| 1. |
- Bjorvang, Richelle D., et al.
(författare)
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Persistent organic pollutants, pre-pregnancy use of combined oral contraceptives, age, and time-to-pregnancy in the SELMA cohort
- 2020
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Ingår i: Environmental Health. - : BMC. - 1476-069X. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- Background We are exposed to several chemicals such as persistent organic pollutants (POPs) in our everyday lives. Prior evidence has suggested that POPs may have adverse effects on reproductive function by disrupting hormone synthesis and metabolism. While there is age-related decline of fertility, the use of hormonal combined oral contraceptives (COCs) and its association to return of fertility remains controversial. The goal of this study is to investigate the association between exposure to POPs, both individually and as a mixture, and fecundability measured as time-to-pregnancy (TTP) according to pre-pregnancy use of COCs and age. Methods Using the SELMA (Swedish Environmental Longitudinal Mother and Child, Allergy and Asthma) study, we have identified 818 pregnant women aged 18-43 years (mean 29 years) with data on how long they tried to get pregnant and what was their most recently used contraceptive method. These data were collected at enrollment to the study (median week 10 of pregnancy). Concentrations of 22 POPs and cotinine were analyzed in the blood samples collected at the same time as the questions on TTP and pre-pregnancy use of contraceptive. Analyses were done on the association between POPs exposure and TTP measured as continuous (months) and binary (infertile for those with TTP > 12 months). To study the chemicals individually, Cox regression and logistic regression were used to estimate fecundability ratios (FRs) and odds ratios (ORs), respectively. Weighted quantile sum (WQS) regression was used to investigate the chemicals as a mixture where chemicals of concern were identified above the 7.6% threshold of equal weights. To perform the subgroup analysis, we stratified the sample according to use of COCs as the most recent pre-pregnancy contraception method and age (< 29 years, and >= 29 years). The models were adjusted for parity, regularity of menses, maternal body mass index (BMI) and smoking status, and stratified as described above. Results Prior to stratification, none of the POPs were associated with fecundability while increased exposure to HCB, PCB 74 and 118 had higher odds of infertility. Upon stratification, POP exposure was significantly associated with longer TTP in women aged >= 29 years who did not use COC. Specifically, PCBs 156, 180, 183, and 187 were associated with reduced fecundability while PCBs 99, 153, 156, 180, 183, and 187 had higher odds of infertility. As a mixture, we identified the chemicals of concern for a longer TTP include PCBs 118, 156, 183, and 187. Moreover, chemicals of concern identified with increased odds of infertility were PCB 74, 156, 183, 187, and transnonachlor. Conclusion Serum concentrations of selected POPs, both as individual chemicals and as a mixture, were significantly associated with lower fecundability and increased odds of infertility in women aged 29 years and above not using COC as their most recent pre-pregnancy contraceptive. Our findings suggest that pre-pregnancy use of oral contraceptive and age may modify the link between POPs and fecundability. The differences of specific chemicals in the individual analysis and as a mixture support the need to study combination effects of chemicals when evaluating reproductive outcomes.
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| 2. |
- Gennings, Chris, et al.
(författare)
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Incorporating regulatory guideline values in analysis of epidemiology data
- 2018
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 120, s. 535-543
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Tidskriftsartikel (refereegranskat)abstract
- Fundamental to regulatory guidelines is to identify chemicals that are implicated with adverse human health effects and inform public health risk assessors about “acceptable ranges” of such environmental exposures (e.g., from consumer products and pesticides). The process is made more difficult when accounting for complex human exposures to multiple environmental chemicals. Herein we propose a new class of nonlinear statistical models for human data that incorporate and evaluate regulatory guideline values into analyses of health effects of exposure to chemical mixtures using so-called ‘desirability functions’ (DFs). The DFs are incorporated into nonlinear regression models to allow for the simultaneous estimation of points of departure for risk assessment of combinations of individual substances that are parts of chemical mixtures detected in humans. These are, in contrast to published so-called biomonitoring equivalent (BE) values and human biomonitoring (HBM) values that link regulatory guideline values from in vivo studies of single chemicals to internal concentrations monitored in humans. We illustrate the strategy through the analysis of prenatal concentrations of mixtures of 11 chemicals with suspected endocrine disrupting properties and two health effects: birth weight and language delay at 2.5 years. The strategy allows for the creation of a Mixture Desirability Function i.e., MDF, which is a uni-dimensional construct of the set of single chemical DFs; thus, it focuses the resulting inference to a single dimension for a more powerful one degree-of-freedom test of significance. Based on the application of this new method we conclude that the guideline values need to be lower than those for single chemicals when the chemicals are observed in combination to achieve a similar level of protection as was aimed for the individual chemicals. The proposed modeling may thus suggest data-driven uncertainty factors for single chemical risk assessment that takes environmental mixtures into account.
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| 3. |
- Gennings, Chris, et al.
(författare)
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Using Metrics of a Mixture Effect and Nutrition from an Observational Study for Consideration towards Causal Inference
- 2022
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 19:4
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Tidskriftsartikel (refereegranskat)abstract
- Environmental exposures to a myriad of chemicals are associated with adverse health effects in humans, while good nutrition is associated with improved health. Single chemical in vivo and in vitro studies demonstrate causal links between the chemicals and outcomes, but such studies do not represent human exposure to environmental mixtures. One way of summarizing the effect of the joint action of chemical mixtures is through an empirically weighted index using weighted quantile sum (WQS) regression. My Nutrition Index (MNI) is a metric of overall dietary nutrition based on guideline values, including for pregnant women. Our objective is to demonstrate the use of an index as a metric for more causally linking human exposure to health outcomes using observational data. We use both a WQS index of 26 endocrine-disrupting chemicals (EDCs) and MNI using data from the SELMA pregnancy cohort to conduct causal inference using g-computation with counterfactuals for assumed either reduced prenatal EDC exposures or improved prenatal nutrition. Reducing the EDC exposure using the WQS index as a metric or improving dietary nutrition using MNI as a metric, the counterfactuals in a causal inference with one SD change indicate significant improvement in cognitive function. Evaluation of such a strategy may support decision makers for risk management of EDCs and individual choices for improving dietary nutrition.
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| 4. |
- Krönke, Anna A., et al.
(författare)
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Persistent organic pollutants in pregnant women potentially affect child development and thyroid hormone status
- 2022
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Ingår i: Pediatric Research. - : Springer Nature. - 0031-3998 .- 1530-0447. ; 91:3, s. 690-698
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Tidskriftsartikel (refereegranskat)abstract
- Background Potentially harmful effects of persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) on prenatal development and the endocrine system have been controversially discussed. Methods Working with a German cohort of 324 pregnant women, we assessed POP levels and used robust linear regression models to determine potential associations between maternal POP concentrations and pre- and postnatal development in the children, as well as the thyroid hormone status of the mother and child. Results Maternal p,p '-dichlorodiphenyldichloroethylene (p,p '-DDE) and most measured PCBs positively correlated with postnatal weight gain. We detected no correlation between newborn birth weight and head circumference, respectively, and maternal PCB and p,p '-DDE serum levels, while body length at birth was negatively associated with the maternal serum concentration of PCB 183. Maternal p,p '-DDE and nearly all PCB serum levels showed a negative correlation with maternal free triiodothyronine (FT3). p,p '-DDE and PCB 74 and 118 were negatively associated with maternal thyroid-stimulating hormone levels. In addition, we identified significant associations between maternal POP levels and thyroid hormone parameters of the child. Conclusions These results indicate that POP exposure likely affects different aspects of pre- and postnatal development and impacts the thyroid hormone status of both mother and child. Impact Pregnant women in a German cohort display a substantial accumulation of POPs. Body mass index and age influence maternal serum POP levels. Maternal POP levels show correlations with the child's length at birth and weight gain, and FT3 levels in the mother and child. Our data provide additional evidence for the potentially harmful influence of POPs. Our data indicate that POPs influence pre- and postnatal development.
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| 5. |
- Svensson, Katherine, et al.
(författare)
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EDC mixtures during pregnancy and body fat at 7 years of age in a Swedish cohort, the SELMA study
- 2024
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Ingår i: Environmental Research. - : Elsevier. - 0013-9351 .- 1096-0953. ; 48
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Tidskriftsartikel (refereegranskat)abstract
- Background: Some endocrine disrupting chemicals (EDC), are “obesogens” and have been associated withoverweight and obesity in children. Daily exposure to different classes of EDCs demands for research withmixtures approach.Objectives: This study evaluates the association, considering sex-specific effects, between prenatal exposure toEDC mixture and children’s body fat at seven years of age.Methods: A total of 26 EDCs were assessed in prenatal urine and serum samples from first trimester in pregnancyfrom 737 mother-child pairs participating in the Swedish Environmental Longitudinal, Mother and child, Asthmaand allergy (SELMA) study. An indicator for children’s “overall body fat” was calculated, using principalcomponent analysis (PCA), based on BMI, percent body fat, waist, and skinfolds measured at seven years of age.Weighted quantile sum (WQS) regression was used to assess associations between EDC mixture and children’sbody fat.Results: Principal component (PC1) represented 83.6 % of the variance, suitable as indicator for children’s“overall body fat”, with positive loadings of 0.40–0.42 for each body fat measure. A significant interaction term,WQS*sex, confirmed associations in the opposite direction for boys and girls. Higher prenatal exposure to EDCmixture was borderline significant with more “overall body fat” for boys (Mean β = 0.20; 95 % CI: − 0.13, 0.53)and less for girls (Mean β = − 0.23; 95 % CI: − 0.58, 0.13). Also, higher prenatal exposure to EDC mixture wasborderline significant with more percent body fat (standardized score) for boys (Mean β = 0.09; 95 % CI: − 0.04,0.21) and less for girls (Mean β = − 0.10 (− 0.26, 0.05). The chemicals of concern included bisphenols, phthalates, PFAS, PAH, and pesticides with different patterns for boys and girls.Discussion: Borderline significant associations were found between prenatal exposure to a mixture of EDCs andchildren’s body fat. The associations in opposite directions suggests that prenatal exposure to EDCs may presentsex-specific effects on children’s body fat.
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| 6. |
- Svensson, Katherine, et al.
(författare)
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Prenatal exposures to mixtures of endocrine disrupting chemicals and children's weight trajectory up to age 5.5 in the SELMA study
- 2021
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Exposure to endocrine disrupting chemicals (EDCs) may impact early growth, although information is limited on exposure to combination of multiple EDCs. We aimed to evaluate the effect of prenatal exposure to EDC mixtures on birthweight z-scores and childhood weight trajectories. Twenty-six proven and suspected EDCs, were analyzed in prenatal urine and blood samples from 1118 mothers participating in the Swedish Environmental Longitudinal Mother and child Asthma and allergy (SELMA) study. Two growth parameters were estimated from each child's weight trajectory from birth to 5.5 years of age: infant growth spurt rate and age at infant peak growth velocity (PGV). Weighted quantile sum (WQS) regression was used to estimate the mixture effect and identify chemicals of concern. A one-unit increase in the EDC mixture WQS index, was associated with decreased birthweight z-scores of 0.11 (95% CI - 0.16, - 0.06), slower infant growth spurt rate of 0.01 (95% CI - 0.03, - 0.01, on the log(10) scale), and delayed age at infant PGV of 0.15 months (95% CI 0.07, 0.24) after adjusting for potential confounders. Stratified analysis by sex, showed that delayed age at infant PGV was mostly observed in girls with 0.51 months (95% CI 0.26, 0.76). Identified chemicals of concern included perfluorinated alkyl substances (PFAS), Triclosan, phthalates, non-phthalate plasticizers, bisphenols, polycyclic aromatic hydrocarbons, pesticides and PCBs. Prenatal exposure to EDC mixtures was associated with lower birthweight and altered infant weight gain trajectories.
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| 7. |
- Svensson, Katherine, et al.
(författare)
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Prenatal exposures to mixtures of endocrine disrupting chemicals and sex-specific associations with children’s BMI and overweight at 5.5 years of age in the SELMA study
- 2023
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 179
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Tidskriftsartikel (refereegranskat)abstract
- Background: Prenatal exposure to mixtures of endocrine disrupting chemicals (EDC) has the potential to disrupt human metabolism. Prenatal periods are especially sensitive as many developmental processes are regulated by hormones. Prenatal exposure to EDCs has inconsistently been associated with children’s body mass index (BMI) and obesity. The objective of this study was to investigate if prenatal exposure to a mixture of EDCs was associated with children’s BMI and overweight (ISO-BMI ≥ 25) at 5.5 years of age, and if there were sex-specific effects. Methods: A total of 1,105 mother–child pairs with complete data on prenatal EDCs concentrations (e.g., phthalates, non-phthalate plasticizers, phenols, PAH, pesticides, PFAS, organochlorine pesticides, and PCBs), children’s measured height and weight, and selected covariates in the Swedish Environmental Longitudinal, Mother and child, Asthma and allergy (SELMA) study were included in this analysis. The mixture effect of EDCs with children’s BMI and overweight was assessed using WQS regression with 100 repeated holdouts. A positively associated WQS index with higher BMI and odds of overweight was derived. Models with interaction term and stratified weights by sex was applied in order to evaluate sex-specific associations. Results: A significant WQS*sex interaction term was identified and associations for boys and girls were in opposite directions. Higher prenatal exposure to a mixture of EDCs was associated with lower BMI (Mean β = -0.19, 95%CI: −0.40, 0.01) and lower odds of overweight (Mean OR = 0.72, 95%CI: 0.48, 1.04) among girls with borderline significance. However, the association among boys did not reach statistical significance. Among girls, the possible chemicals of concern were MEP, 2-OHPH, BPF, BPS, DPP and PFNA. Conclusion: Prenatal exposure to a mixture of EDCs was associated with lower BMI and overweight among girls, and non-significant associations among boys. Chemicals of concern for girls included phthalates, non-phthalate plasticizers, bisphenols, PAHs, and PFAS.
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| 8. |
- Tanner, Eva M, et al.
(författare)
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Early prenatal exposure to suspected endocrine disruptor mixtures is associated with lower IQ at age seven
- 2020
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Ingår i: Environment International. - : Elsevier. - 0160-4120 .- 1873-6750. ; 134, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Background: Endocrine disrupting chemicals (EDCs) are xenobiotics with the ability to interfere with hormone action, even at low levels. Prior environmental epidemiology studies link numerous suspected EDCs, including phthalates and bisphenol A (BPA), to adverse neurodevelopmental outcomes. However, results for some chemicals were inconsistent and most assessed one chemical at a time.Objectives: To evaluate the overall impact of prenatal exposure to an EDC mixture on neurodevelopment in school-aged children, and identify chemicals of concern while accounting for co-exposures.Methods: Among 718 mother-child pairs from the Swedish Environmental Longitudinal, Mother and child, Asthma and allergy study (SELMA) study, we used Weighted Quantile Sum (WQS) regression to assess the association between 26 EDCs measured in 1st trimester urine or blood, with Wechsler Intelligence Scale for Children (IV) Intelligence Quotient (IQ) scores at age 7 years. Models were adjusted for child sex, gestational age, mother's education, mother's IQ (RAVEN), weight, and smoking status. To evaluate generalizability, we conducted repeated holdout validation, a machine learning technique.ResultsUsing repeated holdout validation, IQ scores were 1.9-points (CI = −3.6, −0.2) lower among boys for an inter-quartile-range (IQR) change in the WQS index. BPF made the largest contribution to the index with a weight of 14%. Other chemicals of concern and their weights included PBA (9%), TCP (9%), MEP (6%), MBzP (4%), PFOA (6%), PFOS (5%), PFHxS (4%), Triclosan (5%), and BPA (4%). While we did observe an inverse association between EDCs and IQ among all children when training and testing the WQS index estimate on the full dataset, these results were not robust to repeated holdout validation.Conclusion: Among boys, early prenatal exposure to EDCs was associated with lower intellectual functioning at age 7. We identified bisphenol F as the primary chemical of concern, suggesting that the BPA replacement compound may not be any safer for children. Future studies are needed to confirm the potential neurotoxicity of replacement analogues.
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