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Background: Polybrominated diphenyl ethers are known endocrine disrupting environmental contaminants used as flame retardants. Their levels have increased in humans over the last ten years, raising concerns about their consequences on human health. Some animal studies suggest that PBDEs can affect fetal growth; however, the results of human studies are contradictory. This study evaluates the association between the most common PBDEs in maternal blood measured in early pregnancy and birth weight.Methods: BDE-47, BDE-99, BDE-100 and BDE-153 levels were measured in 349 women during their first prenatal care visit at the University Hospital Center of Sherbrooke (Quebec, Canada). Birth weight and relevant medical information were collected from medical records. In contrast with previous studies, we examined the full range of clinical risk factors known to affect fetal growth as potential confounders, as well as other environmental pollutants that are likely to interact with fetal growth (polychlorinated biphenyls (PCBs), mercury, lead, cadmium and manganese).Results: There was no statistically significant relationship between PBDE levels in early pregnancy and birth weight in both unadjusted and multivariate regression models.Conclusions: Our results suggest that PBDEs in early pregnancy have little or no direct impact on birth weight, at least at the levels of exposure in our population. [ABSTRACT FROM AUTHOR]

Thyroid hormones play a critical role in the growth of many organs, especially the brain. Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) interact with the thyroid pathway and may disturb neurodevelopment. This prospective study was designed to examine associations between maternal blood PBDEs and PCBs in early pregnancy and levels of thyroid hormones in maternal and umbilical-cord blood. Levels of low-brominated PBDEs, 3 PCB congeners, total and free thyroid hormones (triiodothyronine (T3) and thyroxine (T4)), thyroid-stimulating hormone, thyroid peroxidase antibodies, iodine, selenium, and mercury were measured in 380 pregnant women in the first trimester who were recruited at the University Hospital Center of Sherbrooke (Quebec, Canada) between September 2007 and December 2008. Thyroid hormone levels were also assessed at delivery and in cord blood (n = 260). Data were analyzed on both a volume basis and a lipid basis. At less than 20 weeks of pregnancy, no relationship was statistically significant in volume-based analysis. In lipid-based models, an inverse association between maternal PBDEs and total T3 and total T4 and a direct association with free T3 and free T4 were observed. At delivery, in both analyses, we observed negative associations between maternal total T4, free T3, cord-blood free T4, and PBDEs and between maternal free T3 and PCBs. Our results suggest that exposure to PBDEs and PCBs in pregnancy may interfere with thyroid hormone levels. [ABSTRACT FROM PUBLISHER]

Abstract: Background: Environmental prenatal exposure to potentially neurotoxic metals poses a particular challenge with regard to the study of early toxic effects. Monoamine oxidase activity, shown to be influenced by metals in experimental studies, could be a useful biomarker in humans. Objective: To examine the relationship between blood metal concentrations at delivery and placenta MAO activity. Methods: The study was performed in 163 pregnancies. Maternal and cord blood samples were obtained for manganese (Mn), lead (Pb), and cadmium (Cd) determination. Mercury (Hg) was also analysed in maternal hair. Placental samples were stored immediately after expulsion and total MAO activity was measured. Results: MAO activity was significantly positively correlated with maternal and cord blood Mn concentrations in subjects with high MAO activity. In subjects with low MAO activity, maternal hair Hg was negatively correlated with MAO. Conclusion: Our results suggest the use of placental MAO as a potential surrogate marker of Mn toxicity in the newborn and its correlation with psychomotor development should be further investigated. [Copyright &y& Elsevier]

Many studies use the number of fish meals as an estimate of Hg intake, although fish Hg concentrations, even within the same species, can greatly vary. Furthermore, most freshwater advisories only refer to local catch, while market fish advisories only focus on market fish, although both can contribute to Hg body burden. The present study, carried out in lakeside communities from 2 ecosystems in Quebec, Canada, sought to (i) estimate Hg intake from local freshwater sources, hunted waterfowl and market fish and seafood, and (ii) examine the relations between fish consumption, estimated Hg intake and biomarkers of exposure. A total of 238 adults (18–74 years), who had consumed local catch within the past three months, responded to an extensive interview-administered fish and waterfowl frequency questionnaire. Anthropometric measures were taken and a self-administered questionnaire was used to obtain socio-demographic information. Hg intake was estimated as µg Hg/kg body weight/day. Blood and hair samples were analyzed for Hg content. Results showed that persons from one ecosystem ate significantly more fish compared to those from the other (median: 52.1 g/day vs 38.9 g/day), but presented significantly lower concentrations of hair Hg (median: 448.0 ng/g vs 730.5 ng/g), blood organic Hg (median: 1.1 µg/L vs 3.4 µg/L) and inorganic Hg (median: 0.4 µg/L vs 0.8 µg/L). Median daily total Hg intake was 0.080 µg/kg bw/day for the former community and 0.141 µg/kg bw/day for the latter. Overall, 59.5% from the first ecosystem and 41.0% from the other, exceeded the US EPA RfD (0.1 µg/kg bw/day), while 13.2% and 6.0%, respectively, exceeded the Canadian tolerable daily intake (0.47 µg/kg bw/day) for adults. For the two groups, freshwater fish consumption frequency, but not total fish, was positively associated with bioindicators of Hg while estimated Hg intake from freshwater catch as well as from total fish consumption... [Copyright &y& Elsevier]

Abstract: Environmental chemicals can disrupt endocrine balance and in particular thyroid hormone (TH) homeostasis. However, studies differ with respect to thyroid profile changes and gender differences are rarely examined. This study investigated the THs, triodothyronine (T3), thyroxine (T4), and thyroid stimulating hormone (TSH), in relation to serum organochlorines (OCs), bioindicators of mercury (Hg) and blood lead (Pb) in 211 freshwater fish consumers (124 men and 87 women) from two communities in Canada. Thyroid hormones were within the normal range and the bioindicators of exposure were low compared to other reports on fish consumers. Stratified analysis showed that for women, serum T3 concentrations were negatively related to serum concentrations of PCB 138, PCB 153, the non-coplanar congeners, Arochlor 1260, and ΣPCB, as well as p,p′-DDE. No relations were observed between T4 and any of the chemicals measured, but TSH was negatively related to blood Pb. For men, serum T4 was inversely related to PCB 138, non-ortho-substituted (dioxin-like) PCBs and ΣPCB. A significant positive relationship was observed between serum TSH and different PCB congeners (PCB 138, PCB 180, non-coplanar congeners, mono-ortho coplanar congeners, dioxin-like PCBs), as well as ΣPCB. Serum TSH increased with hair and blood Hg concentrations and was highest among those in the highest 50th percentile for both Hg and dioxin-like PCB congeners compared to the others. No associations were observed for T3 in men. These findings suggest that even at low concentrations, these environmental contaminants can interfere with thyroid status and effects may differ by gender. [Copyright &y& Elsevier]

Abstract: Mercury (Hg) is a widespread neurotoxic compound that bio-accumulates in fish and marine mammals. Monoamine oxidase (MAO; EC 1.4.3.4) regulates biogenic amine concentration in the brain and peripheral tissue and has been shown to be a molecular target of Hg compounds in animal models. Blood platelet monoamine oxidase-B (MAO-B) activity may reflect MAO function in the central nervous tissue. Therefore, the objective of this study was to evaluate the relationship between platelet MAO-B and Hg exposure in fish-eating adults (n =127) living along the St. Lawrence River (Lake St. Pierre, Que., Canada). Hg concentrations were determined in blood and hair samples. A significant negative association was observed between platelet MAO-B activity and blood-Hg (r =−0.193, p =0.029) but not with hair-Hg levels (r =−0.125, p =0.169). Multiple linear regression analysis demonstrated that blood-Hg (β =−4.6, p =0.011) and heavy smoking (β =−8.5, p =0.001) were associated with reduced platelet MAO activity in the total population. In addition, this reduction in MAO-B activity appeared to be associated with blood-Hg concentrations above 3.4μg/L (75th percentile). Possible gender related differences were also observed and are discussed. Our results suggest that MAO-B activity in blood platelets may be a useful tool to assess biochemical effects of Hg exposure in human populations. These changes in platelet MAO-B may reflect enzymatic changes in nervous tissue and should be further investigated as a surrogate marker of neurotoxicity. [Copyright &y& Elsevier]

The authors respond to a commentary on their article "Maternal PBDEs and Thyroid Hormones" which appeared in a 2013 issue. They react to the question raised by Doctor Jonathan Chevrier concerning the lack of consistency among epidemiological studies on the association of polybrominated diphenyl ethers (PBDEs) with thyroid hormone levels. The authors express their agreement with the arguments on iodine intake.

Abstract Evaluating in utero exposure to inorganic and multiclass organic contaminants is critical to better evaluate potential harmful effects on prenatal and postnatal development. The analysis of meconium, the first bowel discharge of the newborn, has been proposed as a non-invasive way to assess cumulative prenatal exposure. The aim of this study was to implement an analytical method for quantifying 72 targeted organic compounds, including pesticides, pharmaceutical compounds and daily life xenobiotics, in meconium in addition to selected elements (17 elements). We report initial monitoring results based on the analysis of 396 meconium samples from an Eastern Canada cohort (Quebec, Canada). Element contents in meconium were analysed by mass spectrometry after digestion in nitric acid and peroxide. Targeted organic compounds were extracted and purified from meconium samples by a solid-liquid extraction followed by a dispersive-SPE purification before tandem mass spectrometry analysis. Concentrations of targeted elements were within the range of concentration reported in European and US studies but were lower than concentrations found in a developing country cohort (i.e., Pb, Cd). Out of the 72 targeted organic compounds, 31 were detected at least once and 30 were quantified. Compounds with the highest frequency of detection were caffeine, detected in all samples (from 2.80 to 6186 ng g−1), followed by acetaminophen detected in 53% of the samples (up to ~402 µg g−1) and methyl paraben detected in 20% of the samples (up to ~10 µg g−1). Pesticides were detected in low frequencies (< 2%) and low concentration (< 35 ng g−1). Results show that meconium can be used to monitor prenatal exposure of foetus to a wide array of inorganic and organic contaminants. Highlights • We aim to characterise prenatal exposure to organic and inorganic contaminants using meconium. • We optimised a single method that allows the monitoring of 72 organic contaminants. • Inorganic contaminants were within the range reported in the literature. • Caffeine, acetaminophen and methyl paraben were the most frequently detected compounds. [ABSTRACT FROM AUTHOR]

Acetaminophen is the only over-the-counter pain reliever that is not contraindicated during pregnancy, but recent studies have questioned whether acetaminophen is safe for the fetus, particularly the developing brain. This prospective birth cohort study probed the previously observed association between in utero exposure to acetaminophen and neurodevelopment by using concentrations of acetaminophen measured in meconium, which more objectively captures exposure of the fetus than maternal report. Exposure, measured by liquid chromatography coupled with tandem mass spectrometry, was categorized into nondetection, low detection, and high detection levels. At age 6–8 years, children completed a set of subtests from the Wechsler Intelligence Scale for Children, 4th edition. Additionally, this study examined potential effect modification by child sex on the association between acetaminophen exposure and neurodevelopment. In fully adjusted models, in utero exposure to acetaminophen was not statistically significantly associated with decreased scores on any of the examined subtests in all children combined (n  = 118). The effect of in utero acetaminophen exposure on the Coding subtest was marginally significantly different among boys and girls, with girls performing significantly better on the task with higher levels of acetaminophen compared with girls with undetectable levels of exposure (βgirls, low = 2.83 [0.97, 4.70], βgirls, high = 1.95 [−0.03, 3.93], βboys, low = .02 [−1.78, 1.81], βboys, high = −.39 [−2.09, 1.31], p interaction = .06). Effect modification by child sex was not observed on other subtests. These results do not support prior reports of adverse neurodevelopmental effects of in utero exposure to acetaminophen. [ABSTRACT FROM AUTHOR]

Abstract: Flame retardant dechlorane plus (DP) and several polybrominated diphenylether (PBDE) congeners have been measured in 87 human milk samples collected in two Canadian cities: Kingston and Sherbrooke. The levels of PBDEs in human milk (mean (median), ngg−1 lipid weight=10 (5.9), 4.1 (2.8), 3.0 (1.6), 5.12 (1.6), and 15 (ND) for BDE-47, BDE-99, BDE-100, BDE-153, and BDE-209, respectively) were comparable to those reported in Europe, U.S.A. and China. The levels of DP, with a mean value of 0.98ngg−1 and a median value of 0.60ngg−1 (lipid weight), were two to ten times lower than those of concurrently measured major PBDEs including BDE-209. While there is little difference in the levels of measured contaminants in milk samples collected from the two cities, the contaminants levels in human milk show, indicated by Principal Components Analysis, that DP, deca-BDE, and penta-BDE come from three distinct sources. The mean and median isomer ratio values of DP in milk were 0.67 and 0.69, respectively, very similar to that of DP commercial products. [Copyright &y& Elsevier]

Abstract: Objectives: The objective of the present study was to evaluate motor function in order to assess the effects of long-term, low-level environmental manganese (Mn) exposure in residents of an Ohio community where a large ferro- and silico-Mn smelter has been active for more than 50 years. Methods: One hundred residents from the Mn-exposed Ohio community were evaluated using the Unified Parkinson''s Disease Rating Scale (UPDRS), a postural sway test, and a comprehensive questionnaire exploring demographics and general health. The results were compared to those of 90 residents from a demographically similar comparison town in Ohio. Mn exposure was assessed using modeled airborne Mn and blood Mn (Mn-B). The UPDRS was employed to evaluate parkinsonian motor features. Postural sway was measured using a CATSYS 2000 (Danish Product Development). Results: No significant difference between the exposed and comparison groups was evident as to Mn-B, demographics or major health outcomes. The risk of abnormal UPDRS performance using “Motor and Bradykinesia” criteria was increased in the Mn-exposed group after adjustment for potential confounders such as the presence of other neurotoxic metals, factors affecting susceptibility to Mn, potential factors influencing motor performance, and other possible demographic confounders. No participant was diagnosed with clinical manganism by neurological examination. After adjustment for various potential confounders, the Mn-exposed group showed significantly higher postural sway scores under eyes-open conditions than the comparison group. Conclusions: Subclinical findings on the UPDRS and postural sway in the Mn-exposed group may possibly reflect early subtle effects of chronic low-level Mn exposure. However, the cross-sectional study design, the small to medium effect sizes, and the little biological plausibility are limiting the possibility of a causal relationship between the environmental Mn-air exposure and the early subclinical neurotoxic effects observed. [Copyright &y& Elsevier]

Abstract: Platelet monoamine oxidase-B (MAO-B) has been considered a surrogate biochemical marker of neurotoxicity, as it may reflect changes in the monoaminergic system in the brain. Colour vision discrimination, in part a dopamine dependent process, has been used to identify early neurological effects of some environmental and industrial neurotoxicants. The objective of this cross-sectional study was to explore the relationship between platelet MAO-B activity and acquired colour discrimination capacity in fish-consumers from the St. Lawrence River region of Canada. Assessment of acquired dyschromatopsia was determined using the Lanthony D-15 desaturated panel test. Participants classified with dyschromatopsia (n =81) had significantly lower MAO-B activity when compared to those with normal colour vision (n =32) (26.5±9.6 versus 31.0±9.9 nmol/min/20 μg, P =0.030)). Similarly, Bowman''s Colour Confusion Index (CCI) was inversely correlated with MAO-B activity when the vision test was performed with the worst eye only (r =−0.245, P =0.009), the best eye only (r =−0.188, P =0.048) and with both eyes together (r =−0.309, P =0.001). Associations remained significant after adjustment for age and gender when both eyes (P =0.003) and the worst eye (P =0.045) were tested. Adjustment for heavy smoking weakened the association between MAO-B and CCI in the worst eye (P =0.140), but did not alter this association for both eyes (P =0.006). Adjustment for blood-mercury concentrations did not change the association. This study suggests a relationship between reduced MAO-B activity and acquired colour vision loss and both are associated with tobacco smoking. Therefore, results show that platelet MAO-B may be used as a surrogate biochemical marker of acquired colour vision loss. [Copyright &y& Elsevier]

Childhood obesity is a predictor of adult obesity and has its roots in the pre-pregnancy or pregnancy period. This review presents an overview of the prenatal risk factors for childhood obesity, which were categorized into 2 groups: biological risk factors (maternal pre-pregnancy body mass index, gestational weight gain, diabetes in pregnancy, and caesarean section), and environmental and behavioural risk factors (maternal smoking and exposure to obesogens, maternal dietary patterns, maternal intestinal microbiome and antibiotics exposure, and maternal psychosocial stress). Identifying modifiable predisposing prenatal factors for obesity will inform further development of inventions to prevent obesity over the life course, and future directions for research and intervention are discussed. [ABSTRACT FROM AUTHOR]

Background: The developing fetus and pregnant woman can be exposed to a variety of environmental chemicals that may adversely affect their health. Moreover, environmental exposure and risk disparities are associated with different social determinants, including socioeconomic status (SES) and demographic indicators. Our aim was to investigate whether and how maternal concentrations of a large panel of persistent and non-persistent environmental chemicals vary according to sociodemographic and lifestyle characteristics in a large pregnancy and birth cohort.Methods: Data were analyzed from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a cohort of pregnant women (N=2001) recruited over four years (2008-2011) in 10 cities across Canada. In all, 1890 urine and 1938 blood samples from the first trimester (1st and 3rd trimester for metals) were analysed and six sociodemographic and lifestyle indicators were assessed: maternal age, household income, parity, smoking status, country of birth and pre-pregnancy body mass index (BMI).Results: We found these indicators to be significantly associated with many of the chemicals measured in maternal blood and urine. Women born outside Canada had significantly higher concentrations of di-2-ethylhexyl and diethyl phthalate metabolites, higher levels of all metals except cadmium (Cd), as well as higher levels of polychlorinated biphenyls (PCBs) and legacy organochlorine pesticides (OCPs). Nulliparity was associated with higher concentrations of dialkyl phosphates (DAPs), arsenic, dimethylarsinic acid (DMAA), perfluoroalkyl substances (PFASs) and many of the persistent organic pollutants. Smokers had higher levels of bisphenol A, Cd and perfluorohexane sulfonate, while those women who had never smoked had higher levels of triclosan, DMAA, manganese and some OCPs.Conclusion: Our results demonstrated that inequitable distribution of exposure to chemicals among populations within a country can occur. Sociodemographic and lifestyle factors are an important component of a thorough risk assessment as they can impact the degree of exposure and may modify the individual's susceptibility to potential health effects due to differences in lifestyle, cultural diets, and aging. [ABSTRACT FROM AUTHOR]

Previous surveys of neonatal medicine in China have not collected comprehensive information on workforce, investment, health care practice, and disease expenditure. The goal of the present study was to develop a national database of neonatal care units and compare present outcomes data in conjunction with health care practices and costs. We summarized the above components by extracting data from the databases of the national key clinical subspecialty proposals issued by national health authority in China, as well as publicly accessible databases. Sixty-one newborn clinical units from provincial or ministerial hospitals at the highest level within local areas in mainland China, were included for the study. Data were gathered for three consecutive years (2008–2010) in 28 of 31 provincial districts in mainland China. Of the 61 newborn units in 2010, there were 4,948 beds (median = 62 [IQR 43–110]), 1,369 physicians (median = 22 [IQR 15–29]), 3,443 nurses (median = 52 [IQR 33–81]), and 170,159 inpatient discharges (median = 2,612 [IQR 1,436–3,804]). During 2008–2010, the median yearly investment for a single newborn unit was US$344,700 (IQR 166,100–585,800), median length of hospital stay for overall inpatient newborns 9.5 (IQR 8.2–10.8) days, median inpatient antimicrobial drug use rate 68.7% (IQR 49.8–87.0), and median nosocomial infection rate 3.2% (IQR1.7–5.4). For the common newborn diseases of pneumonia, sepsis, respiratory distress syndrome, and very low birth weight (<1,500 grams) infants, their lengths of hospital stay, daily costs, hospital costs, ratios of hospital cost to per-capita disposable income, and ratios of hospital cost to per-capita health expenditure, were all significantly different across regions (North China, Northeast China, East China, South Central China, Southwest China, and Northwest China). The survival rate of extremely low birth weight (ELBW) infants (Birth weight <1,000 grams) was 76.0% during 2008–2010 in the five hospitals where each unit had more than 20 admissions of ELBW infants in 2010; and the median hospital cost for a single hospital stay in ELBW infants was US$8,613 (IQR 8,153–9,216), which was 3.0 times (IQR 2.0–3.2) the average per-capita disposable income, or 63 times (IQR 40.3–72.1) the average per-capita health expenditure of local urban residents in 2011. Our national database provides baseline data on the status of advanced neonatal medicine in China, gathering valuable information for quality improvement, decision making, longitudinal studies and horizontal comparisons. [ABSTRACT FROM AUTHOR]

We have examined several emerging brominated flame retardants (BFRs) including 2-ethyl-1-hexyl- 2,3,4,5-tetrabromobenzoate (TBB), bis(2-ethylhexyl) tetrabromophthalate (TBPH), 1,2-bis(2,4,6- tribromophenoxy) ethane (BTBPE), 4,5,6,7-tetrabromo-1,1,3-trimethyl-3-(2,3,4,5-tetrabromophenyl)- indane (OBIND), and decabromodiphenyl ethane (DBDPE) in paired human maternal serum (n = 102) and breast milk (n = 105) collected in 2008-2009 in the Sherbrooke region in Canada. Three legacy BFRs were also included in the study for comparison: decabromobiphenyl (BB-209), 2,2',4,4',5,5'-hexabromobiphenyl (BB- 153), and 2,2',4,4',5,5'-hexabromodiphenyl ethers (BDE-153). TBB, BB-153, and BDE-153 had detection frequencies greater than 55% in both serum and milk samples. Their lipid weight (lw) adjusted median concentrations (ng g-1 lw) in serum and milk were 1.6 and 0.41 for TBB, 0.48 and 0.31 for BB-153, and 1.5 and 4.4 for BDE-153, respectively. The detection frequencies for the other BFRs measured in serum and milk were 16.7% and 32.4% for TBPH, 3.9% and 0.0% for BTBPE, 2.0% and 0.0% for BB-209, 9.8% and 1.0% for OBIND, and 5.9% and 8.6% for DBDPE. The ratio of TBB over the sum of TBB and TBPH (fTBB) in serum (0.23) was lower than that in milk (0.46), indicating TBB has a larger tendency than TBPH to be redistributed from blood to milk. Overall, these data confirm the presence of non-PBDE BFRs in humans, and the need to better understand their sources, routes of exposure, and potential human health effects. [ABSTRACT FROM AUTHOR]

Abstract: Five hexachloronorbornene-based flame retardants, Dechlorane Plus (DP), Dechlorane 602 (Dec 602), Dechlorane 603 (Dec 603), Dechlorane 604 (Dec 604) and hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO), were measured in human milk and maternal serum. Dec 602, Dec 603 and HCDBCO were detected in both sample matrices with detection frequencies over 60%. Dec 604 was not detected in serum and only detected in 4.8% of milk samples. DP was present in over 77–87% of serum and 40–50% of milk samples. DP levels found in this study were lower than those reported in two Chinese studies. The ratio of the two DP isomers found in human samples (f anti-DP =0.8) remained similar to the ratio reported in the DP technical mixture. Levels of Dec 602 and Dec 603 in serum were correlated. Levels of Dec 602 and HCBDCO were also correlated in serum samples as well as in milk samples. These biomonitoring results have provided baseline information about the presence of these flame retardants in nursing women in Canada, which can be used for estimating human exposure to these chemicals. [Copyright &y& Elsevier]

Objective: To compare the quality of the uterine scar with one or two layer closure after caesarean section by studying biomechanical and pathological properties of the scar. Methods: A randomized controlled trial performed on eight term pregnant ewes assigned into two groups during caesarean according to type of uterine closure: single-layer or double-layer. Hysterectomy was performed 8 months after caesarean delivery. Tensile strength of all scars and of unscarred myometrium was measured. Pathological properties of the scars were analyzed histologically. Results: The force required to reach the yield point was similar between scarred and unscarred myometrium ( p = 0.96), and between the scars in single-layer and double-layer closure groups ( p = 0.65). There was a significant increase in fibrosis width on the superficial part of the uterus in the double-layer closure group compared to the single-layer group ( p = 0.02). Conclusions: Double-layer uterine closure modified wound healing without significant change in biomechanical properties. [ABSTRACT FROM AUTHOR]

Prenatal exposure to persistent organic pollutants (POPs), widespread in North America, is associated with increased Attention Deficit/Hyperactivity Disorder (ADHD) symptoms and may be a modifiable risk for ADHD phenotypes. However, the effects of moderate exposure to POPs on task-based inhibitory control performance, related brain function, and ADHD-related symptoms remain unknown, limiting our ability to develop interventions targeting the neural impact of common levels of exposure. The goal of this study was to examine the association between prenatal POP exposure and inhibitory control performance, neural correlates of inhibitory control and ADHD-related symptoms. Prospective data was gathered in an observational study of Canadian mother-child dyads, with moderate exposure to POPs, including polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), as part of the GESTation and the Environment (GESTE) cohort in Sherbrooke, Quebec, Canada. The sample included 87 eligible children, 46 with maternal plasma samples, functional magnetic resonance imaging (fMRI) data of Simon task performance at 9–11 years, and parental report of clinical symptoms via the Behavioral Assessment System for Children 3 (BASC-3). Simon task performance was probed via drift diffusion modeling, and parameter estimates were related to POP exposure. Simon task-based fMRI data was modeled to examine the difference in incongruent vs congruent trials in regions of interest (ROIs) identified by meta analysis. Of the 46 participants with complete data, 29 were male, and mean age was 10.42 ± 0.55 years. Increased POP exposure was associated with reduced accuracy (e.g. PCB molar sum rate ratio = 0.95; 95% CI [0.90, 0.99]), drift rate (e.g. for PCB molar sum β = −0.42; 95% CI [-0.77, −0.07]), and task-related brain activity (e.g. in inferior frontal cortex for PCB molar sum β = −0.35; 95% CI [-0.69, −0.02]), and increased ADHD symptoms (e.g. hyperactivity PCB molar sum β = 2.35; 95%CI [0.17, 4.53]), supporting the possibility that prenatal exposure to POPs is a modifiable risk for ADHD phenotypes. We showed that exposure to POPs is related to task-based changes in neural activity in brain regions important for inhibitory control, suggesting a biological mechanism underlying previously documented associations between POPs and neurobehavioral deficits found in ADHD phenotypes. • Prenatal PCB and PBDE exposure relate to neurobehavioral deficits found in ADHD. • Increased PCB and PBDE exposure were associated with decrements in task performance. • Computational modeling revealed POP exposure slows drift rate on task performance. • PCB and PBDE levels were positively associated with increased ADHD symptoms. • PCB and PBDE exposure could be a modifiable risk factor for ADHD phenotypes. [ABSTRACT FROM AUTHOR]

Abstract: Background: In a group of 43 confined space welders dose–effect relationships had been identified for adverse neurological/neuropsychological functional effects in relation to manganese (Mn) in blood or air (cumulative exposure index). The welders’ exposure to Mn was unprotected and with poor ventilation, lasting on average 16.5 months. A follow-up examination 3.5 years later, after cessation of confined space welding, was carried out to re-assess the status of mood, movement/neuromotor and cognitive functions, and olfaction. Methods: In 2008, 26 welders (70% response rate) were retested using a similar methodology as at baseline (). A general linear model was used to estimate individual-specific endpoint differences over time. Mean age was 47 years, mean years of education 12.4, and mean total years of welding 16.9 years. Thirteen participants no longer welded. Results: At follow-up, mean blood Mn concentration had decreased from 10.0 to 8.4μg/L (p =0.002). Those still welding had higher blood Mn than those no longer welding (9.9μg/L vs. 6.8μg/L, p =0.002). Several domains of cognitive functioning improved substantially as shown by large effect sizes. Emotional disturbance improved only slightly clinically, but complaints of depression and anxiety persisted. Motor dexterity/tactile function and graphomotor tremor improved significantly, while psychomotor speed remained unchanged. The findings of the neurological examination (UPDRS) did not change compared to baseline, whereas rigidity, dominant postural hand tremor and body sway worsened. Olfactory test scores remained depressed. Conclusion: After 3.5 years of cessation of confined space welding, only cognitive function improved significantly, while olfactory, extrapyramidal, and mood disturbances remained constant or were exacerbated. This suggests differential intrinsic vulnerabilities of the brain loci involved with Mn exposure. As the Mn exposure of the Bay Bridge welders frequently exceeded the Cal-OSHA TLV of 0.2mgMn/m3 at baseline, a more stringent preventive measure is recommended for confined space welding. [Copyright &y& Elsevier]