PCB and dioxin levels in plasma and human milk of 418 Dutch women and their infants. Predictive value of PCB congener levels in maternal plasma for fetal and infant's exposure to PCBs and dioxins

Polychlorinated biphenyls (PCBs) as well as dioxins (polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs)) are potentially hazardous compounds in the environment for human beings. In order to investigate PCB and dioxin exposure of Dutch women and their neonates, levels were examined in 418 mother-infant pairs. Four non-planar PCB congener levels (PCB 118, 138, 153 and 180) were measured in maternal plasma and in umbilical cord plasma. The 209 mothers who breast-fed their infants collected human milk samples for the analysis of seventeen 2,3,7,8-substituted PCDD and PCDF congener levels, three planar PCB and twenty-three non-planar PCB congener levels. The dioxin and planar PCB levels we measured in human milk (mean 30 respectively 16 pg TEQ/g fat), belong to the highest background levels analysed all over the world but they are in the normal range for highly industrialised, densely populated countries in Western Europe. Correlation coefficients between PCB 118, 138, 153 and 180 congener levels in maternal plasma and PCB levels in cord plasma or PCB and dioxin levels in human milk are highly significant. However, the 95% predictive interval is too wide to predict accurately the PCB and dioxin levels to which an individual infant is exposed in utero or postnatally by breast-feeding, from the PCB levels in maternal plasma

Evaluating the Role of the Steroid and Xenobiotic Receptor (SXR/PXR) in PCB-153 Metabolism and Protection against Associated Adverse Effects during Perinatal and Chronic Exposure in Mice.

BACKGROUND:Polychlorinated biphenyls (PCBs) are environmental toxicants; PCB exposure has been associated with adverse effects on wildlife and humans. However, the mechanisms underlying these adverse effects are not fully understood. The steroid and xenobiotic receptor [SXR; also known as the pregnane X receptor (PXR) and formally known as NR1I2] is a nuclear hormone receptor that regulates inducible metabolism of drugs and xenobiotics and is activated or inhibited by various PCB congeners. OBJECTIVES:The aim of this study was to investigate the effects of exposure to PCB-153, the most prevalent PCB congener in human tissues, on SXR knockout mice (SXRKO) and to elucidate the role of SXR in PCB-153 metabolism and promotion of its harmful effects. METHODS:Wild-type (WT) and SXRKO mice were chronically or perinatally exposed to a low dose (54μg/kg/d) of PCB-153. Blood, livers, and spleens were analyzed using transcriptome sequencing (RNA-seq) and molecular techniques to investigate the impacts of exposure on metabolism, oxidative stress, and hematological parameters. RESULTS:SXRKO mice perinatally exposed to PCB-153 displayed elevated oxidative stress, symptoms of hemolytic anemia, and premature death. Transcriptomal analysis revealed that expression of genes involved in metabolic processes was altered in SXRKO mice. Elevated levels of the PCB-153 metabolite, 3-OH-PCB-153, were found in exposed SXRKO mice compared to exposed WT mice. Blood hemoglobin (HGB) levels were lower throughout the lifespan, and the occurrence of intestinal tumors was larger in SXRKO mice chronically exposed to PCB-153 compared to vehicle and WT controls. DISCUSSION:Our results suggest that altered metabolism induced by SXR loss of function resulted in the accumulation of hydroxylated metabolites upon exposure to PCB-153, leading to oxidative stress, hemolytic anemia, and tumor development in a mouse model. These results support a major role for SXR/PXR in protection against xenobiotic-induced oxidative stress by maintaining proper metabolism in response to PCB-153 exposure. This role of SXR could be generally applicable to other environmental toxicants as well as pharmaceutical drugs. https://doi.org/10.1289/EHP6262

PCBs in cod (<i>Gadus morhua</i>), flounder (<i>Platichthys flesus</i>), blue mussel (<i>Mytilus edulis</i>) and brown shrimp (<i>Crangon crangon</i>) from the Belgian Continental Shelf: relation to biological parameters and trend analysis

PCB levels in cod, flounder, mussel and shrimp, covering a ten-year period, were assessed for temporal trends and their relation to biological parameters. A significant relation was found between the PCB levels on a wet weight basis and the total lipid content. Normalising on the total lipid content reduced the differences in PCB levels between the organisms and between different tissues within the organisms. A general downward trend was observed for the PCB levels on the Belgian continental shelf

Metabolism of 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) atropisomers in tissue slices from phenobarbital or dexamethasone-induced rats is sex-dependent.

1. Chiral polychlorinated biphenyls (PCBs) such as PCB 136 enantioselectively sensitize the ryanodine receptor (RyR). In light of recent evidence that PCBs cause developmental neurotoxicity via RyR-dependent mechanisms, this suggests that enantioselective PCB metabolism may influence the developmental neurotoxicity of chiral PCBs. However, enantioselective disposition of PCBs has not been fully characterized. 2. The effect of sex and cytochrome P450 (P450) enzyme induction on the enantioselective metabolism of PCB 136 was studied using liver tissue slices prepared from naïve control (CTL), phenobarbital (PB; CYP2B inducer) or dexamethasone (DEX; CYP3A inducer) pretreated adult Sprague-Dawley rats. PCB 136 metabolism was also examined in hippocampal slices derived from untreated rat pups. 3. In liver tissue slices, hydroxylated PCB (OH-PCB) profiles depended on sex and inducer pretreatment, and OH-PCB levels followed the rank orders male &gt; female and PB &gt; DEX &gt; CTL. In contrast, the enantiomeric enrichment of PCB 136 and its metabolites was independent of sex and inducer pretreatment. Only small amounts of PCB 136 partitioned into hippocampal tissue slices and no OH-PCB metabolites were detected. 4. Our results suggest that enantioselective metabolism, sex and induction status of P450 enzymes in the liver may modulate the neurotoxic outcomes of developmental exposure to chiral PCBs

Dioxin and PCB levels in blood and human milk in relation to living areas in the Netherlands

Dioxins and polychlorinated biphenyls (PCBs) are ubiquitous toxic compounds in the environment. Negative influences of these compounds on the health status of human beings have been described. Especially susceptible might be the fetus, which is exposed in utero, and the newborn breast-fed infant, since both are exposed to relatively high levels of dioxins and PCBs during a critical period of organ growth and development. We investigated PCB levels in 406 maternal plasma samples as well as PCB and dioxin levels in 172 human milk samples with relation to living area of women living for at least five years in the western industrialized part of the Netherlands or the northern more rural part. The western part was further subdivided into one urban and two highly industrialized areas. After correction for covariates, we found significantly higher levels of PCB 118 in maternal plasma as well as significantly higher levels of the dioxin-TEQ and of ten individual dioxin and PCB congener levels in human milk in the western more industrialized areas of the Netherlands compared to the northern more rural part. We did not find significant differences in planar, mono-ortho or di-ortho PCB-TEQ levels in human milk between all different areas. We conclude that significantly higher levels of a number of dioxin and PCB congeners are found in women living in industrialized areas compared to women living in rural areas in the Netherlands

Plasma polychlorinated biphenyl levels in Dutch preschool children either breast-fed or formula-fed during infancy

OBJECTIVES: This study examined the influence of lactational and in utero exposure to polychlorinated biphenyls (PCBs) on plasma PCB levels in children. METHODS: Plasma PCB levels were measured in 173 children at 3.5 years, of whom 91 were breast-fed and 82 were formula-fed in infancy. RESULTS: Median plasma PCB levels were 3.6 times higher in breast-fed children (0.75 microgram/L) than in their formula-fed peers (0.21 microgram/L). Breast-feeding period and breast-milk PCB levels were important predictors for PCB levels in the breast-fed group. For children in the formula-fed group, PCB levels were significantly related to their material plasma PCB levels. CONCLUSIONS: PCB levels in Dutch preschool children are related to transfer of maternal PCBs; therefore, strategies should be aimed at reducing maternal PCB body burden

Persistent Organic Pollutants (POPs) and inorganic elements in predatory bird livers and eggs 2007 to 2009: a Predatory Bird Monitoring Scheme (PBMS) Report

The Predatory Bird Monitoring Scheme (PBMS; http://pbms.ceh.ac.uk/) is the umbrella project that encompasses the Centre for Ecology & Hydrology’s National Capability contaminant monitoring and surveillance work on avian predators. By monitoring sentinel vertebrate species, the PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife. Sparrowhawk livers were analysed for a range of persistent organic pollutants (POPs) and heavy metals. Sparrowhawks are studied because they have a wide distribution across the Britain and can be used as a sentinel species for the terrestrial environment. Mean PCB and mercury liver concentrations were below those thought to have an adverse effect on individual birds. Pollutants, such as mercury and PCBs, can affect development and hatchability. Therefore, the PBMS also monitors the levels of contaminants in the eggs of a range of species including those of conservation concern, such as golden eagle and the re-introduced white-tailed sea eagle. Other species that are monitored are the northern gannet, which is used as a monitor of the marine environment, and merlin that hunts in upland habitats. The residues measured in the eggs of golden eagle and gannets collected between 2007 and 2009 were below those thought to have an adverse effect, but some residues in individual merlin eggs were above concentrations suggested to be indicative of no effect concentrations for birds generally. Few white-tailed see eagle eggs are received for analysis by the PBMS but many of the eggs that have been analysed, including one of the eggs analysed for this report, have DDE, PCB and/or mercury concentrations above levels associated with adverse effects on bird embryos and hatching success. In terms of long-term trends, there has been a decline in congener sum PCB contamination in the eggs of most of the species that have been monitored, except for coastal nesting golden eagles. In contrast however, there has been no significant decline over time in PCB concentrations in sparrowhawk livers and concentrations of ‘Paris 10’ congener sum and PCB-TEQ concentrations have also largely remained unchanged in both livers and eggs since monitoring began in 1996. Evidence for changes over time in mercury concentrations in predatory birds or their eggs is inconsistent across the species monitored. Where a decline has been detected, it has occurred before approximately 1990 and remained largely unchanged since then

Levels and distribution of polychlorinated biphenyls in the atmosphere close to Chinese Great Wall Station, Antarctica: Results from XAD-resin passive air sampling

Antarctica is an important research region for assessing persistence and long-range atmospheric transport (LRAT) of persistent organic pollutants (POPs). In this study, XAD-resin passive air sampling was conducted near the Chinese Great Wall Station, Antarctica, during a one-year sampling period in 2009-2010. The air concentrations of polychlorinated biphenyls (PCBs) were at a very low level, with total PCBs in the range of 26.74-45.08 pg m(-3). PCB profiles were dominated by tetra-PCBs, tri-PCBs and di-PCBs, indicating LRAT was responsible for the pollutants in the Antarctic atmosphere. The sampling site near the Chinese Great Wall Station did not show higher PCB levels than the other sites, suggesting that PCB sources associated with the Great Wall Station were negligible. PCB-11 is a non-Aroclor congener, which has specific sources compared to other Aroclor PCB congeners. PCB-11 was observed in all air samples, with an average concentration of 1.22 pg m(-3). To our knowledge, this study is the first investigation of PCB levels and distribution in the atmosphere around the Chinese Great Wall Station, Antarctica.</p

PCBs in cod (<i>Gadus morhua</i>), flounder (<i>Platichthys flesus</i>), blue mussel (<i>Mytilus edulis</i>) and brown shrimp (<i>Crangon crangon</i>) from the Belgian Continental Shelf: relation to biological parameters and trend analysis

PCB levels in cod, flounder, mussel and shrimp, covering a ten-year period, were assessed for temporal trends and their relation to biological parameters. A significant relation was found between the PCB levels on a wet weight basis and the total lipid content. Normalising on the total lipid content reduced the differences in PCB levels between the organisms and between different tissues within the organisms. A general downward trend was observed for the PCB levels on the Belgian continental shelf