Use of crayfish in biomonitoring studies of environmental pollution of the river Meuse

The river Meuse, located in western Europe, is contaminated by different pollutants, of both organic and inorganic nature. The predominant sources of Meuse contamination in The Netherlands are agricultural activities and pollution derived from urban areas. Crayfish, water, and sediment samples were collected at four different locations of the river Meuse, in order to cover a large part of the catchment area of this river in The Netherlands. Crayfish may be very useful in biomonitoring studies, since they can integrate body load by pollutants over time in an area-bound manner. In these crayfish, levels of aromatic DNA adducts, heavy metal residues, polychlorinated biphenyls (PCBs), and organochlorine pesticides were determined in hepatopancreatic tissue. Also analyzed were water and sediment samples derived from the same locations, for polycyclic aromatic hydrocarbons (PAHs), heavy metals, and organochlorine compounds. In sediments from the four different sampling sites, no clear differences were observed in PCB levels. Organochlorine pesticide concentrations were highest at location A, the most upstream sampling site, whereas a general decrease was observed following the river Meuse downstream. A similar pattern was observed for the metal compounds. For PAH sediment levels no consistent tendency could be observed. Highest values were detected at site B, followed by, respectively, locations A, D, and C. In water samples, a different pattern was observed. The highest metal concentration was observed at location D, whereas the total organochlorine level was higher at sites B and D, compared to the two other sampling sites. Differences in pollution levels in crayfish between sampling sites were evident. Site D, the most downstream-situated site examined, appeared to be the most polluted site with respect to PCBs, DDT, DDE, and Cu in crayfish. Moreover, DNA adduct levels, which may serve as a dosimeter for the internal dose of aromatic compounds such as PAHs and PCBs, were also significantly higher in hepatopancreatic tissue of crayfish captured at site D, compared to the three other sampling sites. Moreover, significant correlations were observed between DNA adduct levels and the lower chlorinated PCB congeners (PCB 28-PCB 101). By correlating the different pollutants in water and/or sediment with xenobiotic levels in crayfish, no consistency could be observed, indicating that monitoring aquatic species may provide specific information on the presence of surface water pollutants. These results indicate that crayfish can be used as biological indicators of exposure to both organic and inorganic pollution in aquatic systems.     

Body burden of polychlorinated biphenyls among persons employed in capacitor manufacturing

Summary In an effort to assess exposure among workers engaged in capitor manufacture, PCB concentration was determined in plasma (290) and adipose tissue (61). In general, males had higher concentrations of PCBs than females.The correlation of plasma concentration (1–546 ppb) of the more highly chlorinated PCBs, which had been used in the past, with total duration of employment suggested accumulation over time. The gc-ec pattern of these PCB peaks was, in most cases, characteristic of exposure to a PCB mixture with 54% chlorine.The less highly chlorinated PCBs, di-, tri-, and tetrachlorobiphenyls, were the source of current exposure, and were observed in concentrations of 6–2530 ppb in plasma. Higher exposure occurred among persons with direct contact with PCBs, in jobs such as capacitor filling.Adipose tissue concentrations, for both the more highly chlorinated PCBs (1–165 ppm) and lower chlorinated PCBs (0.6-414 ppm), were proportional to those in plasma.Abbreviations PCB polychlorinated biphenyl - p,p-DDE 2,2-bis-(4-chlorophenyl)-1,1-dich-loroethylene - DDT dichlorodiphenyltrichloroethane Presented in part, at the XIX. International Congress on Occupational Health, Dubrovnik, September, 1978     

Ortho-substituted PCBs kill thymocytes.

The effects of exposure of acutely dissociated rat thymocytes to various polychlorinated biphenyl (PCB) congeners were examined using flow cytometry. Non-planar, ortho-substituted congeners caused a rapid cell death at low micromolar concentrations, while coplanar, dioxin-like congeners at the same concentration were without significant effect. The most potent of the congeners studied was PCB 52 (2,2',5,5'-tetrachlorobiphenyl), which had an IC50 of 3.96 microM at 20 min. Prior to loss of viability there was a decrease in mitochondrial membrane potential Delta Psi m, an accumulation of intracellular calcium, and a progressive leakiness of the plasma membrane. Application of PCB 52 in calcium-free medium reduced the calcium accumulation, but did not reduce cell death. Agents that depolarized mitochondria also did not induce the same degree of cell death caused by PCB 52. Cyclosporin A, which prevents opening of the mitochondria permeability transition channel, protected against cell death but did not protect against mitochondrial depolarization or calcium accumulation. Rapamycin and FK 506 at high concentration provided partial protection against cell death. These observations indicate that the ortho-substituted PCB 52 disrupts plasma, mitochondrial and endoplasmic reticulum membranes. We hypothesize that PCB 52 incorporates into lipid bilayers and with its bulky, three-dimensional ortho-substituted congener structure disrupts membrane function to a greater degree than coplanar congeners.     

Late-gestation rat myometrial cells express multiple isoforms of phospholipase A2 that mediate PCB 50-induced release of arachidonic acid with coincident prostaglandin production.

Previous reports have shown that ortho-substituted polychlorinated biphenyls (PCBs) are uterotonic and activate phospholipase A2 to release arachidonic acid (AA) from membrane phospholipids. AA serves as the precursor to various eicosanoids, which, in addition to AA itself, are capable of modulating uterine function. To examine whether PCBs stimulate phospholipase A2 (PLA2) to mobilize arachidonic acid from late-gestation rat uterus, primary cultures of gestation day 20 (gd20) rat myometrial cells (RMC) were labeled with 0.5 microCi 3H-AA prior to a 10-, 20-, or 30-min exposure to 2,2',4,6-tetrachlorobiphenyl (PCB 50) (1-50 microM) or 0.1% DMSO (solvent control). PCB 50 stimulated the release of 3H-AA from gd20 RMC in concentration- and time-dependent manners (p < 0.05). PCB 50 stimulation of RMC was attenuated with ethylene glycol bis(2-aminoethyl ether)-N,N,N'N'-tetraacetic acid (EGTA) and nifedipine, suggesting that AA release was dependent on the influx of extracellular calcium through L-type voltage-operated calcium channels. PCB 50-induced release of AA from RMC was also attenuated with the PLA2-specific inhibitors methyl arachidonyl fluorophosphonate (MAFP), bromoenol lactone (BEL), and manoalide (p < 0.05). Stimulation of PLA2 enzymes in response to PCB exposure occurred via p38 mitogen activated protein kinase (MAPK) activation as indicated by the significant attenuation of PCB 50-induced AA release from RMC in the presence of SB 202190. In addition to stimulating AA release, PCB 50 induced a significant production of prostaglandins from gd20 RMC compared with controls (p < 0.05). These results suggest that myometrial cells express multiple PLA2 isoforms that may serve as a target and effector for ortho-substituted PCB-mediated stimulation of uterine function through arachidonic acid and prostaglandin release.     

Aryl hydrocarbon receptor-activating polychlorinated biphenyls and their hydroxylated metabolites induce cell proliferation in contact-inhibited rat liver epithelial cells.

Polychlorinated biphenyls (PCBs) exhibit tumor-promoting effects in experimental animals. We investigated effects of six model PCB congeners and hydroxylated PCB metabolites on proliferation of contact-inhibited rat liver epithelial WB-F344 cells. The 'dioxin-like' PCB congeners, PCB 126, PCB 105, and 4'-OH-PCB 79, a metabolite of the planar PCB 77 congener, induced cell proliferation in a concentration-dependent manner. In contrast, the 'non-dioxin-like' compounds that are not aryl hydrocarbon receptor (AhR) agonists, PCB 47, PCB 153, and 4-OH-PCB 187, an abundant noncoplanar PCB metabolite, had no effect on cell proliferation at concentrations up to 10 muM. The concentrations of dioxin-like PCBs leading to cell proliferation corresponded with the levels inducing the expression of cytochrome P450 1A1 mRNA, suggesting that the release from contact inhibition was associated with AhR activation. The effects of PCB 126 and PCB 153 on expression of proteins controlling G0/G1-S-phase transition and S-phase progression were compared. Only PCB 126 was found to upregulate cyclin A and D2 protein levels, and to increase both total cyclin-dependent kinase 2 (cdk2) and cyclin A/cdk2 complex activities. Despite the observed upregulation of cyclin D2, no increase in cdk4 activity was observed. The expression of cdk inhibitor p27Kip1 was not affected by either PCB 126 or PCB 153. These results suggest that dioxin-like PCBs can induce cell proliferation of contact-inhibited rat liver epithelial cells by increasing cyclin A protein levels, a process that then leads to upregulation of cyclin A/cdk2 activity and initiation of DNA replication. This mechanism could be involved in tumor-promoting effects of dioxin-like PCBs.     

Thyroid hormones are associated with exposure to persistent organic pollutants in aging residents of upper Hudson River communities

The aim of this study was to evaluate the association between persistent organic pollutants (POPs) and thyroid hormones in an aging population. Forty-eight women and 66 men, aged 55–74 years and living in upper Hudson River communities completed a questionnaire and provided blood specimens. Serum was analyzed for thyrotropin (thyroid stimulating hormone, TSH), free (fT₄) and total thyroxine (T₄), total triiodothyronine (T₃), and for POPs. POPs included 39 polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) determined by gas chromatography with electron capture detection (GC–ECD), and nine polybrominated diphenyl ethers (PBDEs) determined by high-resolution gas chromatography with high-resolution mass spectrometry detection (HRGC–HRMS). Multivariable linear regression analysis was used to evaluate associations between thyroid hormones and sums of POPs, adjusted for covariates and stratified by sex. Effects were expressed as differences in thyroid hormone levels associated with a doubling in the level of exposure. Among women, DDT + DDE increased T₄ by 0.34 μg/dL (P = 0.04) and T₃ by 2.78 ng/dL (P = 0.05). Also in women, sums of PCBs in conjunction with PBDEs elicited increases of 24.39–80.85 ng/dL T₃ (P < 0.05), and sums of PCBs in conjunction with DDT + DDE elicited increases of 0.18–0.31 μg/dL T₄ (P < 0.05). For men estrogenic PCBs were associated with a 19.82 ng/dL T₃ decrease (P = 0.003), and the sum of estrogenic PCBs in conjunction with DDT + DDE elicited an 18.02 ng/dL T₃ decrease (P = 0.04). Given age-related declines in physiologic reserve, the influence of POPs on thyroid hormones in aging populations may have clinical implications and merits further investigation.     

Specificity of Neurobehavioral Outcomes Associated with Prenatal Alcohol Exposure

A current issue in alcohol research is whether a "neurobehavioral profile" can be identified for prenatal alcohol exposure, even when dysmorphic features are not present, or whether comparable neurobehavioral deficits are detected when damage is incurred by numerous neurotoxicants to which the fetus is exposed during a common developmental period. Failure to detect such differences may, in part, be an artifact of the global developmental tests used to assess outcome. Cognitive effects of prenatal exposure to three different teratogens [polychlorinated biphenyls (PCBs), alcohol, and cocaine] are examined to determine whether exposure to each substance results in a common or different pattern of impairment on the same set of newer, more narrow band infant tests. Comparison of findings from three independent cohorts indicate that PCB exposure was related to poorer recognition memory on the Fagan Test of Infant Intelligence (FTII) in Michigan infants exposed prenatally to PCB-contaminated fish, whereas prenatal alcohol exposure was unrelated to recognition memory but to slower processing speed on a new FTII measure and slower reaction time on Haith's Visual Expectancy Paradigm (VExP) in our Detroit alcohol-exposed infants. Preliminary findings from a new study of infants recently born to Taiwanese women accidentally contaminated with sizable amounts of PCBs indicate recognition memory deficits, confirming our Michigan findings, but no processing speed effects on the FTII. Recent findings from our Detroit cohort suggest that heavy prenatal cocaine exposure is related to poorer recognition memory on the FTII, but faster reaction times on the VExP, a pattern different from that seen for either PCBs or alcohol.     

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.     

Study on Rheological Properties of Bituminous Binders and Mixtures Containing Waste Printed Circuit Boards (PCBs) and SBR Compound Modified Bitumen

Improper handling of waste printed circuit boards (PCBs) can cause serious pollution to the water and soil environments. In order to explore a new method of recycling waste PCBs, this study investigated the effect of PCBs and butadiene styrene rubber (SBR) on the rheological properties of neat bitumen. The dynamic shear rheological (DSR) test was used to study the effect of different PCB contents on the high-temperature rheological properties of SBR-modified bitumen. Fluorescence microscopy and Fourier-transform infrared spectroscopy were used to study the microstructure change law and modification mechanism of PCB and SBR composite modified bitumen. Finally, the feasibility of the bitumen properties was verified through a test of the bituminous mixture properties. The DSR test results showed that the addition of PCBs improves the elastic recovery modulus, dynamic shear modulus, and rutting factor of SBR-modified bitumen, indicating that the high-temperature properties were improved. Infrared spectroscopy analysis revealed that a new absorption peak was generated in the infrared spectrum of the compound bitumen after the addition of PCBs, and the intensity of the original absorption peak also changed, indicating that PCBs and SBR-modified bitumen were mainly physically blended and accompanied by a weak chemical reaction. It was further found that the absorption peak of the unsaturated C=C double bond was significantly enhanced, and the increase in the content of the unsaturated bond C=C in the main chain of the polymer significantly increases the stiffness of the bitumen. Macroscopically, the high-temperature rutting resistance was improved to a certain extent. The fluorescence diagram shows that when PCBs do not exceed 10%, the PCBs can form a homogeneous structure and be dispersed in SBR-modified bitumen. The road test of PCBs and SBR composite modified bituminous mixtures showed that PCBs can significantly improve the rutting resistance and water stability of SBR-modified bitumen at high temperatures at the recommended optimum content. The crack resistance at low temperatures is weakened but still meets actual engineering requirements. The correlation analysis between the properties of bitumen and bituminous mixtures is carried out based on grey correlation theory. The results show that the index of modified bitumen has a very good guiding effect on the bituminous mixture properties. The development of PCBs and SBR composite-modified bitumen provides a new practical method for recycling waste PCBs.