Increased incidence of preterm delivery in mothers residing in an industrialized area in Taiwan

Ambient Environment and the Epidemiology of Preterm Birth

Preterm birth (PTB) is associated with substantial mortality and morbidity. We describe environmental factors that may influence PTB risks. We focus on exposures associated with an individual's ambient environment, such as air pollutants, water contaminants, extreme heat, and proximities to point sources (oil/gas development or waste sites) and greenspace. These exposures may further vary by other PTB risk factors such as social constructs and stress. Future examinations of risks associated with ambient environment exposures would benefit from consideration toward multiple exposures - the exposome - and factors that modify risk including variations associated with the structural genome, epigenome, social stressors, and diet.

Seasonality and risk factor analysis of respiratory syncytial virus infection in children in Taiwan-A retrospective study from 1995 to 2005

Respiratory syncytial virus (RSV) is one of the important pathogens leading to acute respiratory tract infection in infants and young children. We aimed to investigate the seasonality of RSV infection in different parts of Taiwan and to delineate the risk factors for severe RSV infections. We collected RSV-infected patients' data by retrospective chart review. A total of 1740 RSV-infected children aged under 18 years were enrolled. The infection was acquired during hospitalization in 103 (7.1%) children, while none of them required ventilator support or needed intensive care before RSV infection. The need for intensive care or ventilator support was significantly associated with congenital heart disease (CHD), chronic lung disease, and neuromuscular diseases. Age <1 year and nosocomially acquired infection are also significant predictors for the need of intensive care. Only the presence of CHD, especially acyanotic CHD, was significantly associated with a fatal outcome. RSV infection occurs all year round. Monthly distribution of RSV infections in Northern Taiwan showed a bimodal pattern, with one peak from March to May, and another from August to October. The distribution in Southern Taiwan showed a single peak from April to July. The occurrence of RSV correlates positively with temperature and rain. The bimodal seasonal distribution pattern in Northern Taiwan may be a transitional pattern shifting from a single high winter peak in temperate areas to a wider summer peak in tropical areas. Continuous surveillance is needed to explore the possible effect of global warming on the seasonality of RSV infection.

Industrial Air Pollution Leads to Adverse Birth Outcomes: A Systematized Review of Different Exposure Metrics and Health Effects in Newborns

Objectives: To review the evidence of associations between adverse birth outcomes (ABO) and industrial air pollution.

Methods: Searches were conducted in PubMed, and Scopus databases, and additional articles were found from snowball search techniques. The included studies feature a study population of mothers with live-born babies exposed to industrial air pollutants, and they examine the effects of industrial pollutants on adverse birth outcomes—namely, low birth weight, term low birth weight, preterm birth, and small for gestational age.

Results: Altogether, 45 studies were included in this review. Exposure to PM2.5, PAHs, benzene, cadmium, and mixtures of industrial air pollutants and living near an industrial area affect birth outcomes.

Conclusion: This study concludes that industrial air pollution is an important risk factor for ABO, especially low birth weight and preterm birth. The strongest evidence is associations between ABO and air pollution from power plants and petrochemical industries. Understanding of specific chemicals that are critical to birth outcomes is still vague. However, the evidence is strongest for more specific air pollutants from the industry, such as PAH, benzene, BTEX, and cadmium.

Killing two birds with one stone: Pregnancy is a sensitive window for endocrine effects on both the mother and the fetus

Pregnancy is a complex process requiring tremendous physiological changes in the mother in order to fulfill the needs of the growing fetus, and to give birth, expel the placenta and nurse the newborn. These physiological modifications are accompanied with psychological changes, as well as with variations in habits and behaviors. As a result, this period of life is considered as a sensitive window as impaired functional and physiological changes in the mother can have short- and long-term impacts on her health. In addition, dysregulation of the placenta and of mechanisms governing placentation have been linked to chronic diseases later-on in life for the fetus, in a concept known as the Developmental Origin of Health and Diseases (DOHaD). This concept stipulates that any change in the environment during the pre-conception and perinatal (in utero life and neonatal) period to puberty, can be "imprinted" in the organism, thereby impacting the health and risk of chronic diseases later in life. Pregnancy is a succession of events that is regulated, in large part, by hormones and growth factors. Therefore, small changes in hormonal balance can have important effects on both the mother and the developing fetus. An increasing number of studies demonstrate that exposure to endocrine disrupting compounds (EDCs) affect both the mother and the fetus giving rise to growing concerns surrounding these exposures. This review will give an overview of changes that happen during pregnancy with respect to the mother, the placenta, and the fetus, and of the current literature regarding the effects of EDCs during this specific sensitive window of exposure.

Cancer Incidence and Mortality among Petroleum Industry Workers and Residents Living in Oil Producing Communities: A Systematic Review and Meta-Analysis

Petroleum extraction and refining are major sources of various occupational exposures and of air pollution and may therefore contribute to the global cancer burden. This systematic review and meta-analysis is aimed at evaluating the cancer risk in petroleum-exposed workers and in residents living near petroleum facilities. Relevant studies were identified and retrieved through PubMed and Web of Science databases. Summary effect size (ES) and 95% confidence intervals (CI) were analysed using random effect models, and heterogeneity across studies was assessed (I2). Overall, petroleum industry work was associated with an increased risk of mesothelioma (ES = 2.09, CI: 1.58-2.76), skin melanoma (ES = 1.34, CI: 1.06-1.70 multiple myeloma (ES =1.81, CI: 1.28-2.55), and cancers of the prostate (ES = 1.13, Cl: 1.05-1.22) and urinary bladder (ES = 1.25, CI: 1.09-1.43) and a decreased risk of cancers of the esophagus, stomach, colon, rectum, and pancreas. Offshore petroleum work was associated with an increased risk of lung cancer (ES = 1.20; 95% CI: 1.03-1.39) and leukemia (ES = 1.47; 95% CI: 1.12-1.92) in stratified analysis. Residential proximity to petroleum facilities was associated with childhood leukemia (ES = 1.90, CI: 1.34-2.70). Very few studies examined specific exposures among petroleum industry workers or residents living in oil producing communities. The present review warrants further studies on specific exposure levels and pathways among petroleum-exposed workers and residents living near petroleum facilities.

Maternal proximity to petrochemical industrial parks and risk of premature rupture of membranes

BACKGROUND

Living near petrochemical industries has been reported to increase the risks of adverse birth outcomes, such as low birth weight and preterm delivery. However, evidence regarding the role of petrochemical exposure in pregnancy complications remains limited. This study evaluated the association between maternal proximity to petrochemical industrial parks (PIPs) during pregnancy and the occurrence of premature rupture of membranes (PROM).

METHODS

We performed a population-based 1:3 case-control study by using the 2004-2014 Taiwanese Birth Certificate Database. Birth records reported as stillbirth or bearing congenital anomalies were excluded. Cases were newborns reported to have PROM, whereas controls were randomly sampled from those without any pregnancy complications by matching birth year and urbanization index of the residential township. The proximity to PIPs was evaluated by calculating the distance to the nearest PIP of the maternal residential township during pregnancy. Furthermore, petrochemical exposure opportunity, accounting for monthly prevailing wind direction, was quantified during the entire gestational period. We applied conditional logistic regression models to evaluate the associations.

RESULTS

In total, 29371 PROM cases were reported during the study period, with a corresponding 88113 healthy controls sampled. The results revealed that living within a 3-km radius of PIPs during pregnancy would increase the risk of PROM (odds ratio [OR] = 1.76, 95% CI: 1.66-1.87). Furthermore, compared with the lowest exposed group, those with high petrochemical exposure opportunity had a significantly increased risk of PROM occurrence (OR = 1.69-1.75). The adverse effects remained robust in the subgroup analysis for both term- and preterm-PROM.

CONCLUSIONS

The results of the present work provide evidence that living near PIPs during pregnancy would increase the risk of PROM, and additional studies are warranted to confirm our findings.

Effects of dibenzothiophene, a sulfur-containing heterocyclic aromatic hydrocarbon, and its alkylated congener, 2,4,7-trimethyldibenzothiophene, on placental trophoblast cell function

Worldwide demand for petroleum products has resulted in increased oil and gas activities in many countries. Conventional and unconventional oil and gas extraction, production, and transport lead to increased levels of petroleum-derived polycyclic aromatic hydrocarbons (PAHs) in the environment. PAH exposure has profound effects on reproduction by affecting pathways involved in placental trophoblast cell function and impairing normal placental development and function-key contributors to reproductive success. However, other components found in petroleum and wastewaters from oil and gas extraction, including the sulfur-containing heterocyclic aromatic compounds such as dibenzothiophene (DBT) and its alkylated derivatives, may also impact reproductive success. The goal of this study was to examine the effect of exposure to DBT, a compound commonly detected in the environment, and one of its alkylated analogues, 2,4,7-trimethyldibenzothiophene (2,4,7-DBT), on steroidogenic and angiogenic pathways critical for mammalian development in placental trophoblast cells (HTR-8/SVneo cells). 2,4,7-DBT but not DBT increased estradiol output in association with increased tube-like formation (surrogate for angiogenesis). These changes in angiogenesis did not appear to be related to altered expression of the key placental angiogenic gene targets (ANGPTL4, VEGFA, and PGF). Neither compound showed a concentration related effect on progesterone synthesis or its receptor expression. Our results suggest that 2,4,7-DBT can disrupt key pathways important for placental trophoblast function and highlight the importance of determining the impact of exposure to both parent and alkylated compounds. Further, these data suggest that exposure to sulfur-containing heterocyclic aromatic compounds may lead to placental dysfunction and impact reproductive success at environmentally relevant levels.

Systematic review of the association between oil and natural gas extraction processes and human reproduction

This systematic review identified 45 original published research articles related to oil and gas extraction activities and human reproductive endpoints. Reproductive outcomes were categorized as [1] birth outcomes associated with maternal exposure, [2] semen quality, fertility, and birth outcomes associated with adult paternal exposure, [3] reproductive cancers, and [4] disruption of human sex steroid hormone receptors. The results indicate there is moderate evidence for an increased risk of preterm birth, miscarriage, birth defects, decreased semen quality, and prostate cancer. The quality of the evidence is low and/or inadequate for stillbirth, sex ratio, and birth outcomes associated with paternal exposure, and testicular cancer, female reproductive tract cancers, and breast cancer, and the evidence is inconsistent for an increased risk of low birth weight; therefore, no conclusions can be drawn for these health effects. There is ample evidence for disruption of the estrogen, androgen, and progesterone receptors by oil and gas chemicals, which provides a mechanistic rationale for how exposure to oil and gas activities may increase the health risks we have outlined. The results from this systematic review suggest there is a negative impact on human reproduction from exposure to oil and gas activities. Many of the 45 studies reviewed identified potential human health effects. Most of these studies focused on conventional oil and gas activities. Few studies have been conducted to evaluate the impact of unconventional oil and gas operations on human health. The impact of unconventional oil and gas activities may be greater than that of conventional activity, given that unconventional activities employ many of the same approaches and use dozens of known endocrine-disrupting chemicals in hydraulic fracturing.

The impact of petrochemical industrialisation on life expectancy and per capita income in Taiwan: an 11-year longitudinal study

BACKGROUND

Petrochemical industries have been identified as important sources of emissions of chemical substances, and adverse health outcomes have been reported for residents who live nearby. The purpose of the current study was to examine the adverse effects of petrochemical industrialization in Taiwan on the life expectancy and personal income of people living in nearby communities.

METHODS

This study compared life expectancies and personal income between one industrial county (Yunlin County) and one reference county (Yilan County), which had no significant industrial activity that might emit pollutants, in Taiwan through analysis of 11 year long and publicly available data. Data from before and after the petrochemical company in the industrial county started (year 1999) operating were compared.

RESULTS

Residents of the industrialized county had lesser increases in life expectancy over time than did residents of a similar but less-industrialized county, with difference means ranging from 0.89 years (p<0.05) to 1.62 years (p<0.001) at different stages. Male residents were more vulnerable to the effects of industrialization. There were no significant differences in individual income between the two counties.

CONCLUSIONS

Countries, including Taiwan and the U.S., embracing petrochemical industries now face the challenge of environmental injustice. Our findings suggested that life expectancy lengthening was slowed and income growth was stalled for residents living in the industrial communities.

Survival analysis of long-term exposure to different sizes of airborne particulate matter and risk of infant mortality using a birth cohort in Seoul, Korea

BACKGROUND

Several studies suggest that airborne particulate matter (PM) is associated with infant mortality; however, most focused on short-term exposure to larger particles.

OBJECTIVES

We evaluated associations between long-term exposure to different sizes of particles [total suspended particles (TSP), PM ≤ 10 μm in aerodynamic diameter (PM₁₀), ≤ 10-2.5 μm (PM(10-2.5)), and ≤ 2.5 μm (PM(2.5))] and infant mortality in a cohort in Seoul, Korea, 2004-2007.

METHODS

The study includes 359,459 births with 225 deaths. We applied extended Cox proportional hazards modeling with time-dependent covariates to three mortality categories: all causes, respiratory, and sudden infant death syndrome (SIDS). We calculated exposures from birth to death (or end of eligibility for outcome at 1 year of age) and pregnancy (gestation and each trimester) and treated exposures as time-dependent variables for subjects' exposure for each pollutant. We adjusted by sex, gestational length, season of birth, maternal age and educational level, and heat index. Each cause of death and exposure time frame was analyzed separately.

RESULTS

We found a relationship between gestational exposures to PM and infant mortality from all causes or respiratory causes for normal-birth-weight infants. For total mortality (all causes), risks were 1.44 (95% confidence interval, 1.06-1.97), 1.65 (1.18-2.31), 1.53 (1.22-1.90), and 1.19 (0.83-1.70) per interquartile range increase in TSP, PM₁₀, PM(2.5), and PM(10-2.5), respectively; for respiratory mortality, risks were 3.78 (1.18-12.13), 6.20 (1.50-25.66), 3.15 (1.26-7.85), and 2.86 (0.76-10.85). For SIDS, risks were 0.92 (0.33-2.58), 1.15 (0.38-3.48), 1.42 (0.71-2.87), and 0.57 (0.16-1.96), respectively.

CONCLUSIONS

Our findings provide supportive evidence of an association of long-term exposure to PM air pollution with infant mortality.

Different effects of PM10 exposure on preterm birth by gestational period estimated from time-dependent survival analyses

PURPOSE

We conducted this study to determine if the preterm risks due to PM(10) exposure vary with the exposure periods during pregnancy. This study was also conducted to estimate the different effects of PM(10) exposure on preterm birth by exposure periods using the extended Cox model with PM(10) exposure as a time-dependent covariate.

METHODS

We studied birth data obtained from the Korea National Statistical office for 374,167 subjects who were delivered between 1998 and 2000 in Seoul, South Korea. We used PM(10) data that was measured hourly to give 24-h averages at 27 monitoring stations in Seoul. The extended Cox model with time-dependent exposure was used to determine if the risk of preterm delivery could be associated with PM(10) exposures for each trimester during pregnancy.

RESULTS

Effect of PM10 exposure prior to the 37 weeks of gestational period was stronger on the risk of premature birth than that posterior to the 37 weeks of gestational weeks. This trend was consistent for each trimester; however, the hazard ratios for preterm delivery associated with PM(10) exposure in the first and third trimester were slightly higher than those of the second trimester.

CONCLUSIONS

The risk of preterm birth associated with exposure to PM(10) differed with the exposure period of the neonates. Therefore, when studying the impact of air pollution exposure during pregnancy, the exposure period during pregnancy should be considered.

Epidemiologic evidence of relationships between reproductive and child health outcomes and environmental chemical contaminants

This review summarizes the level of epidemiologic evidence for relationships between prenatal and/or early life exposure to environmental chemical contaminants and fetal, child, and adult health. Discussion focuses on fetal loss, intrauterine growth restriction, preterm birth, birth defects, respiratory and other childhood diseases, neuropsychological deficits, premature or delayed sexual maturation, and certain adult cancers linked to fetal or childhood exposures. Environmental exposures considered here include chemical toxicants in air, water, soil/house dust and foods (including human breast milk), and consumer products. Reports reviewed here included original epidemiologic studies (with at least basic descriptions of methods and results), literature reviews, expert group reports, meta-analyses, and pooled analyses. Levels of evidence for causal relationships were categorized as sufficient, limited, or inadequate according to predefined criteria. There was sufficient epidemiological evidence for causal relationships between several adverse pregnancy or child health outcomes and prenatal or childhood exposure to environmental chemical contaminants. These included prenatal high-level methylmercury (CH(3)Hg) exposure (delayed developmental milestones and cognitive, motor, auditory, and visual deficits), high-level prenatal exposure to polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), and related toxicants (neonatal tooth abnormalities, cognitive and motor deficits), maternal active smoking (delayed conception, preterm birth, fetal growth deficit [FGD] and sudden infant death syndrome [SIDS]) and prenatal environmental tobacco smoke (ETS) exposure (preterm birth), low-level childhood lead exposure (cognitive deficits and renal tubular damage), high-level childhood CH(3)Hg exposure (visual deficits), high-level childhood exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (chloracne), childhood ETS exposure (SIDS, new-onset asthma, increased asthma severity, lung and middle ear infections, and adult breast and lung cancer), childhood exposure to biomass smoke (lung infections), and childhood exposure to outdoor air pollutants (increased asthma severity). Evidence for some proven relationships came from investigation of relatively small numbers of children with high-dose prenatal or early childhood exposures, e.g., CH(3)Hg poisoning episodes in Japan and Iraq. In contrast, consensus on a causal relationship between incident asthma and ETS exposure came only recently after many studies and prolonged debate. There were many relationships supported by limited epidemiologic evidence, ranging from several studies with fairly consistent findings and evidence of dose-response relationships to those where 20 or more studies provided inconsistent or otherwise less than convincing evidence of an association. The latter included childhood cancer and parental or childhood exposures to pesticides. In most cases, relationships supported by inadequate epidemiologic evidence reflect scarcity of evidence as opposed to strong evidence of no effect. This summary points to three main needs: (1) Where relationships between child health and environmental exposures are supported by sufficient evidence of causal relationships, there is a need for (a) policies and programs to minimize population exposures and (b) population-based biomonitoring to track exposure levels, i.e., through ongoing or periodic surveys with measurements of contaminant levels in blood, urine and other samples. (2) For relationships supported by limited evidence, there is a need for targeted research and policy options ranging from ongoing evaluation of evidence to proactive actions. (3) There is a great need for population-based, multidisciplinary and collaborative research on the many relationships supported by inadequate evidence, as these represent major knowledge gaps. Expert groups faced with evaluating epidemiologic evidence of potential causal relationships repeatedly encounter problems in summarizing the available data. A major driver for undertaking such summaries is the need to compensate for the limited sample sizes of individual epidemiologic studies. Sample size limitations are major obstacles to exploration of prenatal, paternal, and childhood exposures during specific time windows, exposure intensity, exposure-exposure or exposure-gene interactions, and relatively rare health outcomes such as childhood cancer. Such research needs call for investments in research infrastructure, including human resources and methods development (standardized protocols, biomarker research, validated exposure metrics, reference analytic laboratories). These are needed to generate research findings that can be compared and subjected to pooled analyses aimed at knowledge synthesis.

Blood levels of polycyclic aromatic hydrocarbons in children of Lucknow, India

Polycyclic aromatic hydrocarbons (PAHs) are compounds with two or more fused benzene rings produced by incomplete combustion of organic substances involved in natural and anthropogenic processes. Children are exposed to these compounds through inhalation, dietary ingestion, and, also, soil at the playground. It has been well established that PAHs have carcinogenic, mutagenic, and teratogenic effects. Considering possible health risks due to PAHs exposure among children, the present study was carried out in collaboration with the Pediatrics Department, King George's Medical University (KGMU), Lucknow, to determine its exposure in children by estimating blood PAHs levels. Due to the variable composition of PAHs mixtures emitted from different environmental sources, any single compound or metabolite may not be representative of all exposure conditions. For these reasons, the measurement of blood PAHs levels as a possible biomarker, especially of the EPA (Environmental Protection Agency, USA) priority list, has been proposed. Acenaphthylene, anthracene, phenanthrene, fluoranthene, naphthalene, pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, and benzo(a)pyrene were determined by HPLC-FD/UV. On the basis of the individual compound, the median (50th percentile) of naphthalene (19 ppb) was highest, however, benzo(a)pyrene (4.0 ppb) level was found to be lowest among all detected PAHs. The median level of total noncarcinogenic PAHs (113.55 ppb) was higher than the total carcinogenic PAHs (32.35 ppb) in blood samples of children. A significant correlation was found between period of time spent in the surrounding breathing zone of the cooking place and total noncarcinogenic PAHs (p < 0.05), while the blood carcinogenic PAHs level in children was found to be associated with lower status of their families (p < 0.05). It is speculated that there may be chances of health hazards through exposure to PAHs, those not yet declared hazardous and present at higher concentrations in the Indian environment. Further study with a larger sample size and accompanying environmental data is desired to validate the findings of this pilot study and strengthen the database of PAHs exposure in India.

A time-series analysis of any short-term effects of meteorological and air pollution factors on preterm births in London, UK

Although much is known about the incidence and burden of preterm birth, its biological mechanisms are not well understood. While several studies have suggested that high levels of air pollution or exposure to particular climatic factors may be associated with an increased risk of preterm birth, other studies do not support such an association. To determine whether exposure to various environmental factors place a large London-based population at higher risk for preterm birth, we analyzed 482,568 births that occurred between 1988 and 2000 from the St. Mary's Maternity Information System database. Using an ecological study design, any short-term associations between preterm birth and various environmental factors were investigated using time-series regression techniques. Environmental exposures included air pollution (ambient ozone and PM(10)) and climatic factors (temperature, rainfall, sunshine, relative humidity, barometric pressure, and largest drop in barometric pressure). In addition to exposure on the day of birth, cumulative exposure up to 1 week before birth was investigated. The risk of preterm birth did not increase with exposure to the levels of ambient air pollution or meteorological factors experienced by this population. Cumulative exposure from 0 to 6 days before birth also did not show any significant effect on the risk of preterm birth. This large study, covering 13 years, suggests that there is no association between preterm births and recent exposure to ambient air pollution or recent changes in the weather.

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.

Epidemiology and environmental factors in preterm labour

An epidemiological and environmental approach is the appropriate starting point to understanding preterm labour. Although there are multiple aetiologies it seems likely that anthropometric and environmental risk factors in combination with inherent genetic susceptibilities contribute to an increased risk of preterm labour for certain women. Poct 2pulation-based studies identifying risk factors and quantifying outcomes facilitate informed counselling and provide a framework for developing prediction tools. Carefully conducted case-control and cohort studies identify associations that may contribute to an understanding of causation. A combined approach encompassing epidemiology, pathophysiology and clinical research is required to understand the aetiologies, prevention and optimal management of preterm labour. This review focuses on the epidemiology of preterm labour and the role of environmental factors.

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.

Environmental factors and developmental outcomes in the lung

The developing lung is highly susceptible to damage from exposure to environmental toxicants particularly due to the protracted maturation of the respiratory system, extending from the embryonic phase of development in utero through to adolescence. The functional organization of the lungs requires a coordinated ontogeny of critical developmental processes that include branching morphogenesis, cellular differentiation and proliferation, alveolarization, and maturation of the pulmonary immune, vasculature, and neural systems. Therefore, exposure to environmental pollutants during crucial periods of prenatal and/or postnatal development may determine the course of lung morphogenesis and maturation. Depending on the timing of exposure and pathobiological response of the affected tissue, exposure to environmental pollutants can potentially result in long-term alterations that affect the structure and function of the respiratory system. Besides an immature respiratory system at birth, children possess unique differences in their physiology and behavioral characteristics compared to adults that are believed to augment the vulnerability of their developing lungs to perturbations by environmental toxins. Furthermore, an interaction between genetic predisposition and increased opportunity for exposure to chemical and infectious disease increase the hazards and risks for infants and children. In this article, the evidence for perturbations of lung developmental processes by key ambient pollutants (environmental tobacco smoke [ETS], ozone, and particulate matter [PM]) are discussed in terms of biological factors that are intrinsic to infants and children and that influence exposure-related lung development and respiratory outcomes.

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.

Air pollution and very low birth weight infants: a target population?

OBJECTIVE

The goal was to examine systematically the association between maternal exposure to particulate matter of <10 microm and very low birth weight (<1500 g) delivery for evidence of an effect on duration of gestation and/or intrauterine growth restriction.

METHODS

This case-control study took place between April 1, 1986, and March 30, 1988, in Georgia Health Care District 9 and included 128 mothers of very low birth weight infants, all of whom were preterm and were classified as either small for gestational age or appropriate for gestational age, and 197 mothers of term, appropriate-for-gestational-age infants weighing > or = 2500 g. Maternal exposure to particulate matter of <10 microm was estimated with 2 exposure measures, namely, a county-level measure based on residence in a county with an industrial point source and an environmental transport model based on the geographic location of the birth home.

RESULTS

Considering preterm/appropriate-for-gestational-age infants as cases and term/appropriate-for-gestational-age infants as controls, adjusted odds ratios for maternal exposure to particulate matter of <10 microm were statistically significant (adjusted odds ratio for county-level model: 4.31; adjusted odds ratio for environmental transport model: 3.68). Although elevated, no statistically significant association was found between maternal exposure and preterm/appropriate-for-gestational-age delivery when compared to preterm/small-for-gestational-age delivery.

CONCLUSIONS

There are increased odds of maternal exposure to ambient particulate matter of <10 microm for very low birth weight preterm/appropriate-for-gestational-age delivery, compared with term/appropriate-for-gestational-age delivery, which suggests that the observed association between maternal exposure to air pollution and low infant birth weight (particularly <1500 g) is at least partially attributable to an effect on duration of gestation.

Exposures to air pollutants during pregnancy and preterm delivery

The association between preterm delivery (PTD) and exposure to air pollutants has recently become a major concern. We investigated this relationship in Incheon, Republic of Korea, using spatial and temporal modeling to better infer individual exposures. The birth cohort consisted of 52,113 singleton births in 2001-2002, and data included residential address, gestational age, sex, birth date and order, and parental age and education. We used a geographic information system and kriging methods to construct spatial and temporal exposure models. Associations between exposure and PTD were evaluated using univariate and multivariate log-binomial regressions. Given the gestational age, birth date, and the mother's residential address, we estimated each mother's potential exposure to air pollutants during critical periods of the pregnancy. The adjusted risk ratios for PTD in the highest quartiles of the first trimester exposure were 1.26 [95% confidence interval (CI), 1.11-1.44] for carbon monoxide, 1.27 (95% CI, 1.04-1.56) for particulate matter with aerodynamic diameter < or = 10 microm, 1.24 (95% CI, 1.09-1.41) for nitrogen dioxide, and 1.21 (95% CI, 1.04-1.42) for sulfur dioxide. The relationships between PTD and exposures to CO, NO2, and SO2 were dose dependent (p < 0.001, p < 0.02, p < 0.02, respectively) . In addition, the results of our study indicated a significant association between air pollution and PTD during the third trimester of pregnancy. In conclusion, our study showed that relatively low concentrations of air pollution under current air quality standards during pregnancy may contribute to an increased risk of PTD. A biologic mechanism through increased prostaglandin levels that are triggered by inflammatory mediators during exposure periods is discussed.

Do subject characteristics modify the effects of particulate air pollution on daily mortality among the elderly?

OBJECTIVE

Studies have reported associations between mortality and air pollution, but questions subsist on the identification of susceptible subgroups in the population. We studied individual characteristics that modify the relationship between particulate air pollution and mortality among elderly.

METHOD

We examined 527 nonaccidental deaths (197 cardiorespiratory deaths) among the 1469 subjects from the Personnes Agees QUID cohort in Bordeaux between 1988 and 1997. Air pollution was measured as black smoke by urban monitoring background stations. We used a case crossover approach and calculated odds ratio by conditional logistic regression models.

RESULTS

We observed associations between the third lag day and cardiorespiratory mortality for an increase of 10 microg/m3 of black smoke (odds ratio = 1.30, 95% confidence interval: 1.01-1.68).

CONCLUSIONS

Our results provide insight into factors possibly conferring susceptibility to the acute effect of urban air pollution.

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

Over the last years, concern for the possible influence of exposure to air pollutants in children during gestation or the first years of life has grown; exposure levels which may be reached nowadays in our dwellings and in our streets. In the present study evidence over the possible impact of ambient air pollution on the foetus and the infants (i.e.: less than 1 year) published during the last decade, 1994--2003, are revised. Studies on infant mortality and exposure to particles show an outstanding consistence in the magnitude of the effects, despite the different designs used. As a whole, data show that an increase in 10 microg/m3 of particle concentration (measured as PM10) is associated with to about 5% increase in post-neonatal mortality for all causes and around 22% for post-neonatal mortality for respiratory diseases. Regarding damage in foetal health, although results are not always consistent, most studies show associations with exposure to air pollution during pregnancy. However, the precise mechanisms of action of air pollutants on adverse reproductive results are still unknown, so is the period of exposure most relevant during pregnancy and the specific pollutant which may represent a higher risk. Follow-up studies evaluating personal exposure to different air pollutants are required, allowing for the adequate evaluation of the impact of each pollutant in different periods of pregnancy, as well as providing hypotheses on their possible mechanisms of action.

Environmental contaminant-mixture effects on CNS development, plasticity, and behavior

Environmental contaminants within the polycyclic aromatic hydrocarbon (PAH) and halogenated aromatic hydrocarbon class have been shown to cross the placenta exposing the fetus to the contaminant body burden of the mother. Consequently, a gestational exposure to environmental contaminants may result in increased adverse health outcomes, possibly affecting cognitive performance. Benzo(a)pyrene [B(a)P] and 2,3,7,8, tetrachlorodibenzo-p-dioxin (TCDD) are two prototypical environmental contaminants. A systematic review of the literature suggests that there may be a relationship between vulnerability in susceptible populations and health disparities. The purpose of this mini-review is to provide a point of reference for neurotoxicological studies of environmental contaminant mixture effects on indices of development in general, and on neurodevelopment in particular. Environmental contaminant-mixture-induced decrements in (1) birth index, (2) N-methyl-D-aspartate receptor (NMDA) mRNA expression, (3) long-term potentiation (LTP), (4) fixed-ratio performance learning behavior, and (5) experience-dependent activity related cytoskeletal-associated protein (Arc) mRNA and protein expression collectively support associations between neurobehavioral deficits and gestational exposure to environmental levels of these contaminants. Collectively, data are presented in this mini-review evaluating the effect of gestational exposure to environmental contaminant-mixtures on specific indices of learning and memory, including hippocampal-based synaptic plasticity mechanisms. These indices serve as templates for learning and memory, and as such, from a vulnerability perspective, may serve as targets for dysregulation during development in susceptible populations that have been disproportionately exposed to these contaminants. Included in this review is also a discussion of the relevance of developing biomarkers for use within the framework of cumulative risk-assessment.