Neurodevelopmental Effects of Low-level Prenatal Mercury Exposure From Maternal Fish Consumption in a Mediterranean Cohort: Study Rationale and Design

Background

Mercury is a neurotoxic environmental pollutant. However, the literature on the neurodevelopmental effect of low-level prenatal mercury exposure from maternal fish intake is inconsistent. We assessed the association between prenatal mercury exposure and infant neurodevelopment in coastal areas of 4 Mediterranean countries.

Methods

This was a prospective cohort study that planned to enroll approximately 1700 mother–infant pairs. Pregnant women and their newborn children were recruited in selected hospitals of the study areas. Biological samples, including maternal hair and cord blood, were collected from mothers and children, and the concentrations of mercury and other elements were measured. Exposures to lifestyle, environmental, and social factors were assessed through questionnaires. The main outcome was child neurodevelopment at 18 months, as measured by the Bayley Scales of Infant and Toddler Development, Third Edition.

Conclusions

This cohort has a number of strengths. First, mercury concentration was measured in several biological samples, which allows for a better understanding of mercury kinetics and is useful for sensitivity analyses. Therefore, we expect to be able to adjust for the potential confounding effects of lifestyle and social factors and for the effects of other elements that were measured in the biological samples. Finally, this is a multinational study and thus permits assessment of the relation between mercury and child neurodevelopment in different populations.Key words: cohort study, mercury, polyunsaturated fatty acids, nervous system development, fish     

Indeterminate Prenatal Ultrasounds and Maternal Anxiety: A Prospective Cohort Study

Maternal and Child Health Journal - Prenatal ultrasounds often yield indeterminate (incomplete or minor abnormality) findings with limited clinical utility. We evaluate impact of indeterminate...     

Role of Long-Chain Polyunsaturated Fatty Acids in Early Human Neurodevelopment

While breast-fed infants receive considerable amounts of preformed dietary arachidonic and docosahexaenoic acids in human milk, most of the currently available infant formulae are devoid of long-chain polyunsaturated fatty acids. Observational data obtained in preterm as well as in full-term infants indicate that breast feeding as compared to feeding formula is associated with better results in various tests on visual and cognitive development. In several randomised, placebo controlled, double-blind studies carried out in preterm infants, feeding formula with as compared to without long-chain polyunsaturated fatty acids resulted in improved maturation of visual functions. However, beneficial effects of providing dietary long-chain polyunsaturated fatty acids were seen only in some but not in all randomised studies on the development of visual functions in full-term infants. Data obtained in two recent randomised clinical trials on cognitive functions in full-term infants indicate that supplementation of formula with arachidonic and docosahexaenoic acids offers some neurodevelopmental benefits detectable at the ages of 4 and 10 months. Confirmation of shortterm results in longer follow-up studies appears desirable, but available evidence support the supplementation of both preterm and term infant formulae with arachidonic and docosahexaenoic acids in amounts and ratios characteristic to those found in mature human milk.     

Associations of Maternal Consumption of Dairy Products during Pregnancy with Perinatal Fatty Acids Profile in the EDEN Cohort Study

Maternal diet is the main source of fatty acids for developing offspring in-utero and in breastfed infants. Dairy products (DP) are important sources of fat in the European population diet. C15:0 and C17:0 fatty acids have been suggested as biomarkers of dairy fat consumption. This study’s aim is to describe the associations between maternal DP (milk included) consumption during pregnancy and C15:0, C17:0 and polyunsaturated fatty acid (PUFA) levels in perinatal biofluids. Study populations were composed of 1763, 1337 and 879 French mothers from the EDEN (“Étude des Déterminants pre- et post-natals de la santé de l’ENfant”) study, with data on maternal and cord red blood cells’ (RBC) membrane and colostrum, respectively. Associations were assessed using linear regression models adjusted for recruitment center, maternal age, healthy dietary pattern or fish consumption. Greater adherence to a ”cheese” consumption pattern was associated with lower linoleic acid level in colostrum and higher C15:0 and C17:0 levels but in a less consistent manner for C17:0 across biofluids. Greater adherence to “semi-skimmed milk, yogurt” and “reduced-fat DP” patterns was related to higher docosahexaenoic acid and total n-3 PUFA levels and lower n-6/n-3 long-chain PUFA ratio in maternal and cord RBC. Our results suggest that C15:0 could be a good biomarker of maternal dairy fat consumption in perinatal biofluids.     

Intake of Fish and Marine n-3 Polyunsaturated Fatty Acids and Risk of Cardiovascular Disease Mortality: A Meta-Analysis of Prospective Cohort Studies

Previous epidemiological studies have investigated the association of fish and marine n-3 polyunsaturated fatty acids (n-3 PUFA) consumption with cardiovascular disease (CVD) mortality risk. However, the results were inconsistent. The purpose of this meta-analysis is to quantitatively evaluate the association between marine n-3 PUFA, fish and CVD mortality risk with prospective cohort studies. A systematic search was performed on PubMed, Web of Science, Embase and MEDLINE databases from the establishment of the database to May 2021. A total of 25 cohort studies were included with 2,027,512 participants and 103,734 CVD deaths. The results indicated that the fish consumption was inversely associated with the CVD mortality risk [relevant risk (RR) = 0.91; 95% confidence intervals (CI) 0.85−0.98]. The higher marine n-3 PUFA intake was associated with the reduced risk of CVD mortality (RR = 0.87; 95% CI: 0.85–0.89). Dose-response analysis suggested that the risk of CVD mortality was decreased by 4% with an increase of 20 g of fish intake (RR = 0.96; 95% CI: 0.94–0.99) or 80 milligrams of marine n-3 PUFA intake (RR = 0.96; 95% CI: 0.94–0.98) per day. The current work provides evidence that the intake of fish and marine n-3 PUFA are inversely associated with the risk of CVD mortality.     

Early-Life Bisphenol A Exposure and Child Body Mass Index: A Prospective Cohort Study

Background: Early-life exposure to bisphenol A (BPA) may increase childhood obesity risk, but few prospective epidemiological studies have investigated this relationship.Objective: We sought to determine whether early-life exposure to BPA was associated with increased body mass index (BMI) at 2–5 years of age in 297 mother–child pairs from Cincinnati, Ohio (HOME Study).Methods: Urinary BPA concentrations were measured in samples collected from pregnant women during the second and third trimesters and their children at 1 and 2 years of age. BMI z-scores were calculated from weight/height measures conducted annually from 2 through 5 years of age. We used linear mixed models to estimate BMI differences or trajectories with increasing creatinine-normalized BPA concentrations.Results: After confounder adjustment, each 10-fold increase in prenatal (β = –0.1; 95% CI: –0.5, 0.3) or early-childhood (β = –0.2; 95% CI: –0.6, 0.1) BPA concentrations was associated with a modest and nonsignificant reduction in child BMI. These inverse associations were suggestively stronger in girls than in boys [prenatal effect measure modification (EMM) p-value = 0.30, early-childhood EMM p-value = 0.05], but sex-specific associations were imprecise. Children in the highest early-childhood BPA tercile had lower BMI at 2 years (difference = –0.3; 95% CI: –0.6, 0.0) and larger increases in their BMI slope from 2 through 5 years (BMI increase per year = 0.12; 95% CI: 0.07, 0.18) than children in the lowest tercile (BMI increase per year = 0.07; 95% CI: 0.01, 0.13). All associations were attenuated without creatinine normalization.Conclusions: Prenatal and early-childhood BPA exposures were not associated with increased BMI at 2–5 years of age, but higher early-childhood BPA exposures were associated with accelerated growth during this period.Citation: Braun JM, Lanphear BP, Calafat AM, Deria S, Khoury J, Howe CJ, Venners SA. 2014. Early-life bisphenol A exposure and child body mass index: a prospective cohort study. Environ Health Perspect 122:1239–1245; http://dx.doi.org/10.1289/ehp.1408258     

Serum Omega-6 Polyunsaturated Fatty Acids and the Metabolic Syndrome: A Longitudinal Population-based Cohort Study

The serum fatty acid composition reflects the dietary fatty acid composition from the past few days to several weeks. However, the role of serum omega-3 (from fish and fish oils) and omega-6 (from vegetable oils) polyunsaturated fatty acids (PUFAs) in the course of metabolic syndrome is poorly understood. At the Primary Health Care Unit in Pieks?m?ki, Finland, all subjects born in 1942, 1947, 1952, 1957, and 1962 (n = 1,294) were invited for health checkups in 1997-1998 and 2003-2004. Metabolic syndrome was defined by using the new, harmonized criteria. The serum omega-3 PUFAs, omega-6 PUFAs, and total fatty acids were analyzed by proton nuclear magnetic resonance spectroscopy. Altogether, data from both checkups were available for 665 subjects. After adjustment for age, sex, and baseline body mass index, the incidence of metabolic syndrome between the 2 checkups with a 6.4-year follow-up was inversely associated (P < 0.001) with the increased relative proportion of omega-6 PUFAs in serum lipids. Further adjustment for body mass index change, lipid medication, smoking, alcohol intake, and physical activity conveyed similar results. The authors did not find any significant associations between omega-3 PUFAs and the incidence of metabolic syndrome. Therefore, their results suggest that the change in the relative proportion of omega-6 PUFAs in serum lipids is inversely related to the incidence of metabolic syndrome.     

The Association of Prenatal Exposure to Perfluorinated Chemicals with Maternal Essential and Long-Chain Polyunsaturated Fatty Acids during Pregnancy and the Birth Weight of Their Offspring: The Hokkaido Study

Background

Fatty acids (FAs) are essential for fetal growth. Exposure to perfluorinated chemicals (PFCs) may disrupt FA homeostasis, but there are no epidemiological data regarding associations of PFCs and FA concentrations.

Objectives

We estimated associations between perfluorooctane sulfonate (PFOS)/perfluorooctanoate (PFOA) concentrations and maternal levels of FAs and triglyceride (TG) and birth size of the offspring.

Methods

We analyzed 306 mother–child pairs in this birth cohort between 2002 and 2005 in Japan. The prenatal PFOS and PFOA levels were measured in maternal serum samples by liquid chromatography–tandem mass spectrometry. Maternal blood levels of nine FAs and TG were measured by gas chromatography–mass spectrometry and TG E-Test Wako kits, respectively. Information on infants’ birth size was obtained from participant medical records.

Results

The median PFOS and PFOA levels were 5.6 and 1.4 ng/mL, respectively. In the fully adjusted model, including maternal age, parity, annual household income, blood sampling period, alcohol consumption, and smoking during pregnancy, PFOS but not PFOA had a negative association with the levels of palmitic, palmitoleic, oleic, linoleic, α-linolenic, and arachidonic acids (p < 0.005) and TG (p-value = 0.016). Female infants weighed 186.6 g less with mothers whose PFOS levels were in the fourth quartile compared with the first quartile (95% CI: –363.4, –9.8). We observed no significant association between maternal levels of PFOS and birth weight of male infants.

Conclusions

Our data suggest an inverse association between PFOS exposure and polyunsaturated FA levels in pregnant women. We also found a negative association between maternal PFOS levels and female birth weight.

Citation

Kishi R, Nakajima T, Goudarzi H, Kobayashi S, Sasaki S, Okada E, Miyashita C, Itoh S, Araki A, Ikeno T, Iwasaki Y, Nakazawa H. 2015. The association of prenatal exposure to perfluorinated chemicals with maternal essential and long-chain polyunsaturated fatty acids during pregnancy and the birth weight of their offspring: the Hokkaido Study. Environ Health Perspect 123:1038–1045; http://dx.doi.org/10.1289/ehp.1408834     

Associations of Pre- and Postnatal Air Pollution Exposures with Child Blood Pressure and Modification by Maternal Nutrition: A Prospective Study in the CANDLE Cohort

Background: Limited data suggest air pollution exposures may contribute to pediatric high blood pressure (HBP), a known predictor of adult cardiovascular diseases.Methods: We investigated this association in the Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) study, a sociodemographically diverse pregnancy cohort in the southern United States with participants enrolled from 2006 to 2011. We included 822 mother–child dyads with available address histories and a valid child blood pressure measurement at 4–6 y. Systolic (SBP) and diastolic blood pressures (DBP) were converted to age-, sex-, and height-specific percentiles for normal-weight U.S. children. HBP was classified based on SBP or DBP ≥90th percentile. Nitrogen dioxide (NO2) and particulate matter ≤2.5μm in aerodynamic diameter (PM2.5) estimates in both pre- and postnatal windows were obtained from annual national models and spatiotemporal models, respectively. We fit multivariate Linear and Poisson regressions and explored multiplicative joint effects with maternal nutrition, child sex, and maternal race using interaction terms.Results: Mean PM2.5 and NO2 in the prenatal period were 10.8 [standard deviation (SD): 0.9] μg/m3 and 10.0 (SD: 2.4) ppb, respectively, and 9.9 (SD: 0.6) μg/m3 and 8.8 (SD: 1.9) ppb from birth to the 4-y-old birthday. On average, SBP percentile increased by 14.6 (95% CI: 4.6, 24.6), and DBP percentile increased by 8.7 (95% CI: 1.4, 15.9) with each 2-μg/m3 increase in second-trimester PM2.5. PM2.5 averaged over the prenatal period was only significantly associated with higher DBP percentiles [β= 11.6 (95% CI: 2.9, 20.2)]. Positive associations of second-trimester PM2.5 with SBP and DBP percentiles were stronger in children with maternal folate concentrations in the lowest quartile (pinteraction= 0.05 and 0.07, respectively) and associations with DBP percentiles were stronger in female children (pinteraction= 0.05). We did not detect significant association of NO2, road proximity, and postnatal PM2.5 with any outcomes.Conclusions: The findings suggest that higher prenatal PM2.5 exposure, particularly in the second trimester, is associated with elevated early childhood blood pressure. This adverse association could be modified by pregnancy folate concentrations. https://doi.org/10.1289/EHP7486     

Fish Consumption and Risk of Stroke in Chinese Adults: A Prospective Cohort Study in Shanghai,China

Present studies on the association of fish consumption with risk of stroke have shown controversial results, and this association within the Chinese population remains unknown. We aimed to investigate the association between fish consumption and incidence of total stroke, ischemic stroke and hemorrhagic stroke among adults in China. We analyzed the data of 57,701 adults aged 20–74 years, with no history of stroke, in a prospective cohort study in Shanghai. Fish consumption was calculated from a food frequency questionnaire at baseline and divided into four categories (less than 300, 300–450, 450–600 and more than 600 g/week). Participant information was linked to health information systems in which stroke event information was collected up until 31 December 2021. The hazard ratios (HR) and 95% confidence intervals (CI) of the associations of fish consumption with risk of total stroke, ischemic stroke and hemorrhagic stroke were estimated using cox proportional hazards regression models. Dose–response relationships were estimated using restricted cubic spline analyses. During a median follow-up of 4.56 years, 807 newly developed stroke events were ascertained, including 664 ischemic stroke events and 113 hemorrhagic stroke events. Fish consumption of 300–450 g/week was associated with a reduced risk of total stroke (HR: 0.78, 95% CI: 0.64–0.94) and ischemic stroke (0.70 (0.57–0.88)) compared with fish consumption of less than 300 g/week, after adjustment for comprehensive covariates including sociodemographic characteristics, lifestyle, dietary patterns and disease histories. No significant association was found between fish consumption and hemorrhagic stroke. The findings of our study support the consumption level of fish recommended in the dietary guidelines.     

Maternal Fish Consumption and Infant Birth Size and Gestation: New York State Angler Cohort Study

Background  

The scientific literature poses a perplexing dilemma for pregnant women with respect to the consumption of fish from natural bodies of water. On one hand, fish is a good source of protein, low in fat and a rich source of other nutrients all of which have presumably beneficial effects on developing embryos and fetuses. On the other hand, consumption of fish contaminated with environmental toxicants such as polychlorinated biphenyls (PCBs) has been associated with decrements in gestation and birth size.     

Low-Level Prenatal Toxin Exposures and Breastfeeding Duration: A Prospective Cohort Study

Introduction Maternal exposure to tobacco smoke is associated with shortened breastfeeding duration, but few studies have examined the effects on breastfeeding outcomes of low level exposures to other toxic chemicals. Moreover, it is unclear if passive smoking is associated with duration of breastfeeding. Our objective was therefore to examine the effect of low-level prenatal exposures to common environmental toxins (tobacco smoke, lead, and phthalates) on breastfeeding exclusivity and duration. Methods We conducted an analysis of data from the Health Outcomes and Measures of the Environment (HOME) Study. Serum and urine samples were collected at approximately 16 and 26 weeks gestation and at delivery from 373 women; 302 breastfed their infants. Maternal infant feeding interviews were conducted a maximum of eight times through 30 months postpartum. The main predictor variables for this study were gestational exposures to tobacco smoke (measured by serum cotinine), lead, and phthalates. Passive smoke exposure was defined as cotinine levels of 0.015–3.0 μg/mL. Primary outcomes were duration of any and exclusive breastfeeding. Results Serum cotinine concentrations were negatively associated with the duration of any breastfeeding (29.9 weeks unexposed vs. 24.9 weeks with passive exposure, p?=?0.04; and 22.4 weeks with active exposure, p?=?0.12; p?=?0.03 for linear trend), but not duration of exclusive breastfeeding. Prenatal levels of blood lead and urinary phthalate metabolites were not significantly associated with duration of any or exclusive breastfeeding. Conclusions Passive exposure to tobacco smoke during pregnancy was associated with shortened duration of any breastfeeding.     

Associations between Plasmatic Polyunsaturated Fatty Acids Concentrations and Cognitive Status and Decline in Neurocognitive Disorders

Objective

To examine the association of plasmatic and erythrocyte concentrations polyunsaturated fatty acids (PUFA) with both cognitive status and decline.

Design

Longitudinal observational cohort study. Setting: Memory Clinic of Lyon Sud university hospital.

Participants

140 patients, aged 60 and older, were referred to the memory clinic, and successively included in the cohort, between March 2010 and February 2014.

Measurements

Concentration of ω-3 PUFA (eicosapentaenoic: EPA and docosahexaenoic: DHA) and ω-6 PUFA (arachidonic: AA), were measured at baseline in plasma and in the erythrocytes membrane. Cognitive status was assessed using the mini mental state examination (MMSE), at baseline and every six months during follow-up. The median follow-up period was of 11,5 months.

Results

Compared to participants with minor neurocognitive disorders (MMSE≥24), participants with major neurocognitive disorders (NCD) had lower plasmatic concentrations of EPA and DHA (p<0.05) at baseline. Erythrocyte AA and DHA concentrations were significantly lower in patients with cognitive decline (defined as a ≥2 points loss of MMSE per year), while no difference in plasmatic concentrations was observed.

Conclusions

Our study suggests that ω-3 PUFA plasma concentrations (mainly EPA and DHA) could be associated with cognitive status in older people. Moreover, in this exploratory study, lower erythrocyte PUFA concentrations (AA and DHA) were associated with accelerated decline and could be proposed as a surrogate marker for prediction of cognitive decline.

     

Fish Consumption,Long-Chain Omega-3 Polyunsaturated Fatty Acid Intake and Risk of Metabolic Syndrome: A Meta-Analysis

Fish and long-chain ω-3 polyunsaturated fatty acid (LCω3PUFA) intake in relation to the risk of cardiovascular diseases have been well studied. However, studies that directly link fish consumption or LCω3PUFA intake to the risk of metabolic syndrome (MetS) are sparse and the results are inconsistent. We reviewed literature through December 2014 and used random-effects or fixed-effects models, as appropriate, to pool the associations of fish or LCω3PUFA intake with the risk of MetS. Nine independent cross-sectional samples (seven cross-sectional studies) and three independent prospective cohorts (two prospective cohort studies) were identified as eligible for this meta-analysis. By pooling data from the prospective cohorts (7860 participants and 1671 incident cases), a significant inverse association between fish consumption and incidence of MetS was found. The pooled RR (95% CI) was 0.71 (0.58, 0.87), comparing the highest to the lowest category of fish consumption, and 0.94 (0.90, 0.98) for one serving/week increment. Consistent results were found for LCω3PUFA intake. Non-significant inverse association of fish or LCω3PUFA intake with risk of MetS was found when pooling the cross-sectional studies. By quantitatively summarizing the literature, a modest inverse association between fish or LCω3PUFA intake and risk of MetS cannot be excluded.     

多不饱和脂肪酸小鼠抗氧化功能的实验研究

目的 观察喂饲多不饱和脂肪酸对老龄小鼠抗氧化功能的影响.方法 设 对照组和0.34、0.67、2.00 g/kg多不饱和脂肪酸3个剂量组,每组10只12月龄雄性小鼠,每日经口给样品1次,连续给予30 d,检测小鼠血液中MDA、SOD、GSH-Px水平.结果 2.00 g/kg组MDA水平较对照组显著降低,差异有统计学意义(P ＜0.05);SOD活力较对照组显著升高,差异有统计学意义(P ＜0.05);GSH-Px水平较对照组有所升高,差异无统计学意义(P＞0.05).结论 该实验使用的多不饱和脂肪酸对小鼠具有抗氧化功能.     

Neonatal Hyperglycemia Related to Parenteral Nutrition Affects Long-Term Neurodevelopment in Preterm Newborn: A Prospective Cohort Study

(1) Background: Recent evidence reported a reduced tolerance of macronutrient parenteral intakes in subjects in critically ill conditions. We designed a prospective cohort study to evaluate the effects of hyperglycemia (HG) related to parenteral nutrition (PN) on neurodevelopment (NDV) in survived preterm newborns. (2) Methods: Enrolled newborns with gestational age < 32 weeks or birth weight < 1500 g, were divided in two cohorts: (A) exposed to moderate or severe HG (glucose blood level > 180 mg/dL) in the first week of life; (B) not exposed to HG. We considered as the primary outcome the rate of preterm newborns survived without NDV delay at 24 months of life, evaluated with Bayley Scales of Infants Development III edition. (3) Results: We analyzed 108 (A 32 vs. B 76) at 24 months of life. Newborns in cohort A showed a higher rate of cognitive and motor delay (A 44% vs. B 22 %, p = 0.024; A 38% vs. B 8%, p < 0.001). When adjusting for background characteristics, HG remained a risk factor for motor delay. (4) Conclusions: High nutritional intakes through PN soon after birth increase the risk of HG. The consequences of this severe metabolic complication affect long-term NDV and survival in preterm newborns.     

Trimester-Specific Reference Ranges for Saturated,Monounsaturated and Polyunsaturated Fatty Acids in Serum of Pregnant Women: A Cohort Study from the ECLIPSES Group

In the course of pregnancy, increasing importance is being placed on maintaining optimal fatty acid (FA) levels and particularly n-3 PUFAs to ensure correct fetal development. However, reference ranges for FA have been reported in only a few studies. Our objective is to provide quantitative reference intervals for SFAs, MUFAs, and PUFAs (n-6 and n-3) in a large population of healthy pregnant women from a developed country. A prospective study of pregnant women (n = 479) was conducted from the first trimester (T1) to the third trimester (T3). A total of 11 fatty acids were analyzed in serum by gas chromatography mass spectrometry and were expressed as absolute (µmol/L) and relative (percentage of total FA) concentration units. Serum concentrations of SFAs, MUFAs, n-6 PUFAs, n-3 PUFAs, various FA ratios, and the EFA index were determined. The reference intervals (2.5/97.5 percentiles) in absolute values from T1 ranged from 1884.32 to 8802.81 µmol/L for SFAs, from 959.91 to 2979.46 µmol/L for MUFAs, from 2325.77 to 7735.74 µmol/L for n-6 PUFAs, and from 129.01 to 495.58 µmol/L for n-3 PUFAs. These intervals mainly include the values of other studies from European populations. However, reference ranges vary according to some maternal factors. The FA levels proposed, obtained from a large sample of pregnant women, will be a useful tool for assessing the degree of adequacy of FAs in pregnant women and will help to carry out dietary interventions based on certain maternal factors.     

Domestic Radon Exposure and Risk of Childhood Cancer: A Prospective Census-Based Cohort Study

Background: In contrast with established evidence linking high doses of ionizing radiation with childhood cancer, research on low-dose ionizing radiation and childhood cancer has produced inconsistent results.Objective: We investigated the association between domestic radon exposure and childhood cancers, particularly leukemia and central nervous system (CNS) tumors.Methods: We conducted a nationwide census-based cohort study including all children < 16 years of age living in Switzerland on 5 December 2000, the date of the 2000 census. Follow-up lasted until the date of diagnosis, death, emigration, a child’s 16th birthday, or 31 December 2008. Domestic radon levels were estimated for each individual home address using a model developed and validated based on approximately 45,000 measurements taken throughout Switzerland. Data were analyzed with Cox proportional hazard models adjusted for child age, child sex, birth order, parents’ socioeconomic status, environmental gamma radiation, and period effects.Results: In total, 997 childhood cancer cases were included in the study. Compared with children exposed to a radon concentration below the median (< 77.7 Bq/m³), adjusted hazard ratios for children with exposure ≥ the 90th percentile (≥ 139.9 Bq/m³) were 0.93 (95% CI: 0.74, 1.16) for all cancers, 0.95 (95% CI: 0.63, 1.43) for all leukemias, 0.90 (95% CI: 0.56, 1.43) for acute lymphoblastic leukemia, and 1.05 (95% CI: 0.68, 1.61) for CNS tumors.Conclusions: We did not find evidence that domestic radon exposure is associated with childhood cancer, despite relatively high radon levels in Switzerland.Citation: Hauri D, Spycher B, Huss A, Zimmermann F, Grotzer M, von der Weid N, Weber D, Spoerri A, Kuehni C, Röösli M, for the Swiss National Cohort and the Swiss Paediatric Oncology Group (SPOG). 2013. Domestic radon exposure and risk of childhood cancer: a prospective census-based cohort study. Environ Health Perspect 121:1239–1244; http://dx.doi.org/10.1289/ehp.1306500     

Relationships between Maternal Gene Polymorphisms in One Carbon Metabolism and Adverse Pregnancy Outcomes: A Prospective Mother and Child Cohort Study in China

Background: To investigate relationships between five single nucleotide polymorphisms (SNP) in four maternal genes involved in one carbon metabolism and adverse pregnancy outcomes, including preterm birth (PTB), low birth weight (LBW), and small-for-gestational-age (SGA). Methods: This was a prospective mother and child cohort study in Wuqiang, China. Pregnant women (n = 939) were recruited from Jun 2016 to Oct 2018. Pregnancy outcomes (PTB, LBW, and SGA) were extracted from medical records and other information including age at childbearing, maternal education level, gravidity, parity, pre-pregnancy weight and height was collected by using a structured questionnaire. The maternal serum folate concentration was measured by using Abbott Architect i2000SR chemiluminescence analyzer in the first prenatal care visit. DNA genotyping of methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, methionine synthase reductase (MTRR) A66G, methionine synthase (MTR) A2756G, and thymidylate synthetase (TYMS) rs3819102 was processed by Sequenom MassARRAY iPLEX Platform. Univariate and multivariate logistics regression analysis were used to test the relationships between 5 SNPs and PTB, LBW, SGA. Results: Totally, 849 dyads of women and infants were included in the analysis. The prevalence of PTD, LBW, and SGA were 3.76%, 1.58%, and 5.31% respectively. The homozygote frequencies of MTHFR C677T, MTHFR A1298C, MTRR A66G, MTR A2756G, and TYMS rs3819102 were 44.2%, 1.4%, 6.7%, 1.3%, and 3.2%, and the alt allele frequencies were 66.1%, 10.8%, 24.9%, 10.5%, and 20.5% respectively. The average serum folate concentration was 11.95 ng/mL and the folate deficiency rate was 0.47%. There were no significant associations between MTHFR C677T, MTHFR A1298C, MTRR A66G, MTR A2756G, TYMS rs3819102 alleles and PTD, LBW, SGA (p > 0.05). Conclusions: In the population with adequate folate status and low prevalence of adverse pregnancy outcomes, MTHFR C677T, MTHFR A1298C, MTRR A66G, MTR A2756G, TYMS rs3819102 alleles may not be related to PTD, LBW, and SGA.