Lowest Exposure Tertile Research Articles

Associations between prenatal maternal exposure to per- and polyfluoroalkyl substances (PFAS) and polybrominated diphenyl ethers (PBDEs) and birth outcomes among pregnant women in San Francisco

BackgroundPerfluoroalkyl substances (PFAS) and polybrominated diphenyl ethers (PBDEs) are used in consumer products for their water repellent and flame retardant properties, respectively. However, there is widespread prenatal exposure and concern about their potential harm to the developing fetus. Here, we utilized data from a demographically diverse cohort of women in San Francisco, CA to examine associations between prenatal exposure to PFAS and PBDEs with gestational age and birth weight for gestational age z-scores.MethodsWomen included in this analysis were enrolled in the Chemicals in our Bodies (CIOB) cohort study (N = 506). PFAS and PBDEs were measured in serum obtained during the second trimester of pregnancy. Linear regression models were used to calculate crude and adjusted β coefficients for the association between PFAS and PBDE concentrations in tertiles and gestational age and birth weight z-scores. Individual PFAS and PBDE concentrations, as well as their sums, were examined in separate models.ResultsThe highest compared to lowest tertile of BDE-47 was associated with shorter gestational age (β = − 0.49, 95% confidence interval [CI] = − 0.95, − 0.02). Additionally, exposure to BDE-47 and BDE-99 in the middle tertile was also associated with a reduction in birth weight z-scores (β = − 0.26, 95% CI = -0.48, − 0.04; β = − 0.25, 95% CI = -0.47, − 0.04, respectively) compared to those in the lowest tertile of exposure. No consistent associations were observed between increasing PFAS concentrations and gestational age or birth weight z-scores.DiscussionAmong a diverse group of pregnant women in the San Francisco Bay Area, we found non-linear associations between prenatal exposure to PBDEs during the second trimester of pregnancy and birth weight z-scores. However, most PFAS congeners were not associated with adverse birth outcomes. PFAS and PBDE concentrations were lower in our cohort relative to other studies. Future research should assess the effects of emerging and persistent PFAS and PBDEs on birth outcomes, as some congeners are being phased out and replaced by chemically similar structures.

BCG Vaccine Protection Against Mycobacterium tuberculosis Infection by Level of Exposure in The Gambia.

In Indonesia, BCG vaccine protection against Mycobacterium tuberculosis infection decreased with increasing exposure to the pathogen. We aimed to validate these findings in Africa. Poisson regression was used to estimate BCG protection, stratified by pathogen exposure using an exposure score, against enzyme-linked immunospot assay conversion at 3 months in 220 Gambian case contacts. Although the interaction between BCG and exposure was not significant (P = .13), BCG protection was strongest in the lowest-exposure tertile (relative risk, 0.35 [95% confidence interval, .15-.82; P = .02] vs 0.50 [.30-.83; P = .008] and 0.71 (.45-1.13; P = .1] for the middle and highest-exposure tertiles, respectively. These results are consistent with those from Indonesia.

Environmental cadmium and lead exposure and anti-Müllerian hormone in pregnant women.

Anti-Müllerian Hormone (AMH) has been suggested as a marker for ovarian function. Cadmium and lead have been suggested to reduce female fecundity. In this study we aimed to investigate whether environmental exposure to cadmium and lead was associated with alterations in serum-AMH. The associations between serum-AMH and whole blood cadmium or lead were investigated by general linear models in a population-based sample of 117 pregnant women. The mean concentrations of blood cadmium and lead were 0.71μg/L and 17.4μg/L, respectively. The mean serum-AMH was 17.3pmol/L. No association between lead and AMH was detected. In the cadmium analysis the adjusted mean AMH level (95% CI) in the highest exposure tertile was 12.4 (6.4;23.8) compared to 5.6 (2.7;11.4) in the lowest exposure tertile (p=0.06). The study provides suggestive evidence that environmental exposure to cadmium, but not lead, may alter the level of AMH.

Abstract P068: Use of Plastic Food Wrappers High in Phthalates is Associated with Metabolic Syndrome Among Mexican Women

Introduction: Exposure to phthalates has been associated to metabolic abnormalities and cardiovascular risk. Commonly used plastic food wrappers may contain up to 40% of phthalates and could be an important source of exposure to these chemicals especially when heated. Hypothesis: Use of plastic food wrappers high in phthalates affects metabolic homeostasis. Methods: We assessed the cross-sectional relation of plastic food wrappers use and metabolic syndrome in 188 women from the Mexican Teachers’ Cohort. We evaluated self-reported frequency of use of food wrappers based on 3 questions and categorized participants in tertiles. Fasting blood samples and anthropometry were obtained in a clinical visit to determine metabolic syndrome status. Continuous variables were log-transformed. We used multivariable logistic and linear regression models to estimate odds ratios, mean % change and 95% confidence intervals (CI) for metabolic syndrome and its components using the lowest tertile of exposure as the reference. Results: Mean (±SD) frequency use of total plastic food wrapper was 1.52± 3 times/week and the prevalence of metabolic syndrome was 34%. Use of total plastic food wrappers was associated with metabolic syndrome even after adjusting for diet and other important confounders. The multivariable-adjusted odds ratio (OR) comparing extreme tertiles was 2.61 (95% CI: 1.03, 6.61; ptrend = 0.10). The association appeared to be driven by use of plastic food wrappers that were heated in a microwave oven. We did not observe an independent association with metabolic syndrome components. Conclusions: In this cross-sectional study use of plastic food wrappers, especially when heated in the microwave oven, was associated with the presence of metabolic syndrome. These associations did not appear to be driven by a particular metabolic syndrome component. Longitudinal studies are warranted to confirm this association, ideally with measures of urinary phthalate metabolites to confirm its mediation in the association.

Prenatal phthalate exposure and reproductive function in young men

BackgroundPrenatal exposure to phthalates is suggested to negatively impact male reproductive function, but human data are lacking. ObjectivesTo study associations between prenatal exposure to diethylhexyl phthalate (DEHP) and diisononyl phthalate (DiNP), and reproductive parameters of adolescent men. MethodsUsing linear regression models adjusted for potential confounders, we studied associations between levels of DEHP- and DiNP metabolites in maternal sera from mean 12 weeks of pregnancy, and testicular size, semen quality and reproductive hormones in 112 adolescent sons, recruited from the general population. ResultsMen in the highest exposure tertile of one DiNP metabolite [mono-(carboxy-iso-octyl) phthalate], compared with men in the lowest tertile had: 4.3mL (95% CI: 0.89, 7.6mL; p<0.001) lower total testicular volume; 30% (95% CI: 3.6, 63%; p=0.02) higher levels of follicle-stimulating hormone; and 0.87mL (95% CI: 0.28, 1.5mL; p=0.004) lower semen volume. Men in the highest exposure tertile of one DEHP metabolite [mono-(2-ethyl-5-hydroxylhexyl) phthalate] had 0.70mL (95% CI: 0.090, 1.3mL; p=0.03) lower semen volume than men in the lowest exposure tertile. The levels of two DiNP metabolites [mono-(hydroxy-iso-nonyl) phthalate and mono-(oxo-iso-nonyl) phthalate] were linearly associated with luteinizing hormone (p<0.01). ConclusionPrenatal levels of some metabolites of DEHP and DiNP seemed negatively associated with reproductive function of adolescent men.

Elevated Cardiometabolic Risk by Chronic Inorganic Arsenic Exposure in Chihuahua, Mexico.

The present cross-sectional study examined associations between inorganic arsenic (iAs) exposure and cardiometabolic (CM) risk factors in a cohort of adult Chihuahua residents (n=933, ?18year old) with a minimum of 5-year uninterrupted residency in the study area were recruited between 2008 and 2012. The concentrations of As in drinking water ranged from 0.05 - 419.8 µg As/L with 84% and 42% of samples exceeding 10 µg As/L and 50 µg As/L, respectively. All subjects had detectable levels of As in urine. The concentration of total speciated As [iAs + methylarsenic (MAs) + dimethylarsenic (DMAs)] ranged from 0.52 to 375.2 µg/L. DMAs was the major urinary metabolite representing on average 75.7% of total speciated As, followed by MAs (14.5%) and iAs (9.8%). Results show that subjects in the highest exposure tertile trough drinking water (58.3 - 419.8 µg As/L) had higher levels of total cholesterol in plasma and were more likely to have dysglycemia (OR 1.60, 95%CI 1.09-2.32), hypertriglyceridemia (OR 1.53, 95%CI 1.07 - 2.20), and high blood pressure (OR 1.57, 95%CI 1.05 - 2.35) than subjects in the lowest exposure tertile (?38.5 µg As/L). Obesity may play a critical role in the associations between iAs exposure and CM risk. In addition, we found statistically significant positive associations of high urinary DMAs/MAs ratio with dysglycemia, hypertriglyceridemia, and high blood pressure. Thus, it is possible that an increased capacity to convert iAs to DMAs, may be a risk factor for CM disease in individuals chronically exposed to iAs. Prospective studies are needed to examine causality of the associations of CM risk with iAs exposure and to determine if iAs metabolism can modify this risk.

Arsenic and lung disease mortality in Bangladeshi adults.

Chronic arsenic exposure through drinking water is a public health problem affecting millions of people worldwide, including at least 30 million in Bangladesh. We prospectively investigated the associations of arsenic exposure and arsenical skin lesion status with lung disease mortality in Bangladeshi adults. Data were collected from a population-based sample of 26,043 adults, with an average of 8.5 years of follow-up (220,157 total person-years). There were 156 nonmalignant lung disease deaths and 90 lung cancer deaths ascertained through October 2013. We used Cox proportional hazards models to estimate adjusted hazard ratios and 95% confidence intervals (CIs) for lung disease mortality. Creatinine-adjusted urinary total arsenic was associated with nonmalignant lung disease mortality, with persons in the highest tertile of exposure having a 75% increased risk for mortality (95% CI = 1.15-2.66) compared with those in the lowest tertile of exposure. Persons with arsenical skin lesions were at increased risk of lung cancer mortality (hazard ratio = 4.53 [95% CI = 2.82-7.29]) compared with those without skin lesions. This prospective investigation of lung disease mortality, using individual-level arsenic measures and skin lesion status, confirms a deleterious effect of ingested arsenic on mortality from lung disease. Further investigations should evaluate effects on the incidence of specific lung diseases, more fully characterize dose-response, and evaluate screening and biomedical interventions to prevent premature death among arsenic-exposed populations, particularly among those who may be most susceptible to arsenic toxicity.

Menstrual cycle characteristics in fertile women from Greenland, Poland and Ukraine exposed to perfluorinated chemicals: a cross-sectional study

Does perfluorooctane sulfonate (PFOS) and perfluorooctanate (PFOA) exposure disrupt the menstrual cyclicity? The female reproductive system may be sensitive to PFOA exposure, with longer menstrual cycle length at higher exposure. PFOS and PFOA are persistent man-made chemicals. Experimental animal studies suggest they are reproductive toxicants but epidemiological findings are inconsistent. A cross-sectional study including 1623 pregnant women from the INUENDO cohort enrolled during antenatal care visits between June 2002 and May 2004 in Greenland, Poland and Ukraine. Information on menstrual cycle characteristics was obtained by questionnaires together with a blood sample from each pregnant woman. Serum concentrations of PFOS and PFOA were measured by liquid chromatography tandem mass spectrometry. Multiple imputations were performed to account for missing data. The association between PFOS/PFOA and menstrual cycle length (short cycle: ≤24 days, long cycle: ≥32 days) and irregularities (≥7 days in difference between cycles) was analyzed using logistic regression with tertiles of exposure. Estimates are given as adjusted odds ratios (ORs) with 95% confidence intervals (CIs). Higher exposure levels of PFOA were associated with longer menstrual cycles in pooled estimates of all three countries. Compared with women in the lowest exposure tertile, the adjusted OR of long cycles was 1.8 (95% CI: 1.0; 3.3) among women in the highest tertile of PFOA exposure. No significant associations were observed between PFOS exposure and menstrual cycle characteristics. However, we observed a tendency toward more irregular cycles with higher exposure to PFOS [OR 1.7 (95% CI: 0.8; 3.5)]. The overall response rate was 45.3% with considerable variation between countries (91.3% in Greenland, 69.1% in Poland and 26.3% in Ukraine). Possible limitations in our study include varying participation rates across countries; a selected study group overrepresenting the most fertile part of the population; retrospective information on menstrual cycle characteristics; the determination of cut-points for all three outcome variables; and lacking information on some determinants of menstrual cycle characteristics, such as stress, physical activity, chronic diseases and gynecological disorders, thus confounding cannot be excluded. The generalizability of the study results is restricted to fertile women who manage to conceive and women who do not use oral contraceptives when getting pregnant or within 2 months before getting pregnant. To our knowledge only one previous epidemiological study has addressed the possible association between perfluorinated chemical exposure and menstrual disturbances. Though pointing toward different disturbances in cyclicity, both studies suggest that exposure to PFOA may affect the female reproductive function. This study contributes to the limited knowledge on effects of exposure to PFOA and PFOS on female reproductive function and suggests that the female reproductive system may be affected by environmental exposure to PFOA. Supported by a scholarship from Aarhus University Research Foundation. The collection of questionnaire data and blood samples was part of the INUENDO project supported by The European Commission (Contract no. QLK4-CT-2001-00 202), www.inuendo.dk. The Ukrainian part of the study was possible by a grant from INTAS (project 012 2205). Determination of PFOA and PFOS in serum was part of the CLEAR study (www.inuendo.dk/clear) supported by the European Commission's 7th Framework Program (FP7-ENV-2008-1-226217). No conflict of interest declared.

Cancer incidence among pesticide applicators exposed to trifluralin in the Agricultural Health Study

Trifluralin, 2,6-dinitro- N, N-dipropyl-4-trifluoromethylaniline, is a 2,6-dinitro herbicide widely used to control annual grasses and broadleaf weeds in agricultural settings. The association between trifluralin use and common cancer incidence was evaluated among 50,127 private and commercial pesticide applicators in the Agricultural Health Study (AHS), a prospective cohort study of licensed pesticide applicators and their spouses in Iowa and North Carolina. Poisson regression was used to examine internal dose–response relationships, while controlling for important lifestyle factors and other agricultural exposures. Two metrics of exposure (lifetime days and intensity-weighted lifetime days) were used in exposure–response analyses with non-exposed applicators, as well as applicators in the lowest tertile of exposure, as reference groups. Incident cancers were identified through state tumor registries from enrollment in 1993 through 2002. Trifluralin exposure was not associated with cancer incidence overall among 51% of private and commercial applicators ( n=25,712) who had used trifluralin. However, there was an excess of colon cancer in the exposure category of higher half of highest tertile (rate ratios (RR) of 1.76 (95% CI=1.05–2.95) using the non-exposed as a referent and 1.93 (95% CI=1.08–3.45) using those with the lowest tertile of exposure as the referent). There was also a non-significantly elevated risk for kidney cancer and bladder cancer in the highest exposure group, although only the kidney cancer finding was consistent across exposure metrics. Although there was a possible link between trifluralin exposure and colon cancer, small numbers and inconsistencies in dose–response and subgroup analyses indicate that this may be a chance finding.