerns over confounding and exposure misclassification, concerns that are common in studies of air pollution and pregnancy outcome.

METHODS

: We compare birth outcomes for Utah mothers within and outside the Utah Valley, before, during, and after the mill closure.

RESULTS

: Mothers who were pregnant around the time of the closure of the mill were less likely to deliver prematurely than mothers who were pregnant before or after; effects were strongest for exposure during the second trimester. Preterm birth within the Utah Valley did not change during the time of mill closure. No patterns for birth weight were observed.

CONCLUSIONS

: These results support other studies that have found effects on preterm birth of air pollution exposure early in pregnancy.

Estimating the health and economic benefits associated with reducing air pollution in the Barcelona metropolitan area (Spain)

OBJECTIVES

To estimate the health and economic benefits that would result from two scenarios of improved air quality in 57 municipalities of the metropolitan area of Barcelona.

METHODS

We used attributable fractions and life tables to quantify the benefits for selected health outcomes, based on published concentration-response functions and economic unit values. The mean weighted concentration of PM(10) for the study population was estimated through concentration surface maps developed by the local government.

RESULTS

The annual mean health benefits of reducing the mean PM(10) exposure estimated for the population in the study area (50microg/m(3)) to the annual mean value recommended by the World Health Organization (20microg/m(3)) were estimated to be 3,500 fewer deaths (representing an average increase in life expectancy of 14 months), 1,800 fewer hospitalizations for cardio-respiratory diseases, 5,100 fewer cases of chronic bronchitis among adults, 31,100 fewer cases of acute bronchitis among children, and 54,000 fewer asthma attacks among children and adults. The mean total monetary benefits were estimated to be 6,400 million euros per year. Reducing PM(10) to comply with the current European Union regulatory annual mean level (40microg/m(3)) would yield approximately one third of these benefits.

CONCLUSIONS

This study shows that reducing air pollution in the metropolitan area of Barcelona would result in substantial health and economic benefits. The benefits are probably underestimated due to the assumptions made in this study. Assessment of the health impact of local air pollution is a useful tool in public health.

The issue of confounding in epidemiological studies of ambient air pollution and pregnancy outcomes

BACKGROUND

Relationships between ambient air pollution levels during pregnancy and adverse pregnancy outcomes have been investigated using one of three analytic approaches: ambient pollution levels have been contrasted over space, time or both space and time. Although the three approaches share a common goal, to estimate the causal effects of pollution on pregnancy outcomes, they face different challenges with respect to confounding.

METHODS

A framework based on counterfactual effect definitions to examine issues related to confounding in spatial, temporal, and spatial-temporal analyses of air pollution and pregnancy outcomes is presented, and their implications for inference are discussed.

RESULTS

In spatial analyses, risk factors that are spatially correlated with pollution levels are confounders; the primary challenges relate to the availability and validity of risk factor measurements. In temporal analyses, where smooth functions of time are commonly used to control for confounding, concerns relate to the adequacy of control and the possibility that abrupt changes in risk might be systematically related to pollution levels. Spatial-temporal approaches are subject to challenges faced in both spatial and temporal analyses.

CONCLUSION

Each approach faces different challenges with respect to the likely sources of confounding and the ability to control for that confounding because of differences in the type, availability, and quality of information required. Thoughtful consideration of these differences should help investigators select the analytic approach that best promotes the validity of their research.

Mathematical form factor studies on the effect of water on airborne particles morphology using a bi-dimensional TEM image processing

Mathematical morphology is a tool for extracting image components that are useful for representation and description. The technique consists of a set-theoretic method of image analysis providing a quantitative description of geometrical structures. A simple application of mathematical morphology to a bi-dimensional processing of TEM images of airborne particles allows us to distinguish between particles grown and/or transported in atmosphere under dry conditions or in rainy days by a simple comparison of the corresponding image form factors. The form factors range in the 0.385-0.031 interval in the case of particles sampled in rainy days, and in the 0.103-0.006 interval in the case of non-rainy conditions. The same classification criterion was applied to filters collected under dry conditions and plunged in water. The results demonstrate that a morphological change may be artificially induced to the particle structure. The artificially wet particles, indeed, display an apparent contraction of their structures evidenced by a two-fold increase of the average values of their form factors. The last experiment roughly simulates the impact of particles on membranes of the respiratory tract.

Air pollution and pulmonary function in asthmatic children: effects of prenatal and lifetime exposures

BACKGROUND

Prenatal and early life periods represent critical windows for oxidant pollutant-induced lung remodeling. The objective of this study was to examine the association of prenatal and lifetime exposures to air pollutants with pulmonary function in a cohort of children with asthma.

METHODS

Prenatal and lifetime exposure to several air pollutants was reconstructed for 232 children with asthma from the San Joaquin Valley of California, USA. Prenatal and lifetime residences were geocoded. We obtained data on monthly average ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), and particulate matter with a median aerodynamic diameter <10 microm (PM10) concentrations. Metrics were created for key developmental periods. Predictive models were developed for 8 pulmonary function measures. A newly-developed stepwise model selection procedure-the Deletion/Substitution/Addition algorithm-was implemented and results were compared with those obtained using traditional stepwise methods.

RESULTS

Second-trimester exposure to NO2 negatively affected forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1), and first trimester exposure to PM10 negatively affected peak expiratory flow (PEF) rate. Exposure to CO in early years of life also had a negative effect on FEV1/FVC and forced expiratory flow between 25% and 75% of FVC (FEF25-75)/FVC. Second trimester exposure to PM10 and exposure to CO in the first 6 years of life had negative effects on forced expiratory flow at 25% of FVC. Prenatal, but not trimester-specific, exposure to CO was negatively associated with FEF25-75. Effects were limited to subgroups, such as children who were African American, those diagnosed with asthma before the age of 2 years, and those exposed to maternal smoking during pregnancy.

CONCLUSION

Prenatal and early-life exposures to CO, PM10, and NO2 have a negative effect on pulmonary function in subgroups of asthmatic children.

Airborne concentrations of volatile organic compounds in neonatal incubators

OBJECTIVE

To identify and quantify airborne volatile organic compounds (VOCs) inside neonatal incubators during various modes of operation within the neonatal intensive care unit (NICU) environment.

STUDY DESIGN

Air samples were taken from 10 unoccupied incubators in four operational settings along with ambient air samples using air sampling canisters. The samples were analyzed following EPA TO-15 using a Tekmar AutoCan interfaced to Agilent 6890 Gas Chromatograph with a 5973 Mass Spectrometer calibrated for 60 EPA TO-15 method target compounds. Non-target compounds were tentatively identified using mass spectral interpretation and with a mass spectral library created by National Institute for Standards and Technology.

RESULT

Two non-target compounds, 2-heptanone and n-butyl acetate, were found at elevated concentrations inside the incubators compared with ambient room air samples. Increase in temperature and addition of humidity produced further increased concentrations of these compounds. Their identities were verified by mass spectra and relative retention times using authentic standards. They were quantified using vinyl acetate and 2-hexanone as surrogate standards.

CONCLUSION

The emission pattern of these two compounds and background measurements indicate that they originate inside the incubator. There is evidence that exposure to some VOCs may adversely impact the fetal and developing infants' health. Currently, as there is no definitive information available on the effects of acute or chronic low-level exposure to these compounds in neonates, future studies evaluating the health effects of neonatal exposure to these VOCs are needed.

Meeting report: atmospheric pollution and human reproduction

BACKGROUND

There is a growing body of epidemiologic literature reporting associations between atmospheric pollutants and reproductive outcomes, particularly birth weight and gestational duration.

OBJECTIVES

The objectives of our international workshop were to discuss the current evidence, to identify the strengths and weaknesses of published epidemiologic studies, and to suggest future directions for research.

DISCUSSION

Participants identified promising exposure assessment tools, including exposure models with fine spatial and temporal resolution that take into account time-activity patterns. More knowledge on factors correlated with exposure to air pollution, such as other environmental pollutants with similar temporal variations, and assessment of nutritional factors possibly influencing birth outcomes would help evaluate importance of residual confounding. Participants proposed a list of points to report in future publications on this topic to facilitate research syntheses. Nested case-control studies analyzed using two-phase statistical techniques and development of cohorts with extensive information on pregnancy behaviors and biological samples are promising study designs. Issues related to the identification of critical exposure windows and potential biological mechanisms through which air pollutants may lead to intrauterine growth restriction and premature birth were reviewed.

CONCLUSIONS

To make progress, this research field needs input from toxicology, exposure assessment, and clinical research, especially to aid in the identification and exposure assessment of feto-toxic agents in ambient air, in the development of early markers of adverse reproductive outcomes, and of relevant biological pathways. In particular, additional research using animal models would help better delineate the biological mechanisms underpinning the associations reported in human studies.

Influences of study design and location on the relationship between particulate matter air pollution and birthweight

A large number of studies have identified a relationship between particulate matter air pollution and birthweight. Although reported associations are small and varied, they have been identified in studies from places around the world. Exposure assignment, covariates and study inclusion criteria vary among studies. To examine the effect of these and other study characteristics on associations between particulate matter and birthweight, US birth records for singletons delivered at 40 weeks gestation in 2001-03 during the months of March, June, September and December were linked to quarterly estimates of pollution exposure, both particulate matter exposure and exposure to multiple pollutants, by county of residence and month of birth. Annual, 9-month and trimester-specific exposures were assigned. Among births linked to particulate matter exposure there was a small association between coarse particle exposure and birthweight (beta -13 g per 10 microg/m(3) increase [95% CI -18.3 g, -7.6 g]) after controlling for maternal factors; this association was attenuated slightly and remained statistically significant after further adjustment for contextual factors, year of birth, region, or urban-rural status. The associations were slightly weaker among births linked to multiple pollutant exposure than among births linked to just particulate matter exposure. The association varied markedly by region, ranging from a decrement of 43 g per 10 microg/m(3)[95% CI -58.6 g, -27.6 g] in the north-west to a null association in the south-west. Trimester findings were smaller, yet remained significant and varied regionally. The association between fine particle exposure and birthweight varied considerably, with an overall small positive association that became null after control for region. This study found that wide regional differences in association may contribute to the varied published findings. The association between coarse particle exposure and birthweight appeared robust, if small; fine particles had no overall association with birthweight.

Ambient air pollution and adverse birth outcomes: methodologic issues in an emerging field

Since the mid-1990s, the number of studies linking air pollutants to low birthweight, small for gestational age, preterm birth and cardiac birth defects has grown steadily. This MiniReview (in conjunction with the May 2007 International Conference on Foetal Programming and Development Toxicity) highlights key methodological issues surrounding this research area, based on our experiences in Southern California. All 'criteria' air pollutants have been linked to birth outcomes. Our own studies found most consistent associations for carbon monoxide and particles. Traffic exhaust toxins are possible causative agents, but air monitoring data relied on by almost all existing studies inadequately capture their intracommunity variability in concentrations. Exposure assessment might be improved by biomarkers and land use-based regression modelling or information on time-activity patterns. Foetal development provides unique opportunities to study exposures acting during narrow susceptibility windows. A time-series approach by design controls for confounders that do not vary temporally but can only address short-term acute effects. Studies employing spatial or medium-term (trimester-specific) temporal contrasts may be more susceptible to residual confounding, and studies adjusting only for risk factors recorded on birth certificates have been criticized. Findings from our recent study in Southern California indicate that air pollution effect estimates are not markedly influenced by risk factors not provided on birth certificates. Yet, studies collecting detailed risk factor information in other geographic regions may be needed to further evaluate the extent of residual confounding in record-based analyses. Investigating biological mechanisms (e.g. using ultrasound measurements and biomarkers for hypothesized pathways) is an important remaining issue.

Estimation of outdoor NO(x), NO(2), and BTEX exposure in a cohort of pregnant women using land use regression modeling

Land use regression (LUR) has been successfully used to assess the intraurban variability of air pollution. In the INMA (Environment and Childhood) Study, ambient nitrogen oxides (NO(x) and NO(2)) and aromatic hydrocarbons (BTEX) were measured at 57 sampling sites in Sabadell (northeast Spain). Multiple regression models were developed to predict residential outdoor concentrations in a cohortof pregnantwomen (n = 657), using geographic data as predictor variables. The models accounted for 68 and 69% of the variance in NO(x) and NO(2) levels, respectively, with four predictor variables (altitude, land coverage, and two road length indicators). These percentages of explained variability could be further improved by replacing the two road length indicators with an ordinal indicator (road type). To our knowledge, this is the first study using LUR to assess the intraurban variability of BTEX in Europe, with a model including altitude and source-proximity variables that explained 74% of the variance in BTEX levels. These models will be used to study the association between prenatal exposure to air pollution and adverse pregnancy outcomes and early childhhod effects in the cohort.

Health effects of ambient air pollution in children

Children seem to be most vulnerable to the harmful effects of ambient air pollutants because their defence mechanisms are still evolving and because they inhale a higher volume of air per body weight than adults. Air pollutants can also harm the foetus if the mother is exposed to high levels of air pollution during pregnancy. An increase in respiratory neonatal mortality has been associated with ambient levels of air pollutants. Exposure to fine particles has been shown to increase allergen sensitisation, increase the risk of worsening asthma and decrease lung function. Lung growth, as measured by lung function, seems to be adversely affected in children exposed to various oxidant air pollutants. Oxidative stress is the main underlying mechanism responsible for the harmful effects of air pollutants and preliminary studies have indicated that antioxidant supplementation can offer some protection.

Does the effect of air pollution on pregnancy outcomes differ by gender? A systematic review

Gender is known to influence pregnancy outcomes. Recent studies have reported an association between air pollution exposure and adverse pregnancy outcomes, but gender differences have not been considered. In order to assess the current evidence of the interactive effects between gender and air pollution on pregnancy outcomes we undertook a systematic literature review. Using a comprehensive list of keywords, English language articles published between 1966 and 2005 were retrieved from major databases. Additional information on gender was obtained from the study authors. Studies were included if they contained well-defined measurements of ambient air pollutants, investigated pregnancy outcomes and reported estimates by gender. In total 11 studies were included. The quality of the studies was assessed using the framework in Systematic Reviews in Health Care Meta-analysis in context and Bracken's Guidelines. Of the 11 studies, four evaluated low birth weight (LBW); one each evaluated very low birth weight and fetal growth and six examined preterm birth (PTB). Females were at higher risk of LBW: adjusted odds ratios (AOR) ranged from 1.07 to 1.62. Males were at higher risk for PTB: AORs ranged from 1.11 to 1.20. In addition, there was some evidence to suggest that the effect of air pollution on LBW is differential by gender; however, the evidence was available only from four studies. This is the first systematic review to consider gender effect. Further high quality studies are needed to establish whether these findings prevail.

Fine particles, a major threat to children

BACKGROUND

There is a growing body of evidence for serious health consequences of exposure to ambient air pollution. The general question of who is susceptible is one of the most important gaps in current knowledge regarding particulate matter (PM)-related health effects. Who is susceptible depends on the specific health endpoint being evaluated and the level and length of exposure. Here, we restrict the review on the impact of fine particle exposure on children's health to the following outcomes: infant death, lung function, respiratory symptoms and reproductive outcomes.

METHODS

This is a strategic review of children's susceptibility to ambient fine particles and characteristics of infant and children which underlie their increased susceptibility to PM.

RESULTS

Ambient fine PM is associated with intra-uterine growth retardation, infant mortality; it is associated with impaired lung function and increased respiratory symptoms, particularly in asthmatics. Concerning infant mortality, exposure to PM is strongly and consistently associated with postneonatal respiratory mortality and less consistently with sudden infant death syndrome. Although most of the studies reported adverse effects for this health outcome, the evidence is weaker than for infant death. Exposure to fine PM has been associated with impaired lung function and lung function growth. Most of the studies reported increased prevalence of symptom with increased exposure to fine PM.

CONCLUSION

Fine PM is a major threat to children, because of their higher exposure to PM compared to adults, the immature state of the lung in childhood and also of the immune function at birth. The first months of life might be a period of particular sensitivity. Although the mechanisms of air pollution effects have not yet been completely understood, pregnant women, infants and children need specific protection against exposure to fine particles.

Outdoor air pollution and infant mortality: analysis of daily time-series data in 10 English cities

BACKGROUND

There is growing concern that moderate levels of outdoor air pollution may be associated with infant mortality, representing substantial loss of life-years. To date, there has been no investigation of the effects of outdoor pollution on infant mortality in the UK.

METHODS

Daily time-series data of air pollution and all infant deaths between 1990 and 2000 in 10 major cities of England: Birmingham, Bristol, Leeds, Liverpool, London, Manchester, Middlesbrough, Newcastle, Nottingham and Sheffield, were analysed. City-specific estimates were pooled across cities in a fixed-effects meta-regression to provide a mean estimate.

RESULTS

Few associations were observed between infant deaths and most pollutants studied. The exception was sulphur dioxide (SO2), of which a 10 mug/m(3) increase was associated with a RR of 1.02 (95% CI 1.01 to 1.04) in all infant deaths. The effect was present in both neonatal and postneonatal deaths.

CONCLUSIONS

Continuing reductions in SO2 levels in the UK may yield additional health benefits for infants.

Season of birth and lung fibrosis among workers exposed to asbestos

The season of birth has been suggested to influence the development of some diseases, but its role in lung fibrosis seems to not have been studied previously. The aim of this study was to investigate the relation between the season of birth and fibrotic abnormalities as detected radiologically in high-resolution computed tomography (HRCT) among workers exposed to asbestos. The HRCT examination was performed on 528 study subjects. Multiple ordinal regression analysis adjusting for covariates was used to study the relations between birth month or season and radiological fibrosis signs. Subjects born in autumn or winter had more extensive fibrotic changes than those born in spring or summer. This applied to all fibrotic changes, apart from subpleural nodules, but only the overall fibrosis score, septal lines, and honeycombing showed statistically significantly higher values in comparison to spring births. The highest scores were detected among those born in autumn and winter months (September-February). These results suggest that there are differences in fibrotic radiological abnormalities according to the season of birth in adults exposed to asbestos. Several hypotheses could explain the observed findings, including the effects of early respiratory infections, cold temperature, and differences in air pollution levels, as well as some metabolic and hormonal effects.

Wear Particles Generated from Studded Tires and Pavement Induces Inflammatory Reactions in Mouse Macrophage Cells

Health risks associated with exposure to airborne particulate matter (PM) have been shown epidemiologically as well as experimentally, pointing to both respiratory and cardiovascular effects. These health risks are of increasing concern in society, and to protect public health, a clarification of the toxic properties of particles from different sources is of importance. Lately, wear particles generated from traffic have been recognized as a major contributing source to the overall particle load, especially in the Nordic countries where studded tires are used. The aim of this study was to further investigate and compare the ability to induce inflammatory mediators of different traffic-related wear particles collected from an urban street, a subway station, and studded tire-pavement wear. Inflammatory effects were measured as induction of nitric oxide (NO), IL-6, TNF-alpha, arachidonic acid (AA), and lipid peroxidation after exposure of the murine macrophage like cell line RAW 264.7. In addition, the redox potential of the particles was measured in a cell-free system. The results show that all particles tested induce IL-6, TNF-alpha, and NO, and those from the urban street were the most potent ones. In contrast, particles collected from a subway station were most potent to induce lipid peroxidation, AA release, and formation of ROS. Particles from studded tire-pavement wear, generated using a road simulator, were able to induce inflammatory cytokines, NO, lipid peroxidation, and ROS formation. Interestingly, particles generated from pavement containing granite as the main stone material were more potent than those generated from pavement containing quartzite as the main stone material.

Global pediatric environmental health

Children are uniquely vulnerable to environmental health problems. Developed countries report as the most common problems ambient (outdoor) air pollution and lead. Developing countries have a wider range of common problems, including childhood injuries, indoor air pollution, infectious disease, and poor sanitation with unsafe water. Globally, the agencies of the United Nations act to protect children and perform essential reporting and standards-setting functions. Conditions vary greatly among countries and are not always better in developing countries. Protecting the health of children requires strengthening the public health and medical systems in every country, rather than a single global agenda.

Particulate matter in the environment: pulmonary and cardiovascular effects

PURPOSE OF REVIEW

The mechanisms related to adverse respiratory and cardiovascular effects in populations exposed to particulate matter are under debate and different models have been used to further our understanding of the various aspects of those effects. In this review we present some studies that may give new insights into the cellular and systemic mechanisms related to particulate matter toxicity.

RECENT FINDINGS

Strong epidemiological evidence is now available regarding exposure markers and health effects. This is evident in the correlation between carbon content in macrophages and decrease in lung function, an increase in the risk of chronic obstructive pulmonary disease, lung cancer and postnatal mortality. The role of outdoor temperature and a missing allele for GSTM1 and the impact of these factors on cardiovascular effects are also reported. At the experimental level, the effects of particulate matter and the interactions between different cell types, the role of toll-like receptor-2 and 4, the translocation of particles through cell monolayers and the activation of endothelial cells by particulate matter are also discussed. The role of composition is under intense debate, and different statistical analyses have been proposed.

SUMMARY

Experimental studies on the effects of particulate matter are giving plausibility to the epidemiological findings, but the possible mechanisms of action are also becoming a hot topic.

Exposición a contaminantes atmosféricos durante el embarazo y desarrollo prenatal y neonatal: protocolo de investigación en el proyecto INMA (Infancia y Medio Ambiente)

INTRODUCTION

The INMA (INfancia y Medio Ambiente [Spanish for Environment and Childhood]) project is a cooperative research network. This project aims to study the effects of environment and diet on fetal and early childhood development. This article aims to present the air pollutant exposure protocol during pregnancy and fetal and early childhood development of the INMA project.

METHODS

The information to assess air pollutant exposure during pregnancy is based on outdoor measurement of air pollutants (nitrogen dioxide [NO2], volatile organic compounds [VOC], ozone, particulate matter [PM10, PM2,5 ] and of their composition [polycyclic aromatic hydrocarbons]); measurement of indoor and personal exposure (VOC and NO2); urinary measurement of a biological marker of hydrocarbon exposure (1-hydroxypyrene); and data gathered by questionnaires and geographic information systems. These data allow individual air pollutant exposure indexes to be developed, which can then be used to analyze the possible effects of exposure on fetal development and child health.

CONCLUSION

This protocol and the type of study allow an approximation to individual air pollutant exposure to be obtained. Finally, the large number of participants (N = 4,000), as well as their geographic and social diversity, increases the study's potential.

The Spanish Environment and Childhood Research Network (INMA study)

Prenatal and early life exposure to environmental agents, including dietary exposure, is associated with child health and human development and predisposes to late adult effects. Children are more vulnerable than adults to chemical, physical and biological hazards in air, water and soil, because they are still growing and their immune system and detoxification mechanisms are not fully developed. The physical, social and intellectual development of children from conception to the end of adolescence requires a protected environment that is also protective of their health. Following WHO and European Union recommendations, the Cooperative Environment and Childhood Research Network was funded by the Spanish Ministry of Health to study effects of environment and diet on foetal and early childhood development in different geographical areas of Spain. This network integrates different multidisciplinary research groups and is comprised of six cohorts--three pre-existing and three de novo--which will prospectively follow up 3600 pregnant women from start of pregnancy until the children are 4-6-year old.

Air pollution: a threat to the health of our children

BACKGROUND/METHODS

Current air pollution levels pose a threat to the health of children starting from conception. The scientific evidence is presented for mortality, morbidity, and sub-clinical effects. The first section deals with exposure data, the following sections with the evidence of health effects from epidemiology and toxicology leading to recommendations.

RESULTS

Improved air quality reduces the number of infants' deaths as well as disease and pain.

CONCLUSIONS

Medical doctors have a responsibility to know the facts and to advise their patients. Doctors when visiting their patients' homes should be aware of the possibly grave impact of the indoor environment for the respiratory health of their patients. They should recognize and advise the parents on problems associated with environmental tobacco smoke, poor ventilation, mould growth, and maintenance of heating installations. With regard to outdoor air pollution, doctors could serve as role models and also advise their patients and parents on environmentally friendly behaviour. Such behaviour not only calls for personal commitment but also for the right infrastructure to be provided (e.g. public transport, district heating). Doctors should be proactive in the community and in their country as advocates for a healthier environment for our children.

Child health and the environment: the INMA Spanish Study

The INMA (INfancia y Medio Ambiente [Environment and Childhood]) is a population-based cohort study in different Spanish cities, that focuses on prenatal environmental exposures and growth, development and health from early fetal life until childhood. The study focuses on five primary areas of research: (1) growth and physical development; (2) behavioural and cognitive development; (3) asthma and allergies; (4) sexual and reproductive development; and (5) environmental exposure pathways. The general aims of the project are: (1) to describe the degree of individual prenatal exposure to environmental pollutants, and the internal dose of chemicals during pregnancy, at birth and during childhood in Spain; (2) to evaluate the impact of the exposure to different contaminants on fetal and infant growth, health and development; (3) to evaluate the role of diet on fetal and infant growth, health and development; and (4) to evaluate the interaction between persistent pollutants, nutrients and genetic determinants on fetal and infant growth, health and development. Extensive assessments will be carried out on 3100 pregnant women and children. Data will be collected by physical examinations, questionnaires, interviews, ultrasound and biological samples. Pregnant women are being assessed at 12, 20 and 32 weeks of gestation to collect information about environmental exposures and fetal growth. The children will be followed until the age of 4 years.

Adverse health effects of outdoor air pollutants

Much research on the health effects of outdoor air pollution has been published in the last decade. The goal of this review is to concisely summarize a wide range of the recent research on health effects of many types of outdoor air pollution. A review of the health effects of major outdoor air pollutants including particulates, carbon monoxide, sulfur and nitrogen oxides, acid gases, metals, volatile organics, solvents, pesticides, radiation and bioaerosols is presented. Numerous studies have linked atmospheric pollutants to many types of health problems of many body systems including the respiratory, cardiovascular, immunological, hematological, neurological and reproductive/ developmental systems. Some studies have found increases in respiratory and cardiovascular problems at outdoor pollutant levels well below standards set by such agencies as the US EPA and WHO. Air pollution is associated with large increases in medical expenses, morbidity and is estimated to cause about 800,000 annual premature deaths worldwide [Cohen, A.J., Ross Alexander, H., Ostro, B., Pandey, K.D., Kryzanowski, M., Kunzail, N., et al., 2005. The global burden of disease due to outdoor air pollution. J Toxicol Environ Health A. 68: 1-7.]. Further research on the health effects of air pollution and air pollutant abatement methods should be very helpful to physicians, public health officials, industrialists, politicians and the general public.

Maternal exposure to low levels of ambient air pollution and preterm birth in Brisbane, Australia

BACKGROUND

[corrected] There is evidence that maternal exposure to ambient air pollution during pregnancy is associated with adverse birth outcomes.

OBJECTIVE

To assess preterm birth (PTB) in relation to maternal exposure to ambient air pollution.

DESIGN

Retrospective cohort.

SETTING

Brisbane, Australia.

POPULATION

A total of 28,200 singleton live births for the period of 1 July 2000 to 30 June 2003.

METHODS

Average maternal exposure estimates for ambient particulate matter (PM(10) and bsp), ozone (O(3)) and nitrogen dioxide were calculated over the first 3 months after last menstrual period (LMP) and the last 3 months prior to birth (individually and combined as trimesters).

MAIN OUTCOME MEASURES

PTB was defined as gestation <37 weeks and odds ratios (OR) were calculated for PTB per interquartile range increase in the maternal exposure estimate for each pollutant. Various covariates were controlled for, including season of birth.

RESULTS

Exposure to PM(10) and O(3) during trimester one was associated with an increased risk of PTB (OR = 1.15, 95% CI 1.06-1.25 and OR = 1.26, 95% CI 1.10-1.45, respectively). The PM(10) exposure effect associated with trimester one was strongly related to exposure during the first month post-LMP (PM(10), month one; OR = 1.19, 95% CI 1.13-1.26).

CONCLUSION

These results suggest that maternal exposure to low levels of ambient air pollution is associated with PTB.

Exposure to wear particles generated from studded tires and pavement induces inflammatory cytokine release from human macrophages

Health risks associated with exposure to airborne particulate matter (PM) have been shown epidemiologically as well as experimentally, pointing to both respiratory and cardiovascular effects. Lately, wear particles generated from traffic have been recognized to be a major contributing source to the overall particle load, especially in the Nordic countries were studded tires are used. In this work, we investigated the inflammatory effect of PM10 generated from the wear of studded tires on two different types of pavement. As comparison, we also investigated PM10 from a traffic-intensive street, a subway station, and diesel exhaust particles (DEP). Human monocyte-derived macrophages, nasal epithelial cells (RPMI 2650), and bronchial epithelial cells (BEAS-2B) were exposed to the different types of particles, and the secretion of IL-6, IL-8, IL-10, and TNF-alpha into the culture medium was measured. The results show a significant release of cytokines from macrophages after exposure for all types of particles. When particles generated from asphalt/granite pavement were compared to asphalt/quartzite pavement, the granite pavement had a significantly higher capacity to induce the release of cytokines. The granite pavement particles induced cytokine release at the same magnitude as the street particles did, which was higher than what particles from both a subway station and DEP did. Exposure of epithelial cells to PM10 resulted in a significant increase of TNF-alpha secreted from BEAS-2B cells for all types of particles used (DEP was not tested), and the highest levels were induced by subway particles. None of the particle types were able to evoke detectable cytokine release from RPMI 2650 cells. The results indicate that PM10 generated by the wear of studded tires on the street surface is a large contributor to the cytokine-releasing ability of particles in traffic-intensive areas and that the type of pavement used is important for the level of this contribution. Furthermore, the airway inflammatory potential of wear particles from tires and pavement might be of a greater magnitude than that of DEP.

Apheis: Health impact assessment of long-term exposure to PM(2.5) in 23 European cities

INTRODUCTION

Apheis aims to provide European decision makers, environmental-health professionals and the general public with up-to-date and easy-to-use information on air pollution (AP) and public health (PH). In the Apheis-3 phase we quantified the PH impact of long-term exposure to PM(2.5) (particulate matter < 2.5 microm) in terms of attributable number of deaths and the potential gain in life expectancy in 23 European cities.

METHODS

We followed the World Health Organization (WHO) methodology for Health Impact Assessment (HIA) and the Apheis guidelines for data collection and analysis. We used the programme created by PSAS-9 for attributable-cases calculations and the WHO software AirQ to estimate the potential gain in life expectancy. For most cities, PM(2.5) levels were calculated from PM10 measurements using a local or European conversion factor.

RESULTS

The HIA estimated that 16,926 premature deaths from all causes, including 11,612 cardiopulmonary deaths and 1901 lung-cancer deaths, could be prevented annually if long-term exposure to PM(2.5 )levels were reduced to 15 microg/m3 in each city. Equivalently, this reduction would increase life expectancy at age 30 by a range between one month and more than two years in the Apheis cities.

CONCLUSIONS

In addition to the number of attributable cases, our HIA has estimated the potential gain in life expectancy for long-term exposure to fine particles, contributing to a better quantification of the impact of AP on PH in Europe.

The association between low level exposures to ambient air pollution and term low birth weight: a retrospective cohort study

BACKGROUND

Studies in areas with relatively high levels of air pollution have found some positive associations between exposures to ambient levels of air pollution and several birth outcomes including low birth weight (LBW). The purpose of this study was to examine the association between LBW among term infants and ambient air pollution, by trimester of exposure, in a region of lower level exposures.

METHODS

The relationship between LBW and ambient levels of particulate matter up to 10 um in diameter (PM10), sulfur dioxide (SO2) and ground-level ozone (O3) was evaluated using the Nova Scotia Atlee Perinatal Database and ambient air monitoring data from the Environment Canada National Air Pollution Surveillance Network and the Nova Scotia Department of Environment. The cohort consisted of live singleton births (> or =37 weeks of gestation) between January 1, 1988 and December 31, 2000. Maternal exposures to air pollution were assigned to women living within 25 km of a monitoring station at the time of birth. Air pollution was evaluated as a continuous and categorical variable (using quartile exposures) for each trimester and relative risks were estimated from logistic regression, adjusted for confounding variables.

RESULTS

There were 74,284 women with a term, singleton birth during the study period and with exposure data. In the analyses unadjusted for year of birth, first trimester exposures in the highest quartile for SO2 and PM10 suggested an increased risk of delivering a LBW infant (relative risk = 1.36, 95% confidence interval = 1.04 to 1.78 for SO2 exposure and relative risk = 1.33, 95% confidence interval = 1.02 to 1.74 for PM10). After adjustment for birth year, the relative risks were attenuated somewhat and not statistically significant. A dose-response relationship for SO2 was noted with increasing levels of exposure. No statistically significant effects were noted for ozone.

CONCLUSION

Our results suggest that exposure during the first trimester to relatively low levels of some air pollutants may be associated with a reduction in birth weight in term-born infants. These findings have implications for the development of effective risk management strategies to minimize the public health impacts for pregnant women.