Serum persistent organic pollutants and diminished ovarian reserve: a single-exposure and mixture exposure approach from a French case-control study

STUDY QUESTION

Are persistent organic pollutants (POPs) associated with a diminished ovarian reserve (DOR) in women of reproductive age?

SUMMARY ANSWER

Amongst 17 POPs detected in over 20% of serum samples, only p,p'-DDE was significantly associated with an increased risk of DOR, and β-hexachlorocyclohexane (β-HCH) was significantly associated with a decreased risk of DOR whilst mixture analyses yielded non-significant associations and did not detect any interactions between POPs.

WHAT IS KNOWN ALREADY

Animal studies have shown that several POPs can alter folliculogenesis and increase follicle depletion. However, only a few studies have been conducted in humans, with small sample sizes and inconsistent results.

STUDY DESIGN, SIZE, DURATION

Our study included 138 cases and 151 controls from the AROPE case-control study. Study participants were women between 18 and 40 years of age recruited amongst couples consulting for infertility in four fertility centres in western France between 2016 and 2020.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cases of DOR were defined as women with anti-Müllerian hormone (AMH) levels ≤1.1 ng/ml and/or antral follicle count (AFC) <7, and controls were women with AMH levels between 1.1 and 5 ng/ml and AFC ≥ 7, without genital malformations and with a menstrual cycle length between 26 and 35 days. A total of 43 POPs (including 15 organochlorine pesticides, 17 polychlorinated biphenyls, and 9 polybromodiphenylethers) were measured in the serum at inclusion into the study. We conducted logistic regression adjusted for potential confounders using a directed acyclic graph to study the effect of each POP on DOR as single exposures, and used Bayesian kernel machine regression (BKMR) to measure the mixture effect of POPs on DOR.

MAIN RESULTS AND THE ROLE OF CHANCE

Of the 43 POPs, 17 were detected in over 20% of the serum samples. In the single-exposure multivariate logistic regressions, p,p'-DDE (median 165.0 IQR 161.0 ng/l in controls) as a continuous exposure was significantly associated with an increased risk of DOR (odds ratio (OR) 1.39, 95% CI 1.10-1.77) and non-significantly associated with an increased risk of DOR for the second and third terciles (OR 1.46, 95% CI 0.74-2.87, and OR 1.72, 95% CI 0.88-3.37, respectively). β-HCH (median 24.2 IQR 21.5 ng/l in controls) was significantly associated with a decreased risk of DOR when β-HCH was treated as a continuous exposure (OR 0.63, 95% CI 0.44-0.89) and for the third tercile of exposure (OR 0.43, 95% CI 0.21-0.84) and non-significantly associated with a decreased risk of DOR for the second tercile (OR 0.77, 95% CI 0.42-1.42). All sensitivity analyses confirmed our results. BKMR showed similar associations for single exposures but found no significant associations for the total mixture effect. In addition, the BKMR results did not suggest any interactions between POPs.

LIMITATIONS, REASONS FOR CAUTION

Controls were recruited amongst infertile couples and thus may not be representative of all women of reproductive age. However, their POP concentrations were in the same range as in the general French population.

WIDER IMPLICATIONS OF THE FINDINGS

This study is the first to examine the associations between serum POPs and DOR. The well-recognized anti-androgenic properties of p,p'-DDE and estrogenic properties of β-HCH could explain these associations of opposite direction. If these results are replicated elsewhere, this could have an impact on fertility prevention messages and help in understanding the impact of POPs on the female reproductive system.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the Fondation de France (grant numbers 2014-50537 and 00110196) and the French Biomedicine Agency (2016). None of the authors have any conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Infant neurodevelopment and behavior in Guadeloupe after lead exposure and Zika maternal infection during pregnancy

BACKGROUND

Prenatal lead exposure is known to have neurotoxic effects on the developing fetus, while some viral infections may have a tropism for the central nervous system. Our objective was to study whether the effects of prenatal lead exposure on infant development and behaviors at 18 months of age are modified by the occurrence of a maternal infection to Zika virus (ZIKV) during pregnancy.

METHODS

During the ZIKV epidemic in Guadeloupe in 2016 a cohort of pregnant women was set up. Blood samples (pregnancy, childbirth and cord) (n = 297) enabled us to measure blood lead levels aimed to determine prenatal lead exposure and the likelihood of maternal infection during pregnancy (ZIKV status + vs -). The 18 months "Ages and Stages Questionnaire" (ASQ) was used to generate scores for global development, fine and gross motor skills, communication, problem solving, and personal-social skills. The questions from a longitudinal cohort study conducted in Canada (Québec) were used to generate hyperactivity, opposition, inattention and physical aggression scores. Associations were tested by multivariate linear regressions.

RESULTS

Prenatal lead exposure was associated with delays in neurodevelopment at 18 months, reflected by lower scores in ASQ totals, and in the fine motor and problem-solving domains. Some of these associations appeared to be sex-specific, observed almost exclusively in boys (ASQ total, fine motor and personal-social scores). Prenatal lead exposure was not associated with behavioral scores. ZIKV infection during pregnancy was associated with a lower fine motor ASQ score, and higher scores for hyperactivity, opposition and physical aggression. Significant interaction between prenatal lead exposure and ZIKV status was observed with a lower personal-social score in ZIKV (-) only, and for hyperactivity and inattention scores, though some of these interactions (ASQ personal-social score, inattention score) were no longer significant when children with microcephaly were excluded from the analyses.

DISCUSSION/CONCLUSION

Our study confirms previous findings of associations between prenatal exposure to lead at low levels and adverse neurodevelopmental outcomes during infancy and the particular vulnerability of boys. It suggests associations between ZIKV infection during pregnancy and adverse effects on a number of neurodevelopmental functions (fine motor function) and behaviors (opposition, hyperactivity), that need to be confirmed at later age. There is no strong evidence of interaction between ZIKV infection and lead exposure but both prenatal risk factors may affect fine motor function.

Simultaneous exposure to both Zika virus and household insecticides during pregnancy, and fetal growth and infant developmental behavior outcomes at 18 months, in Guadeloupe

BACKGROUND

Perinatal infection with Zika virus (ZIKV) could result in adverse growth, developmental and behavioral outcomes, while insecticides used to control mosquitoes are neurotoxic.

OBJECTIVES

We aim to study the role played by exposure during pregnancy to both ZIKV and household insecticides in newborn health, development and behavior at age of 18 months.

METHODS

Maternal and cord blood samples from a cohort of pregnant women (created during Guadeloupe's Zika epidemic of 2016) were used to identify ZIKV infection during pregnancy. A self-administered questionnaire at birth documented prenatal household use of insecticides. Birth weight and head circumference were collected from maternity records (n = 708). Infant development and behaviors were documented at 18 months of age through the Ages and Stages Questionnaire and the Quebec Longitudinal Study of Child Development (n = 409). Logistic and linear regression models were performed, taking into account confounding factors.

RESULTS

Use of household insecticides was associated with smaller head circumference and lower birth weight among newborns from mothers not exposed to ZIKV: 0.3 cm (95% CI: 0.6, 0) and -82 g (95% CI: 165, 0), respectively. Similar decreases were observed with ZIKV exposure among mothers not reporting household insecticides use, and with presence of both exposures. The combined presence of ZIKV exposure and insecticide use was associated with lower ASQ fine motor scores (-3.9; 95% CI: 7.3, -0.4), and higher hyperactivity scores (0.8; 95% CI: 0.0, 1.5), compared to no exposure to either. A higher opposition score was observed in association with ZIKV exposure among non-users of insecticide (0.6; 95% CI: 0.0, 1.2).

CONCLUSION

Adverse neurodevelopmental outcomes at 18 months of age were observed with prenatal ZIKV exposure, and with higher magnitude when mothers reported use of household insecticides. At birth, rates of adverse fetal growth were however similar for the combined presence of exposure and either of the exposures.

Molybdenum-Iodine Cluster Loaded Polymeric Nanoparticles Allowing a Coupled Therapeutic Action with Low Side Toxicity for Treatment of Ovarian Cancer

The ability of cancer cells to develop resistance to anti-cancer drugs, known as multidrug resistance, remains a major cause of tumor recurrence and cancer metastasis. This work explores the double mechanism of toxicity of (D, L-lactide-co-glycolide) acid (PLGA) nanoparticles encapsulating a molybdenum cluster compound, namely Cs₂[{Mo₆I₈}(OOCC₂F₅)₆] (CMIF). Hemocompatibility and biocompatibility assays show the safe potential of CMIF loaded nanoparticles (CNPs) as delivery systems intended for tumor targeting for PDT of ovarian cancer with a slight hemolytic activity and a lack of toxicity up to 50 µM CMIF concentration. Cellular uptake shows a preferential uptake of CNPs in lysosomes, which is not interfering with CMIF activity. The double mechanism of CNPs consists in a production of ROS and a DNA damage activity, from 5 µM and 0.5 µM respectively (CMIF concentration). The cellular death mechanism comprises 80% of necrosis and 20% of direct apoptosis by direct DNA damages. This work confirms CMIF loaded PLGA nanoparticles as an efficient and relevant delivery system for PDT.

Exposure of pregnant women to organophosphate insecticides and child motor inhibition at the age of 10-12 years evaluated by fMRI

BACKGROUND

Organophosphate pesticides (OP) are widely used for both agricultural and domestic purposes. Epidemiological studies suggest neurotoxicity in children after exposure to organophosphates pesticides (OP) at low levels but possible mechanism is still unclear.

OBJECTIVES

We aimed at investigating the effects of prenatal exposure to OPs on inhibitory control of 10-12 year-old-children assessed by a motor inhibition task during functional magnetic resonance imaging (fMRI).

METHODS

Ninety-five children from the PELAGIE cohort (Brittany-France, from 2002) underwent a fMRI examination during which inhibition was assessed by a Go/No-Go task. Task performance was assessed by average response latency, commission rate and composite performance score (PS). Whole brain activation was estimated by modeling the hemodynamic response related to inhibition demand and successful inhibition. OP exposure was assessed by measuring six dialkylphosphate (DAP) metabolites in the urine of women in early pregnancy (<19 WG). Concentrations were summed to obtain overall levels of diethylphosphate (DE), dimethylphosphate (DM) and total non-specific metabolites (DAP), standardized to homogenize sampling conditions and categorized into levels of exposure: low (reference), moderate or high. Regression models were adjusted for potential cofounders considered by restriction and statistical criteria.

RESULTS

Moderate levels of DAP were associated with a decreased commission rate (β = -6.65%, p = 0.04), indicating improved performance. Increasing levels of DM and DE were associated with decreased brain activity in the left inferior and bilateral superior frontal regions during successful inhibition. We did not observe any differential activation related to inhibitory demands.

DISCUSSION

These results suggest that prenatal OPs may be associated with altered pattern of brain activity in regions related to inhibition among children and need to be confirmed by additional studies.

Association between exposure to persistent organic pollutants and mercury, and glucose metabolism in two Canadian Indigenous populations

BACKGROUND

The body burden of metals and persistent organic pollutants (POPs) is particularly high in populations that rely on fish and other marine species for sustenance. This exposure has been associated with an increased risk of type 2 diabetes, but results remain contrasted.

OBJECTIVE

We studied this association in two Indigenous populations of northern Québec (Canada) with markedly different prevalences of diabetes and levels of exposure to POPs and mercury.

METHODS

As part of health surveys conducted in 2004-2009, diabetes prevalence and glucose metabolism (glucose, insulin, HOMA-IR, HOMA-B) in non-diabetic fasting adults were assessed using similar protocols in two populations: Inuit from Nunavik (n = 877) and Cree from Eeyou Istchee territory (n = 780). Blood mercury, plasma polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides/metabolites and polybrominated diphenylethers (PBDEs) levels were measured in samples collected at the time of examination. Logistic and linear regressions and restricted cubic splines analyses were conducted adjusting for sex, age, waist circumference, smoking and omega-3 fatty acid content in plasma phospholipids.

RESULTS

Diabetes prevalence was higher in Cree (20%) than in Inuit (7%), whereas environmental exposure was 2 to 3-fold greater in Inuit than in Cree participants. In the range of exposure common to the two populations, we observed similar linear increases in the risk of diabetes with increasing contaminant exposure. Among Cree participants, fasting glucose was positively associated with plasma PBDE level, and HOMA-B negatively associated with concentrations of ∑PCBs, dichlorodiphenyldichloroethylene, PBDEs and ∑OC pesticides. Among Inuit participants, a trend towards reduced insulin secretion was observed in association with most contaminants, but the relation was nonlinear (greater reduction at intermediate levels of exposure). A significant increase in fasting glucose levels was observed at elevated blood mercury levels (>16 μg/L).

CONCLUSION

The observed association between POPs exposure and diabetes risk in the two populations studied should be confirmed using prospective design. Our results suggest the need for additional research on the physiopathological process through which POPs exposure may induce type 2 diabetes in these Indigenous populations.

Elastic Softness of Hybrid Lead Halide Perovskites

Much recent attention has been devoted towards unraveling the microscopic optoelectronic properties of hybrid organic-inorganic perovskites. Here we investigate by coherent inelastic neutron scattering spectroscopy and Brillouin light scattering, low frequency acoustic phonons in four different hybrid perovskite single crystals: MAPbBr_{3}, FAPbBr_{3}, MAPbI_{3}, and α-FAPbI_{3} (MA: methylammonium, FA: formamidinium). We report a complete set of elastic constants characterized by a very soft shear modulus C_{44}. Further, a tendency towards an incipient ferroelastic transition is observed in FAPbBr_{3}. We observe a systematic lower sound group velocity in the technologically important iodide-based compounds compared to the bromide-based ones. The findings suggest that low thermal conductivity and hot phonon bottleneck phenomena are expected to be enhanced by low elastic stiffness, particularly in the case of the ultrasoft α-FAPbI_{3}.

How a dc Electric Field Drives Mott Insulators Out of Equilibrium

Out of equilibrium phenomena are a major issue of modern physics. In particular, correlated materials such as Mott insulators experience fascinating long-lived exotic states under a strong electric field. Yet, the origin of their destabilization by the electric field is not elucidated. Here we present a comprehensive study of the electrical response of canonical Mott insulators GaM_{4}Q_{8} (M=V, Nb, Ta, Mo; Q=S, Se) in the context of a microscopic theory of electrical breakdown where in-gap states allow for a description in terms of a two-temperature model. Our results show how the nonlinearities and the resistive transition originate from a massive creation of hot electrons under an electric field. These results give new insights for the control of the long-lived states reached under an electric field in these systems which has recently open the way to new functionalities used in neuromorphic applications.

Efficient active waveguiding properties of Mo6 nano-cluster-doped polymer nanotubes

We investigate 1D nanostructures based on a Mo6@SU8 hybrid nanocomposite in which photoluminescent Mo6 clusters are embedded in the photosensitive SU8 resist. Tens of micrometers long Mo6@SU8-based tubular nanostructures were fabricated by the wetting template method, enabling the control of the inner and outer diameter to about 190 nm and 240 nm respectively, as supported by structural and optical characterizations. The image plane optical study of these nanotubes under optical pumping highlights the efficient waveguiding phenomenon of the red luminescence emitted by the clusters. Moreover, the wave vector distribution in the Fourier plane determined by leakage radiation microscopy gives additional features of the emission and waveguiding. First, the anisotropic red luminescence of the whole system can be attributed to the guided mode along the nanotube. Then, a low-loss propagation behavior is evidenced in the Mo6@SU8-based nanotubes. This result contrasts with the weaker waveguiding signature in the case of UV210-based nanotubes embedding PFO (poly(9,9-di-n-octylfluorenyl-2,7-diyl)). It is attributed to the strong reabsorption phenomenon, owing to overlapping between absorption and emission bands in the semi-conducting conjugated polymer PFO. These results make this Mo6@SU8 original class of nanocomposite a promising candidate as nanosources for submicronic photonic integration.

Phosphorescent columnar hybrid materials containing polyionic inorganic nanoclusters

Red NIR phosphorescent hybrid materials with columnar liquid crystalline properties show high luminescence thermal stability and sensitivity to their surrounding atmosphere.

Combined theoretical and time-resolved photoluminescence investigations of [Mo6Bri8Bra6]2− metal cluster units: evidence of dual emission

Distinct emissive species have been identified in [Mo₆Brⁱ₈Br^a₆]²⁻ containing systems. Strong geometrical relaxations of the triplet excited states are responsible for the huge energy shift leading to intense red-NIR emission.

Antiferromagnetic Ordering of Magnetic Clusters Units in Nb(6)F(15)

We have studied the magnetic cluster compound Nb(6)F(15) which has an odd number of 15 valence electrons per (Nb(6)F(12))(3+) cluster core, as a function of temperature using nuclear magnetic resonance, magnetic susceptibility, electron magnetic resonance and neutron powder diffraction. Nuclear magnetic resonance of the (19)F nuclei shows two lines corresponding to the apical F(a-a) nucleus, and to the inner F(i) nuclei. The temperature dependence of the signal from the F(i) nuclei reveals an antiferromagnetic ordering at T < 5 K, with a hyperfine field of ~2 mT. Magnetic susceptibility exhibits a Curie-Weiss behavior with T(N) ~5 K, and μ(eff) ~1.57 μ(B) close to the expected theoretical value for one unpaired electron (1.73 μ(B)). Electron magnetic resonance linewidth shows a transition at 5 K. Upon cooling from 10 to 1.4 K, the neutron diffraction shows a decrease in the intensity of the low-angle diffuse scattering below Q ~0.27 Å(-1). This decrease is consistent with emergence of magnetic order of large magnetic objects (clusters). This study shows that Nb(6)F(15) is paramagnetic at RT and undergoes a transition to antiferromagnetic order at 5 K. This unique antiferromagnetic ordering results from the interaction between magnetic spins delocalized over each entire (Nb(6)F(12) (i))(3+) cluster core, rather than the common magnetic ordering.

Influence of fetal glutathione S-transferase copy number variants on adverse reproductive outcomes

A nested case-control association study was designed to investigate the influence of maternal and fetal copy number variants (CNVs) on reproductive outcomes. Genotypes of ten CNVs encompassing GST and CYP genes were assessed. Significant associations were only found for child CNV genotypes. In particular, the child GSTM1 insertion allele was associated with prematurity protection (odds ratio, 95% CI: 0.67, 0.51-0.89; P < 0.01), whereas the child GSTT2B insertion allele was associated with an increased risk of being small for gestational age (odds ratio, 95% CI: 1.33, 1.07-1.67; P = 0.01). The study highlights the role of the fetal genome in prenatal development and also the need to analyse CNVs in a systematic manner.

Occupational exposure to organic solvent mixtures during pregnancy and the risk of non-syndromic oral clefts

OBJECTIVES

To examine the association between maternal occupational exposure to mixtures of organic solvents during pregnancy and the risk of non-syndromic oral clefts.

METHODS

A case-control study (164 cleft lip with/without cleft palate (CL/P), 76 cleft palate (CP), 236 controls) was conducted in France to investigate the role of maternal occupational exposure to organic solvents at the beginning of pregnancy in the risk of non-syndromic oral clefts. An expert chemist, guided by a detailed description of the women's occupational tasks, assessed exposure for each. Analysis of the findings used logistic regression.

RESULTS

In the control group, 39% of the women who reported working during pregnancy were exposed to at least one type of organic solvent. The risk of oral clefts was associated with oxygenated (for CL/P: OR = 1.8, 95% CI 1.1 to 2.9; and for CP, OR = 1.4, 95% CI 0.7 to 2.7), chlorinated (OR = 9.4, 95% CI 2.5 to 35.3; OR = 3.8, 95% CI 0.7 to 20.7), and petroleum (OR = 3.6, 95% CI 1.5 to 8.8; OR = 1.2, 95% CI 0.3 to 4.9) solvents. The risk of oral clefts increased linearly with level of exposure within the three subgroups of oxygenated solvents we considered (aliphatic alcohols, glycol ethers, and other oxygenated solvents, including esters, ketones, and aliphatic aldehydes).

CONCLUSIONS

Results suggest that maternal occupational exposure to organic solvents during pregnancy may play a role in the aetiology of oral clefts. The limited number of subjects and the problem of multiple exposures require that these results be interpreted cautiously.

Nouvelles avancées dans l’étude de l’influence de l’environnement sur la santé reproductive masculine

BACKGROUND

An important part of the research effort on male reproductive health focus on two important questions: on the one side, that of the temporal deterioration of male reproductive health and, on the other head, that of the influence of exposure to environmental chemicals during intra-uterine life on health during childhood and adulthood. The concepts on endocrine disruption and testicular dysgenesis syndrome make a link between these two questions.

METHODS

This work examines knowledge cumulated over the last couple of years concerning geographical and temporal variations in male reproductive health and the testicular dysgenesis syndrome. Recent results concerning the concept of endocrine disruption and on the environmental influences on male reproduction are presented, as well as on the transgenerational effects on environmental factors on the health of male children.

CONCLUSIONS

Based on clinical and epidemiological data, and with the use of in vitro animal models as well as observations in wildlife, research in this field has enabled progress in the elucidation of mechanisms of action and characterization of environmental influences on male reproductive health.

Beauty product-related exposures and childhood brain tumors in seven countries: results from the SEARCH International Brain Tumor Study

Data from 1218 cases of childhood brain tumors (CBT) diagnosed between 1976 and 1994 and 2223 matched controls from the general population were included in an analysis of maternal beauty product exposure and beauty-related employment in 9 centers in 7 countries. A 50% increased odds ratio (OR) [95% confidence interval (CI) = 1.0-2.1] for CBT was observed among children of mothers who were exposed via personal use of and/or possible ambient contact with beauty products during the 5 years preceding the index child's birth compared with children of mothers never exposed to beauty products during this time period. Overall maternal personal use of hair-coloring agents in the month before or during the pregnancy of the index child's birth was not associated with CBT (OR = 1.0, CI = 0.83-1.3) or with astroglial (OR = 1.1, CI = 0.85-1.4), PNET (OR = 1.0, CI = 0.71-1.5) and other glial subtypes (OR = 1.0, CI = 0.62-1.0). Similarly, no statistically increased ORs or discernable pattern of risk estimates were observed for period of use or for number of applications per year for maternal personal use of hair-coloring agents overall or by histologic type. Among children born on or after 1980, increased ORs for CBT were associated with maternal non-work-related exposure to any beauty products (OR = 2.6, CI = 1.2-5.9), hair-dyes (OR = 11, CI = 1.2-90), and hair sprays (OR = 3.4, CI = 1.0-11). No overall increased OR for CBT was observed among children of mothers employed in beauty-related jobs during the 5 years preceding the index child's birth compared with those who reported no beauty-related employment. In general, other specific beauty product-related exposures were not associated with increased ORs for CBT. Data from our study provide little evidence of an increased risk for CBT with mothers' exposures to beauty products.

Folates en période péri-conceptionnelle et prévention du risque de fente orofaciale : rôle des apports alimentaires en France

BACKGROUND

Orofacial clefts are among the most frequent congenital malformations at birth with a prevalence of 1 in 700 births in Europe. The implication of environmental factors in their etiology has been demonstrated. The role of folic acid, or folates, in the prevention of orofacial clefts is still debated although its efficacy has been demonstrated for the prevention of neural tube defects.

METHODS

A case-control study was conducted in 7 hospitals in 4 centers in France. Cases (N=240) were children with non-syndromic orofacial cleft referred to one of the study hospitals for initial surgical repair in 1998 and 1999. Controls (N=236) matched for gender, geographic origin, and age were chosen in paediatric departments of the same hospitals. Usual dietary intake of folates was estimated using a food frequency questionnaire submitted to the mother at hospital. During the same interview, data on sociodemographic characteristics, medical and obstetrical history, tobacco and alcohol consumption, and vitamin supplements, were obtained. Odds ratios associated with quintiles of dietary intake of folates were estimated using logistic regression adjusting for known confounders.

RESULTS

A significant dose-response relationship between the risk of orofacial clefts and a decrease in the intake of folates from diet was found, stronger for cleft palate without cleft lip. Only few women (<1%) declared having taken vitamin supplements containing folic acid when planning their pregnancy.

CONCLUSION

Our study further suggests that folates are useful for the prevention of orofacial clefts during the periconceptual period. In our study, the estimated average daily intake of folates (270 microg/day) was below French national recommendations for the prevention of neural tube defects (400 microg/day). Since those insufficient folate intakes during the periconceptual period are not presently met by vitamin supplementation, the solution may come from the food fortification program proposed and implemented by the National Agency for Food Safety (AFSSA).

Atrazine in municipal drinking water and risk of low birth weight, preterm delivery, and small-for-gestational-age status

BACKGROUND

Atrazine is a herbicide used extensively worldwide. Bioassays have shown that it is embryotoxic and embryolethal. Evidence of adverse reproductive outcomes from exposure in the general population is sparse.

AIMS

To evaluate the association between atrazine levels in municipal drinking water and the following adverse reproductive outcomes: increased risk of preterm delivery, low birth weight (LBW), and small-for-gestational-age (SGA) status.

METHODS

A total of 3510 births that took place from 1 October 1997, to 30 September 1998 were analysed. Atrazine measurements were available for 2661 samples from water treatment plants over the past decade. A seasonal pattern was identified, with atrazine peaking from May to September. The geometric mean of the atrazine level for this period was calculated for each water distribution unit and merged with the individual data by municipality of residence.

RESULTS

Atrazine levels in water were not associated with an increased risk of LBW or SGA status and were slightly associated with prematurity. There was an increased risk of SGA status in cases in which the third trimester overlapped in whole or in part with the May-September period, compared with those in which the third trimester occurred totally from October to April (OR = 1.37, 95% CI 1.04 to 1.81). If the entire third trimester took place from May to September, the OR was 1.54 (95% CI 1.11 to 2.13).

CONCLUSIONS

Low levels of atrazine, a narrow exposure range, and limitations in the exposure assessment partly explain the lack of associations with atrazine. Findings point to the third trimester of pregnancy as the potential vulnerable period for an increased risk of SGA birth. Exposures other than atrazine and also seasonal factors may explain the increased risk.

The INSERM expert review on glycol ethers: findings and recommendations

The use of glycol ethers and their effects on health have recently attracted the attention of the French health authorities. At their request, INSERM, the French Institute of Health and Medical Research, conducted a collective expertise review on glycol ethers in 1999. INSERM Expertise Reviews are independent procedures performed by experts from several disciplines, to guarantee the objectivity and the relevance of the report. During several work sessions, the experts carried out a critical analysis of and reviewed studies concerning the toxicity of glycol ethers. This process resulted in a series of recommendations and conclusions. All these data have been published in the form of a report and have been used to help the public authorities to make decisions on how to prevent risks for professionals and consumers.

Parental exposure to polycyclic aromatic hydrocarbons and the risk of childhood brain tumors: The SEARCH International Childhood Brain Tumor Study

Experimental evidence suggests that parental exposure to polycyclic aromatic hydrocarbons (PAH), which occurs primarily through tobacco smoke, occupational exposure, and air pollution, could increase the risk of cancer during childhood. Population-based case-control studies carried out in seven countries as part of the SEARCH Program compared data for 1,218 cases of childhood brain tumors and 2,223 controls (1976-1994). Parental occupational exposure to PAH during the 5-year period before birth was estimated with a job exposure matrix. Risk estimates were adjusted for child's age, sex, and study center. Paternal preconceptional occupational exposure to PAH was associated with increased risks of all childhood brain tumors (odds ratio (OR) = 1.3, 95% confidence interval: 1.1, 1.6) and astroglial tumors (OR = 1.4, 95% confidence interval: 1.1, 1.7). However, there was no trend of increasing risk with predicted level of exposure. Paternal smoking alone (OR = 1.4) was also associated with the risk of astroglial tumors in comparison with nonsmoking, non-occupationally-exposed fathers. Risks for paternal occupational exposure were higher, with (OR = 1.6) or without (OR = 1.7) smoking. Maternal occupational exposure to PAH before conception or during pregnancy was rare, and this exposure was not associated with any type of childhood brain tumor. This large study supports the hypothesis that paternal preconceptional exposure to PAH increases the risk of brain tumors in humans.

Risk of congenital anomalies in the vicinity of municipal solid waste incinerators

BACKGROUND

Although municipal solid waste incineration (MSWI) has contributed to increase the overall environmental load of particulate matter containing dioxins and metals, evidence of health consequences to populations is sparse.

AIMS

To assess at a regional level (in southeast France) the impact of these emissions on birth defect rates.

METHODS

Communities with fewer than 50 000 inhabitants surrounding the 70 incinerators that operated at least one year from 1988 to 1997 were studied. Each exposed community (n = 194) was assigned an exposure index estimated from a Gaussian plume model. Poisson models and a reference population of the 2678 unexposed communities in the region were used to calculate relative risks for congenital malformations, adjusted for year of birth, maternal age, department of birth, population density, average family income, and when available, local road traffic.

RESULTS

The rate of congenital anomalies was not significantly higher in exposed compared with unexposed communities. Some subgroups of major anomalies, specifically facial clefts and renal dysplasia, were more frequent in the exposed communities. Among exposed communities, a dose-response trend of risk with increasing exposure was observed for obstructive uropathies. Risks of cardiac anomalies, obstructive uropathies, and skin anomalies increased linearly with road traffic density.

CONCLUSIONS

Although both incinerator emissions and road traffic may plausibly explain some of the excess risks observed, several alternative explanations, including exposure misclassification, ascertainment bias, and residual confounding cannot be excluded. Some of the effects observed, if real, might be attributable to old-technology MSWIs and the persistent pollution they have generated.

Synthesis, crystal structure, and characterization of the first Nb(3) triangular cluster compound bonded to fluorine ligands: association of Nb(3)I(i)F(i)(3)F(a)(8)L(a) units and Nb(IV)L(6) Octahedra with L=O and F

The synthesis and the crystal structure of the first compound containing Nb(3) triangular clusters bonded to fluorine ligands are presented in this work. The structure of Nb(3)IF(7)L(NbL(2))(0.25) with L = O and F, determined by single-crystal X-ray diffraction, is based on a Nb(3)I(i)F(i)(3)F(a)(8)L(a) unit and a NbL(6) octahedron (tetragonal, space group I4/m, a = 13.8638(3) A, c = 8.9183(2) A, V = 1714.14(7) A(3), Z = 8). Two crystallographic positions (noted L5 and L6) are randomly occupied by fluorine and oxygen with two different F:O occupancies. These L ligands build an octahedral site for a single niobium atom, located between the units. The four L5 ligands of the NbL(6) octahedron are shared with four Nb(3) cluster units, while the two other L6 ligands are terminal. The Nb(3) cluster is face-capped by one iodine and edge-bridged by three fluorine ligands. Two of the three niobium atoms constituting the cluster are bonded to three additional apical fluorine ligands, while the third one is bonded to two fluorines and one L5 ligand. The Nb(3) cluster is linked to six adjacent ones via all the apical fluorine ligands. The developed formula of the unit is therefore Nb(3)I(i)F(i)(3)F(a)(-)(a)(8/2)L(a) according to the Schäfer and Schnering notation. The oxidation state of the single niobium and the random distribution of fluorine and oxygen on the two L sites will be discussed on the basis of structural analysis, the bond valence method, and IR and EPR measurements. The structural results will be compared to those of previously reported niobium compounds containing NbF(6) or Nb(F,O)(6) octahedra.