Éditeur(s) : HAL CCSD
Résumé : International audience
BACKGROUND: Several studies suggest that exposure to organophosphate insecticides (OP) during pregnancy impairs neurodevelopment in children. OBJECTIVES: We evaluated associations between biomarkers of prenatal and postnatal OP exposure and cognitive function of 6-year-olds in a French longitudinal birth cohort. METHODS: In 2002-2006, the PELAGIE mother-child cohort enrolled pregnant women from Brittany. For a random subcohort, we measured nonspecific dialkylphosphate metabolites (DAP) of OP in one maternal urine sample, collected before 19 weeks' gestation, and in one urine sample collected from their 6-year-old children. Six subtests of the Wechsler Intelligence Scale for Children-4th edition (WISC-IV) was administered at 6 years to evaluate cognitive function (n=231). Linear regression models controlling for factors including maternal intelligence and the Home Observation for Measurement of the Environment score were used. RESULTS: WISC-IV scores were not significantly associated with prenatal or childhood total DAP metabolites. WISC verbal comprehension score was significantly higher in association with the highest maternal urinary concentrations of diethylphosphate metabolites (DE) (5.5; 95% CI: 0.8, 10.3 for extgreater 13.2 nmol/L versus extlessLOQ), while WISC working memory score was significantly lower in association with the highest urinary concentrations of DE metabolites at age 6 years (-3.6; 95% CI: -7.8, -0.6 for extgreater 11.1 nmol/L versus extlessLOD). CONCLUSION: This study found no evidence that prenatal OP exposure adversely affected cognitive function in 6-year-olds, perhaps because of the higher population's socioeconomic status than in previous studies though other causal and non-causal explanations are also possible. The negative association between WISC score and concurrent DE urinary concentrations requires replication by longitudinal studies investigating childhood OP exposure
Environmental Health Perspectives

hal-01207282
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01207282
DOI : 10.1289/ehp.1409472
PUBMED : 26394442

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Pyrethroids are insecticides frequently used in agriculture and in the home; exposure occurs through dietary and non-dietary pathways, including indoor and outdoor environmental contamination. Our objective was to study the potential determinants of pyrethroid metabolite concentrations measured in children's urine samples and in the dust of their homes. Specifically, we measured urinary metabolites from morning spot samples of 245 six-year- old children living in Brittany (France) in 2009-2012 and from dust vacuumed from the floor of their homes. Mothers reported home insecticide use, dietary habits, sociodemographic data; residential and school proximity to agricultural crops was assessed with spatialized data. The metabolites cis-DBCA, trans-DCCA, cisDCCA, 3-PBA, and F-PBA were detected in 84, 95, 64, 63, and 16% of the urine samples, respectively. Permethrin, cypermethrin, cyfluthrin, deltamethrin, and tetramethrin pyrethroids were detected in 100, 56, 9, 15, and 26% of the dust samples, respectively. Multiple regression analysis suggested diet plays a role in children's exposure, in particular, the food groups "pasta, rice or semolina" (for cis-DCCA and F-PBA), fruit (3-PBA), "breakfast cereals and whole grain bread" (cis-DBCA), and the global proportion of organic food in diet (for cis-DBCA, trans-DCCA). Children with a parent occupationally exposed to pesticides were about 3-times more likely to have higher urinary concentrations of 3-PBA (OR = 2.8, 95% CI [1.2; 6.5]). Dust content was correlated mainly with household insecticide use: higher mean concentrations of permethrin (beta = 0.8 [0.3; 1.3], in mu g/g) and an increased risk of a detectable level of cyfluthrin (OR = 4.7 [1.7; 12.9]) were observed in home dust, for indoor use of at least twice a year. Outdoor insecticide use at least once a year was associated with detection in dust of cypermethrin (OR = 3.0 [1.3; 6.7]) and tetramethrin (OR = 3.7 [1.6; 8.3]). Three positive and one negative correlations (out of 11) between urinary metabolite concentrations and home dust contents of their possible corresponding parent compounds were observed. The strength of this study lies in its concurrent use of biomarkers, environmental measurements, and potential sources of exposure. Its limitations include the use of a single urine sample and imprecise data about pyrethroid use in local agriculture.
ISSN: 0160-4120

hal-01560147
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01560147
DOI : 10.1016/j.envint.2017.04.007
PUBMED : 28453973

Éditeur(s) : HAL CCSD
Résumé : Background. Chlorine is the most widely used disinfectant for drinking water treatment. During treatment process, the natural organic matter present in water reacts with chlorine to form disinfection by-products (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs), the most occurring ones. Several identified DBPs were recognized carcinogens or fetotoxic in animals. We conducted two epidemiological studies to assess the health effects of human exposure to DBPs regarding cancer and reproduction. Association between THM exposure and the risk of bladder cancer: a pooled analysis of 3 European case-control studies. The study included 2381 cases and 3086 controls from 3 case-control studies (France, Finland, Spain). Environmental exposure to SPCs was measured by THM concentrations in water distribution systems, retrospectively estimated through the 40-year exposure window. Information about water uses (tap water ingestion, showers and baths, swimming-pool attendance) was available. An increased risk of bladder cancer was observed, in men only, with increasing THM concentrations in water systems and duration of exposure to chlorinated surface water. No association was observed with exposure through tap water ingestion. Exposure through showers, baths and swimming in pools (available in Spanish study only) was associated with an increased risk of bladder cancer. Three North-American case-control studies were joined to the three European ones into a meta-regression. No specific dose-response relationship was identified for European studies. A global dose-response relationship was consequently estimated, including 4351 cases and 7055 controls. Association between DBP exposure and the risk of preterm birth and Intra-Uterine Growth Retardation (IUGR). This study was conducted within the PELAGIE cohort (3400 pregnant women included in early pregnancy, in Brittany, France, between 2002 and 2006). Exposure during pregnancy was measured by 2 indicators: THM concentrations in water distribution systems and a biomarker of HAA ingestion, the level of trichloroacetic acid in maternal urine at inclusion (in a nested case-control study). The regulatory database SISE-Eaux was used to estimate THMs concentrations in the water distribution systems. Water uses during pregnancy (ingested tap water, swimming-pool attendance, showers and bath frequencies and duration) were collected with questionnaires. Our results suggest an association between prenatal exposure to DBPs (THMs and HAAs) and the risk of IUGR. No association was found with the risk of preterm birth.
Contexte. La chloration est le traitement le plus utilisé pour désinfecter l’eau distribuée à la population. Lors du traitement, des sous-produits de chloration (SPCs) se forment par réaction de la matière organique naturelle présente dans l’eau avec le chlore. Les produits les plus présents sont les trihalométhanes (THMs), les acides haloacétiques (HAAs). Des études toxicologiques (animales et in vitro) ont montré la génotoxicité et/ou carcinogénicité et la reprotoxicité de certains SPCs. Nous avons mené deux études évaluant les effets sur la santé humaine de l’exposition aux SPCs, dans le domaine du cancer et de la reproduction. Association entre exposition aux THMs et risque de cancer de la vessie : une analyse poolée de 3 études cas-témoins européennes. Cette analyse a inclus 2381 cas et 3086 témoins issus de 3 études cas-témoins (France, Espagne, Finlande). L’exposition environnementale aux SPCs a été mesurée par la concentration en THMs estimée rétrospectivement dans les réseaux de distribution d’eau au cours des 40 années de la fenêtre d’exposition. Les usages de l’eau connus sont l’ingestion, les douches et les bains, la fréquentation de piscine (étude espagnole seulement). Une relation croissante a été observée entre le niveau environnemental de THMs, la durée d’exposition à une eau de surface chlorée et le risque de cancer de la vessie, chez les hommes uniquement. Aucune association n’a été observée avec l’exposition via l’ingestion d’eau du robinet. L’exposition via les douches, les bains et la piscine est apparue liée au risque de cancer de la vessie. Trois études cas-témoins nord-américaines ont été intégrées dans une méta-régression. Aucune spécificité européenne de la relation dose-réponse n’a été mise en évidence. Une relation dose-réponse globale incluant 4351 cas et 7055 témoins a été estimée. Association entre exposition aux SPCs et risque de prématurité et de retard de croissance intra-utérin (RCIU). Cette étude est issue de la cohorte bretonne Pélagie (3400 femmes enceintes recrutées en début de grossesse entre 2002 et 2006). L’exposition pendant la grossesse a été mesurée à l’aide de 2 indicateurs : la concentration en THMs de l’eau distribuée dans les réseaux et le dosage d’un biomarqueur urinaire (acide trichloroacétique) pour un sous-échantillon de femmes (étude cas-témoins nichée). Les niveaux dans les réseaux proviennent de la base de données réglementaire SISE-Eaux. Les usages de l’eau du robinet par les femmes pendant la grossesse ont été collectés par questionnaire (quantité d’eau du robinet bue, fréquentation de la piscine, fréquence et durée des douches et des bains). Notre étude suggère une association entre l’exposition prénatale aux SPCs et le risque de RCIU. Aucune association n’est observée avec le risque de prématurité.
https://tel.archives-ouvertes.fr/tel-00927735

Droits : info:eu-repo/semantics/OpenAccess
NNT : 2013REN1B008
tel-00927735
https://tel.archives-ouvertes.fr/tel-00927735
https://tel.archives-ouvertes.fr/tel-00927735/document
https://tel.archives-ouvertes.fr/tel-00927735/file/COSTET_DEIBER_Nathalie4.pdf

Éditeur(s) : HAL CCSD BMJ Publishing Group
Résumé : International audience
Objective The potential impact of environmental exposure to pyrethroid insecticides on child neurodevelopment has only just started to receive attention despite their widespread use. We investigated the associations between prenatal and childhood exposure to pyrethroid insecticides and behavioural skills in 6-year-olds. Methods The PELAGIE cohort enrolled 3421 pregnant women from Brittany, France between 2002 and 2006. 428 mothers were randomly selected for the study when their children turned 6, and 287 (67%) agreed to participate. Children's behaviour was assessed using the Strengths and Difficulties Questionnaire (SDQ). Three subscales (prosocial behaviour, internalising disorders and externalising disorders) were considered. Five pyrethroid metabolites were measured in maternal and child urine samples collected between 6 and 19 gestational weeks and at 6 years of age, respectively. Logistic regression and reverse-scale Cox regression models were used to estimate the associations between SDQ scores and urinary pyrethroid metabolite concentrations, adjusting for organophosphate metabolite concentrations and potential confounders. Results Increased prenatal cis-3-(2,2-dichlorovinyl)-2,2dimethylcyclopropane carboxylic acid (DCCA) concentrations were associated with internalising difficulties (Cox p value=0.05). For childhood 3phenoxybenzoic acid (PBA) concentrations, a positive association was observed with externalising difficulties (Cox p value=0.04) and high ORs were found for abnormal or borderline social behaviour (OR 2.93, 95% CI 1.27 to 6.78, and OR 1.91, 95% CI 0.80 to 4.57, for the intermediate and highest metabolite categories, respectively). High childhood trans-DCCA concentrations were associated with reduced externalising disorders (Cox p value=0.03). Conclusions The present study suggests that exposure to certain pyrethroids, at environmental levels, may negatively affect neurobehavioral development by 6 years of age.
ISSN: 1351-0711

hal-01519255
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01519255
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01519255/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01519255/file/Behavioural%20disorders%20in%206-year-old%20children_JFViel_HAL.pdf
DOI : 10.1136/oemed-2016-104035

Éditeur(s) : HAL CCSD National Institute of Environmental Health Sciences
Résumé : International audience
Background: Glycol ethers (GE) are widely used organic solvents. Despite the potential neurotoxicity of several families of organic solvents, little is known about the impact of GE on the neurodevelopment of infants and children. Objectives: We investigated the relation between urinary concentrations of GE metabolites in pregnant women and neurocognitive abilities in their 6-year-old children in the PELAGIE mother-child cohort. Methods: Five GE metabolites were measured in first morning void urine samples of 204 French pregnant women in early pregnancy (<19 weeks of gestation). Psychologists assessed the neurocognitive abilities of their 6-year-old children with the Wechsler Intelligence Scale for Children IV (WISC) and the Developmental Neuropsychological Assessment (NEPSY). We analyzed the results with linear (WISC) and Poisson regression models (NEPSY), adjusted for potential confounders, including child's stimulation at home. Results: GE metabolites were detected in 90-100% of maternal urine samples. The WISC Verbal Comprehension score was significantly lower for children with the highest tertile of urinary phenoxyacetic acid (PhAA) [beta (third vs. first tertile)=-6.53; 95% CI: -11.44, -1.62]. Similarly, the NEPSY Design Copying subtest score was lower in those with the highest tertile of urinary ethoxyacetic acid (EAA) [beta (third vs. first tertile)=-0.11; 95% CI: -0.21, 0.00]. The other GE metabolites we studied were not significantly associated with WISC or NEPSY scores. Conclusions: Prenatal urine concentrations of two GE metabolites were associated with lower WISC Verbal Comprehension Index scores and NEPSY Design Copying subscale scores, respectively, at age 6 years. PhAA is the primary metabolite of 2-phenoxyethanol (EGPhE), which is commonly found in cosmetics, and precursors of EAA are frequently used in cleaning agents. Additional research is needed to confirm our findings and further explore potential effects of prenatal GE exposures on neurocognitive performance in children.
ISSN: 0091-6765

hal-01519256
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01519256
DOI : 10.1289/EHP39
PUBMED : 27740510

Éditeur(s) : HAL CCSD National Institute of Environmental Health Sciences
Résumé : International audience
BACKGROUND: Glycol ethers are present in a wide range of occupational and domestic products. Animal studies have suggested that some of them may affect ovarian function. OBJECTIVE: To study the relation between women's exposure to glycol ethers and time to pregnancy. METHODS: Urine from randomly selected women in the PELAGIE mother-child cohort who had samples collected before 19 weeks of gestation was tested to measure eight glycol ether metabolites by chromatography coupled to mass spectrometry. Time to pregnancy was collected at the beginning of the pregnancy by asking women how many months they took to conceive. Associations between metabolite levels and time to pregnancy were estimated in 519 women with complete data using discrete-time Cox proportional hazards models to adjust for potential confounders. RESULTS: Glycol ether metabolites were detected in 6% (for ethoxyacetic acid) to 93% (for phenoxyacetic and butoxyacetic acids) of urine samples. Phenoxyacetic acid was the only metabolite with a statistically significant association with longer time to pregnancy (fecundability OR 0.82; 95% CI: 0.63, 1.06 for the second and third quartile combined; fecundability OR 0.70; 95% CI: 0.52, 0.95 for a fourth-quartile (≥1.38 mg/L) vs. first-quartile concentration (<0.14 mg/L)). This association remained stable after multiple sensitivity analyses. CONCLUSION: Phenoxyacetic acid, which was present in most of the urine samples tested in our study, was associated with increased time to pregnancy. This metabolite and its main parent compound, 2-phenoxyethanol, are plausible causes of decreased fecundability, but may also be surrogates for potential co-exposures frequently present in cosmetics.
ISSN: 0091-6765

hal-00866023
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00866023
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00866023/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-00866023/file/Urinary_Glycol_Ether-accepted.pdf
DOI : 10.1289/ehp.1206103

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Background Experimental evidence suggests that developmental exposure to persistent organic pollutants (POP) and to some non persistent pesticides may disrupt metabolic regulation of glucose metabolism and insulin secretion, and thereby contribute to the current epidemic of obesity and metabolic disorders. Quasi-experimental situations of undernutrition in utero have provided some information. However, the evidence in humans concerning the role of the prenatal environment in these disorders is contradictory, and little is known about long-term outcomes, such as type 2 diabetes, of prenatal exposure. Objectives Our aim was to evaluate the effects of prenatal exposure to POP and organophosphate pesticides on fetal markers of glucose metabolism in a sample of newborns from the Pelagie mother–child cohort in Brittany (France). Methods Dialkylphosphate (DAP) metabolites of organophosphate pesticides were measured in maternal urine collected at the beginning of pregnancy. Cord blood was assayed for polychlorinated biphenyl congener 153 (PCB153), p,p′-dichlorodiphenyl dichloroethene (DDE) and other POP. Insulin and adiponectin were determined in cord blood serum (n=268). Results A decrease in adiponectin and insulin levels was observed with increasing levels of DDE, but only in girls and not boys. Adiponectin levels were not related to the concentrations of other POP or DAP metabolites. Decreasing insulin levels were observed with increasing PCB153 concentrations. Insulin levels increased with DAP urinary levels. Additional adjustment for BMI z-score at birth modified some of these relations. Conclusions Our observations bring support for a potential role of organophosphate pesticides and POP in alterations to glucose metabolism observable at birth
ISSN: 0013-9351

hal-01259218
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01259218
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01259218/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01259218/file/Prenatal%20exposure%20to%20persistent%20organic%20pollutants%20and%20organophosphate%20pesticides%2C%20and%20markers%20of%20glucose%20metabolism%20at%20birth.pdf
DOI : 10.1016/j.envres.2016.01.005

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
We recover the Holocene earthquake history of seven seismogenic normal faults in the Fucino system, central Italy. We collected 800 samples from the well-preserved limestone scarps of the faults and modeled their 36Cl concentrations to derive their seismic exhumation history. We found that > 30 large earthquakes broke the faults in synchrony over the last 12 ka. The seven faults released strain at the same periods of time, 12-9 ka, 5-3 ka, and 1.5-1 ka. On all faults, the strain accumulation and release occurred in 3-6 ka supercycles, each included a 3-5 ka phase of slow (≤ 0.5-2 mm/yr) strain accumulation in relative quiescence, followed by a cluster of three to four large earthquakes or earthquake sequences that released most of the strain in < 1-2 ka. The large earthquakes repeated every 0.5 ± 0.3 ka during the paroxysmal phases and every 4.3 ± 0.9 ka between those phases. Earthquakes on the northern faults produced twice larger surface slips (~ 2 m) and had larger magnitudes (Mw 6.2-6.7) than those on the southern faults. On most faults, the relative strain level was found to control the amount of slip and the time of occurrence of the next large earthquake. Faults entered a phase of clustered activity once they had reached a specific relative strain threshold. The Tre Monti fault is identified as the most prone to break over the next century. Our data document earthquake synchrony and clustering at a broader space and time scale than has been reported to date.
ISSN: 0148-0227

hal-00903460
https://hal.archives-ouvertes.fr/hal-00903460
DOI : 10.1002/jgrb.50299

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Pyrethroid insecticides are widely used in agriculture and in homes. Despite the neurotoxicity of these insecticides at high doses, few studies have examined whether lower-level exposures could adversely affect children's neurodevelopment. The PELAGIE cohort included 3421 pregnant women from Brittany, France between 2002 and 2006. When their children reached their sixth birthday, 428 mothers from the cohort were randomly selected, successfully contacted and found eligible. A total of 287 (67%) mothers agreed to participate with their children in the neuropsychological follow-up. Two cognitive domains were assessed by the Wechsler Intelligence Scale for Children: verbal comprehension and working memory. Five pyrethroid and two organophosphate insecticide metabolites were measured in maternal and child first-void urine samples collected between 6 and 19 gestational weeks and at 6 years of age, respectively. Linear regression models were used to estimate associations between cognitive scores and urinary pyrethroid metabolite concentrations, adjusting for organophosphate metabolite concentrations and potential confounders. Maternal prenatal pyrethroid metabolite concentrations were not consistently associated with any children's cognitive scores. By contrast, childhood 3-PBA and cis-DBCA concentrations were both negatively associated with verbal comprehension scores (P-trend = 0.04 and P-trend < 0.01, respectively) and with working memory scores (P-trend = 0.05 and P-trend < 0.01, respectively). No associations were observed for the three other childhood pyrethroid metabolite concentrations (4-F-3-PBA, cis-DCCA, and trans-DCCA). Low-level childhood exposures to deltamethrin (as cis-DBCA is its principal and selective metabolite), in particular, and to pyrethroid insecticides, in general (as reflected in levels of the 3-PBA metabolite) may negatively affect neurocognitive development by 6 years of age. Whatever their etiology, these cognitive deficits may be of importance educationally, because cognitive impairments in children interfere with learning and social development. Potential causes that can be prevented are of paramount public health importance
ISSN: 0160-4120

hal-01162374
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01162374
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01162374/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01162374/file/Pyrethroid%20insecticide%20exposure.pdf
DOI : 10.1016/j.envint.2015.05.009

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
BACKGROUND: Evidence of human sexual transmission during Zika virus emergence is a matter of concern, particularly in procreation, but to date, kinetics of seminal shedding and the effects of infection on human reproductive function have not been described. To investigate the effects of Zika virus infection on semen and clearance of Zika virus from semen and body fluids, we aimed to study a cohort of Zika virus-infected men. METHODS: This prospective observational study recruited men presenting with acute Zika virus infection at Pointe-à-Pitre University Hospital in Guadeloupe, French Caribbean, where a Zika virus outbreak occurred between April and November, 2016. Blood, urine, and semen were collected at days 7, 11, 20, 30, 60, 90, and 120 after symptom onset, and semen characteristics, such as total sperm count, sperm motility, vitality, and morphology, and reproductive hormone concentrations, such as testosterone, inhibin, follicle-stimulating hormone, and luteinising hormone, were assessed. At days 7, 11, and 20, semen was processed to isolate motile spermatozoa. Zika virus RNA was detected by RT-PCR using whole blood, serum, urine, seminal plasma, semen cells, and motile spermatozoa fractions. Zika virus was isolated from different sperm fractions on Vero E6 cultures. FINDINGS: 15 male volunteers (mean age 35 years [SD 5; range 25-44) with acute Zika virus infection and positive Zika virus RNA detection in blood or urine were enrolled. Total sperm count was decreased from median 119 × 10(6) spermatozoa (IQR 22-234) at day 7 to 45·2 × 10(6) (16·5-89·6) at day 30 and 70 × 10(6) (28·5-81·4) at day 60, respectively, after Zika virus infection. Inhibin values increased from 93·5 pg/mL (IQR 55-162) at day 7 to 150 pg/mL (78-209) at day 120 when total sperm count recovered. In motile spermatozoa obtained after density gradient separation, Zika virus RNA was found in three of 14 patients at day 7, four of 15 at day 11, and four of 15 at day 20, and replication-competent virus was found in the tested patient. Seminal shedding kinetics seemed heterogeneous among patients. Whole blood was the fluid most frequently positive for Zika virus RNA (62 of 92 samples) and three patients remained positive at day 120. INTERPRETATION: Semen alterations early after acute Zika virus infection might affect fertility and could be explained by virus effects on the testis and epididymis. Frequency of shedding and high viral load in semen, together with the presence of replicative virus in a motile spermatozoa fraction, can lead to Zika virus transmission during sexual contact and assisted reproduction procedures. Whole blood seems to be the best specimen for Zika virus RNA detection, diagnosis, and follow-up. FUNDING: Agence de la Biomédecine/Agence Régionale de Santé de la Guadeloupe/Inserm-REACTing.
ISSN: 0140-6736

hal-01647078
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01647078
DOI : 10.1016/S1473-3099(17)30444-9
PUBMED : 28838639

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
We analyse the fluid flow regime within sediments on the Eastern levee of the modern Mississippi Canyon using 3D seismic data and downhole logging data acquired at Sites U1322 and U1324 during the 2005 Integrated Ocean Drilling Program (IODP) Expedition 308 in the Gulf of Mexico. Sulphate and methane concentrations in pore water show that sulphate-methane transition zone, at 74 and 94 m below seafloor, are amongst the deepest ever found in a sedimentary basin. This is in part due to a basinward fluid flow in a buried turbiditic channel (Blue Unit, 1000 mbsf), which separates sedimentary compartments located below and above this unit, preventing normal upward methane flux to the seafloor. Overpressure in the lower compartment leads to episodic and focused fluid migration through deep conduits that bypass the upper compartment, forming mud volcanoes at the seabed. This may also favour seawater circulation and we interpret the deep sulphate-methane transition zones as a result of high downward sulphate fluxes coming from seawater that are about 5-10 times above those measured in other basins. The results show that geochemical reactions within shallow sediments are dominated by seawater downwelling in the Mars-Ursa basin, compared to other basins in which the upward fluid flux is controlling methane-related reactions. This has implications for the occurrence of gas hydrates in the subsurface and is evidence of the active connection between buried sediments and the water column.
ISSN: 1468-8115

hal-00590501
https://hal.archives-ouvertes.fr/hal-00590501
DOI : 10.1111/j.1468-8123.2010.00304.x

Éditeur(s) : HAL CCSD Lippincott, Williams & Wilkins
Résumé : International audience
BACKGROUND: Exposure to solvents during pregnancy has long been suspected of increasing the risk of congenital malformations, but the lack of prospective assessment of specific solvent exposures has prevented definitive conclusions. METHODS: In a cohort of 3421 pregnant women in Brittany (2002-2006), occupational solvent exposure was assessed from self-report during pregnancy and from a job-exposure matrix. Congenital malformations were diagnosed among live births, stillbirths, and medical pregnancy terminations. In a nested case-control sample, urinary concentrations of 10 metabolites of glycol ethers and chlorinated solvents were measured in maternal samples collected during early pregnancy (n = 79 cases, 580 controls). RESULTS: Dose-response trends linked occupational solvent exposure (both self-reported and based on a job-exposure matrix) to the risk of major congenital malformations--especially oral clefts, urinary tract malformations, and male genital malformations. Detection of some glycol ether metabolites and trichloroacetic acid in urine was associated with increased risks of oral clefts and of urinary tract and limb defects. CONCLUSIONS: This prospective study, using three independent methods of exposure assessment, suggests several specific associations between solvent exposure during early pregnancy and congenital malformations. Results based on urinary biomarkers, although limited by small numbers, identify work situations that require further investigation.
ISSN: 1044-3983

hal-00875918
https://hal.archives-ouvertes.fr/hal-00875918
DOI : 10.1097/EDE.0b013e31826c2bd8
PUBMED : 23007043