Sorbent Wicking Device for Sampling Hydrophobic Organic Compounds in Unsaturated Soil Pore Water. II: Chemical Capture, Recovery, and Analysis

Experiments investigated the chemical capture and quantitative recovery of chlorinated hydrophobic organic compounds (HOCs) sampled from the pore-water of unsaturated soils with a new in situ sorbent wicking device. The sampling device is comprised of an annular porous stainless-steel interface encasing granular-activated carbon and a fiberglass wick. Laboratory column studies using Ottawa sand spiked with tri- and tetrachlorobenzenes evaluated the accuracy of the sampling device in assessing average pore-water concentrations. The findings from these experiments showed that the sorbent-wick sampler provided reliable and repeatable estimates of the pore-water concentrations of the chlorobenzenes in the unsaturated soil columns at pore-water concentrations as low as several parts per billion. Field trials were conducted in a land biotreatment unit containing industrial soil/sludge materials to assess the availability of trace levels of aqueous-phase polychlorinated biphenyls (PCBs). The land treatment unit had undergone 5?years of intrinsic remediation and the test results indicated that the samplers were able to replicate the aqueous-phase PCB homolog pattern measured in ex situ aqueous extraction tests. Orthosubstituted PCBs were dominant in sorbent-wick samples and aqueous extracts; these PCBs appear relatively recalcitrant in land biotreatment units. The sorbent-wicking device offers the ability to obtain time-averaged mass and volumetric flux rates of HOCs in land treatment units.     

Release of Polychlorinated Biphenyls from River Sediment to Water under Low-Flow Conditions: Laboratory Assessment

The diffusive release of polychlorinated biphenyls (PCBs) from sediments to water under low-flow conditions was measured for surficial sediments with different PCB concentrations collected from the Grasse River near Massena, N.Y. Data on PCB sediment-water equilibrium partitioning and PCB mass release flux from sediments were used to assess the extent and mass transfer rate of PCB release under low-flow conditions in the Grasse River. Microcosm studies were employed to evaluate the release flux of PCBs under quiescent conditions for various river sediments and sediment mixtures. The observed total-PCB release fluxes ranged from about 1 to 20 mg/m2?year, showing predominantly dichloro- through tetrachlorobiphenyls. Analyses of water column samples from the Grasse River under low-flow conditions also indicated the predominance of dichloro- through tetrachlorobiphenyls as in the microcosm tests. Data on PCB equilibrium partitioning between water and sediment were used to estimate sediment porewater concentrations, and these data combined with the microcosm flux data were used to estimate average, aqueous-boundary-layer total-PCB mass transfer coefficients of 0.3–1.5 cm/day. These values are consistent with estimates of mass transfer coefficients based on aqueous-boundary-layer correlations, and with PCB mass transfer coefficients inferred from the field data for low-flow conditions in the fall and winter (approximately 2 cm/day). The correspondence of the laboratory results with the field measurements and mass transfer rates demonstrates the usefulness of the microcosm technique for estimating fluxes of PCBs from river sediments under low-flow minimum bioturbation conditions.     

Evaluation of Chemical Treatments for a Mixed Contaminant Soil

Treatability tests were conducted on soil from the reservoir No. 2 burning ground at the former Plum Brook Ordnance Works in Sandusky, Ohio. This soil is contaminated with explosives 2,4,6-trinitrotolune (TNT) and 2,4/2,6-dinitrotoluene (DNT), polychlorinated biphenyls (PCB, Aroclor 1260), as well as lead. Lime treatment (alkaline hydrolysis) and persulfate oxidation were tested individually and in combination to treat explosives and PCBs. Lime treatment removed 98% of TNT, 75% of DNT, and 80% of PCBs. Similar removal levels were found for persulfate treatment as well as lime followed by persulfate. The percentage of contaminant removal was found to be independent of initial contaminant concentrations. Treatments of the most contaminated soil did not meet the preliminary remediation goals for explosives or PCBs but would allow for disposal in a nonhazardous waste landfill. Treatment of soil with lower initial concentrations easily met the residential (most stringent) preliminary remediation goals of 16, 61, and 0.22?mg?kg?1 for TNT, 2,6-DNT, and PCB (Aroclor 1260), respectively. Neither alkaline hydrolysis nor persulfate oxidation transferred more than 0.02% of the lead from the soil into the reaction waters. Lead was successfully stabilized via phosphate addition.     

Microwave-Enhanced Thermal Desorption of Polyhalogenated Biphenyls from Contaminated Soil

The effect of microwave (MW) field on the rate of thermal desorption of polychlorinated biphenyls (PCBs) from long-term contaminated soil was examined in the laboratory environment. For these purposes a modified MW oven was used, with a uniformly extended MW field and a power consumption of 200–600 W. The weight of the soil samples was 100 g, the sum of concentrations of seven indicative congeners of PCB Nos. 28, 52, 101, 118, 153, 138, and 180 was, on average, 264 mg/kg of dry matter. It was experimentally proven that the efficiencies of PCB desorptions were high, over 99.9%. The maximal desorption temperature of 600°C was reached within 15–17 min. It came to light that the presence of alkaline additives in the soil (such as carbonates and alkaline metal hydroxides) did not have an apparent effect on the desorption of PCBs under those conditions. The results concerning the efficiency of PCB separations are in agreement with our previous findings regarding the efficiency of thermal desorption without using MWs in the pilot (input 35 kg) and industrial (input 15 t) desorption chambers with a stationary layer of the same type of contaminated soil. The main disadvantage of experiments with thermal desorption without the action of MWs was the low rate of heating up the soil. This study was focused to solve the problem of contamination in a complex way; we also studied the effect of MWs on the rate of the deterioration of the separated PCBs in aqueous condensates, the deterioration of PCBs in contaminated waste water containing alkaline agents (soda and lye), and on the catalytic reductive dechlorination of PCBs in the system Pd supported on active coal with sodium formate as the hydrogen donor. Experiments with the MW-enhanced catalytic reductive oxidation show over 98.5% reduction in the concentration of PCBs. An important and new finding is the more than 98% reduction in the concentration of PCBs when the MW field was applied on the contaminated water into which only 2.5% of Na2CO3 was added. Further studies on possible influences of MWs on the reaction kinetic are needed. Meanwhile we attribute the positive MW effects to their thermal properties rather than to their influence on the reaction mechanism.     

Decrease in levels and body burden of dioxins, dibenzofurans, PCBS, DDE, and HCB in blood and milk in a mother nursing twins over a thirty-eight month period

This paper presents measured dioxin, dibenzofuran, PCB, DDE and HCB blood and milk levels and estimated body burdens in a mother who nursed twins for thirty-eight months. A total of thirteen milk samples and three blood samples were collected and analyzed. Measured PCDD and PCDF levels in milk decreased from 309 and 21 ng/kg (ppt) to 173 and 9 ng/kg, respectively, between March 1993 and September 1995. Based on the decrease in breast milk dioxin levels, we estimate that the nursing mother reduced her dioxin body burden from 310 to 96 ng dioxin toxic equivalents (TEQs), or approximately 69%. In two and one half years the level of HCB in the mother's milk decreased from 10.7 to less than 1.8 ng/g (ppb), the level of DDE decreased from 246 to 46 ng/g and the total level of non-coplanar PCBs decreased from 285 to 63 ng/g, on a lipid basis. We estimate that the twin's consumption of dioxins, dibenzofurans, and coplanar PCBs from breast feeding was approximately 115 ng TEQ per twin.     

Elimination of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) from human blood in the Yusho and Yu-Cheng rice oil poisonings

The pharmacokinetics of polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in humans was studied by monitoring the blood concentrations of individuals who ingested a contaminated rice oil in Japan (yusho) in 1968 and in Taiwan (yu-cheng) in 1979. Sixteen yusho patients were followed from 1982 to 1990 and three yu-cheng individuals from 1980 to 1989. From the three yu-cheng patients, blood lipid values for the two persistent toxic congeners, 2,3,4,7,8-pentachlorodibenzofuran (PnCDF) and 1,2,3,4,7,8-hexachlorodibenzofuran (HxCDF), varied from 50 micrograms/kg at first sampling to about 1 micrograms/kg at last sampling corresponding to half-lives for elimination (t1/2) of 2-21/2 years. The blood lipid values for the same PCDF congeners in yusho patients varied from 5 micrograms/kg down to 0.1 micrograms/kg. The calculated t1/2 were more variable with median values closer to 10 years. Planar PCBs #126 and #169 were present at lower concentrations than the PCDFs. For seven of the other PCB congeners, half-lives for elimination in the yu-cheng individuals varied from 1.2 up to 4.6 yr depending on the degree of chlorination. For the yusho patients, the elimination for the PCBs was longer. These results show that clearance of the toxic PCDFs and PCBs in humans is non-linear with faster elimination at higher exposure followed by slower decreases as background levels are approached. Such a clearance pattern can best be explained by a two compartment liver and fat pharmacokinetic model.     

Biotreatment of Surfactant Flush Wastewater from Wood Treatment Soil

The high cost of surfactant enhanced aquifer remediation (SEAR) could be reduced if contaminants in the extracted surfactant flushing water could be biodegraded, and the surfactant reinjected. To test this concept, ex situ biotreatment using immobilized bacteria was simulated in laboratory columns. Nonionic surfactant solutions of 1,000–5,000?mg/L Tergitol NP-10 (TNP10) were flushed through contaminated soil collected from a wood-treatment site. The highest TNP10 dose increased the effluent concentrations of tetrachlorophenol (TeCP) and tetrachlorohydroquinone (TCHQ) by about 3 and 16 times, respectively. These wash solutions were then treated by the aerobic bacterium Sphingomonas chlorophenolica RA2 immobilized in polyurethane foam. The immobilized bacteria were capable of degrading pentachlorophenol, TeCP and TCHQ in soil flushing wastewater containing up to 4,900?mg/L TNP10. Surfactant sorption to the biotreatment columns occurred, but these losses decreased over time as the sorption capacity of the foam was exhausted. The results suggest that SEAR wastewater could be biotreated, thus enabling reinjection of the surfactant.     

2,4,6-Trinitrotoluene Transformation Using Spinacia Oleracea: Saturation Kinetics of the Nitrate Reductase Enzyme

A series of aqueous phase and soil-slurry phase microcosm studies were conducted on 2,4,6-trinitrotoluene (TNT) to obtain kinetic data for optimizing a treatment protocol using an enzyme extract from spinach (Spinacia oleracea). Crude extract was obtained by homogenization of fresh leaves with a buffered protease inhibitor, and employed as phytoremediation agent. Aqueous phase microcosms containing 20?mg/L TNT and soil–slurry microcosms containing 1 g of a characterized sandy loam soil contaminated with 2,500?mg/kg TNT and 1,000?mg/kg hexahydro-1,3,5-trinitro-1,3,5-triazine were dosed with fixed aliquots of extract and analyzed for TNT transformation over time. The TNT concentration was monitored using a colorimetric method for nitroaromatic compounds based on EPA Method 8515. Nitrate reductase activity of the applied crude extract was simultaneously quantified. The transformation of TNT was described by a pseudofirst-order reaction. Coupling kinetic rate information with enzyme activity allowed for estimation of a second-order rate constant with respect to activity. A rectangular hyperbola function normalized for enzyme activity described observed kinetic data based on enzyme saturation, similar to a Michaelis–Menten relationship. Pseudofirst-order rate constants for the aqueous phase and soil–slurry phase experiments were fit to this function. The maximum rate of reaction (kmax) for TNT transformation was 0.50 and 0.04?h?1 for aqueous phase and soil–slurry phase experiments, respectively, while respective half-saturation constants (Ksat*) were comparable in value at 0.63 and 0.28?U/μmol–NO2, respectively. A Hanes–Woolf plot of reaction velocity versus TNT concentration with and without soil suggests an uncompetitive inhibition mechanism may be affecting overall nitrate reductase efficacy. Temperature effects for both aqueous phase and soil–slurry phase microcosms followed the Arrhenius relationship with estimated activation energies of 54.7 and 26.1?kJ/mol, respectively.     

In vivo and in vitro percutaneous absorption and skin decontamination of arsenic from water and soil

Polychlorinated biphenyls (PCBs) are ubiquitous and persistent environmental pollutants. The major resident site for these PCBs is the soil, and human skin is frequently in contact with soil. Our objective was to determine the percutaneous absorption of the PCBs Aroclor 1242 and Aroclor 1254 from soil. PCB-contaminated soil was prepared at levels of 44 ppm Aroclor 1242 and 23 ppm Aroclor 1254. PCB concentrations on skin were 1.75 micrograms/cm2 for Aroclor 1242 and 0.91 microgram/cm2 for Aroclor 1254. In vivo percutaneous absorption in the rhesus monkey was determined by urinary and fecal [14C]-PCB excretion for a 5-wk period following topical dosing. Absorption of Aroclor 1242 was determined in vitro with human skin for comparative purposes. In vivo in the rhesus monkey the percutaneous absorption of Aroclor 1242 was 13.8 +/- 2.7 (SD)% of the dose and the absorption of Aroclor 1254 was 14.1 +/- 1.0%. These absorption amounts are similar to the absorption of Aroclor 1242 and 1254 from other vehicles (mineral oil, trichlorobenzene, acetone). With in vitro percutaneous absorption through human skin, most of the Aroclor 1242 and Aroclor 1254 resided in the skin and the amounts were dependent upon dosing vehicle (water > mineral oil > soil). Both PCBs readily partitioned from water into soil and human powdered stratum corneum. By difference the partitioning favored both PCBs going from soil into stratum corneum. These data emphasize the role of soil in percutaneous absorption and provide information for appropriate risk assessment.     

Fate and risk evaluation of persistent organic contaminants and related compounds in Victoria Harbour, Hong Kong

The Environment Protection Department of Hong Kong has a monitoring program for persistent organic contaminants in sediments of Victoria Harbour, the main harbour of Hong Kong. A fugacity model has been used, based on this sedimentary data, to estimate inputs to the system (probably from sewage, stormwater and industrial discharges) as well as the fate of the contaminants, particularly in terms of the aqueous and biotic concentrations. The risk of deleterious effects on the natural marine system, as well as on the consumers of seafood from the system, was carried out using the estimated aqueous and biotic concentrations together with accepted environmental quality guidelines. The result of our analysis indicated that the chlorohydrocarbons, PCBs (as Aroclor 1254) total DDT and total HCH pose a significant risk, and probably have caused damage to the marine ecosystem as well as posing a hazard to seafood consumers. Much higher concentrations of the less toxic total alkanes, nonaromatic hydrocarbons, linear alkyl benzenes and the compounds giving a unresolved complex mixture (UCM) cannot be evaluated due to a lack of environmental guidelines and the complexity of these substances. However, it is probable that these substances add adverse effects to those due to the other contaminants.     

PCBs and PCTs in wolves (Canis lupus, L) in Galicia (N.W. Spain)

Levels of PCBs and PCTs (the Aroclor1260 and Aroclor5460 congeners, respectively) in viscera of wolves of Galicia (N.W. Spain) were determined by capillary GC with electron-capture detection. Mean PCB levels ranged from 0.13 mg/kg of dry tissue in kidney to 3.70 mg/kg in liver. PCTs were detected only in suprarenal capsule, their mean level being 3.77 mg/kg.     

Dioxin-like and non-dioxin-like toxic effects of polychlorinated biphenyls (PCBs): implications for risk assessment

Polychlorinated biphenyls (PCBs) are persistent, bioaccumulative, and toxic contaminants in the environment. Individual PCB congeners exhibit different physicochemical properties and biological activities that result in different environmental distributions and toxicity profiles. The variable composition of PCB residues in environmental matrices and their different mechanisms of toxicity complicate the development of scientifically based regulations for the risk assessment. In this article various approaches for the assessment of risks of PCBs have been critically examined. Recent developments in the toxic equivalency factor (TEF) approach for the assessment of toxic effects due to dioxin-like PCBs have been examined. PCB exposure studies that describe non-dioxin-like toxic effects, particularly neurobehavioral effects and their effective doses in animals were compiled. A comparative assessment of effective doses for dioxin-like and non-dioxin-like effects by PCBs has been made to evaluate the relative significance of non-ortho-and ortho-substituted PCBs in risk assessment. Using mink as an example, relative merits and implications of using TEF and total PCB approaches for assessing the potential for toxic effects in wildlife was examined. There are several advantages and limitations associated with each method used for PCB risk assessment. Toxic effects due to coplanar PCBs occur at relatively smaller concentrations than those due to non-dioxin-like PCBs and therefore the TEF approach derives the risk assessment of PCBs, in the environment. The need for the refinement of TEF approach for more accurate assessment of risks is discussed.     

Treatment of Cr(VI) in COPR Using Ferrous Sulfate–Sulfuric Acid or Cationic Polysulfides

Column tests were conducted to evaluate two treatment strategies for reducing and stabilizing hexavalent chromium, Cr(VI), in chromium ore processing residue (COPR): permeation with a FeSO4–H2SO4 solution and blending with a cationic polysulfide reagent (CaSX). Cr(VI) leached at concentrations exceeding 50?mg/L from untreated COPR permeated with synthetic groundwater for >20 pore volumes of flow (PVF), and concentrations of Cr(VI) in the solid phase remained high (6,600?mg/kg). Permeation with solutions containing FeSO4–H2SO4 eliminated Cr(VI) from the effluent after initial, elevated leaching of Cr(VI) (100–1,500?mg/kg); however, high solid-phase concentrations of Cr(VI) remained in the column residuals (>1,300?mg/kg). COPR treated with CaSX leached Cr at <0.33?mg/L for 23.5 PVF and had solid-phase concentrations of Cr(VI) <10?mg/kg, although mineralogical analyses of treated solids showed potential chromate-containing mineral phases. Mineralogical analyses showed that precipitation and cementation occurred in the pore space of the COPR permeated with FeSO4–H2SO4, initially lowering the hydraulic conductivity > two orders of magnitude. However, acid dissolution channels eventually formed, resulting in preferential flow. COPR permeated with FeSO4–H2SO4 contained less brownmillerite and Cr(VI)-bearing hydrocalumite and hydrogarnet relative to untreated COPR. For COPR treated with CaSx, S encapsulated the subparticles of COPR with some micropore penetration, suggesting permanence of excess reductant after leaching with 23.5 PVF of synthetic rainwater.     

Dioxins, dibenzofurans, dioxin-like PCBs, and DDE in U.S. fast food, 1995

Food, especially dairy products, meat, and fish, is the primary source of environmental exposure to dioxins in the general population. Little data exists on dioxin levels in the popular and widely consumed "fast foods". Data presented in a previously published pilot study was limited to measuring only the levels of dioxins and dibenzofurans in three types of U.S. fast food. This study adds to the previous paper by presenting data, in addition to dioxins and dibenzofurans, on the closely related dioxin-like polychlorinated biphenyls (PCBs), and the persistent metabolite of DDT, 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (DDE), in four types of popular U.S. fast food. These include McDonald's Big Mac Hamburger, Pizza Hut's Personal Pan Pizza Supreme, Kentucky Fried Chicken (KFC) three piece original recipe mixed dark and white meat luncheon package, and H?agen-Daz chocolate-chocolate chip ice cream. Dioxin plus dibenzofuran dioxin toxic equivalents (TEQ) ranged from 0.03 to 0.28 TEQ pg/g wet or whole weight for the Big Mac, from 0.03 to 0.29 for the Pizza, from 0.01 to 0.31 for the KFC, and from 0.03 to 0.49 TEQ pg/g for the ice cream. Daily TEQ consumption per kilogram body weight (kg/BW), assuming an average 65 kg adult and a 20 kg child, from one serving of each of these fast food ranged between 0.046 and 1.556 pg/kg in adults whereas in children the values were between 0.15 and 5.05 pg/kg. Total measured PCDD/Fs in the Big Mac, Personal Pan Pizza, KFC, and the H?agen-Daz ice cream varied from 0.58 to 9.31 pg/g. Measured DDE levels in the fast foods ranged from 180 to 3170 pg/g. Total mono-ortho PCB levels ranged up to 500 pg/g or 1.28 TEQ pg/g for the KFC and for di-ortho PCBs up to 740 pg/g or 0.014 TEQ pg/g for the pizza sample. Total PCB values in the four samples ranged up to 1170 pg/g or 1.29 TEQ pg/g for the chicken sample.     

Amphoteric Effect of Humic Acids in Surfactant-Aided Photolysis of Polychlorobiphenyls

Polychlorobiphenyls (PCBs) are one of the most environmentally problematic organic contaminants present in soils and sediments due to their long-life in direct disposal or spills in soil. It is known that surfactant-aided soil washing followed by a photodechlorination process has the ability to separate PCBs from the soil and decompose them all in one step. However, the influence of humic substances on the removal of PCBs in surfactant-aided ultraviolet systems is of special interest because of the involvement of humic materials in the soil-washing process. A PCB congener, 4,4′-dichlorobiphenyl (DCB), was used as a probe in this study. At low humic acid (HA) concentrations, humic substances promote the photochemical reaction, but a high dose of HA leads to retardation of the DCB decay. A mechanism for the amphoteric effect of HA on the photodecay of DCB is proposed in this study, and two mathematical models are developed to successfully rationalize the amphoteric effect of HA in the photolysis process.     

Cyclodextrin-Enhanced Electrokinetic Remediation of Soils Contaminated with 2,4-Dinitrotoluene

The removal of 2,4-dinitrotoluene (2,4-DNT), a munitions waste constituent and an industrial intermediate, from contaminated soils was evaluated using enhanced electrokinetic (EK) remediation. Two model soils were spiked with 480?mg of 2,4-DNT/kg of dry soil for the EK experiments. The spiked soils were kaolin, a low-buffering clayey soil, and glacial till, a high-buffering silty soil. The glacial till was obtained from a field site and contained 2.8% organic matter. Deionized (DI) water and cyclodextrin solutions were used as the EK purging solutions. Cyclodextrin was selected as a nonhazardous solubility enhancer for enhancing the desorption and removal of 2,4-DNT from soils in EK remediation. Two aqueous solutions of hydroxypropyl β-cyclodextrin (HPCD) at concentrations of 1 and 2% were selected for kaolin and glacial till, respectively, based on results for batch extraction of 2,4-DNT from the same soils. During the EK experiments, greater current and electro-osmotic flow were observed for HPCD solutions than for DI water. After the completion of the EK experiments, the soils in the EK cell were extruded and the residual 2,4-DNT in the soils was determined. Less 2,4-DNT remained in the kaolin soil (up to 94% transformed) than in the glacial till soil (20% transformed) due to strong retention of 2,4-DNT by the soil organic matter in glacial till. For kaolin, less 2,4-DNT remained in the soil using HPCD solutions than using DI water. For glacial till, comparable levels of 2,4-DNT remained in the soil for both EK solutions. Since no 2,4-DNT was detected in the effluents from the EK cells, the decrease in 2,4-DNT concentration in the kaolin and glacial till soils was attributed to electrochemical transformation of 2,4-DNT to other species.     

Repeated exposure of adult rats to Aroclor 1254 causes brain region-specific changes in intracellular Ca2+ buffering and protein kinase C activity in the absence of changes in tyrosine hydroxylase

Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants, some of which may be neurotoxic. In vitro studies from this laboratory indicated that noncoplanar PCBs perturbed intracellular signal transduction mechanisms including Ca2+ homeostasis, receptor-mediated inositol phosphate production, and translocation of protein kinase C (PKC). In the present study, we examined the effects of PCBs in vivo by dosing adult male Long-Evans rats orally with Aroclor 1254 (0, 10, or 30 mg/kg/day; 5 days/week for 4 weeks) in corn oil. At 24 h after the last dose, rats were tested for motor activity in a photocell device for 30 min. Immediately, the rats were euthanized, blood was collected for thyroid hormone analysis, and brains were removed, dissected into regions (cerebellum, frontal cortex, and striatum), and subcellular fractions were obtained for neurochemical analysis. Following Aroclor 1254 treatment, body weight gain in the high-dose group was significantly lower than the control and low-dose groups. Horizontal motor activity was significantly lower in rats dosed with 30 mg/kg Aroclor 1254. Ca2+ buffering by microsomes was significantly lower in all three brain regions from the 30 mg/kg group. In the same dose group, mitochondrial Ca2+ buffering was affected in cerebellum but not in cortex or striatum. Similarly, total cerebellar PKC activity was decreased significantly while membrane-bound PKC activity was significantly elevated at 10 and 30 mg/kg. PKC activity was not altered either in cortex or the striatum. Neurotransmitter levels in striatum or cortex were slightly altered in PCB-exposed rats compared to controls. Furthermore, repeated oral administration of Aroclor 1254 to rats did not significantly alter forebrain tyrosine hydroxylase immunoreactivity or enzymatic activity. Circulating T4 (total and free) concentrations were severely depressed at both doses in Aroclor 1254-exposed rats compared to control rats, suggesting a severe hypothyroid state. These results indicate that (1) in vivo exposure to a PCB mixture can produce changes in second messenger systems that are similar to those observed after in vitro exposure of neuronal cell cultures; (2) second messenger systems seem to be more sensitive than alterations in neurotransmitter levels or tyrosine hydroxylase involved in dopamine synthesis during repeated exposure to PCBs; and (3) the observed motor activity changes were independent of changes in striatal dopamine levels.     

Serum concentration of calcium, 1,25 vitamin D and parathyroid hormone are not correlated with coronary calcifications. An electron beam computed tomography study

As a consequence of contamination by effluents from local electronics manufacturing facilities, the New Bedford Harbor and estuary in southeastern Massachusetts is among the sites in the United States that are considered the most highly contaminated by polychlorinated biphenyls (PCBs). Since 1993, measures of intrauterine PCB exposure have been obtained for a sample of New Bedford area infants. Among 122 mother-infant pairs, we identified four milk samples with total PCB levels that were significantly higher than the rest, with estimated total PCBs ranging from 1,100 to 2,400 ng/g milk fat compared with an overall mean of 320 ng/g milk fat for the 122 women. The congener profile and history of one case was consistent with past occupational PCB exposures. Otherwise, the source of PCB exposures in these cases was difficult to specify. Environmental exposures including those from fish consumption were likely, whereas residence adjacent to a PCB-contaminated site was considered an unlikely exposure source. In all four cases, the infants were full-term, healthy newborns. Because the developing nervous system is believed to be particularly susceptible to PCBs (for example, prenatal PCB exposures have been associated with prematurity, decrements in birth weight and gestation time, and behavioral and developmental deficits in later infancy and childhood, including decrements in IQ), it is critical to ascertain if breast-feeding is a health risk for the women's infants. Despite the potential for large postnatal PCB exposures via breast milk, there is limited evidence of significant developmental toxicity associated with the transmission of moderate PCB concentrations through breast milk. Breast-feeding is associated with substantial health benefits including better cognitive skills among breast-fed compared with formula-fed infants. We conclude, based on evidence from other studies, that the benefits of breast-feeding probably outweigh any risk from PCB exposures via breast milk among the four New Bedford infants. In this case report, PCB analysis of breast milk and infant cord serum was a research tool. PCB analysis of milk is rarely done clinically, in part because it is difficult to use the results of such analyses to predict health risks. Substantial effort is needed to achieve a better understanding of the clinical and public health significance of PCB exposures, particularly among potentially susceptible groups such as infants and children. Such efforts are critical to improving the clinical and public health management of widespread and ongoing population exposures to PCBs.     

A mutation in the neurofibromatosis type 2 tumor-suppressor gene, giving rise to widely different clinical phenotypes in two unrelated individuals

Polychlorinated biphenyls (PCBs) are industrial chemicals that are long-lasting global environmental contaminants. PCBs have been reported to adversely affect reproduction in laboratory and wild animals by reducing the incidence of breeding and the survival rate of young. The present study was undertaken to determine the toxic potential of PCBs on in vitro fertilization (IVF) in the mouse. Aroclor 1221, 1254, and 1268, and 3, 3', 4, 4'-tetrachlorobiphenyl (TCB), a PCB congener, were added to IVF medium at various concentrations (0.01, 0.1, 1, and 10 micrograms/mL). Cumulus masses containing oocytes were obtained from superovulated B6D2F1 mice and cultured in medium containing PCB to which capacitated sperm were added. Oocytes were assessed for fertilization 20 to 24 h after insemination. A-1221, A-1268, and TCB reduced the fertilization rate at the 1 microgram/mL and 10 micrograms/mL doses, while inhibition of fertilization by A-1254 reached significance at 0.1 microgram/ml. Furthermore, all of these chemicals caused an increased incidence of degenerative ova and abnormal 2-cell embryos at the higher dose levels (1 microgram/mL and 10 micrograms/mL). The results suggest that higher dosages of PCB and TCB adversely affect fertilization and cause an increased incidence of degeneration of oocytes and abnormality in the early mouse embryos.