Indoor exposure and adverse birth outcomes related to fetal growth, miscarriage and prematurity-a systematic review

The purpose of this review was to summarize existing epidemiological evidence of the association between quantitative estimates of indoor air pollution and all-day personal exposure with adverse birth outcomes including fetal growth, prematurity and miscarriage. We carried out a systematic literature search of MEDLINE and EMBASE databases with the aim of summarizing and evaluating the results of peer-reviewed epidemiological studies undertaken in “westernized” countries that have assessed indoor air pollution and all-day personal exposure with specific quantitative methods. This comprehensive literature search identified 16 independent studies which were deemed relevant for further review and two additional studies were added through searching the reference lists of all included studies. Two reviewers independently and critically appraised all eligible articles using the Critical Appraisal Skills Programme (CASP) tool. Of the 18 selected studies, 14 adopted a prospective cohort design, three were case-controls and one was a retrospective cohort study. In terms of pollutants of interest, seven studies assessed exposure to electro-magnetic fields, four studies assessed exposure to polycyclic aromatic hydrocarbons, four studies assessed PM_2.5 exposure and three studies assessed benzene, phthalates and noise exposure respectively. Furthermore, 12 studies examined infant growth as the main birth outcome of interest, six examined spontaneous abortion and three studies assessed gestational age at birth and preterm delivery. This survey demonstrates that there is insufficient research on the possible association of indoor exposure and early life effects and that further research is needed.

Gene-environment interaction among GSTT1, PON2 polymorphisms and organic solvents on gestational age in a Chinese women cohort

PURPOSE

To investigate interactions on gestational age among two environmental risk factors and four maternal genetic polymorphisms: organic solvents, passive smoking, CYP1A1 rs4646903 (MspI), EPHX1 rs2234922 (His139Arg), GSTT1 and PON2 rs12026 (Ala148Gly).

METHODS

A pregnant women cohort was conducted at Beijing Yanshan Petrochemical Corporation, and 1,097 mothers with live singleton births were included in analysis. Generalized Multifactor Dimensionality Reduction (GMDR) method was used to explore interactions among these factors with adjustment for important potential confounders. Multiple linear regression models were used to estimate the association of interaction with gestational age.

RESULTS

A three-factor model of organic solvents, GSTT1 and PON2 rs12026 had the highest testing balanced accuracy (57.05 %) and best cross-validation consistency (10/10). Compared with organic solvents unexposed mothers with GSTT1 non-null genotype and PON2 rs12026 CC genotype, organic solvents exposed mothers with GSTT1 null genotype and PON2 rs12026 CG + GG genotype had the largest reduction in gestational age (-0.36 weeks, 95%CI: -0.70 to -0.02). The significant reductions in different groups were from 0.24 weeks to 0.36 weeks.

CONCLUSIONS

Maternal genetic susceptibility GSTT1 and PON2 rs12026 could significantly modify the association of organic solvents with gestational age.

Green spaces and adverse pregnancy outcomes

OBJECTIVE

The objective of this study was to evaluate the associations between proximity to green spaces and surrounding greenness and pregnancy outcomes, such as birth weight, low birth weight (LBW), very LBW (VLBW), gestational age, preterm deliveries (PTD) and very PTD (VPTD).

METHODS

This study was based on 39,132 singleton live births from a registry birth cohort in Tel Aviv, Israel, during 2000-2006. Surrounding greenness was defined as the average of satellite-based Normalised Difference Vegetation Index (NDVI) in 250 m buffers and proximity to major green spaces was defined as residence within a buffer of 300 m from boundaries of a major green space (5000 m(2)), based on data constructed from OpenStreetMap. Linear regression (for birth weight and gestational age) and logistic regressions models (for LBW, VLBW, PTD and VPTD) were used with adjustment for relevant covariates.

RESULTS

An increase in 1 interquartile range greenness was associated with a statistically significant increase in birth weight (19.2 g 95% CI 13.3 to 25.1) and decreased risk of LBW (OR 0.84, 95% CI 0.78 to 0.90). Results for VLBW were in the same direction but were not statistically significant. In general, no associations were found for gestational age, PTD and VPTD. The findings were consistent with different buffer and green space sizes and stronger associations were observed among those of lower socioeconomic status.

CONCLUSIONS

This study confirms the results of a few previous studies demonstrating an association between maternal proximity to green spaces and birth weight. Further investigation is needed into the associations with VLBW and VPTD, which has never been studied before.

Maternal dioxin exposure and pregnancy outcomes over 30 years of follow-up in Seveso

Animal evidence suggests an association between exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and adverse pregnancy outcomes. Epidemiologic studies report inconsistent results, but are limited by narrow range of exposure, small sample size, and lack of a biologic measure of highest lifetime exposure. On July 10, 1976, a chemical explosion in Seveso, Italy resulted in the highest known residential exposure to TCDD. In 1996, we initiated the Seveso Women's Health Study (SWHS), a retrospective cohort of TCDD exposure and reproductive health. Individual-level TCDD was measured in serum collected soon after the explosion. After 20years of follow-up, we found no association between maternal TCDD in 1976 serum or estimated at pregnancy and spontaneous abortion (SAB), fetal growth, or gestational length. Here, we present an updated analysis of TCDD exposure and adverse pregnancy outcomes from a subsequent follow-up of the SWHS cohort in 2008-2009. SWHS women had 1211 post-explosion pregnancies through the 2008-2009 follow-up. We found no association between TCDD estimated at pregnancy and SAB, fetal growth, or gestational length. However, we found a non-significant inverse association between maternal 1976 serum TCDD and birthweight (adjusted β=-22.8, 95% CI: -80.1, 34.6). The association was stronger among first post-explosion births, but remained non-significant (adjusted β=-47.7, 95% CI: -107.3, 11.9). SWHS is the first study to be able to consider two potentially relevant measures of TCDD exposure: highest lifetime dose and in utero. Our results, although non-significant, suggest that highest dose may be more relevant in epidemiologic studies of TCDD and pregnancy outcomes.

Impact of biomass fuels on pregnancy outcomes in central East India

BACKGROUND

Smoke from biomass burning has been linked to reduced birth weight; association with other birth outcomes is poorly understood. Our objective was to evaluate effects of exposure to biomass smoke on birth weight, preterm birth and stillbirth.

METHODS

Information on household cooking fuel was available for secondary analysis from two cohorts of pregnant women enrolled at delivery in India (n = 1744). Birth weight was measured and the modified Ballard performed to assess gestational age. Linear and logistic regression models were used to explore associations between fuel and birth outcomes. Effect sizes were adjusted in multivariate models for socio-demographic characteristics using propensity score techniques and for medical/obstetric covariates.

RESULTS

Compared to women who use gas (n = 265), women cooking with wood (n = 1306) delivered infants that were on average 112 grams lighter (95% CI -170.1, -54.6) and more likely to be preterm (OR 3.11, 95% CI 2.12, 4.59). Stillbirths were also more common in the wood group (4% versus 0%, p < 0.001). In adjusted models, the association between wood use and birth weight was no longer significant (14 g reduction; 95% CI -93, 66); however, the increased odds for preterm birth persisted (aOR 2.29; 95% CI 1.24, 4.21). Wood fuel use did not increase the risk of delivering either a low birth weight or small for gestational age infant.

CONCLUSIONS

The association between wood fuel use and reduced birth weight was insignificant in multivariate models using propensity score techniques to account for socio-demographic differences. In contrast, we demonstrated a persistent adverse impact of wood fuel use on preterm delivery. If prematurity is confirmed as a consequence of antenatal exposure to household air pollution, perinatal morbidity and mortality from household air pollution may be higher than previously appreciated.

[Malignant neoplasms in the neonate]

Cancer in children has characteristics that differentiate it from other types reported in later ages. Overall survival at 3 years is up to 70% depending on the tumor studied. Major organs and systems affected are the hematopoietic system, central nervous system and sympathetic and mesenchymal tissues. The increased incidence of neonatal tumors observed in this and other studies is based on the increasing number of solid tumors (teratomas and neuroblastomas) because cases of central nervous system tumors and leukemias have remained constant. Ultrasonography is the first line of approach and can detect up to 70% of fetal anomalies. The physiology of the newborn causes the necessary multidisciplinary treatment in neoplastic disease to be modified substantially in this age group to avoid toxicity and sequelae. The most common treatment is surgery. Achieving timely diagnostic treatment options are effective in improving the survival of these patients.

Applicability of a high-throughput shotgun plasma protein screening approach in understanding maternal biological pathways relevant to infant birth weight outcome

There are reports linking maternal nutritional status, smoking and environmental chemical exposures to adverse pregnancy outcomes. However, biological bases for association between some of these factors and birth outcomes are yet to be established. The objective of this preliminary work is to test the capability of a new high-throughput shotgun plasma proteomic screening in identifying maternal changes relevant to pregnancy outcome. A subset of third trimester plasma samples (N=12) associated with normal and low-birth weight infants were fractionated, tryptic-digested and analyzed for global proteomic changes using a MALDI-TOF-TOF-MS methodology. Mass spectral data were mined for candidate biomarkers using bioinformatic and statistical tools. Maternal plasma profiles of cytokines (e.g. IL8, TNF-α), chemokines (e.g. MCP-1) and cardiovascular endpoints (e.g. ET-1, MMP-9) were analyzed by a targeted approach using multiplex protein array and HPLC-Fluorescence methods. Target and global plasma proteomic markers were used to identify protein interaction networks and maternal biological pathways relevant to low infant birth weight. Our results exhibited the potential to discriminate specific maternal physiologies relevant to risk of adverse birth outcomes. This proteomic approach can be valuable in understanding the impacts of maternal factors such as environmental contaminant exposures and nutrition on birth outcomes in future work.

BIOLOGICAL SIGNIFICANCE

We demonstrate here the fitness of mass spectrometry-based shot-gun proteomics for surveillance of biological changes in mothers, and for adverse pathway analysis in combination with target biomarker information. This approach has potential for enabling early detection of mothers at risk for low infant birth weight and preterm birth, and thus early intervention for mitigation and prevention of adverse pregnancy outcomes. This article is part of a Special Issue entitled: Can Proteomics Fill the Gap Between Genomics and Phenotypes?

Effects of maternal prenatal smoking and birth outcomes extending into the normal range on academic performance in fourth grade in North Carolina, USA

BACKGROUND

Research has documented the adverse relationship of child cognitive development with maternal prenatal smoking and poor birth outcomes. The potential, however, for maternal prenatal smoking to modify the association between birth outcomes and cognitive development is unclear.

METHODS

We linked statewide North Carolina birth data for non-Hispanic white and non-Hispanic black children to end-of-grade test scores in reading and mathematics at fourth grade (n = 65 677). We fit race-stratified multilevel models of test scores regressed on maternal smoking, birth outcomes (as measured by continuous and categorical gestational age and birthweight percentile for gestational age), and their interaction, controlling for maternal- and child-level socio-economic factors.

RESULTS

Smoking was consistently associated with decrements in test scores, and better birth outcomes were associated with improvements in test scores, even in clinically normal ranges. Test scores increased quadratically with improving birth outcomes among smoking and non-smoking mothers. Among non-Hispanic white children, the magnitude of the association between gestational age and test scores was larger for children whose mothers smoked during pregnancy compared with the non-smoking group. However, among non-Hispanic black children, birth outcomes did not appear to interact with maternal smoking on test scores.

CONCLUSIONS

Maternal prenatal smoking may interact with birth outcomes on reading and mathematics test scores, particularly among non-Hispanic white children. Improvements in birth outcomes, even within the clinically normal range, may be associated with improved academic performance. Pregnancy-related exposures and events exert a significant and long-term impact on cognitive development.

[Impact of endocrine disrupting chemicals on birth outcomes]

BACKGROUND

Endocrine disruptors are ubiquitous chemicals contaminants in the environment, wildlife, and humans. Their adverse effects on reproduction are well-documented. There is growing evidence that they can contribute to the current emergence of chronic diseases.

OBJECTIVES

Our aim is to assess the relationships between endocrine disruptors and the neonatal health outcomes.

METHODS

Two persons have independently reviewed Medline and Toxline databases about the following pollutants: bisphenol A, phthalates, parabens, brominated flame retardants and perfluorinated compounds. Only the human epidemiological studies, in general population with an abstract available, published between 2007 January the 1st and 2011 December the 31st, were analysed. The quality of each study was assessed with the Strobe score.

RESULTS

Twenty-five out of 680 studies were included in the analysis. All pollutants were widely detected in maternal and new borns samples. Most of the studies have shown associations between bisphenol A, brominated flame retardants and perfluorinated compounds and lower birth weight. The effects on gestational age were less documented and have shown no clear connection. Results for phthalates were more ambiguous. Only one non-instructive study was found on parabens.

DISCUSSION

Due to the inherent methological bias on endocrine disruptors research, further additional studies on environmental health must be investigated. It seems necessary to adopt preventive health measures first for vulnerable population.

Distribution of poly- and perfluoroalkyl substances in matched samples from pregnant women and carbon chain length related maternal transfer

Although levels of poly- and perfluoroalkyl substances (PFASs) in human maternal and neonatal blood have been widely reported in the literature, relationship of maternal-fetal transmission of PFASs with carbon chain length is presently not well understood. In this study, 11 PFASs were analyzed in matched samples, including not only maternal blood (MB, n = 31) and cord blood (CB, n = 30), but also placenta (n = 29) and amniotic fluid (AF, n = 29). Except for perfluorohexanoic acid (PFHxA), the detection frequencies of PFASs were similar among placenta, MB, and CB (>80% for 8 PFASs, nondetectable for 2 PFASs). Though only perfluorooctanoic acid (PFOA) was frequently detected (>90%) in AF, with a median concentration of 0.043 ng/mL, other 5 PFASs were also detectable in AF samples with low concentrations (mean: 0.013-0.191 ng/mL). This suggests that in addition to blood-borne in utero exposure, the fetus is also exposed to low levels of PFASs through AF. Concentrations of PFOA in AF were positively correlated with those in MB (r = 0.738, p < 0.01) and CB (r = 0.683, p < 0.001), suggesting that AF concentration could reflect fetal PFOA exposure during pregnancy and can be used as a biomarker. To clarify the effects of carbon chain length on maternal transfer of PFASs, we calculated maternal transfer efficiencies of PFASs from MB to CB (TMB-CB). A U-shaped trend in TMB-CB of C7-C12 perfluoroalkyl carboxylic acids (PFCAs) with increasing carbon chain length was found in this study for the first time. The U-shaped TMB-CB of PFCAs with carbon chain length is an integrated result of opposite trend of the ratios between MB/placenta and placenta/CB based on carbon chain length. This is the first study to report the occurrence of PFASs in human placenta. The results reported here enable better understanding of the maternal-fetal transmission of PFASs.

Regulatory decisions on endocrine disrupting chemicals should be based on the principles of endocrinology

For years, scientists from various disciplines have studied the effects of endocrine disrupting chemicals (EDCs) on the health and wellbeing of humans and wildlife. Some studies have specifically focused on the effects of low doses, i.e. those in the range that are thought to be safe for humans and/or animals. Others have focused on the existence of non-monotonic dose-response curves. These concepts challenge the way that chemical risk assessment is performed for EDCs. Continued discussions have clarified exactly what controversies and challenges remain. We address several of these issues, including why the study and regulation of EDCs should incorporate endocrine principles; what level of consensus there is for low dose effects; challenges to our understanding of non-monotonicity; and whether EDCs have been demonstrated to produce adverse effects. This discussion should result in a better understanding of these issues, and allow for additional dialog on their impact on risk assessment.

Predictive models and computational toxicology

Understanding the potential health risks posed by environmental chemicals is a significant challenge elevated by the large number of diverse chemicals with generally uncharacterized exposures, mechanisms, and toxicities. The ToxCast computational toxicology research program was launched by EPA in 2007 and is part of the federal Tox21 consortium to develop a cost-effective approach for efficiently prioritizing the toxicity testing of thousands of chemicals and the application of this information to assessing human toxicology. ToxCast addresses this problem through an integrated workflow using high-throughput screening (HTS) of chemical libraries across more than 650 in vitro assays including biochemical assays, human cells and cell lines, and alternative models such as mouse embryonic stem cells and zebrafish embryo development. The initial phase of ToxCast profiled a library of 309 environmental chemicals, mostly pesticidal actives having rich in vivo data from guideline studies that include chronic/cancer bioassays in mice and rats, multigenerational reproductive studies in rats, and prenatal developmental toxicity endpoints in rats and rabbits. The first phase of ToxCast was used to build models that aim to determine how well in vivo animal effects can be predicted solely from the in vitro data. Phase I is now complete and both the in vitro data (ToxCast) and anchoring in vivo database (ToxRefDB) have been made available to the public (http://actor.epa.gov/). As Phase II of ToxCast is now underway, the purpose of this chapter is to review progress to date with ToxCast predictive modeling, using specific examples on developmental and reproductive effects in rats and rabbits with lessons learned during Phase I.

Fetal growth and prenatal exposure to bisphenol A: the generation R study

BACKGROUND

Prenatal exposure to bisphenol A (BPA) has been associated with adverse birth outcomes, but findings of previous studies have been inconsistent.

OBJECTIVE

We investigated the relation of prenatal BPA exposure with intrauterine growth and evaluated the effect of the number of measurements per subject on observed associations.

METHODS

This study was embedded in a Dutch population-based prospective cohort study, with urine samples collected during early, mid-, and late pregnancy. The study comprised 219 women, of whom 99 had one measurement, 40 had two measurements, and 80 had three measurements of urinary BPA. Fetal growth characteristics were repeatedly measured by ultrasound during pregnancy and combined with measurements at birth. Linear regression models for repeated measurements of both BPA and fetal growth were used to estimate associations between urinary concentrations of creatinine-based BPA (BPACB) and intrauterine growth.

RESULTS

The relationship between BPACB and fetal growth was sensitive to the number of BPA measurements per woman. Among 80 women with three BPA measurements, women with BPACB > 4.22 μg/g crea (creatinine) had lower growth rates for fetal weight and head circumference than did women with BPACB < 1.54 μg/g crea, with estimated differences in mean values at birth of -683 g (20.3% of mean) and -3.9 cm (11.5% of mean), respectively. When fewer measurements were available per woman, the exposure-response relationship became progressively attenuated and statistically nonsignificant.

CONCLUSION

Our findings suggest that maternal urinary BPA may impair fetal growth. Because previous studies have shown contradictory findings, further evidence is needed to corroborate these findings in the general population.

Maternal exposure to particulate air pollution and term birth weight: a multi-country evaluation of effect and heterogeneity

BACKGROUND

A growing body of evidence has associated maternal exposure to air pollution with adverse effects on fetal growth; however, the existing literature is inconsistent.

OBJECTIVES

We aimed to quantify the association between maternal exposure to particulate air pollution and term birth weight and low birth weight (LBW) across 14 centers from 9 countries, and to explore the influence of site characteristics and exposure assessment methods on between-center heterogeneity in this association.

METHODS

Using a common analytical protocol, International Collaboration on Air Pollution and Pregnancy Outcomes (ICAPPO) centers generated effect estimates for term LBW and continuous birth weight associated with PM(10) and PM(2.5) (particulate matter ≤ 10 and 2.5 µm). We used meta-analysis to combine the estimates of effect across centers (~ 3 million births) and used meta-regression to evaluate the influence of center characteristics and exposure assessment methods on between-center heterogeneity in reported effect estimates.

RESULTS

In random-effects meta-analyses, term LBW was positively associated with a 10-μg/m3 increase in PM10 [odds ratio (OR) = 1.03; 95% CI: 1.01, 1.05] and PM(2.5) (OR = 1.10; 95% CI: 1.03, 1.18) exposure during the entire pregnancy, adjusted for maternal socioeconomic status. A 10-μg/m3 increase in PM(10) exposure was also negatively associated with term birth weight as a continuous outcome in the fully adjusted random-effects meta-analyses (-8.9 g; 95% CI: -13.2, -4.6 g). Meta-regressions revealed that centers with higher median PM(2.5) levels and PM(2.5):PM(10) ratios, and centers that used a temporal exposure assessment (compared with spatiotemporal), tended to report stronger associations.

CONCLUSION

Maternal exposure to particulate pollution was associated with LBW at term across study populations. We detected three site characteristics and aspects of exposure assessment methodology that appeared to contribute to the variation in associations reported by centers.

Household fuels, low birth weight, and neonatal death in India: the separate impacts of biomass, kerosene, and coal

We examined the impact of maternal use of different household cooking fuels in India on low birth weight (LBW<2500g), and neonatal mortality (death within 28 days of birth). Using cross-sectional data from India's National Family Health Survey (NFHS-3), we separately analyzed the prevalence of these two outcomes in households utilizing three types of high-pollution fuels for cooking - biomass, coal, and kerosene - using low-pollution fuels (gas and biogas) as the comparison "control" group. Taking socioeconomic and child-specific factors into account, we employed logistic regression to examine the impact of fuel use on fetal and infant health. The results indicate that household use of high-pollution fuels is significantly associated with increased odds of LBW and neonatal death. Compared to households using cleaner fuels (in which the mean birth weight is 2901g), the primary use of coal, kerosene, and biomass fuels is associated with significant decreases in mean birth weight (of -110g for coal, -107g for kerosene, and -78g for biomass). Kerosene and biomass fuel use are also associated with increased risk of LBW (p<0.05). Results suggest that increased risk of neonatal death is strongly associated with household use of coal (OR 18.54; 95% CI: 6.31-54.45), and perhaps with kerosene (OR 2.30; 95% CI: 0.95-5.55). Biomass is associated with increased risk of neonatal death among infants born to women with no more than primary education (OR 7.56; 95% CI: 2.40-23.80). These results are consistent with a growing literature showing health impacts of household air pollution from these fuels.

Environmental risk factors of pregnancy outcomes: a summary of recent meta-analyses of epidemiological studies

BACKGROUND

Various epidemiological studies have suggested associations between environmental exposures and pregnancy outcomes. Some studies have tempted to combine information from various epidemiological studies using meta-analysis. We aimed to describe the methodologies used in these recent meta-analyses of environmental exposures and pregnancy outcomes. Furthermore, we aimed to report their main findings.

METHODS

We conducted a bibliographic search with relevant search terms. We obtained and evaluated 16 recent meta-analyses.

RESULTS

The number of studies included in each reported meta-analysis varied greatly, with the largest number of studies available for environmental tobacco smoke. Only a small number of the studies reported having followed meta-analysis guidelines or having used a quality rating system. Generally they tested for heterogeneity and publication bias. Publication bias did not occur frequently.The meta-analyses found statistically significant negative associations between environmental tobacco smoke and stillbirth, birth weight and any congenital anomalies; PM2.5 and preterm birth; outdoor air pollution and some congenital anomalies; indoor air pollution from solid fuel use and stillbirth and birth weight; polychlorinated biphenyls (PCB) exposure and birth weight; disinfection by-products in water and stillbirth, small for gestational age and some congenital anomalies; occupational exposure to pesticides and solvents and some congenital anomalies; and agent orange and some congenital anomalies.

CONCLUSIONS

The number of meta-analyses of environmental exposures and pregnancy outcomes is small and they vary in methodology. They reported statistically significant associations between environmental exposures such as environmental tobacco smoke, air pollution and chemicals and pregnancy outcomes.

Potential changes in disease patterns and pharmaceutical use in response to climate change

As climate change alters environmental conditions, the incidence and global patterns of human diseases are changing. These modifications to disease profiles and the effects upon human pharmaceutical usage are discussed. Climate-related environmental changes are associated with a rise in the incidence of chronic diseases already prevalent in the Northern Hemisphere, for example, cardiovascular disease and mental illness, leading to greater use of associated heavily used Western medications. Sufferers of respiratory diseases may exhibit exacerbated symptoms due to altered environmental conditions (e.g., pollen). Respiratory, water-borne, and food-borne toxicants and infections, including those that are vector borne, may become more common in Western countries, central and eastern Asia, and across North America. As new disease threats emerge, substantially higher pharmaceutical use appears inevitable, especially of pharmaceuticals not commonly employed at present (e.g., antiprotozoals). The use of medications for the treatment of general symptoms (e.g., analgesics) will also rise. These developments need to be viewed in the context of other major environmental changes (e.g., industrial chemical pollution, biodiversity loss, reduced water and food security) as well as marked shifts in human demographics, including aging of the population. To identify, prevent, mitigate, and adapt to potential threats, one needs to be aware of the major factors underlying changes in the use of pharmaceuticals and their subsequent release, deliberately or unintentionally, into the environment. This review explores the likely consequences of climate change upon the use of medical pharmaceuticals in the Northern Hemisphere.

Environmental contaminant exposures and preterm birth: a comprehensive review

Preterm birth is a significant public health concern, as it is associated with high risk of infant mortality, various morbidities in both the neonatal period and later in life, and a significant societal economic burden. As many cases are of unknown etiology, identification of the contribution of environmental contaminant exposures is a priority in the study of preterm birth. This is a comprehensive review of all known studies published from 1992 through August 2012 linking maternal exposure to environmental chemicals during pregnancy with preterm birth. Using PubMed searches, studies were identified that examined associations between preterm birth and exposure to five categories of environmental toxicants, including persistent organic pollutants, drinking-water contaminants, atmospheric pollutants, metals and metalloids, and other environmental contaminants. Individual studies were summarized and specific suggestions were made for future work in regard to exposure and outcome assessment methods as well as study design, with the recommendation of focusing on potential mediating toxicological mechanisms. In conclusion, no consistent evidence was found for positive associations between individual chemical exposures and preterm birth. By identifying limitations and addressing the gaps that may have impeded the ability to identify true associations thus far, this review can guide future epidemiologic studies of environmental exposures and preterm birth.

Natural killer cells promote immune tolerance by regulating inflammatory TH17 cells at the human maternal-fetal interface

Natural killer (NK) cells accumulate at the maternal-fetal interface in large numbers, but their exact roles in successful pregnancy remain poorly defined. Here, we provide evidence that T(H)17 cells and local inflammation can occur at the maternal-fetal interface during natural allogenic pregnancies. We found that decidual NK cells promote immune tolerance and successful pregnancy by dampening inflammatory T(H)17 cells via IFN-γ secreted by the CD56(bright)CD27(+) NK subset. This NK-cell-mediated regulatory response is lost in patients who experience recurrent spontaneous abortions, which results in a prominent T(H)17 response and extensive local inflammation. This local inflammatory response further affects the regulatory function of NK cells, leading to the eventual loss of maternal-fetal tolerance. Thus, our data identify NK cells as key regulatory cells at the maternal-fetal interface by suppressing T(H)17-mediated local inflammation.

Low level maternal smoking and infant birthweight reduction: genetic contributions of GSTT1 and GSTM1 polymorphisms

BACKGROUND

Genetic susceptibility to tobacco smoke might modify the effect of smoking on pregnancy outcomes.

METHODS

We conducted a case-control study of 543 women who delivered singleton live births in Kaunas (Lithuania), examining the association between low-level tobacco smoke exposure (mean: 4.8 cigarettes/day) during pregnancy, GSTT1 and GSTM1 polymorphisms and birthweight of the infant. Multiple linear-regression analysis was performed adjusting for gestational age, maternal education, family status, body mass index, blood pressure, and parity. Subsequently, we tested for the interaction effect of maternal smoking, GSTT1 and GSTM1 genes polymorphisms with birthweight by adding all the product terms in the regression models.

RESULTS

The findings suggested a birthweight reduction among light-smoking with the GSTT1-null genotype (-162.9 g, P = 0.041) and those with the GSTM1-null genotype (-118.7 g, P = 0.069). When a combination of these genotypes was considered, birthweight was significantly lower for infants of smoking women the carriers of the double-null genotypes (-311.2 g, P = 0.008). The interaction effect of maternal smoking, GSTM1 and GSTT1 genotypes was marginally significant on birthweight (-234.5 g, P = 0.078). Among non-smokers, genotype did not independently confer an adverse effect on infant birthweight.

CONCLUSIONS

The study shows the GSTT1-null genotype, either presents only one or both with GSTM1-null genotype in a single subject, have a modifying effect on birthweight among smoking women even though their smoking is low level. Our data also indicate that identification of the group of susceptible subjects should be based on both environmental exposure and gene polymorphism. Findings of this study add additional evidence on the interplay among two key GST genes and maternal smoking on birth weight of newborns.

Exposure to drinking water trihalomethanes and their association with low birth weight and small for gestational age in genetically susceptible women

Little is known about genetic susceptibility to individual trihalomethanes (THM) in relation to adverse pregnancy outcomes. We conducted a nested case-control study of 682 pregnant women in Kaunas (Lithuania) and, using individual information on drinking water, ingestion, showering and bathing, and uptake factors of THMs in blood, estimated an internal THM dose. We used logistic regression to evaluate the relationship between internal THM dose, birth outcomes and individual and joint (modifying) effects of metabolic gene polymorphisms. THM exposure during entire pregnancy and specific trimesters slightly increased low birth weight (LBW) risk. When considering both THM exposure and maternal genotypes, the largest associations were found for third trimester among total THM (TTHM) and chloroform-exposed women with the GSTM1–0 genotype (OR: 4.37; 95% CI: 1.36–14.08 and OR: 5.06; 95% CI: 1.50–17.05, respectively). A test of interaction between internal THM dose and GSTM1–0 genotype suggested a modifying effect of exposure to chloroform and bromodichloromethane on LBW risk. However, the effect on small for gestational age (SGA) was not statistically significant. These data suggest that THM internal dose may affect foetal growth and that maternal GSTM1 genotype modifies the THM exposure effects on LBW.

Pesticide exposure in children

Pesticides are a collective term for a wide array of chemicals intended to kill unwanted insects, plants, molds, and rodents. Food, water, and treatment in the home, yard, and school are all potential sources of children's exposure. Exposures to pesticides may be overt or subacute, and effects range from acute to chronic toxicity. In 2008, pesticides were the ninth most common substance reported to poison control centers, and approximately 45% of all reports of pesticide poisoning were for children. Organophosphate and carbamate poisoning are perhaps the most widely known acute poisoning syndromes, can be diagnosed by depressed red blood cell cholinesterase levels, and have available antidotal therapy. However, numerous other pesticides that may cause acute toxicity, such as pyrethroid and neonicotinoid insecticides, herbicides, fungicides, and rodenticides, also have specific toxic effects; recognition of these effects may help identify acute exposures. Evidence is increasingly emerging about chronic health implications from both acute and chronic exposure. A growing body of epidemiological evidence demonstrates associations between parental use of pesticides, particularly insecticides, with acute lymphocytic leukemia and brain tumors. Prenatal, household, and occupational exposures (maternal and paternal) appear to be the largest risks. Prospective cohort studies link early-life exposure to organophosphates and organochlorine pesticides (primarily DDT) with adverse effects on neurodevelopment and behavior. Among the findings associated with increased pesticide levels are poorer mental development by using the Bayley index and increased scores on measures assessing pervasive developmental disorder, inattention, and attention-deficit/hyperactivity disorder. Related animal toxicology studies provide supportive biological plausibility for these findings. Additional data suggest that there may also be an association between parental pesticide use and adverse birth outcomes including physical birth defects, low birth weight, and fetal death, although the data are less robust than for cancer and neurodevelopmental effects. Children's exposures to pesticides should be limited as much as possible.

Environmental exposures: how to counsel preconception and prenatal patients in the clinical setting

A growing body of scientific evidence suggests that preconception and prenatal exposures can impact fetal development adversely and lead to potential long-lasting health effects. Reproductive health professionals have little training on these exposures and how to counsel patients effectively. We present short summaries of some of the most common environmental exposures and give providers practical tools with which to counsel patients in the clinical setting. These tools may enable practitioners to help prevent harmful environmental exposures and to reduce the risk of future adverse health impacts for the prenatal and preconception patient population.

Differential effect of DDT, DDE, and DDD on COX-2 expression in the human trophoblast derived HTR-8/SVneo cells

The purpose of this study was to investigate the effect of 1,1,1-trichloro-2,2-bis-(chlorophenyl)ethane (DDT), 1,1-bis-(chlorophenyl)-2,2-dichloroethene (DDE), and 1,1-dichloro-2,2-bis(chlorophenyl)ethane (DDD) isomers on COX-2 expression in a human trophoblast-derived cell line. Cultured HTR-8/SVneo trophoblast cells were exposed to DDT isomers and its metabolites for 24 h, and COX-2 mRNA and protein expression were assessed by RT-PCR, Western blotting, and ELISA. Prostaglandin E₂ production was also measured by ELISA. Both COX-2 mRNA and protein were detected under control (unexposed) conditions in the HTR-8/SVneo cell line. COX-2 protein expression and prostaglandin E₂ production but not COX-2 mRNA levels increased only after DDE and DDD isomers exposure. It is concluded that DDE and DDD exposure induce the expression of COX-2 protein, leading to increased prostaglandin E2 production. Interestingly, the regulation of COX-2 by these organochlorines pesticides appears to be at the translational level.

Reduced birth weight in relation to pesticide mixtures detected in cord blood of full-term infants

Previous research has shown that prenatal exposure to pesticides may be associated with decreased fetal growth. The specific pesticides investigated and results reported across studies have been inconsistent, and there is a mounting need for the consideration of mixtures rather than individual agents in studies of health outcomes in relation to environmental exposures. There are also many individual pesticides that have not been investigated in human health studies to date. We conducted a pilot study in rural Zhejiang province, China, measuring 20 non-persistent pesticides (10 insecticides, 6 herbicides, 3 fungicides, and 1 repellant) in umbilical cord blood of 112 full term (> 37 weeks) infants. The pesticides detected with the greatest frequency were diethyltoluamide (DEET) (73%), a repellant, and vinclozolin (49%), a fungicide. The samples had detectable concentrations for a mean of 4.6 pesticides (SD=1.9) with a maximum of 10. Adjusting for potential confounders, newborn birth weight was inversely associated with the number of pesticides detected in cord blood (p=0.04); birth weight decreased by a mean of 37.1g (95% CI, -72.5 to -1.8) for each detected pesticide. When assessing relationships by pesticide type, detection of fungicides was also associated with decreased birth weight (adjusted β=-116 g [95% CI, -212 to -19.2]). For individual pesticides analyzed as dichotomous (detect vs. non-detect) variables, only vinclozolin (adjusted β=-174 g [95% CI, -312 to -36.3]) and acetochlor (adjusted β=-165 g [95% CI, -325 to -5.7]) were significantly associated with reduced birth weight. No significant associations were seen between birth weight and individual pesticides assessed as continuous or 3-level ordinal variables. Our findings from this pilot investigation suggest that exposure to fungicides may adversely impact fetal growth. Exposure to mixtures of multiple pesticides is also of concern and should be explored in addition to individual pesticides. Additional research is needed to establish causality and to understand the function and impact of fungicides and pesticide mixtures on fetal development.

Trends in self-reported spontaneous abortions: 1970-2000

Little is known about how the miscarriage rate has changed over the past few decades in the United States. Data from Cycles IV to VI of the National Survey of Family Growth (NSFG) were used to examine trends from 1970 to 2000. After accounting for abortion availability and the characteristics of pregnant women, the rate of reported miscarriages increased by about 1.0% per year. This upward trend is strongest in the first seven weeks and absent after 12 weeks of pregnancy. African American and Hispanic women report lower rates of early miscarriage than do whites. The probability of reporting a miscarriage rises by about 5% per year of completed schooling. The upward trend, especially in early miscarriages, suggests awareness of pregnancy rather than prenatal care to be a key factor in explaining the evolution of self-reported miscarriages. Any beneficial effects of prenatal care on early miscarriage are obscured by this factor. Differences in adoption of early-awareness technology, such as home pregnancy tests, should be taken into account when analyzing results from self-reports or clinical trials relying on awareness of pregnancy in its early weeks.

Synthesis and photocatalytic activity of titania monoliths prepared with controlled macro- and mesopore structure

Herein, we report a one-pot synthesis of crack-free titania monoliths with hierarchical macro-mesoporosity and crystalline anatase walls. Bimodal macroporosity is created through the polymer-induced phase separation of poly(furfuryl alcohol). The cationic polymerization of furfuryl alcohol is performed in situ and subsequently the polymer becomes immiscible with the aqueous phase, which includes titanic acid. Addition of template, Pluronic F127, increases the mesopore volume and diameter of the resulting titania, as the poly(ethylene glycol) block interacts with the titania precursor, leading to assisted assembly of the metal oxide framework. The hydrophobic poly(propylene glycol) micelle core could itself be swollen with monomeric and oligomeric furfuryl alcohol, allowing for mesopores as large as 18 nm. Variations in synthesis parameters affect porosity; for instance furfuryl alcohol content changes the size and texture of the macropores, water content changes the grain size of the titania and Pluronic F127 content changes the size and volume of the mesopore. Morphological manipulation improves the photocatalytic degradation of methylene blue. Light can penetrate several millimeters into the porous monolith, giving these materials possible application in commercial devices.

Ambient air pollution, birth weight and preterm birth: a systematic review and meta-analysis

Low birth weight and preterm birth have a substantial public health impact. Studies examining their association with outdoor air pollution were identified using searches of bibliographic databases and reference lists of relevant papers. Pooled estimates of effect were calculated, heterogeneity was quantified, meta-regression was conducted and publication bias was examined. Sixty-two studies met the inclusion criteria. The majority of studies reported reduced birth weight and increased odds of low birth weight in relation to exposure to carbon monoxide (CO), nitrogen dioxide (NO(2)) and particulate matter less than 10 and 2.5 microns (PM(10) and PM(2.5)). Effect estimates based on entire pregnancy exposure were generally largest. Pooled estimates of decrease in birth weight ranged from 11.4 g (95% confidence interval -6.9-29.7) per 1 ppm CO to 28.1g (11.5-44.8) per 20 ppb NO(2), and pooled odds ratios for low birth weight ranged from 1.05 (0.99-1.12) per 10 μg/m(3) PM(2.5) to 1.10 (1.05-1.15) per 20 μg/m(3) PM(10) based on entire pregnancy exposure. Fewer effect estimates were available for preterm birth and results were mixed. Pooled odds ratios based on 3rd trimester exposures were generally most precise, ranging from 1.04 (1.02-1.06) per 1 ppm CO to 1.06 (1.03-1.11) per 20 μg/m(3) PM(10). Results were less consistent for ozone and sulfur dioxide for all outcomes. Heterogeneity between studies varied widely between pollutants and outcomes, and meta-regression suggested that heterogeneity could be partially explained by methodological differences between studies. While there is a large evidence base which is indicative of associations between CO, NO(2), PM and pregnancy outcome, variation in effects by exposure period and sources of heterogeneity between studies should be further explored.

Effects of elevated ambient temperature on reproductive outcomes and offspring growth depend on exposure time

Reproductive performance has been shown to be greatly affected by changes in environmental factors, such as temperature. However, it is also crucial to identify the particular stage of pregnancy that is most adversely affected by elevated ambient temperature. The aims of this study were to determine the effect on reproductive outcomes of exposure to elevated ambient temperature during different stages of pregnancy and to determine the effect of prenatal heat stress on offspring growth. Sixty pregnant rats were used in this study. The rats were divided equally into four groups as group 1 (control), group 2 (exposed to elevated temperature following implantation), group 3 (exposed to elevated temperature during pre- and periimplantation), and group 4 (exposed to elevated temperature during pre- and periimplantation and following implantation). Groups 3 and 4 had prolonged gestation periods, reduced litter sizes, and male-biased sex ratios. Moreover, the growth patterns of group 3 and 4 pups were adversely affected by prenatal exposure to elevated temperature. The differences between group 1 and group 3 and between group 1 and group 4 were highly significant. However, no significant differences were observed between groups 1 and 2 in the gestation length, sex ratios, and growth patterns. Thus, it can be concluded that exposure to elevated ambient temperature during pre- and periimplantation has stronger adverse effects on reproductive outcomes and offspring growth than postimplantation exposure.

Birth defects in Iraq and the plausibility of environmental exposure: A review

An increased prevalence of birth defects was allegedly reported in Iraq in the post 1991 Gulf War period, which was largely attributed to exposure to depleted uranium used in the war. This has encouraged further research on this particular topic. This paper reviews the published literature and provided evidence concerning birth defects in Iraq to elucidate possible environmental exposure. In addition to published research, this review used some direct observation of birth defects data from Al-Ramadi Maternity and Paediatric Hospital in Al-Anbar Governorate in Iraq from1st July 2000 through 30th June 2002. In addition to depleted uranium other war-related environmental factors have been studied and linked directly or indirectly with the increasing prevalence of birth defects. However, the reviewed studies and the available research evidence do not provide a clear increase in birth defects and a clear indication of a possible environmental exposure including depleted uranium although the country has been facing several environmental challenges since 1980.

Hormones and endocrine-disrupting chemicals: low-dose effects and nonmonotonic dose responses

For decades, studies of endocrine-disrupting chemicals (EDCs) have challenged traditional concepts in toxicology, in particular the dogma of "the dose makes the poison," because EDCs can have effects at low doses that are not predicted by effects at higher doses. Here, we review two major concepts in EDC studies: low dose and nonmonotonicity. Low-dose effects were defined by the National Toxicology Program as those that occur in the range of human exposures or effects observed at doses below those used for traditional toxicological studies. We review the mechanistic data for low-dose effects and use a weight-of-evidence approach to analyze five examples from the EDC literature. Additionally, we explore nonmonotonic dose-response curves, defined as a nonlinear relationship between dose and effect where the slope of the curve changes sign somewhere within the range of doses examined. We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from the cell culture, animal, and epidemiology literature. We illustrate that nonmonotonic responses and low-dose effects are remarkably common in studies of natural hormones and EDCs. Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities. We conclude that when nonmonotonic dose-response curves occur, the effects of low doses cannot be predicted by the effects observed at high doses. Thus, fundamental changes in chemical testing and safety determination are needed to protect human health.

Effects of the organophosphate insecticides phosmet and chlorpyrifos on trophoblast JEG-3 cell death, proliferation and inflammatory molecule production

Epidemiological data have associated environmental organophosphate insecticide (OP) exposure during pregnancy with fetal growth deficits. To better understand OP injury that may adversely affect pregnancy, we used the JEG-3 choriocarcinoma cell line, which provide a recognized in vitro model to study placental function. The effects of the OP phosmet (Pm) and chlorpyrifos (Cp) on JEG-3 cells viability, proliferation, cell cycle and inflammatory molecule production were evaluated. Both insecticides affected cellular viability in a concentration- and time-dependent manner, inducing apoptosis and decreasing [(3)H]-thymidine incorporation. However, only Pm reduced DNA synthesis independently of cellular death and decreased the cell percentage at the S-phase. Unlike apoptosis, TNFα production varied with the concentration tested, suggesting that other TNFα independent mechanisms might trigger cell death. No induction of the inflammatory molecule nitric oxide was detected. The mRNA levels of pro-inflammatory IL-6, IL-17 and the anti-inflammatory IL-13 cytokines were differentially modulated. These findings show that Pm and Cp generate a specific toxicity signature, altering cell viability and inducing an inflammatory cytokine profile, suggesting that trophoblasts may represent a possible target for OP adverse effects.

Occupational exposure to chemicals and fetal growth: the Generation R Study

BACKGROUND

Developmental diseases, such as birth defects, growth restriction and preterm delivery, account for >25% of infant mortality and morbidity. Several studies have shown that exposure to chemicals during pregnancy is associated with adverse birth outcomes. The aim of this study was to identify whether occupational exposure to various chemicals might adversely influence intrauterine growth patterns and placental weight.

METHODS

Associations between maternal occupational exposure to various chemicals and fetal growth were studied in 4680 pregnant women participating in a population-based prospective cohort study from early pregnancy onwards in the Netherlands (2002–2006), the Generation R Study. Mothers who filled out a questionnaire during mid-pregnancy (response: 77% of enrolment) were included if they conducted paid employment during pregnancy and had a spontaneously conceived singleton live born pregnancy (n = 4680). A job exposure matrix was used, linking job titles to expert judgement on exposure to chemicals in the workplace. Fetal growth characteristics were repeatedly measured by ultrasound and were used in combination with measurements at birth. Placental weight was obtained from medical records and hospital registries. Linear regression models for repeated measurements were used to study the associations between maternal occupational exposure to chemicals and intrauterine growth.

RESULTS

We observed that maternal occupational exposure to polycyclic aromatic hydrocarbons, phthalates, alkylphenolic compounds and pesticides adversely influenced several domains of fetal growth (fetal weight, fetal head circumference and fetal length). We found a significant association between pesticide and phthalate exposure with a decreased placental weight.

CONCLUSIONS

Our results suggest that maternal occupational exposure to several chemicals is associated with impaired fetal growth during pregnancy and a decreased placental weight. Further studies are needed to confirm these findings and to assess post-natal consequences.

Contribution of gestational exposure to ambient traffic air pollutants to fetal cord blood manganese

Motor vehicle emissions have become a major source of air pollution. Contributions of motor vehicle emissions to exposure to toxic metals such as manganese remain inconclusive. This study investigates the relationship between the concentration of manganese in cord blood and exposure to criteria air pollutants during pregnancy. A total of 1526 mother-newborn pairs were recruited by stratified sampling between April, 2004 and July, 2005. The newborns' mothers completed questionnaires that collected information on their demographic characteristics, medical histories, and living environments. Cord blood samples were collected at birth and analyzed by inductively coupled plasma mass spectrometry for manganese. Information about criteria air pollutants which included CO, NO(2), ozone, SO(2), and PM(10) was obtained from monitoring stations run by the Taiwan Environmental Agency. Using the Arc9 Geographic Information System's kriging method, the concentration of each criteria pollutant was estimated at each newborn's residence. The geometric mean for cord blood manganese concentrations was 47.0 μg/L (GSD=1.4). After adjusting for confounding factors such as family income, maternal education, maternal smoking, alcohol drinking during pregnancy, maternal age, child gender, parity, gestational age, and birth season, the results of a multiple linear regression model indicated that cord blood manganese concentration was significantly associated with NO(2) concentration in each trimester, as well as the whole duration of gestation. Between the pregnant women exposed to the highest and those to the lowest quartile of NO(2), a 6 μg/L difference in cord blood manganese concentration was found. This finding suggests that despite other sources of manganese exposure, maternal exposure to ambient NO(2), a surrogate for traffic emission, significantly contributed to fetal cord blood manganese level. Further study is warranted to determine whether the contribution of manganese due to traffic emission causes adverse health effects in fetuses.

Automated time activity classification based on global positioning system (GPS) tracking data

BACKGROUND

Air pollution epidemiological studies are increasingly using global positioning system (GPS) to collect time-location data because they offer continuous tracking, high temporal resolution, and minimum reporting burden for participants. However, substantial uncertainties in the processing and classifying of raw GPS data create challenges for reliably characterizing time activity patterns. We developed and evaluated models to classify people's major time activity patterns from continuous GPS tracking data.

METHODS

We developed and evaluated two automated models to classify major time activity patterns (i.e., indoor, outdoor static, outdoor walking, and in-vehicle travel) based on GPS time activity data collected under free living conditions for 47 participants (N = 131 person-days) from the Harbor Communities Time Location Study (HCTLS) in 2008 and supplemental GPS data collected from three UC-Irvine research staff (N = 21 person-days) in 2010. Time activity patterns used for model development were manually classified by research staff using information from participant GPS recordings, activity logs, and follow-up interviews. We evaluated two models: (a) a rule-based model that developed user-defined rules based on time, speed, and spatial location, and (b) a random forest decision tree model.

RESULTS

Indoor, outdoor static, outdoor walking and in-vehicle travel activities accounted for 82.7%, 6.1%, 3.2% and 7.2% of manually-classified time activities in the HCTLS dataset, respectively. The rule-based model classified indoor and in-vehicle travel periods reasonably well (Indoor: sensitivity > 91%, specificity > 80%, and precision > 96%; in-vehicle travel: sensitivity > 71%, specificity > 99%, and precision > 88%), but the performance was moderate for outdoor static and outdoor walking predictions. No striking differences in performance were observed between the rule-based and the random forest models. The random forest model was fast and easy to execute, but was likely less robust than the rule-based model under the condition of biased or poor quality training data.

CONCLUSIONS

Our models can successfully identify indoor and in-vehicle travel points from the raw GPS data, but challenges remain in developing models to distinguish outdoor static points and walking. Accurate training data are essential in developing reliable models in classifying time-activity patterns.

Congenital anomalies in newborns to women employed in jobs with frequent exposure to organic solvents--a register-based prospective study

Background

The foetal effects of occupational exposure to organic solvents in pregnancy are still unclear. Our aim was to study the risk of non-chromosomal congenital anomalies at birth in a well-defined population of singletons born to women employed as painters and spoolers in early pregnancy, compared to women in non-hazardous occupations.

Method

The study population for this prospective cohort study was singleton newborns delivered to working mothers in the industrial community of Mončegorsk in the period 1973-2005. Occupational information and characteristics of the women and their newborns was obtained from the local population-based birth register.

Results

The 597 women employed as painters, painter-plasterers or spoolers had 712 singleton births, whereof 31 (4.4%) were perinatally diagnosed with 37 malformations. Among the 10 561 newborns in the group classified as non-exposed, 397 (3.9%) had one or more malformations. The overall prevalence in the exposed group was 520/10 000 births [95% confidence limits (CL): 476, 564], and 436/10 000 births (95% CL: 396, 476) in the unexposed. Adjusted for young maternal age, smoking during pregnancy, maternal congenital malformation and year of birth, the odds ratio (OR) was 1.24 (95% CL: 0.85, 1.82); for multiple anomalies it was 1.54 (95% CL: 0.66, 3.59).

The largest organ-system specific difference in prevalence between the two groups was observed for malformations of the circulatory system: 112/10 000 (95% CL: 35, 190) in the exposed group, and 42/10 000 (95% CL: 29, 54) in the unexposed, with an adjusted OR of 2.03 (95% CL: 0.85, 4.84). The adjusted ORs for malformations of the genital organs and musculoskeletal system were 2.24 (95% CI: 0.95, 5.31) and 1.12 (95% CI: (0.62, 2.02), respectively.

Conclusion

There appeared to be a higher risk of malformations of the circulatory system and genital organs at birth among newborns to women in occupations with organic solvent exposure during early pregnancy (predominantly employed as painters). However, the findings were not statistically conclusive. Considering that these two categories of malformations are not readily diagnosed perinatally, the difference in prevalence between the exposed and unexposed may have been underestimated.

Association of prenatal exposure to polybrominated diphenyl ethers and infant birth weight

Polybrominated diphenyl ethers (PBDEs) are a class of persistent compounds that have been used as flame retardants in vehicles, household furnishings, and consumer electronics. This study examined whether concentrations of PBDEs in maternal serum during pregnancy were associated with infant birth weight, length, head circumference, and length of gestation. Participants were pregnant women (n = 286) enrolled in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) Study, a longitudinal cohort study of low-income, predominantly Mexican families living in the Salinas Valley, California. Blood samples were collected near the 26th week of pregnancy in 1999-2000, and concentrations of 10 PBDE congeners (BDE-17, -28, -47, -66, -85, -99, -100, -153, -154, and -183) were measured. Multiple linear regression models were used to investigate the association of lipid-adjusted, log(10)-transformed PBDE concentrations and birth outcome. In adjusted analyses, negative associations with birth weight were seen with BDE-47 (β = -115 g, 95% confidence interval (CI): -229, -2), BDE-99 (β = -114 g, 95% CI: -225, -4), and BDE-100 (β = -122 g, 95% CI: -235, -9). These findings were diminished slightly and were no longer statistically significant when maternal weight gain was included in the models. PBDE congeners were not associated with birth length, head circumference, or gestational duration.

Bridging epidemiology and model organisms to increase understanding of endocrine disrupting chemicals and human health effects

Concerning temporal trends in human reproductive health has prompted concern about the role of environmentally mediated risk factors. The population is exposed to chemicals present in air, water, food and in a variety of consumer and personal care products, subsequently multiple chemicals are found human populations around the globe. Recent reviews find that endocrine disrupting chemicals (EDCs) can adversely affect reproductive and developmental health. However, there are still many knowledge gaps. This paper reviews some of the key scientific concepts relevant to integrating information from human epidemiologic and model organisms to understand the relationship between EDC exposure and adverse human health effects. Additionally, areas of new insights which influence the interpretation of the science are briefly reviewed, including: enhanced understanding of toxicity pathways; importance of timing of exposure; contribution of multiple chemical exposures; and low dose effects. Two cases are presented, thyroid disrupting chemicals and anti-androgens chemicals, which illustrate how our knowledge of the relationship between EDCs and adverse human health effects is strengthened and data gaps reduced when we integrate findings from animal and human studies.

Effect of maternal exposure to ozone on reproductive outcome and immune, inflammatory, and allergic responses in the offspring

There is growing concern that exposure to air pollutants during pregnancy affects health outcomes in the offspring due to alterations in the development of immune and other homeostatic processes. To assess the risks of maternal inhalation exposure to ozone (O(3)), timed pregnant BALB/c mice were exposed to different concentrations of O(3) (0, 0.4, 0.8, and 1.2 ppm) for 4 h/day for 10 days during gestation (GD9-GD18), and pulmonary inflammation and immune responses were assessed in the offspring at 6 weeks-of-age. Maternal O(3) exposure reduced the number of productive dams by 25% at the highest O(3) concentration (1.2 ppm) and decreased the rate of weight gain in the offspring. Delayed-type hypersensitivity responses to bovine serum albumin were suppressed in the female offspring by maternal exposure to the two highest concentrations of O(3), whereas humoral immune responses to sheep red blood cells were not altered in either sex. Maternal exposure to 1.2 ppm O(3) increased lactate dehydrogenase (LDH) activity in bronchoalveolar lavage fluid (BALF) of the offspring but did not affect the number of inflammatory cells or levels of total protein, IFN-γ, IL-17, and IL-4 cytokines in BALF, or CD4(+), CD8(+), CD25(+), and TCRβ(+)CD1d(+) T-cells in the spleen. Offspring born from air-exposed dams sensitized early in life (postnatal day [PND] 3) to ovalbumin (OVA) antigen and then challenged as adults developed eosinophilia, elevated levels of LDH activity and total protein in BALF, and increased pulmonary responsiveness to methacholine, compared with animals sensitized at PND42. Maternal O(3) exposure in the 1.2 ppm O(3) group decreased BALF eosinophilia and serum OVA-specific IgE in the female offspring sensitized early in life but did not affect development of allergic airway inflammation by offspring sensitized late in life. In summary, maternal exposure to O(3) affected reproductive outcome and produced modest decreases in immune function and indicators of allergic lung disease in surviving offspring.

Comparing exposure assessment methods for traffic-related air pollution in an adverse pregnancy outcome study

BACKGROUND

Previous studies reported adverse impacts of traffic-related air pollution exposure on pregnancy outcomes. Yet, little information exists on how effect estimates are impacted by the different exposure assessment methods employed in these studies.

OBJECTIVES

To compare effect estimates for traffic-related air pollution exposure and preeclampsia, preterm birth (gestational age less than 37 weeks), and very preterm birth (gestational age less than 30 weeks) based on four commonly used exposure assessment methods.

METHODS

We identified 81,186 singleton births during 1997-2006 at four hospitals in Los Angeles and Orange Counties, California. Exposures were assigned to individual subjects based on residential address at delivery using the nearest ambient monitoring station data [carbon monoxide (CO), nitrogen dioxide (NO(2)), nitric oxide (NO), nitrogen oxides (NO(x)), ozone (O(3)), and particulate matter less than 2.5 (PM(2.5)) or less than 10 (PM(10))μm in aerodynamic diameter], both unadjusted and temporally adjusted land-use regression (LUR) model estimates (NO, NO(2), and NO(x)), CALINE4 line-source air dispersion model estimates (NO(x) and PM(2.5)), and a simple traffic-density measure. We employed unconditional logistic regression to analyze preeclampsia in our birth cohort, while for gestational age-matched risk sets with preterm and very preterm birth we employed conditional logistic regression.

RESULTS

We observed elevated risks for preeclampsia, preterm birth, and very preterm birth from maternal exposures to traffic air pollutants measured at ambient stations (CO, NO, NO(2), and NO(x)) and modeled through CALINE4 (NO(x) and PM(2.5)) and LUR (NO(2) and NO(x)). Increased risk of preterm birth and very preterm birth were also positively associated with PM(10) and PM(2.5) air pollution measured at ambient stations. For LUR-modeled NO(2) and NO(x) exposures, elevated risks for all the outcomes were observed in Los Angeles only--the region for which the LUR models were initially developed. Unadjusted LUR models often produced odds ratios somewhat larger in size than temporally adjusted models. The size of effect estimates was smaller for exposures based on simpler traffic density measures than the other exposure assessment methods.

CONCLUSION

We generally confirmed that traffic-related air pollution was associated with adverse reproductive outcomes regardless of the exposure assessment method employed, yet the size of the estimated effect depended on how both temporal and spatial variations were incorporated into exposure assessment. The LUR model was not transferable even between two contiguous areas within the same large metropolitan area in Southern California.

Prenatal exposure to organochlorine compounds and birth size

OBJECTIVE

To investigate the possible association between birth size and cord concentrations of some organochlorine compounds (OCs), including 4,4'-dichlorodiphenyltrichloroethane (DDT), 4,4'-1,1-dichloro-2,2-bis(p-dichlorodiphenyl)ethylene (DDE), hexachlorobenzene (HCB), β-hexachlorocyclohexane (β-HCH), 4 polychlorinated biphenyl (PCB) congeners (118, 138, 153, and 180), and their sum (ΣPCBs) in a birth cohort in Valencia, Spain.

STUDY DESIGN

A total of 494 mothers and their newborns (born 2003-2006) participated in the study. Multivariate linear regression analyses were performed between birth weight, length, or head circumference and OC concentrations.

RESULTS

Median concentrations of 4,4'-DDT, 4,4'-DDE, HCB, β-HCH, and ΣPCBs were 0.02, 0.46, 0.22, 0.09, and 0.35 ng/mL, respectively. For birth weight there was a significant decrease of 63 and 107 g for each 10-fold increase in cord serum 4,4'-DDT and 4,4'-DDE concentrations, and a marginally significant decrease of 79 and 53 g for each 10-fold increase in HCB and β-HCH concentrations. A significant decrease of 0.39 cm in birth length was found for each 10-fold increase in HCB concentrations. For newborns with cord 4,4'-DDT concentrations above the median there was a significant decrease of 0.26 cm in birth head circumference.

CONCLUSIONS

These results reveal that prenatal exposure to some OCs could impair the anthropometric development of the fetus, reducing the birth weight, length, and head circumference.

Shortening of gestational length among native-born and immigrants in Spain (1997-2008)

During the last decade there have been significant socio-demographic changes in Spain with potential impact on gestational length. The aim of the study was to describe the evolution of gestational age during 1997-2008, separately for native-born and immigrant population, in order to assess their contribution to the overall pattern of gestational length. A cross-sectional study of 5,018,229 singleton births born between 1997 and 2008 was carried out. The annual mean of gestational age was calculated and compared by means of ANOVA test, globally and also separately for natives and immigrants. Proportions of deliveries by gestational age and maternal characteristics were calculated in 4 periods and compared by means of Chi-square tests. Crude and adjusted multinomial logistic regression models were fitted separately for native-born and immigrant women. Our results show that in the last 12 years a progressive shortening in the mean gestational age has taken place in Spain. While the overall decrease of gestational length along the period was 1.5 days, closer to that in Spanish women (1.3 days), it was 2.3 days among immigrants. In both groups this shortening was mainly due to an increase in the proportion of 37-39 weeks deliveries at the expense of a substantial decrease in those with 40 weeks. These trends remained after controlling for known confounding variables such as maternal age, parity and occupation. Further analysis of its causes and public health implications are recommended.