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PubMed2000

Nonfatal work-related inhalations: surveillance data from hospital emergency departments, 1995-1996.

BACKGROUND: Data from a stratified sample of hospital emergency rooms in the USA were used to describe nonfatal work-related inhalation injuries and illnesses during July 1995 to July 1996. METHODS: Information was abstracted from emergency room records by the Consumer Product Safety Commission (CPSC) as part of the National Electronic Injury Surveillance System (NEISS) for all work-related injuries and illnesses regardless of product involvement. RESULTS: There were an estimated 44,423 occupational inhalation cases nationwide, with an annual rate of 3.6 cases/10(4) workers/year. The rate for men (4.4 cases/10(4)) was greater than that observed for women (2.6 cases/10(4)), and the rates tended to decline with increasing age. An estimated 4.6% of the cases were hospitalized for further treatment. The highest rate by industry was 16.4 cases/10(4) for public administration (which included fire and police departments). Among non-firefighters, there were an estimated 6,470 cases nationwide in which respiratory symptoms or conditions were noted, which yielded an annual rate of 0.5 cases/10(4) (95% CI 0.3, 0.7). Chlorine compounds were a common agent for the cases with adverse respiratory outcomes. CONCLUSIONS: The NEISS data provide an efficient method to learn about the national frequency of work-related inhalation injuries and illnesses. The National Institute for Occupational Safety and Health (NIOSH) is exploring two ways to use these data: first, to routinely review the reports to conduct surveillance for work-related inhalation cases; and second, to consider working with CPSC to conduct follow-back interviews of selected cases in order to learn more about the circumstances of the exposure, prior training of the case, and outcome of the exposure. Am. J. Ind. Med. 38:140-148, 2000. Published 2000 Wiley-Liss, Inc.

Adolescent↗

PubMed2005

Riboflavin- and cobalamin-mediated biodegradation of chloroform in a methanogenic consortium.

Chloroform (CF) is an important priority pollutant contaminating groundwater. Reductive dechlorination by anaerobic microorganisms is a promising strategy towards the remediation of CF. The objective of this study was to evaluate the use of redox active vitamins as electron shuttles to enhance the anaerobic biodegradation of CF in an unadapted methanogenic consortium not previously exposed to chlorinated compounds. Only negligible degradation of CF was observed in control cultures lacking redox active vitamins. The addition of riboflavin (RF), cyanocobalamin (CNB12), and hydroxycobalamin (HOB12) enabled biodegradation of CF. The reactions were predominantly catalyzed biologically as evidenced by the lack of any CF conversion in heat-killed controls amended with the cobalamins or minor conversion with RF. In live cultures, significant increases in the rate of CF conversion was observed at substoichiometric molar ratios as low as 0.1 to 0.01 vitamin:CF for RF and CNB12, respectively. At the highest molar vitamin:CF ratios tested of 0.2, the first-order rate constant of CF degradation was 5.3- and 91-fold higher in RF and CNB12 amended cultures, respectively, compared to the unamended control culture. The distribution of biotransformation products was highly impacted by the type of redox active vitamin utilized. Cultures supplemented with RF provided high yields of dichloromethane (DCM). On the other hand, cobalamins promoted the near complete mineralization of organochlorine in CF to inorganic chloride and lowered the yield of DCM. In cultures where no or little CF bioconversion occurred, prolonged exposure to CF resulted in cell lysis, as evidenced by the release of intracellular chloride. The results taken as a whole suggest that the anaerobic bioremediation of CF-contaminated sites can greatly be improved with strategies aimed at increasing the concentration of redox active vitamins.

Biodegradation, Environmental↗

PubMed1985

Teratologic evaluation of Alcide liquid in rats and mice. I.

Alcide, a liquid sterilizer, was evaluated for teratogenic potential in rats and mice. Sodium chlorite and lactic acid, the active ingredients of this compound, form chlorine dioxide when mixed. Pregnant rats and mice were administered 1 ml and 0.1 ml, respectively, of Alcide liquid by gavage on days 6-15 of gestation. The general health of the dams was evaluated and the fetuses examined for external, visceral and skeletal malformations. There was no evidence of maternal toxicity among treated rats and mice. Fetal viability, weight, length and number of resorptions were comparable with control groups. Teratogenic toxicity was not detected in either species. There was some incidence of skeletal and visceral anomalies; however, these variances were not significantly different from control animals.

Abnormalities, Drug-Induced↗

PubMed2005

Quantitative determination of endogenous sorbitol and fructose in human nerve tissues by atmospheric-pressure chemical ionization liquid chromatography/tandem mass spectrometry.

Attachment of anions to sorbitol and fructose has been shown to enhance sensitivity in both electrospray ionization (ESI) and atmospheric-pressure chemical ionization (APCI) mass spectrometry. The post-column addition of CHCl3 produced Cl-adducts of sorbitol and fructose but their signals were suppressed due to the elevated background. Different chlorinated compounds and different additive methods were systematically investigated to form more abundant Cl-adduct precursor ions and deprotonated product ions. The major causes of the high background were explored and effective methods were developed to improve the signal-to-noise ratios and reproducibility. The compositions of mobile phase, percentages of organic modifiers (MeCN, MeOH and water), columns, oven temperature, flow rates and different gradients were investigated to separate sorbitol from fructose along with their isomers including glucose, galactose, mannose, sorbose, mannitol, and dulcitol. The optimized separation was achieved on a Luna 5 mu NH2 100A column (150 x 4.6 mm) using a mobile phase containing MeCN with 0.1% of CH2Cl2 and 50% MeOH in water at a flow rate of 800 microL/min and an oven temperature of 40 degrees C using a gradient liquid chromatography (LC) system. Human nerve tissue samples were extracted by protein precipitation followed by mixed-mode solid-phase extraction. The LC/ESI-MS/MS method produced higher peak intensities than LC/APCI-MS/MS. However, there were matrix effects from extracted tissues in LC/ESI-MS/MS but not in LC/APCI-MS/MS. Consequently, APCI proved to be the more effective method of ionization. Then the LC/APCI-MS/MS method was fully validated and successfully applied to analysis of clinical samples. The concentrations of endogenous sorbitol and fructose were determined using calibration curves employing sorbitol-13C6 and fructose-13C6 as surrogate analytes. The method has provided excellent intra- and inter-assay precision and accuracy with linear ranges of 0.2-80 ng/mg for sorbitol and 1-400 ng/mg for fructose in human nerve tissues.

Atmospheric Pressure↗

PubMed2002

Distribution of organobrominated and organochlorinated contaminants in Belgian human adipose tissue.

We have measured the levels of flame retardants, polybrominated diphenyl ethers (PBDEs), in 20 recent human adipose tissues from Belgium and compared them to other organohalogen compounds such as polychlorinated biphenyls (PCBs), hexachlorobenzene, 2,2-bis(4-chlorophenyl)-1,1,1-trichloroethane (p,p'-DDT), and its metabolite, 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE). After Soxhlet extraction and cleanup on acidified silica solid-phase extraction cartridges, analysis was achieved by capillary gas chromatography/electron impact mass spectrometry. The method allowed the determination of 5 PBDE and 35 PCB congeners. Concentrations of PBDEs (sum of congeners IUPAC Nos. 28, 47, 99, 100, and 153) ranged between 2.2 and 11.7 ng/g lipid weight and were on the lower end of reported PBDE concentrations in European countries. The median value for the sum of PCBs (35 congeners) was 841 ng/g lipid weight and ranged from 286 to 1802 ng/g lipid weight. The median value for the sum of DDTs (calculated from p,p'-DDE and p,p'-DDT) was 290 ng/g lipid weight and ranged from 47 to 2802 ng/g lipid weight. The sum of PCBs showed a good correlation with the sum of DDTs (r=0.77, P<0.05), while the correlation with the sum of PBDEs was weaker (r=0.56, P<0.05). No age dependency was found for PBDEs (r=0.09), while PCBs and DDTs showed higher correlation coefficients with age (r=0.59 and 0.40, respectively, P<0.05).

Adipose Tissue↗

PubMed1998

Digestive tract absorption of PCDD/Fs, PCBs, and HCB in humans: mass balances and mechanistic considerations.

Gastrointestinal absorption of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs) and hexachlorobenzene (HCB) from food was investigated in seven individuals aged 24 to 81 years with different contaminant body burdens using a mass balance approach. The difference between the ingested and excreted amounts of the chlorinated compounds was defined as net absorption. No analyzed compound was absorbed completely, and some were excreted to a greater extent than ingested, resulting in a net excretion. The absorption behavior was predominantly controlled by blood lipid levels: good correlations were obtained between the net absorption and the lipid-based concentrations in the blood for almost all of the persistent compounds studied. Expressed in international toxicity equivalents (I-TEq), the maximum absorption of PCDD/Fs among the volunteers was 63% and, for the three oldest volunteers, a net excretion of I-TEq was found. The high absorption levels of many compounds could not be explained on the basis of diffusive gradients estimated from the difference between the lipid-based food and blood concentrations; the diffusive gradient was consistently negative. Adding a factor to account for the reduction in the lipid content of the food during passage through the digestive tract did not resolve this problem. To explain this discrepancy, a "fat-flush" theory was postulated, which hypothesizes that the fat compartment of the absorbing tissue expands due to the uptake of dietary fat, resulting in a decrease of this compartment's lipid-based concentrations below the food's, hence facilitating absorption. The fat-flush hypothesis provides a theoretical basis for a two-step model of organic pollutant transfer in the gastrointestinal tract, with absorption and excretion as distinct processes occurring at different locations.

Adult↗

PubMedDate not supplied

Microbial reductive dechlorination of PCBs.

Reductive dechlorination is an advantageous process to microorganisms under anaerobic conditions because it is an electron sink, thereby allowing reoxidation of metabolic intermediates. In some organisms this has been demonstrated to support growth. Many chlorinated compounds have now been shown to be reductively dechlorinated under anaerobic conditions, including many of the congeners in commercial PCB mixtures. Anaerobic microbial communities in sediments dechlorinate Aroclor at rates of 3 micrograms Cl/g sediment x week. PCB dechlorination occurs at 12 degrees C, a temperature relevant for remediation at temperate sites, and at concentrations of 100 to 1000 ppm. The positions dechlorinated are usually meta > para > ortho. The biphenyl rings, and the mono-ortho- and diorthochlorobiphenyls were not degraded after a one year incubation. Hence subsequent aerobic treatment may be necessary to meet regulatory standards. Reductive dechlorination of Aroclors does reduce their dioxin-like toxicity as measured by bioassay and by analysis of the co-planar congeners. The most important limitation to using PCB dechlorination as a remediation technology is the slower than desired dechlorination rates and no means yet discovered to substantially enhance these rates. Long term enrichments using PCBs as the only electron acceptor resulted in an initial enhancement in dechlorination rate. This rate was sustained but did not increase in serial transfers. Bioremediation of soil contaminated with Aroclor 1254 from a transformer spill was dechlorinated by greater than 50% following mixing of the soil with dechlorinating organisms and river sediment.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteria, Anaerobic↗

PubMed1979

Translocation, distribution, and environmental degradation of hexachlorophene in tomatoes.

The translocation, distribution, metabolism and environmental degradation of hexachlorophene were investigated in tomato plants (Lycopersicon esculentum Mill cv. beefsteak). All plants were grown under standardized conditions and treated with leaf-applied 14C-ring-labeled hexachlorophene (HCP). Treatment time ranged from 0 to 70 days. Autoradiographic analyses were performed on all plants. Selected plant tissues were extracted and chromatographed, using thin layer (TLC) and gas liquid chromatography (GLC). Hexachlorophene was not translocated from the plant leaves. No metabolites of hexachlorophene was found. A slight, but statistically nonsignificant, amount of HCP was lost from the leaves and the inert controls. At the end of the 70-day treatment, based on TLC and regression analysis of thin layer chromatographic plates, averages of 89.5% and 75.9% of the applied HPC remained unaltered on the treated plants and controls, respectively. This indicated that 10.5% and 24.1%, respectively, of the original HCP had been altered. Differences between the treatments and controls were statistically significant after 28 days of exposure. Further analyses of the above data, using gas chromatographic methods, showed that as many as 14 peaks were found in the treated samples and the controls, including the parent material. Ultraviolet photolysis seemed to be the mechanism responsible for alteration of the hexachlorophene. Three extracted chlorinated compounds have been identified by GC-mass spectral (MS) analysis including 2,2'-dihydroxy-3,5',6,6'-tetrachlorodiphenylmethane, 2,2'-dihydroxy-3,5,5',6,6'-pentachlorodiphenylmethane, and 2,2'-dihydroxy-3,3',5,5',6,6'-hexachlorodiphenylmethane (parent HCP). Eleven other electrophylic compounds have been found in various treated plant or control extracts. Further analyses will be necessary to verify the identification of the other degradation products.

Biodegradation, Environmental↗

PubMed1977

Chlorinated benzene induction of hepatic porphyria.

1,4-Dichlorobenzene and 1,2,4-trichlorobenzene were compared with hexachlorobenzene which is known to cause porphyria. Although hexachlorobenzene administration resulted in a manyfold increase in liver porphyrin levels and urinary excretion of porphyrins, the lesser chlorinated compounds did not do so.

Animals↗

PubMed1999

Purification and characterization of a low-molecular-weight xylanase produced by acrophialophora nainiana

A low-molecular-weight xylanase activity (XynI) was isolated from the fungus Acrophialophora nainiana after growth in a solid medium containing wheat bran. XynI was purified to apparent homogeneity by ultrafiltration and gel filtration chromatography. The purified enzyme had a molecular weight value of approx. 17 kDa, as determined by SDS-PAGE. This enzyme was most active at 50 degreesC and pH 6.0. At 50 degreesC the half-life was 150 min. The apparent Km value for birchwood xylan was much lower than the Km value for oat spelt xylan. XynI was activated by L-cysteine, DTE, beta-mercaptoethanol, and L-tryptophan. XynI did not show significant sequence homology with other xylanases. The analysis of hydrolysis products of xylans and wood pulps showed that XynI was able to release xylooligomers ranging from X2 to X3 and X2 to X6, respectively. The enzyme was not active against acetylated xylan. A small amount of xylose was released from deacetylated, birchwood, and oat spelt xylans. The results obtained with enzymatic treatment of Kraft pulp indicated a reduction in the amount of chlorine compounds required for the process and enhanced brightness gain.

Journal Article↗

PubMed1998

Pollution in the Baltic Sea.

The Baltic Sea is almost totally surrounded by land and therefore more endangered by pollution than other marine areas. The sources of marine pollution are municipal and industrial waste inputs directly into the sea or via rivers, and atmospheric inputs mainly from traffic and agriculture. The increase of inorganic plant nutrients (NH3, NOx, PO4) caused eutrophication and consequent oxygen depletion in coastal bottom waters as well as in the depths of the open sea. In the anoxic sediments, hydrogen sulfide can be produced by protein-decomposing and sulfate-reducing bacteria. The bottom fauna will be destroyed and only H2S tolerant microorganisms can survive. Originating from cellulose manufacturing and from paper mills, large amounts of poisonous chlorinated compounds contaminated the coastal waters of Sweden and Finland until the 1980s. Most of this material is still present in sediments of the central Baltic Sea and can be resuspended by near bottom currents. To reduce pollution and improve the situation in the Baltic Sea, the surrounding countries organized the Helsinki Convention, which came into force on 3.5.1980. The Helsinki Commission (HELCOM) founded in 1974 acts as coordinator and is responsible for the enforcement of the Baltic monitoring program and international research projects. The activities of HELCOM have led to the reduction of dangerous pollutants which in turn has caused the regeneration of flora and fauna in some areas. Further improvements can be expected.

Agriculture↗

PubMed2004

Limitations of low resolution mass spectrometry in the electron capture negative ionization mode for the analysis of short- and medium-chain chlorinated paraffins.

The analysis of complex mixtures of chlorinated paraffins (CPs) with short (SCCPs, C(10)-C(13)) and medium (MCCPs, C(14)-C(17)) chain lengths can be disturbed by mass overlap, if low resolution mass spectrometry (LRMS) in the electron capture negative ionization mode is employed. This is caused by CP congeners with the same nominal mass, but with five carbon atoms more and two chlorine atoms less; for example C(11)H(17)(37)Cl(35)Cl(6) ( m/ z 395.9) and C(16)H(29)(35)Cl(5) ( m/ z 396.1). This can lead to an overestimation of congener group quantity and/or of total CP concentration. The magnitude of this interference was studied by evaluating the change after mixing a SCCP standard and a MCCP standard 1+1 (S+MCCP mixture) and comparing it to the single standards. A quantification of the less abundant C(16) and C(17) congeners present in the MCCP standard was not possible due to interference from the major C(11) and C(12) congeners in the SCCPs. Also, signals for SCCPs (C(10)-C(12)) with nine and ten chlorine atoms were mimicked by MCCPs (C(15)-C(17)) with seven and eight chlorine atoms (for instance C(10)H(12)Cl(10) by C(15)H(24)Cl(8)). A similar observation was made for signals from C(15)-C(17) CPs with four and five chlorine atoms resulting from SCCPs (C(10)-C(12)) with six and seven chlorine atoms (such as C(15)H(28)Cl(4) by C(10)H(16)Cl(6)) in the S+MCCP mixture. It could be shown that the quantification of the most abundant congeners (C(11)-C(14)) is not affected by any interference. The determination of C(10) and C(15) congeners is partly disturbed, but this can be detected by investigating isotope ratios, retention time ranges and the shapes of the CP signals. Also, lower chlorinated compounds forming [M+Cl](-) as the most abundant ion instead of [M-Cl](-) are especially sensitive to systematic errors caused by superposition of ions of different composition and the same nominal mass.

Journal Article↗

PubMed2005

Redox-iodometry: a new potentiometric method.

A new iodometric method for quantifying aqueous solutions of iodide-oxidizing and iodine-reducing substances, as well as plain iodine/iodide solutions, is presented. It is based on the redox potential of said solutions after reaction with iodide (or iodine) of known initial concentration. Calibration of the system and calculations of unknown concentrations was performed on the basis of developed algorithms and simple GWBASIC-programs. The method is distinguished by a short analysis time (2-3 min) and a simple instrumentation consisting of pH/mV meter, platinum and reference electrodes. In general the feasible concentration range encompasses 0.1 to 10(-6) mol/L, although it goes down to 10(-8) mol/L (0.001 mg Cl2/L) for oxidants like active chlorine compounds. The calculated imprecision and inaccuracy of the method were found to be 0.4-0.9% and 0.3-0.8%, respectively, resulting in a total error of 0.5-1.2%. Based on the experiments, average imprecisions of 1.0-1.5% at c(Ox)>10(-5) M, 1.5-3% at 10(-5) to 10(-7) M, and 4-7% at <10(-7) M were found. Redox-iodometry is a simple, precise, and time-saving substitute for the more laborious and expensive iodometric titration method, which, like other well-established colorimetric procedures, is clearly outbalanced at low concentrations; this underlines the practical importance of redox-iodometry.

Ascorbic Acid↗

PubMed2003

Anaerobic oxidation of 2-chloroethanol under denitrifying conditions by Pseudomonas stutzeri strain JJ.

A bacterium that uses 2-chloroethanol as sole energy and carbon source coupled to denitrification was isolated from 1,2-dichloroethane-contaminated soil. Its 16 S rDNA sequence showed 98% similarity with the type strain of Pseudomonas stutzeri (DSM 5190) and the isolate was tentatively identified as Pseudomonas stutzeri strain JJ. Strain JJ oxidized 2-chloroethanol completely to CO(2) with NO(3)(- )or O(2) as electron acceptor, with a preference for O(2) if supplied in combination. Optimum growth on 2-chloroethanol with nitrate occurred at 30 degrees C with a mu(max) of 0.14 h(-1) and a yield of 4.4 g protein per mol 2-chloroethanol metabolized. Under aerobic conditions, the mu(max) was 0.31 h(-1). NO(2)(-) also served as electron acceptor, but reduction of Fe(OH)(3), MnO(2), SO(4)(2-), fumarate or ClO(3)(-) was not observed. Another chlorinated compound used as sole energy and carbon source under aerobic and denitrifying conditions was chloroacetate. Various different bacterial strains, including some closely related Pseudomonas stutzeri strains, were tested for their ability to grow on 2-chloroethanol as sole energy and carbon source under aerobic and denitrifying conditions, respectively. Only three strains, Pseudomonas stutzeri strain LMD 76.42, Pseudomonas putida US2 and Xanthobacter autotrophicus GJ10, grew aerobically on 2-chloroethanol. This is the first report of oxidation of 2-chloroethanol under denitrifying conditions by a pure bacterial culture.

Anaerobiosis↗

PubMed1986

Effect of desferrioxamine on the development of hexachlorobenzene-induced porphyria.

The present work deals with the effect of desferrioxamine (DF) on hexachlorobenzene (HCB)-induced porphyria in female rats with the purpose of further investigation of the role of iron in the development of this porphyria. The results obtained show that the repeated injection of DF (three times a week: 100 mg/kg each i.m.) delayed and diminished remarkably the urinary excretion of precursors and porphyrins as well as the accumulation of the latter in liver promoted by HCB (1 g/kg daily given by stomach tube). This was probably due to attenuation by DF of the alterations produced by the fungicide in the two key enzymes: porphyrinogen carboxy-lyase (PCL) and delta-aminolaevulinate synthase (ALA-S). In fact, DF by reducing liver iron levels produced a smaller decrease of the target enzyme (PCL) and a concomitant smaller induction of ALA-S. DF alone did not modify any of these variables or the liver to body weight ratio. DF added at 10(-2) and 10(-3) M to the incubation media of ALA-S and PCL did not alter either of the enzymatic activities, whether in normal or HCB-porphyric preparations. The results obtained show that DF improved the biochemical picture during HCB porphyria. They suggest that iron plays an indirect role in the decrease of PCL enzyme, possibly at the HCB metabolization step. A common iron-involving mechanism for the production of porphyria by different chlorinated compounds is suggested.

5-Aminolevulinate Synthetase↗

PubMed1992

Structural and electronic properties of MX compounds related to TA100 mutagenicity. A semi-empirical molecular orbital QSAR study.

The structural and electronic properties of chlorofuranones including MX and its anhydride were calculated using the semi-empirical AM1 method to elucidate the key features related to the strong mutagenic activity of MX. Significant correlations were found between Ames TA100 mutagenicity and the following electronic parameters of chlorofuranones: LUMO energy (r = 0.9607, n = 17), electron affinity (r = 0.9557), LUMO electron density at the alpha-carbon (r = 0.8855) and partial charge of the alpha-carbon (r = 0.8812). Based on these results, a molecular orbital QSAR model for the mutagenic activity of 17 MX analogues is presented. The controversial role of the open-chain tautomers of MX compounds, chlorinated butenoic acids, is discussed briefly.

Furans↗

PubMed1994

Environmental pollution and human health.

Contacts of humans with chemicals from the environment occur via air, water or food. In the past most attention was paid to the contamination of water. Well developed and stringent legislation exists in most countries, although health impairments never occurred from environmental chemicals in drinking water. Xenobiotics in water mainly have a marker function for the general pollution of the environment. Therefore measures to detect and eliminate the sources of contamination are often inappropriately taken. For some persistent and (usually) lipophilic xenobiotics in food, especially from animal origin, acts as carrier. The lipophilic persistent chlorinated compounds, such as DDT, PCBs and dioxins and the heavy metals lead, cadmium and mercury are accumulated in livestock and are there leading to much higher concentrations than in the environment. So far these compounds have not yet reached concentrations which are representing a health risk. A range of environmental chemicals coming from the air act directly on the site of first contact through their cytotoxic property. For many of them the margin of safety is low or even non-existent. Inorganic acid anhydrides, such as SO2, SO3 or NOx often occur in industrialized areas at levels affecting the pulmonary function of susceptible people, such as asthmatics or patients with chronic bronchitis. Ozone and photochemical smog represent another group of important environmental irritants. The intake of airborne lead has diminished in the last 20 years by a factor of 2-3 as a consequence of the most remarkable decrease in the use of leaded gasoline.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollutants↗

PubMed1991

Sensitive periods for behavioral toxicity of polychlorinated biphenyls: determination by cross-fostering in rats.

Polychlorinated biphenyls (PCBs) are transferred to developing organisms via the milk rather than through placental barriers. Recent epidemiological data, however, suggest a greater importance of the prenatal exposure period for the development of neuropsychological disorders. The relative effectiveness of pre- and postnatal PCB exposure was compared in a cross-fostering experiment in rats. Female Wistar rats were fed diets containing 0 or 30 mg PCB/kg. After birth half of the litters in each exposure group were nursed by dams of the other condition. Six different congeners were determined in the brains of the offspring at various ages. Internal exposure to higher chlorinated congeners peaked at weaning in groups with postnatal or permanent exposure, whereas the concentration of a low-chlorinated compound was lower at weaning than at birth or at later age stages. Brain tissue levels in prenatally treated rats declined with aging. In two behavioral paradigms, active avoidance learning and retention of a visual discrimination task, prenatally exposed rats exhibited alterations similar to those of permanently treated subjects, while postnatal exposure caused no detectable behavioral changes. These results support the above-mentioned epidemiological studies which related neurodevelopmental deficits in children to prenatal PCB exposure.

Animals↗