Childhood polybrominated diphenyl ether (PBDE) exposure and executive function in children in the HOME Study

Prenatal exposure to polybrominated diphenyl ethers (PBDEs) have been reported to impair executive function in children, but little is known whether childhood PBDE exposures play a role. Using the Health Outcomes and Measures of the Environment (HOME) Study, a prospective birth cohort in the greater Cincinnati area, we investigated the association between repeated measures of PBDEs during childhood and executive function at 8 years in 208 children and whether effect modification by child sex was present. We used child serum collected at 1, 2, 3, 5, and 8 years to measure PBDEs. The Behavior Rating Inventory of Executive Function was completed by parents to assess executive function at 8 years. We used multiple informant models to examine childhood PBDEs during several exposure windows. Null associations were observed between early childhood PBDEs and executive function. However, we observed significant adverse associations between a 10-fold increase in concurrent concentrations of BDE-28 (β = 4.6, 95% CI 0.5, 8.7) and BDE-153 (β = 4.8, 95% CI 0.8, 8.8) with behavioral regulation. In addition, PBDEs at 8 years were significantly associated with poorer emotional and impulse control. No associations were noted between childhood PBDEs and metacognition or global executive function. However, child sex significantly modified the associations, with significantly poorer executive function among males with higher concurrent BDE-153, and null associations in females. Our study findings suggest that concurrent PBDE exposures during childhood may be associated with poorer executive function, specifically behavior regulation. Males may also be more sensitive to adverse associations of concurrent PBDEs on executive function.     

Highly Chlorinated Toxic Contaminants in Pesticide-Treated Wooden Art Objects

Although the contamination of wooden art objects with pesticides is well known, to the authors' knowledge no attempt has yet been made to investigate the eventual presence of other toxic compounds that have been produced during the degradation of pesticides or that may be present in the technical formulations. Here, the authors report on the presence of polychlorinated biphenyls (PCBs) and polychlorinated terphenyls (PCTs) in scrapings from wooden antique art objects, namely printing blocks, sculptures, and masks. These antiques belong to 2 fine art museums in Belgium—Antwerp's Ethnographic Museum and the Plantin-Moretus Museum. It is documented that these art objects were treated with pesticides in the 1950s. In addition, 2-heptachlorodibenzo-p-dioxin (HpCDD) isomers and octachlorodibenzo-p-dioxin (OCDD) were also identified. The presence of these toxic compounds in these antiques requires a better understanding of safety for the persons (conservators, museum employees, restorers, and visitors) coming in contact with these objects.     

Chemoprevention of liver cancer by plant polyphenols

Primary liver cancer or hepatocellular carcinoma (HCC) is one of the most frequent tumors representing the fifth commonest malignancy worldwide and the third cause of mortality from cancer. Currently, the treatments for HCC are not so effective and new strategies are needed for its fight. Chemoprevention, the use of natural or synthetic chemical agents to reverse, suppress or prevent carcinogenesis is considered an important way for confronting HCC. Many of the chemopreventive agents are phytochemicals, namely non-nutritive plant chemicals with protective or disease preventive properties. In this review, we focus on plant polyphenols, one of the most important classes of phytochemicals, their chemopreventive properties against HCC and discuss the molecular mechanisms accounting for this activity.     

Polychlorinated dibenzo‐p‐dioxins and dibenzofurans levels in piglet liver with various diseases

This study deals with the levels of toxic polychlorinated dibenzo‐p‐dioxin and furan congeners (PCDD/Fs) in the livers of piglets affected by infectious diseases using isotope dilution high‐resolution gas chromatography/high‐resolution mass spectrometry (HRGC/HRMS). Seventeen toxic congeners in the liver samples infected with bacterial and viral diseases were compared. For porcine reproductive and respiratory syndrome virus (PRRSV) samples, the North American‐ and European‐type PRRS diseases were observed. This study shows that there are significantly different levels of PCDD/Fs, present, which vary according to the types of diseases as evidenced by our analysis of the piglet liver samples.     

多氯联苯对大鼠骨髓间充质干细胞c-fos和c-jun表达影响的研究

目的探讨多氯联苯(PCB126)对大鼠骨髓间充质干细胞(MSCs)c-fos和c-jun表达的影响。方法采用percoll分离液(密度1.073g/cm3)分离Wistar大鼠MSCs、培养并传代,实验分为3组:对照组、低剂量组(10-7mol/L PCB126)和高剂量组(10-6mol/L PCB126)。PCB126分别作用于MSCs 12h和24h后,利用MTT方法检测细胞的增殖率,免疫荧光化学方法检测细胞c-fos的表达;PCB126分别作用于MSCs 30min、1h、2h、4h、8h、12h和24h后,利用RT-PCR分析c-fos和c-jun mRNA的表达;Western blot方法分析细胞c-fos和c-jun蛋白的表达。结果 10-6mol/L和10-7mol/L组12h时细胞的增殖率分别为13.8%和19.1%,24h时分别为31.5%和36.1%,48h时分别为42.5%和43.6%(t=8.42,P<0.01)。10-6mol/L和10-7mol/L组12h时c-fos的阳性率分别为54.6%(231/446)和51.3%(214/416)(χ2=15.59,P<0.01;χ2=15.45,P<0.01),24h时c-fos的阳性率分别为83.2%(376/425)和73.0%(309/423)(χ2=60.56,P<0.01;χ2=25.79,P<0.01)。RT-PCR结果显示,10-6mol/L组和10-7mol/L组在30 min和1h时c-fos mRNA的表达显著上调;两组在不同时间c-jun mRNA均上调且10-6mol/L组的表达水平明显高于10-7mol/L组(t=7.88,P<0.01)。10-6mol/L和10-7mol/L组12h时c-fos和c-jun蛋白表达上调(t=9.91和t=8.84,P<0.01),24h时c-fos和c-jun表达显著上调(t=9.52,P<0.01)。结论 PCB126能促进MSCs增殖,上调癌相关基因c-fos和c-jun的表达,PCB126影响MSCs的功能与c-fos和c-jun的表达异常有关。     

Prenatal Methylmercury, Postnatal Lead Exposure, and Evidence of Attention Deficit/Hyperactivity Disorder among Inuit Children in Arctic Qu��bec

Background: Prenatal exposure to methylmercury (MeHg) and polychlorinated biphenyls (PCBs) has been associated with impaired performance on attention tasks in previous studies, but the extent to which these cognitive deficits translate into behavioral problems in the classroom and attention deficit/hyperactivity disorder (ADHD) remains unknown. By contrast, lead (Pb) exposure in childhood has been associated with ADHD and disruptive behaviors in several studies.Objectives: In this study we examined the relation of developmental exposure to MeHg, PCBs, and Pb to behavioral problems at school age in Inuit children exposed through their traditional diet.Methods: In a prospective longitudinal study conducted in the Canadian Arctic, exposure to contaminants was measured at birth and at school age. An assessment of child behavior (n = 279; mean age = 11.3 years) was obtained from the child’s classroom teacher on the Teacher Report Form (TRF) from the Child Behavior Checklist, and the Disruptive Behavior Disorders Rating Scale (DBD).Results: Cord blood mercury concentrations were associated with higher TRF symptom scores for attention problems and DBD scores consistent with ADHD. Current blood Pb concentrations were associated with higher TRF symptom scores for externalizing problems and with symptoms of ADHD (hyperactive-impulsive type) based on the DBD.Conclusions: To our knowledge, this study is the first to identify an association between prenatal MeHg and ADHD symptomatology in childhood and the first to replicate previously reported associations between low-level childhood Pb exposure and ADHD in a population exposed to Pb primarily from dietary sources.     

Cryptorchidism and endocrine disrupting chemicals

Prospective clinical studies have suggested that the rate of congenital cryptorchidism has increased since the 1950s. It has been hypothesized that this may be related to environmental factors. Testicular descent occurs in two phases controlled by Leydig cell-derived hormones insulin-like peptide 3 (INSL3) and testosterone. Disorders in fetal androgen production/action or suppression of Insl3 are mechanisms causing cryptorchidism in rodents. In humans, prenatal exposure to potent estrogen diethylstilbestrol (DES) has been associated with increased risk of cryptorchidism. In addition, epidemiological studies have suggested that exposure to pesticides may also be associated with cryptorchidism. Some case-control studies analyzing environmental chemical levels in maternal breast milk samples have reported associations between cryptorchidism and chemical levels. Furthermore, it has been suggested that exposure levels of some chemicals may be associated with infant reproductive hormone levels.     

Thyroid effects of endocrine disrupting chemicals

In recent years, many studies of thyroid-disrupting effects of environmental chemicals have been published. Of special concern is the exposure of pregnant women and infants, as thyroid disruption of the developing organism may have deleterious effects on neurological outcome. Chemicals may exert thyroid effects through a variety of mechanisms of action, and some animal experiments and in vitro studies have focused on elucidating the mode of action of specific chemical compounds. Long-term human studies on effects of environmental chemicals on thyroid related outcomes such as growth and development are still lacking. The human exposure scenario with life long exposure to a vast mixture of chemicals in low doses and the large physiological variation in thyroid hormone levels between individuals render human studies very difficult. However, there is now reasonably firm evidence that PCBs have thyroid-disrupting effects, and there is emerging evidence that also phthalates, bisphenol A, brominated flame retardants and perfluorinated chemicals may have thyroid disrupting properties.