Spatiotemporal association between birth outcomes and coke production and steel making facilities in Alabama, USA: a cross-sectional study

Endocrine disruption and male reproductive disorders: unanswered questions

Maternal exposure to endocrine-disrupting chemicals (EDCs) in human pregnancy is widely considered as an important cause of adverse changes in male reproductive health due to impaired foetal androgen production/action. However, the epidemiological evidence supporting this view is equivocal, except for certain phthalates, notably diethyl hexyl phthalate (DEHP). Maternal phthalate exposure levels associated with adverse reproductive changes in epidemiological studies are several thousand-fold lower than those needed to suppress foetal androgen production in rats, and direct studies using human foetal testis tissue show no effect of high phthalate exposure on androgen production. This conundrum is unexplained and raises fundamental questions. Human DEHP exposure is predominantly via food with highest exposure associated with consumption of a Western style (unhealthy) diet. This diet is also associated with increased exposure to the most common EDCs, whether persistent (chlorinated or fluorinated chemicals) or non-persistent (phthalates, bisphenols) compounds, which are found at highest levels in fatty and processed foods. Consequently, epidemiological studies associating EDC exposure and male reproductive health disorders are confounded by potential dietary effects, and vice versa. A Western diet/lifestyle in young adulthood is also associated with low sperm counts. Disentangling EDC and dietary effects in epidemiological studies is challenging. In pregnancy, a Western diet, EDC exposure, and maternal living in proximity to industrial sites are all associated with impaired foetal growth/development due to placental dysfunction, which predisposes to congenital male reproductive disorders (cryptorchidism, hypospadias). While the latter are considered to reflect impaired foetal androgen production, effects resulting from foetal growth impairment (FGI) are likely indirect. As FGI has numerous life-long health consequences, and is affected by maternal lifestyle, research into the origins of male reproductive disorders should take more account of this. Additionally, potential effects on foetal growth/foetal testis from the increasing use of medications in pregnancy deserves more research attention.

Associations Between Preterm Birth, Inhibitory Control-Implicated Brain Regions and Tracts, and Inhibitory Control Task Performance in Children: Consideration of Socioeconomic Context

Preterm birth (PTB) is associated with increased risk for unfavorable outcomes such as deficits in attentional control and related brain structure alterations. Crucially, PTB is more likely to occur within the context of poverty. The current study examined associations between PTB and inhibitory control (IC) implicated brain regions/tracts and task performance, as well as the moderating role of early life poverty on the relation between PTB and IC-implicated regions/tracts/task performance. 2,899 children from the ABCD study were sampled for this study. Mixed effects models examined the relation between PTB and subsequent IC performance as well as prefrontal gray matter volume, white matter fractional anisotropy (FA), and mean diffusivity (MD). Household income was examined as a moderator. PTB was significantly associated with less improvement in IC task performance over time and decreased FA in left uncinate fasciculus (UF) and cingulum bundle (CB). Early life poverty moderated the relation between PTB and both CB FA and UF MD.

Is residential proximity to polluted sites during pregnancy associated with preterm birth or low birth weight? Results from an integrated exposure database in North Carolina (2003-2015)

BACKGROUND

Preterm birth (PTB) and term low birth weight (LBW) have been associated with pollution and other environmental exposures, but the relationship between these adverse outcomes and specific characteristics of polluted sites is not well studied.

OBJECTIVES

We conducted a retrospective cohort study to examine relationships between residential proximity to polluted sites in North Carolina (NC) and PTB and LBW. We further stratified exposure to polluted sites by route of contaminant emissions and specific contaminants released at each site.

METHODS

We created an integrated exposure geodatabase of polluted sites in NC from 2002 to 2015 including all landfills, Superfund sites, and industrial sites. Using birth certificates, we assembled a cohort of 1,494,651 singleton births in NC from 2003 to 2015. We geocoded the gestational parent residential address on the birth certificate, and defined exposure to polluted sites as residence within one mile of a site. We used log-binomial regression models to estimate adjusted risk ratios (aRR) and 95% confidence intervals (CI). Binomial models were used to estimate adjusted risk differences (aRD) per 10,000 births and 95% CIs for associations between exposure to polluted sites and PTB or LBW.

RESULTS

We observed weak associations between residential proximity to polluted sites and PTB [aRR(95% CI): 1.07(1.06,1.09); aRD(95% CI): 61(48,74)] and LBW [aRR(95% CI): 1.09(1.06,1.12); aRD(95% CI): 24(17,31)]. Secondary analyses showed increased risk of both PTB and LBW among births exposed to sites characterized by water emissions, air emissions, and land impoundment. In analyses of specific contaminants, increased risk of PTB was associated with proximity to sites containing arsenic, benzene, cadmium, lead, mercury, and polycyclic aromatic hydrocarbons. LBW was associated with exposure to arsenic, benzene, cadmium, lead, and mercury.

SIGNIFICANCE

This study provides evidence for potential reproductive health effects of polluted sites, and underscores the importance of accounting for heterogeneity between polluted sites when considering these exposures.

IMPACT STATEMENT

We documented an overall increased risk of both PTB and LBW in births with gestational exposure to polluted sites using a harmonized geodatabase of three site types, and further examined exposures stratified by site characteristics (route of emission, specific contaminants present). We observed increased risk of both PTB and LBW among births exposed to sites with water emissions or air emissions, across site types. Increased risk of PTB was associated with gestational proximity to sites containing arsenic, benzene, cadmium, lead, mercury, and polycyclic aromatic hydrocarbons; increased risk of LBW was associated with exposure to arsenic, benzene, cadmium, lead, and mercury.

Perinatal Health Inequalities in the Industrial Region of Estonia: A Birth Registry-Based Study

Despite the increasing number of studies on industrially contaminated sites (ICS) and their health effects, there are very few studies on perinatal health outcomes in ICSs. In the present study, we examined the perinatal health inequalities by comparing adverse birth outcomes (ABOs) in the oil shale industry region of Ida-Viru County in Estonia with national-level figures and investigated the effects of maternal environmental and sociodemographic factors. Based on the 208,313 birth records from 2004-2018, Ida-Viru ICS has a birth weight 124.5 g lower than the average of 3544 g in Estonia. A higher prevalence of preterm birth (4.3%) and low birth weight (4.8%) in Ida-Viru ICS is found compared to 3.3% on both indicators at the national level. Multiple logistic regression analysis shows the statistically significant association of ABOs with fine particle (PM_2.5) air pollution, mother's ethnicity, and education throughout Estonia. However, in Ida-Viru ICS, the ABOs odds are remarkably higher in these characteristics except for the mother's ethnicity. Furthermore, the ABOs are associated with the residential proximity to ICS. Thus, the Ida-Viru ICS has unequally higher odds of adverse perinatal health across the environmental and sociodemographic factors. In addition to reducing the air pollutants, policy actions on social disparities are vital to address the country's unjustly higher perinatal health inequalities, especially in the Ida-Viru ICS.

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.

The carcinogen cadmium elevates CpG-demethylation and enrichment of NFYA and E2F1 in the promoter of oncogenic PRMT5 and EZH2 methyltransferases resulting in their elevated expression in vitro

Cadmium (Cd) is considered as a carcinogenic chemical with potential to endanger normal cellular functioning. The present study was aimed to investigate the impact of Cd on the expression of two oncogenic epigenetic regulators, viz., protein arginine methyltransferase 5 (PRMT5) and the polycomb repressive complex 2 (PRC2) member enhancer of Zeste homolog 2 (EZH2). Our results indicate that Cd at 1 μM concentration increases the viability of HepG2 and MCF7 cells and significantly upregulates the expression of PRMT5 and EZH2, leading to an increased global level of symmetric dimethylarginine (SDMA), H4R3me2s, and H3K27me3. The luciferase reporter assay showed that the promoter activity of PRMT5 and EZH2 is significantly enhanced in both cell lines. Furthermore, Cd exposure induces global DNA hypomethylation due to a decrease in DNA methyltransferases (DNMTs) expression. Methylation-specific and bisulfite sequencing PCR reveal that the proximal promoters of PRMT5 and EZH2, which harbour CpG islands, are almost demethylated when exposed to Cd. The Cd exposure also increases the protein level of transcription factors NFYA and E2F1; consistently, the two transcription factors are found to be enriched at the PRMT5 and EZH2 promoter in chromatin immunoprecipitation experiments. The alterations induced by Cd in the two cancer cell lines were also observed in a non-cancerous cell line (HEK-293). In conclusion, we propose that Cd increases the expression of two oncogenic methyltransferases, possibly with a DNA methylation-dependent mechanism. Further studies focused on the epigenetic alterations induced by Cd would provide mechanistic insights on the carcinogenicity of this metal toxicant at the molecular level.

Potential for city parks to reduce exposure to BTEX in air

Benzene, toluene, ethylbenzene, and xylenes (BTEX) are hazardous air pollutants commonly found in outdoor air. Several studies have explored the potential of vegetation to mitigate BTEX in outdoor air, but they are limited to a northern temperate climate and their results lack consensus. To investigate this subject in a subtropical climate, we deployed passive air samplers for two weeks in parks and outside nearby residences at four locations: three in an urban area and one in a rural area in Alabama, USA. All BTEX concentrations were below health-based guidelines and were comparable to those found in several other studies in populated settings. Concentrations of TEX, but not benzene, were 3-39% lower in parks than at nearby residences, and the differences were significant. Site type (park vs. residential) was a significant predictor of TEX concentrations, while distance to the nearest major road was a significant predictor of BTX concentrations. In and around two of the parks, toluene : benzene ratios fell outside the range expected for vehicular emissions (p < 0.01), suggesting that there were additional, industrial sources of benzene near these two locations. The ratio of m-,p-xylene : ethylbenzene was high at all locations except one residential area, indicating that BTEX were freshly emitted. Concentrations of individual BTEX compounds were highly correlated with each other in most cases, except for locations that may have been impacted by nearby industrial sources of benzene. Results of this study suggest that parks can help reduce exposure to TEX by a modest amount in some situations.

Residential mobility of pregnant women and implications for assessment of spatially-varying environmental exposures

Health studies on spatially-varying exposures (e.g., air pollution) during pregnancy often estimate exposure using residence at birth, disregarding residential mobility. We investigated moving patterns in pregnant women (n = 10,116) in linked cohorts focused on Connecticut and Massachusetts, U.S., 1988-2008. Moving patterns were assessed by race/ethnicity, age, marital status, education, working status, population density, parity, income, and season of birth. In this population, 11.6% of women moved during pregnancy. Movers were more likely to be younger, unmarried, and living in urban areas with no previous children. Among movers, multiple moves were more likely for racial/ethnic minority, younger, less educated, unmarried, and lower income women. Most moves occurred later in pregnancy, with 87.4% of first moves in the second or third trimester, although not all cohort subjects enrolled in the first few weeks of pregnancy. Distance between first and second residence had a median value of 5.2 km (interquartile range 11.3 km, average 57.8 km, range 0.0-4277 km). Women moving larger distances were more likely to be white, older, married, and work during pregnancy. Findings indicate that residential mobility may impact studies of spatially-varying exposure during pregnancy and health and that subpopulations vary in probability of moving, and timing and distance of moves.

Prenatal TVOCs exposure negatively influences postnatal neurobehavioral development

Prenatal exposure to volatile organic compounds may restrict fetal development and adversely influence infants' life. Therefore, we investigated the relationship between prenatal exposure to total volatile organic compounds (TVOC) and postnatal neurobehavioral development. A subsample of 383 pregnant participants was chosen from the prospective birth cohort study of Mother and Children's Environmental Health Study; MOCEH (N=1,751) from three regions of the Republic of Korea (Seoul, Cheon-an, and Ulsan). Participants were enrolled during their first trimester with informed consent. We investigated maternal characteristics including socio-economic and obstetrical history using questionnaires. An environmental hygienist measured participating mothers' personal TVOC exposure using passive samplers during pregnancy. Participants visited the research center at 6, 12, 24 and 36 months. At each visit, questionnaires about infantile environment and health conditions were answered and a neurobehavioral test (BSID-II) was conducted by certified investigators. We conducted multiple general linear and mixed model analyses to investigate the relationship between TVOC and infantile neurobehavioral development (SAS 9.3). Mean prenatal TVOC exposure was 284.2μg/m³. In longitudinal analyses on infantile neurobehavioral development, adjusted mean psychomotor development index and mental developmental index scores in high TVOC exposure group (cut off at Q3: 374.0 ug/m3) were 3 points lower than the low exposure group. Results suggested exposure to higher TVOC during the fetal period may adversely influence neurobehavioral development in the early life stage.

Effect Modification by Environmental Quality on the Association between Heatwaves and Mortality in Alabama, United States

Background: Previous studies have shown that heatwaves are associated with increased mortality. However, it remains unclear whether the associations between heatwaves and mortality are modified by the environmental quality. Methods: We used the United States (US) Environmental Protection Agency's Environmental Quality Index (EQI) and its five domain indices (air, water, land, built, and sociodemographic) to represent the cumulative environmental quality. We applied a time-stratified case-crossover design to analyze the disparities in the association between heatwaves and non-accidental deaths (NAD) among counties with different environmental qualities, in metropolitan areas in Alabama (AL), United States. Results: We found significant associations between heatwaves and NAD and a significant effect modification of this relationship by EQI. There were higher odds ratios in counties with the worst cumulative environmental qualities compared to counties with the best cumulative environmental qualities. For example, the percent change in odds ratio (mean and (95% CI)) between heatwave days and non-heatwave days was -10.3% (-26.6, 9.6) in counties with an overall EQI of 1 (the best overall environment) and 13.2% (4.9, 22.2) in counties with an overall EQI of 3 (the worst overall environment). Among the five domains, air quality had the strongest effect modification on the association. Conclusion: Our findings provide evidence that the associations between heatwaves and NAD vary among areas with different environmental qualities. These findings suggest that integration of air quality and heatwave warning systems may provide greater protection to public health.

The Burden of Genetic and Epigenetic Traits in Prematurity

Despite decades of investigations and accumulated scientific knowledge, preterm birth (PTB) remains a significant burden worldwide. Several mechanisms have been proposed to explain this condition, and a number of risk factors from infectious to behavioral and genetic/epigenetic factors influence this outcome. The heritability of PTB is estimated to be 17% to 36%, which demonstrates that genetic predisposition plays a key role in PTB. Structural DNA modifications without changes in the DNA sequence and post-transcriptional regulation also have an impact on gene expression and thus influence pregnancy outcomes. There is a complex interplay between environmental factors and the individual's genetics and epigenetics that may culminate in PTB, but the complete regulatory pathways and networks involved in this context are still unclear. Here, we outline what is known so far about the genetic and epigenetic factors involved in preterm delivery, including polymorphisms, DNA methylation, and microRNAs, and suggest fields for research.

Environmental chemicals and preterm birth: Biological mechanisms and the state of the science

PURPOSE OF REVIEW

Preterm birth is a significant worldwide health problem of uncertain origins. The extant body of literature examining environmental contaminant exposures in relation to preterm birth is extensive but results remain ambiguous for most organic pollutants, metals and metalloids, and air pollutants. In the present review we examine recent epidemiologic studies investigating these associations, and identify recent advances and the state of the science. Additionally, we highlight biological mechanisms of action in the pathway between chemical exposures and preterm birth, including inflammation, oxidative stress, and endocrine disruption, that deserve more attention in this context.

RECENT FINDINGS

Important advances have been made in the study of the environment and preterm birth, particularly in regard to exposure assessment methods, exploration of effect modification by co-morbidities and exposures, and in identification of windows of vulnerability during gestation. There is strong evidence for an association between maternal exposure to some persistent pesticides, lead, and fine particulate matter, but data on other contaminants is sparse and only suggestive trends can be noted with the current data.

SUMMARY

Beyond replicating current findings, further work must be done to improve understanding of mechanisms underlying the associations observed between environmental chemical exposures and preterm birth. By examining windows of vulnerability, disaggregating preterm birth by phenotypes, and measuring biomarkers of mechanistic pathways in these epidemiologic studies we can improve our ability to detect associations with exposure, provide additional evidence for causality in an observational setting, and identify opportunities for intervention.

Exposure to ambient air pollution during pregnancy and preterm birth: A Spanish multicenter birth cohort study

BACKGROUND AND OBJECTIVE

Preterm birth is a major determinant of infant mortality and morbidity. Air pollution has been suggested as a risk factor for preterm delivery; however, the scientific evidence on this impact remains inconsistent. We assessed the association between residential exposure to air pollution during pregnancy and preterm birth (gestational age at delivery <37 weeks) in Spain.

METHODS

This study was based on 2409 pregnant women participating in the INMA birth cohorts in Asturias, Gipuzkoa, Sabadell and Valencia. Ambient levels of nitrogen dioxide (NO2) and benzene were estimated for each woman's residence for each trimester and for the whole pregnancy, using temporally adjusted land-use regression models. The association between air pollution exposure and preterm birth was assessed for each cohort separately by means of logistic regression models controlling for potential confounders, under single- and two-pollutant models, for all the women in the study and for those spending more than 15h/day at home. Combined estimates of the association across cohorts were obtained through meta-analysis.

RESULTS

Throughout the whole sample, suggestive but no statistically significant associations were found between exposure and preterm birth. For pregnant women spending more time at home significant associations were found for both pollutants, under single- and two-pollutant models. Under the last ones, NO2 exposure during the second trimester and the whole pregnancy was associated with a higher risk of preterm delivery (OR=1.58, (95%CI: 1.04-2.42) per 10μg/m(3) increase). Benzene exposure during the third trimester was also associated with preterm birth in that subsample (OR=1.45, (95%CI: 1.00-2.09) per 1μg/m(3) increase).

CONCLUSION

We found suggestive associations between NO2 and benzene exposure during pregnancy and preterm birth. Estimates of the association were higher among women who spent more time at home, probably reflecting a better exposure assessment in this group.

Potential selection bias associated with using geocoded birth records for epidemiologic research

PURPOSE

There is an increasing use of geocoded birth registry data in environmental epidemiology research. Ungeocoded records are routinely excluded.

METHODS

We used classification and regression tree analysis and logistic regression to investigate potential selection bias associated with this exclusion among all singleton Florida births in 2009 (n = 210,285).

RESULTS

The rate of unsuccessful geocoding was 11.5% (n = 24,171). This ranged between 0% and 100% across zip codes. Living in a rural zip code was the strongest predictor of being ungeocoded. Other predictors for geocoding status varied with urbanity status. In urban areas, maternal race (adjusted odds ratio [aOR] ranging between 1.08 for Hispanic and 1.18 for black compared to white), maternal age [aOR: 1.16 (1.10-1.23) for ages 20-34 compared to <20], maternal nativity [aOR: 1.20 (1.15-1.25) for non-US versus US born], delivery at a birth center [aOR: 1.72 (1.49-2.00) compared to hospital delivery], multiparity [aOR: 0.91 (0.88-0.94)], maternal smoking [aOR: 0.82 (0.76-0.88)], and having nonprivate insurance [aOR: 1.25 (1.20-1.30) for Medicaid versus private insurance] were significantly associated with being ungeocoded. In rural areas, births delivered at birth center [aOR: 2.91 (1.80-4.73)] or home [aOR: 1.94 (1.28-2.95)] had increased odds compared to hospital births. The characteristics predictive of being ungeocoded were also significantly associated with adverse birth outcomes such as low birth weight and preterm delivery, and the association for maternal age was different when ungeocoded births were included and excluded.

CONCLUSIONS

Geocoding status is not random. Women with certain exposure-outcome characteristics may be more likely to be ungeocoded and excluded, indicating potential selection bias.

The role of social determinants in explaining racial/ethnic disparities in perinatal outcomes

In the United States, there continue to be significant racial/ethnic disparities in preterm birth (PTB) rates, infant mortality, and fetal mortality rates. One potential mediator of these disparities is social determinants of health, including individual socioeconomic factors; community factors such as crime, poverty, housing, and the racial/ethnic makeup of the community; and the physical environment. Previous work has identified statistically significant associations between each of these factors and adverse pregnancy outcomes. However, there are recent studies that provide new, innovative insights into this subject, including adding social determinant data to population-based datasets; exploring multiple constructs in their analysis; and examining environmental factors. The objective of this review will be to examine this recent research on the association of each of these sets of social determinants on racial/ethnic disparities PTB, infant mortality, and fetal mortality to highlight potential areas for targeted intervention to reduce these differences.

Epigenetics: linking social and environmental exposures to preterm birth

Preterm birth remains a leading cause of infant mortality and morbidity. Despite decades of research, marked racial and socioeconomic disparities in preterm birth persist. In the Unites States, more than 16% of African-American infants are born before 37 wk of gestation compared with less than 11% of white infants. While income and education differences predict a portion of these racial disparities, income and education are proxies of the underlying causes rather than the true cause. How these differences lead to the pathophysiology remains unknown. Beyond tobacco smoke exposure, most preterm birth investigators overlook environment exposures that often correlate with poverty. Environmental exposures to industrial contaminants track along both socioeconomic and racial/ethnic lines due to cultural variation in personal product use, diet, and residential geographical separation. Emerging evidence suggests that environmental exposure to metals and plasticizers contribute to preterm birth and epigenetic modifications. The extent to which disparities in preterm birth result from interactions between the social and physical environments that produce epigenetic modifications remains unclear. In this review, we highlight studies that report associations between environmental exposures and preterm birth as well as perinatal epigenetic sensitivity to environmental contaminants and socioeconomic stressors.

Using an External Exposome Framework to Examine Pregnancy-Related Morbidities and Mortalities: Implications for Health Disparities Research

Objective: We have conducted a study to assess the role of environment on the burden of maternal morbidities and mortalities among women using an external exposome approach for the purpose of developing targeted public health interventions to decrease disparities. Methods: We identified counties in the 48 contiguous USA where observed low birthweight (LBW) rates were higher than expected during a five-year study period. The identification was conducted using a retrospective space-time analysis scan for statistically significant clusters with high or low rates by a Discrete Poisson Model. Results: We observed statistically significant associations of LBW rate with a set of predictive variables. However, in one of the two spatiotemporal models we discovered LBW to be associated with five predictive variables (teen birth rate, adult obesity, uninsured adults, physically unhealthy days, and percent of adults who smoke) in two counties situated in Alabama after adjusting for location changes. Counties with higher than expected LBW rates were similarly associated with two environmental variables (ozone and fine particulate matter). Conclusions: The county-level predictive measures of LBW offer new insights into spatiotemporal patterns relative to key contributory factors. An external framework provides a promising place-based approach for identifying “hotspots” with implications for designing targeted interventions and control measures to reduce and eliminate health disparities.

Exposure to emissions from municipal solid waste incinerators and miscarriages: a multisite study of the MONITER Project

BACKGROUND

Miscarriages are an important indicator of reproductive health but only few studies have analyzed their association with exposure to emissions from municipal solid waste incinerators. This study analyzed the occurrence of miscarriages in women aged 15-49years residing near seven incinerators of the Emilia-Romagna Region (Northern Italy) in the period 2002-2006.

METHODS

We considered all pregnancies occurring in women residing during the first trimester of pregnancy within a 4km radius of each incinerator. Addresses were geocoded and exposures were characterized by a dispersion model (ADMS Urban model) producing pollution maps for incinerators based on PM10 stack measurements and for other pollution sources based on NOx ground measurements. Information on pregnancies and their outcomes was obtained from the Hospital Discharge Database. Simplified True Abortion Risks (STAR)×100 estimated pregnancies were calculated. We ran logistic regressions adjusting for maternal characteristics, exposure to other sources of pollution, and sites, considering the whole population and stratifying by miscarriage history.

RESULTS

The study analyzed 11,875 pregnancies with 1375 miscarriages. After adjusting for confounders, an increase of PM10 due to incinerator emissions was associated with an increased risk of miscarriage (test for trend, p=0.042). The odds ratio for the highest quartile of exposed versus not exposed women was 1.29, 95% CI 0.97-1.72. The effect was present only for women without previous miscarriages (highest quartile of exposed versus not exposed women 1.44, 95% CI 1.06-1.96; test for trend, p=0.009).

CONCLUSION

Exposure to incinerator emissions is associated with an increased risk of miscarriage. This result should be interpreted with those of a previous study on reproductive health conducted in the same area that observed an association between incinerator exposure and preterm births.