Metabolism of hexachlorobenzene in humans: association between serum levels and urinary metabolites in a highly exposed population

Coking-Produced Aromatic Compounds in Urine of Exposed and Nonexposed Populations: Exposure Levels, Source Identification, and Model-Based Health Implications

Coking contamination in China is complex and poses potential health risks to humans. In this study, we collected urine samples from coking plant workers, nearby residents, and control individuals to analyze 25 coking-produced aromatic compounds (ACs), including metabolites of polycyclic aromatic hydrocarbons (PAHs) and their derivatives, chlorophenols, and nitrophenols. The median concentration of total ACs in urine of workers was 102 μg·g-1 creatinine, significantly higher than that in the other two groups. Hydroxy-PAHs and hydroxy hetero-PAHs were the dominant ACs. Workers directly exposed from coking industrial processes, i.e., coking, coal preparation, and chemical production processes, showed higher concentrations of hydroxy-PAHs and hydroxy hetero-PAHs (excluding 5-hydroxyisoquinoline), while those from indirect exposure workshops had higher levels of other ACs, indicating different sources in the coking plant. The AC mixture in workers demonstrated positive effects on DNA damage and lipid peroxidation with 5-hydroxyisoquinoline and 3-hydroxycarbazole playing a significant role using a quantile g-computation model. Monte Carlo simulation revealed that coking contamination elevated the carcinogenic risk for exposed workers by 5-fold compared to controls with pyrene, pentachlorophenol, and carbazole contributing the most, and workers from coking process are at the highest risk. This study enhances understanding of coking-produced AC levels and provides valuable insights into coking contamination control.

Breast cancer progression and kynurenine pathway enzymes are induced by hexachlorobenzene exposure in a Her2-positive model

Breast cancer is one of the leading cancers among women worldwide. Given the evidence that pesticides play an important role in breast cancer, interest has grown in pesticide impact on disease progression. Hexachlorobenzene (HCB), an aryl hydrocarbon receptor (AhR) ligand, promotes triple-negative breast cancer cell migration and invasion. Estrogen receptor β (ERβ) inhibits cancer motility, while G protein-coupled ER (GPER) modulates the neoplastic transformation. Tryptophan is metabolized through the kynurenine pathway by indoleamine-2,3-dioxygenase (IDO) and tryptophan-2,3-dioxygenase (TDO), with kynurenine signaling activation often predicting worse prognosis in cancer. In this context, we examined the HCB (0.005; 0.05; 0.5 and 5 μM) effect on LM3 cells, a human epidermal growth factor receptor 2 (HER2)-positive breast cancer model. Results show that HCB increases IDO and TDO mRNA levels and promotes cell viability, proliferation and migration through the AhR pathway. Moreover, HCB boosts mammosphere formation, vascular endothelial growth factor and cyclooxygenase-2 expression and reduces IL-10 levels. For some parameters, U-shaped or inverted U-shaped dose-response curves are shown. HCB alters ER levels, reducing ERβ while increasing GPER. These results demonstrate that exposure to environmentally relevant concentrations of HCB up-regulates the kynurenine pathway and dysregulates ERβ and GPER levels, collaborating in HER2-positive breast cancer progression.

Endocrine disruptor hexachlorobenzene induces cell migration and invasion, and enhances aromatase expression levels in human endometrial stromal cells

Endometriosis is the presence and growth of endometrial tissue outside of the uterus. Previous studies have suggested that endocrine disrupting chemicals such as organochlorine pesticides could be a risk factor for endometriosis. Hexachlorobenzene (HCB) is a weak ligand of the aryl hydrocarbon receptor (AhR) and promotes metalloproteinase and cyclooxygenase-2 (COX-2) expression, as well as, c-Src activation in human endometrial stromal cells (T-HESC) and in rat endometriosis model. Our aim was to evaluate the effect of HCB exposure on oestrogen receptor (ER) ɑ and β, progesterone receptor (PR) and aromatase expression, as well as, on cell migration and invasion in T-HESC and primary cultures of endometrial stromal cells from eutopic endometria of control subjects (ESC). Results show that HCB increases ERɑ and aromatase protein levels and reduces PR content in both T-HESC and ESC. However, the pesticide only increases ERβ expression in ESC, without changes in T-HESC. Moreover, cell migration and invasion are promoted by pesticide exposure involving the AhR, c-Src, COX-2 and ER pathways in T-HESC. HCB also triggers ERɑ activation via phosphorylation in Y537 through AhR/c-Src pathway. Our results provide experimental evidence that HCB induces alterations associated with endometriosis, suggesting that these mechanisms could contribute to pesticide exposure-induced endometriosis development.

Systemic RNA oxidation can be used as a biomarker of infection in challenged with Vibrio parahaemolyticus

More and more evidence support the concept that RNA oxidation plays a substantial role in the progress of multiple diseases; however, only a few studies have reported RNA oxidation caused by microbial pathogens. Urinary 8-oxo-7,8-dihydroguanosine (8-oxo-Gsn) and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dGsn), which are broadly used as indicators of oxidative damage of RNA and DNA, were analyzed in this study to determine which can be used as a biomarker of infection in challenged with Vibrio parahaemolyticus (V. parahaemolyticus). In this work, 24 specific-pathogen-free (SPF) male SD rats were randomly divided into two groups: an infection group and a phosphate-buffered saline (PBS) control group. Our results proved that 8-oxo-Gsn rather than 8-oxo-dGsn was significantly increased after challenged with V. parahaemolyticus in urine and tissue samples of SD rats compared with the PBS control group. Simultaneously, white blood cells (WBCs) counts, intestinal inflammation and inflammatory factors (including CRP, IL-6, IL-1β, TNF-α, IL-10, and IL-17A) were also increased sharply. Which has more clinical value is that the trend of urinary 8-oxo-Gsn was consistent with WBCs, intestinal inflammation and all kinds of inflammatory factors. More importantly is that urinary 8-oxo-Gsn of infection group was positively correlated with WBCs and various inflammatory cytokines. In a word, our results demonstrated that as a systemic RNA oxidation biomarker, we hope 8-oxo-Gsn can be used as a biomarker of the severity of microbial pathogens infection, rather than a specific biomarker of microbial pathogens infection.

Pesticides in human milk collected from Jinhua, China: Levels, influencing factors and health risk assessment

In China, many studies have been carried out on pesticide residues in human milk, yet all of them are on organochlorine pesticides (OCPs) and mostly focused on large, economically developed cities. In this study, 27 pesticides including OCPs, pyrethroid pesticides (PYRs) and organophosphate pesticides (OPPs) in human milk were investigated in Jinhua, an inland and medium sized city in China. Method based on QuEChERS extraction and gas chromatography-mass spectrometer (GC-MS) determination was adopted to analyze the above pesticide residues. The influencing factors as well as the health risks were also evaluated. Results show that PYRs and OPPs in human milk samples were both undetectable. Regarding OCPs, the detection rate of hexachlorobenzene (HCB), β-hexachlorocyclohexane (β-HCH) and p,p'-dichlorodiphenyl-dichloroethylene (p,p'-DDE) were 83.6%, 36.4% and 58.2%, respectively, and their mean value were 29.4, 32.0 and 85.2 ng/g lipid, respectively. p,p'-DDE levels in human milk was significantly (p < 0.05) related to maternal age, but no association was detected between OCPs residues and other factors (living environment, dietary habit, living style, etc.), suggesting that OCPs in human milk in Jinhua were originated from nonspecific source. All estimated daily intake of pesticides (EDI_pesticides) by infants were under the guideline suggested by Food and Agriculture Organization (FAO) and China Ministry of Health (CMH). Yet 9% of EDIs_HCB and 16% of EDIs_HCHs exceeded the guideline recommended by Health Canada. The associations between DDE residues and the delivery way as well as HCBs residues and the birth weight were seemly significant, yet the significance disappeared when consider age or gestational age as a cofounder, indicating that OCPs residue in mother's body in Jinhua has no obvious influence on fetus development and the delivery way.

Angiogenesis signaling in breast cancer models is induced by hexachlorobenzene and chlorpyrifos, pesticide ligands of the aryl hydrocarbon receptor

Breast cancer incidence is increasing globally and pesticides exposure may impact risk of developing this disease. Hexachlorobenzene (HCB) and chlorpyrifos (CPF) act as endocrine disruptors, inducing proliferation in breast cancer cells. Vascular endothelial growth factor-A (VEGF-A), cyclooxygenase-2 (COX-2) and nitric oxide (NO) are associated with angiogenesis. Our aim was to evaluate HCB and CPF action, both weak aryl hydrocarbon receptor (AhR) ligands, on angiogenesis in breast cancer models. We used: (1) in vivo xenograft model with MCF-7 cells, (2) in vitro breast cancer model with MCF-7, and (3) in vitro neovasculogenesis model with endothelial cells exposed to conditioned medium from MCF-7. Results show that HCB (3 mg/kg) and CPF (0.1 mg/kg) stimulated vascular density in the in vivo model. HCB and CPF low doses enhanced VEGF-A and COX-2 expression, accompanied by increased levels of nitric oxide synthases (NOS), and NO release in MCF-7. HCB and CPF high doses intensified VEGF-A and COX-2 levels but rendered different effects on NOS, however, both pesticides reduced NO production. Moreover, our data indicate that HCB and CPF-induced VEGF-A expression is mediated by estrogen receptor and NO, while the increase in COX-2 is through AhR and NO pathways in MCF-7. In conclusion, we demonstrate that HCB and CPF environmental concentrations stimulate angiogenic switch in vivo. Besides, pesticides induce VEGF-A and COX-2 expression, as well as NO production in MCF-7, promoting tubulogenesis in endothelial cells. These findings show that pesticide exposure could stimulate angiogenesis, a process that has been demonstrated to contribute to breast cancer progression.

AhR ligands reactivate LINE-1 retrotransposon in triple-negative breast cancer cells MDA-MB-231 and non-tumorigenic mammary epithelial cells NMuMG

Breast cancer is the most common cancer type in females worldwide. Environmental exposure to pesticides affecting hormonal homeostasis does not necessarily induce DNA mutations but may influence gene expression by disturbances in epigenetic regulation. Expression of long interspersed nuclear element-1 (LINE-1) has been associated with tumorigenesis in several cancers. In nearly all somatic cells, LINE-1 is silenced by DNA methylation in the 5́'UTR and reactivated during disease initiation and/or progression. Strong ligands of aryl hydrocarbon receptor (AhR) activate LINE-1 through the transforming growth factor-β1 (TGF-β1)/Smad pathway. Hexachlorobenzene (HCB) and chlorpyrifos (CPF), both weak AhR ligands, promote cell proliferation and migration in breast cancer cells, as well as tumor growth in rat models. In this context, our aim was to examine the effect of these pesticides on LINE-1 expression and ORF1p localization in the triple-negative breast cancer cell line MDA-MB-231 and the non-tumorigenic epithelial breast cell line NMuMG, and to evaluate the role of TGF-β1 and AhR pathways. Results show that 0.5 μM CPF and 0.005 μM HCB increased LINE-1 mRNA expression through Smad and AhR signaling in MDA-MB-231. In addition, the methylation of the first sites in 5́'UTR of LINE-1 was reduced by pesticide exposure, although the farther sites remained unaffected. Pesticides modulated ORF1p localization in MDA-MB-231: 0.005 μM HCB and 50 μM CPF increased nuclear translocation, while both induced cytoplasmic retention at 0.5 and 5 μM. Moreover, both stimulated double-strand breaks, enhancing H2AX phosphorylation, coincidentally with ORF1p nuclear localization. In NMuMG similar results were observed, since they heighten LINE-1 mRNA levels. CPF effect was through AhR and TGF-β1 signaling, whereas HCB action depends only of AhR. In addition, both pesticides increase ORF1p expression and nuclear localization. Our results provide experimental evidence that HCB and CPF exposure modify LINE-1 methylation levels and induce LINE-1 reactivation, suggesting that epigenetic mechanisms could contribute to pesticide-induced breast cancer progression.

Impact of endocrine disruptor hexachlorobenzene on the mammary gland and breast cancer: The story thus far

Breast cancer incidence is increasing globally and exposure to endocrine disruptors has gained importance as a potential risk factor. Hexachlorobenzene (HCB) was once used as a fungicide and, despite being banned, considerable amounts are still released into the environment. HCB acts as an endocrine disruptor in thyroid, uterus and mammary gland and was classified as possibly carcinogenic to human. This review provides a thorough analysis of results obtained in the last 15 years of research and evaluates data from assays in mammary gland and breast cancer in diverse animal models. We discuss the effects of environmentally relevant HCB concentrations on the normal mammary gland and different stages of carcinogenesis, and attempt to elucidate its mechanisms of action at molecular level. HCB weakly binds to the aryl hydrocarbon receptor (AhR), activating both membrane (c-Src) and nuclear pathways. Through c-Src stimulation, AhR signaling interacts with other membrane receptors including estrogen receptor-α, insulin-like growth factor-1 receptor, epidermal growth factor receptor and transforming growth factor beta 1 receptors. In this way, several pathways involved in mammary morphogenesis and breast cancer development are modified, inducing tumor progression. HCB thus stimulates epithelial cell proliferation, preneoplastic lesions and alterations in mammary gland development as well as neoplastic cell migration and invasion, metastasis and angiogenesis in breast cancer. In conclusion, our findings support the hypothesis that the presence and bioaccumulation of HCB in high-fat tissues and during highly sensitive time windows such as pregnancy, childhood and adolescence make exposure a risk factor for breast tumor development.

Total arsenic concentrations in Chinese children's urine by different geographic locations, ages, and genders

Little is known about the variation of Chinese children's exposure to arsenic by geography, age, gender, and other potential factors. The main objective of this study was to investigate the total arsenic concentration in Chinese children's urine by geographic locations, ages, and genders. In total, 259 24-h urine samples were collected from 210 2- to 12-year-old children in China and analyzed for total arsenic and creatinine concentrations. The results showed that the upper limit (upper limit of the 90% confidence interval for the 97.5 fractile) was 27.51 µg/L or 55.88 µg/g creatinine for Chinese children. The total urinary arsenic levels were significantly different for children in Guangdong, Hubei, and Gansu provinces (P < 0.05), where the upper limits were 24.29, 58.70, and 44.29 µg/g creatinine, respectively. In addition, the total urinary arsenic levels were higher for 2- to 7-year-old children than for 7- to 12-year-old children (P < 0.05; the upper limits were 59.06 and 44.29 µg/g creatinine, respectively) and higher for rural children than for urban children (P < 0.05; the upper limits were 59.06 and 50.44 µg/g creatinine, respectively). The total urinary arsenic levels for boys were not significantly different from those for girls (P > 0.05), although the level for boys (the upper limit was 59.30 µg/g) was slightly higher than that for girls (the upper limit was 58.64 µg/g creatinine). Because the total urinary arsenic concentrations are significantly different for general populations of children in different locations and age groups, the reference level of total urinary arsenic might be dependent on the geographic site and the child's age.

Biomonitoring of chlorophenols in human urine from several Asian countries, Greece and the United States

Chlorophenols (CPs) are used in the production of pesticides and preservatives. Although human exposure to CPs has been known for years, current exposure levels to these chemicals in Asian countries are not known. In this study, we analyzed concentrations of eight CPs in 300 human urine samples collected from nine countries. Of these CPs, 2,5-dichlorophenol and 2,4-dichlorophenol were found at the highest median concentrations (median for all nine countries: 1.78 and 0.34 ng/mL, respectively). Pentachlorophenol was found in 59% of the samples analyzed at a median concentration of 0.07 ng/mL. Urine samples from Japan had the highest concentration of total CPs (median: 16.7 ng/mL) with 2,5-dichlorophenol accounting for 93.1% of the total concentration. The estimated daily intake (DI) for precursors of dichlorophenols varied widely, but several samples showed values higher than the acceptable DI recommended by the United States Environmental Protection Agency (EPA). These results suggest that CP exposure, especially to dichlorophenols, is prevalent in several countries, particularly in Asia, suggesting a pressing need for further assessment of the global sources and potential health effects of these chemicals.

Vitamin D3 supplementation attenuates the early stage of mouse hepatocarcinogenesis promoted by hexachlorobenzene fungicide

Hexachlorobezene (HCB), a fungicide widely distributed in the environment, promotes the development of hepatocellular preneoplastic lesions (PNL) and tumors in rodents. In contrast, vitamin D₃ (VD₃) supplementation presents a potential role for the prevention/treatment of chronic liver diseases. Thus, we investigated whether VD₃ supplementation attenuates the early stage of HCB-promoted hepatocarcinogenesis. Female Balb/C mice were injected a single dose of diethylnitrosamine (DEN, 50 mg/kg) at postnatal day 15. From day 40 onwards, mice were fed with a standard diet containing 0.02% HCB alone or supplemented with VD₃ (10,000 or 20,000 IU/Kg diet) for 20 weeks. Untreated mice were fed just standard diet. After this period, mice were euthanized and liver and serum samples were collected. Compared to the untreated group, DEN/HCB treatment decreased total hepatic glutathione levels and glutathione peroxidase (GSH-Px) activity while increased lipid peroxidation, p65 protein expression, cell proliferation/apoptosis and the PNL development. In contrast, dietary VD₃ supplementation enhanced vitamin D receptor (VDR) protein expression, total glutathione levels and GSH-Px activity while diminished lipid hydroperoxide levels. Also, VD₃ supplementation decreased p65 protein expression, hepatocyte proliferation, the size and the liver area occupied by PNL. Therefore, our findings indicate that VD₃ supplementation attenuates the early stage of HCB-promoted hepatocarcinogenesis.

Cats' Internal Exposure to Selected Brominated Flame Retardants and Organochlorines Correlated to House Dust and Cat Food

Pet cats may be used as a biomarker for assessing exposures to organohalogen compounds (OHCs) adsorbed to household dust in home environments. This study explores two exposure routes of OHCs, ingestion of OHCs (i) via house dust and (ii) via cat food. House dust from 17 Swedish homes and serum from the participating families' pet cats were collected, and cat food was purchased matching the diet reported. Paired samples of cat serum, house dust, and cat food were analyzed for brominated flame retardants/natural products (polybrominated diphenyl ethers (PBDEs), decabromobiphenyl (BB-209), decabromodiphenyl ethane (DBDPE), 2,4,6-tribromophenol (2,4,6-TBP), OH-PBDEs) and organochlorines (polychlorinated biphenyls (PCBs), 1,1-bis(4,4'-dichlorodiphenyl)-2,2,2-trichloroethane (4,4'-DDT), 1,1-bis(4,4'-dichlorodiphenyl)-2,2-dichloroethene (4,4'-DDE), hexachlorobenzene (HCB), pentachlorophenol (PCP)). Significant correlations were found between serum and dust samples from the living rooms for BDE-47 (p < 0.035), BDE-99 (p < 0.035), and BDE-153 (p < 0.039), from the adult's bedroom for BDE-99 (p < 0.019) and from all rooms for BDE-99 (p < 0.020) and BB-209 (p < 0.048). This is the first time a correlation between cat serum levels and household dust has been established, a finding that supports the hypothesis that dust is a significant exposure route for cats. Serum levels were also significantly correlated with concentrations found in cat food for 6-OH-BDE47 (p < 0.002), 2,4,6-TBP (p < 0.035), and BB-209 (p < 0.007). DBDPE was found in high concentrations in all dust (median 154 pmol/g) and food samples (median 0.7 pmol/g lw) but was below detection in serum samples, suggesting low or no bioavailability for DBDPE in cats.

Hexachlorobenzene modulates the crosstalk between the aryl hydrocarbon receptor and transforming growth factor-β1 signaling, enhancing human breast cancer cell migration and invasion

Given the number of women affected by breast cancer, considerable interest has been raised in understanding the relationships between environmental chemicals and disease onset. Hexachlorobenzene (HCB) is a dioxin-like compound that is widely distributed in the environment and is a weak ligand of the aryl hydrocarbon receptor (AhR). We previously demonstrated that HCB acts as an endocrine disruptor capable of stimulating cell proliferation, migration, invasion, and metastasis in different breast cancer models. In addition, increasing evidence indicates that transforming growth factor-β1 (TGF-β1) can contribute to tumor maintenance and progression. In this context, this work investigated the effect of HCB (0.005, 0.05, 0.5, and 5μM) on TGF-β1 signaling and AhR/TGF-β1 crosstalk in the human breast cancer cell line MDA-MB-231 and analyzed whether TGF-β1 pathways are involved in HCB-induced cell migration and invasion. RT-qPCR results indicated that HCB reduces AhR mRNA expression through TGF-β1 signaling but enhances TGF-β1 mRNA levels involving AhR signaling. Western blot analysis demonstrated that HCB could increase TGF-β1 protein levels and activation, as well as Smad3, JNK, and p38 phosphorylation. In addition, low and high doses of HCB were determined to exert differential effects on AhR protein levels, localization, and activation, with a high dose (5μM) inducing AhR nuclear translocation and AhR-dependent CYP1A1 expression. These findings also revealed that c-Src and AhR are involved in HCB-mediated activation of Smad3. HCB enhances cell migration (scratch motility assay) and invasion (Transwell assay) through the Smad, JNK, and p38 pathways, while ERK1/2 is only involved in HCB-induced cell migration. These results demonstrate that HCB modulates the crosstalk between AhR and TGF-β1 and consequently exacerbates a pro-migratory phenotype in MDA-MB-231 cells, which contributes to a high degree of malignancy. Taken together, our findings help to characterize the molecular mechanism underlying the effects of HCB on breast cancer progression.

Tetrachlorobenzoquinone exhibits neurotoxicity by inducing inflammatory responses through ROS-mediated IKK/IκB/NF-κB signaling

Tetrachlorobenzoquinone (TCBQ) is a joint metabolite of persistent organic pollutants (POPs), hexachlorobenzene (HCB) and pentachlorophenol (PCP). Previous studies have been reported that TCBQ contributes to acute hepatic damage due to its pro-oxidative nature. In the current study, TCBQ showed the highest capacity on the cytotoxicity, ROS formation and inflammatory cytokines release among four compounds, i.e., HCB, PCP, tetrachlorohydroquinone (TCHQ, reduced form of TCBQ) and TCBQ, in PC 12 cells. Further mechanistic study illustrated TCBQ activates nuclear factor-kappa B (NF-κB) signaling. The activation of NF-κB was identified by measuring the protein expressions of inhibitor of nuclear factor kappa-B kinase (IKK) α/β, p-IKKα/β, an inhibitor of NF-κB (IκB) α, p-IκBα, NF-κB (p65) and p-p65. The translocation of NF-κB was assessed by Western blotting of p65 in nuclear/cytosolic fractions, electrophoretic mobility shift assay (EMSA) and luciferase reporter gene assay. In addition, TCBQ significantly induced protein and mRNA expressions of inflammatory cytokines and mediators, such as interleukin-1 beta (IL-1β), IL-6, tumor necrosis factor-alpha (TNF-α), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and the production of nitric oxide (NO) and prostaglandin E2 (PGE2). Pyrrolidine dithiocarbamate (PDTC), a specific NF-κB inhibitor inhibited these effects efficiently, further suggested TCBQ-induced inflammatory responses involve NF-κB signaling. Moreover, antioxidants, i.e., N-acetyl-l-cysteine (NAC), Vitamin E and curcumin, ameliorated TCBQ-induced ROS generation as well as the activation of NF-κB, which implied that ROS serve as the upstream molecule of NF-κB signaling. In summary, TCBQ exhibits a neurotoxic effect by inducing oxidative stress-mediated inflammatory responses via the activation of IKK/IκB/NF-κB pathway in PC12 cells.

Levels and predictors of persistent organic pollutants in an adult population from four Spanish regions

This research aimed to assess serum concentrations of a group of persistent organic pollutants (POPs) in a sample of adults recruited in four different regions from Spain and to assess socio-demographic, dietary, and lifestyle predictors of the exposure. The study population comprised 312 healthy adults selected from among controls recruited in the MCC-Spain multicase-control study. Study variables were collected using standardized questionnaires, and pollutants were analyzed by means of gas chromatography with electron capture detection. Multivariable analyses were performed to identify predictors of log-transformed pollutant concentrations, using combined backward and forward stepwise multiple linear regression models. Detection rates ranged from 89.1% (hexachlorobenzene, HCB) to 93.6% (Polychlorinated biphenyl-153 [PCB-153]); p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) showed the highest median concentrations (1.04ng/ml), while HCB showed the lowest (0.24ng/ml). In the multivariable models, age was positively associated with HCB, p,p'-DDE, and PCB-180. BMI was associated positively with p,p'-DDE but negatively with PCB-138. Total accumulated time residing in an urban area was positively associated with PCB-153 concentrations. The women showed higher HCB and lower p,p'-DDE concentrations versus the men. Notably, POP exposure in our study population was inversely associated with the breastfeeding received by participants and with the number of pregnancies of their mothers but was not related to the participants' history of breastfeeding their children or parity. Smoking was negatively associated with HCB and PCB-153 concentrations. Consumption of fatty foods, including blue fish, was in general positively associated with POP levels. Although POP environmental levels are declining worldwide, there is a need for the continuous monitoring of human exposure in the general population. The results of the present study confirm previous findings and point to novel predictors of long-term exposure to persistent organic pollutants.

Chronic exposure to hexachlorobenzene results in down-regulation of connexin43 in the breast

Decreased expression of connexins has been associated with cancer, but the underlying mechanisms are poorly understood. We have previously shown that a 5 day exposure to hexachlorobenzene (HCB) resulted in decreased connexins expression in hepatocytes 45 days later, and that this down-regulation was linked to activation of Akt through the ILK pathway. Because HCB promotes cancer in both the liver and breast, the present study aimed to determine if the mechanisms are similar in both tissues. MCF-12A breast cells were thus transfected with vectors coding for either Akt or a constitutively active form of Akt. In those cells, activation of Akt was correlated with decreased Cx43 levels. Female rats were then exposed to HCB by gavage either following the same protocol used previously for the liver or through a chronic exposure. While no changes were observed after the 5 days exposure protocol, chronic exposure to HCB resulted in increased Akt levels and decreased Cx43 levels in breast cells. In vitro, Akt was activated in MCF-12A cells exposed to HCB either for 7 days or chronically, but no changes were observed in junctional proteins. Together, these results suggested that, while activation of Akt can decrease Cx43 expression in breast cells in vitro, other mechanisms are involved during HCB exposure, leading to a decrease in Cx43 levels in a model- and duration-dependent manner. Finally, we showed that HCB effects are tissue specific, as we did not observe the same results in breast and liver tissues.

Legacy and emerging organic pollutants in liver and plasma of long-finned pilot whales (Globicephala melas) from waters surrounding the Faroe Islands

Concentrations of PCBs, organochlorine pesticides (OCPs), brominated flame retardants and a suite of relevant metabolites of these POPs, in all 175 different compounds, were determined in liver and plasma of traditionally hunted pilot whales (n=14 males and n=13 females of different age groups) from the Faroe Islands. The main objectives of this study were to determine differences in the presence and concentrations of the compounds in the liver and plasma, how they depend on developmental stage (calves, sub adults, and adult females), and to assess maternal transfer of the compounds to suckling calves. Generally, the lipid weight (lw) concentrations of quantified POPs in the liver and plasma of pilot whales were positively correlated, and lw concentrations of most POPs did not differ between these matrices. However, concentrations of some individual POPs differed significantly (p<0.05) between plasma and liver; CB-153 (p=0.044), CB-174 (p=0.027) and BDE-47 (p=0.017) were higher in plasma than in liver, whereas p,p'-DDE (p=0.004) and HCB (p<0.001) were higher in liver than in plasma. POP concentrations differed between age/gender groups with lower levels in adult females than in juveniles. The relative distribution of compounds also differed between the age groups, due to the influence of the maternal transfer of the compounds. The results indicated that larger, more hydrophobic POPs were transferred to the offspring less efficiently than smaller or less lipid soluble compounds. Very low levels of both OH- and/or MeSO2-PCB and PBDE metabolites were found in all age groups, with no significant (p>0.05) differences between the groups, strongly suggesting a very low metabolic capacity for their formation in pilot whales. The lack of difference in the metabolite concentrations between the age groups also indicates less maternal transfer of these contaminant groups compared to the precursor compounds.

The transferability from rat subacute 4-week oral toxicity study to translational research exemplified by two pharmaceutical immunosuppressants and two environmental pollutants with immunomodulating properties

Exposure to chemicals may have an influence on the immune system. Often, this is an unwanted effect but in some pharmaceuticals, it is the intended mechanism of action. Immune function tests and in depth histopathological investigations of immune organs were integrated in rodent toxicity studies performed according to an extended OECD test guideline 407 protocol. Exemplified by two immunosuppressive drugs, azathioprine and cyclosporine A, and two environmental chemicals, hexachlorobenzene and benzo[a]pyrene, results of subacute rat studies were compared to knowledge in other species particular in humans. Although immune function has a high concordance in mammalian species, regarding the transferability from rodents to humans various factors have to be taken into account. In rats, sensitivity seems to depend on factors such as strain, sex, stress levels as well as metabolism. The two immunosuppressive drugs showed a high similarity of effects in animals and humans as the immune system was the most sensitive target in both. Hexachlorobenzene gave an inconsistent pattern of effects when considering the immune system of different species. In some species pronounced inflammation was observed, whereas in primates liver toxicity seemed more obvious. Generally, the immune system was not the most sensitive target in hexachlorobenzene-treatment. Immune function tests in rats gave evidence of a reaction to systemic inflammation rather than a direct impact on immune cells. Data from humans are likewise equivocal. In the case of benzo[a]pyrene, the immune system was the most sensitive target in rats. In the in vitro plaque forming cell assay (Mishell-Dutton culture) a direct comparison of cells from different species including rat and human was possible and showed similar reactions. The doses in the rat study had, however, no realistic relation to human exposure, which occurs exclusively in mixtures and in a much lower range. In summary, a case by case approach is necessary when testing immunotoxicity. Improvements for the translation from animals to humans related to immune cells can be expected from in vitro tests which offer direct comparison with reactions of human immune cells. This may lead to a better understanding of results and variations seen in animal studies.

Temporal trend and age-dependent serum concentration of phenolic organohalogen contaminants in Japanese men during 1989-2010

The temporal trend in serum concentrations of phenolic organohalogen contaminants (POCs) were investigated in two age groups of men from Kyoto, Japan, from 1989 to 2010. These concentrations and trends were compared with neutral contaminants including polychlorinated biphenyls (PCBs) and pesticides. Serum concentrations of pentachlorophenol (PenCP) and 4-hydroxy-PCB187 were age-dependent and decreased to approximately one-half during the two decades, whereas no contamination trends were observed for 2,4,6-tribromophenol (TriBP), tetrabromobisphenol A (TBBPA) and 6-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (6-OH-BDE47). 6-OH-BDE47 was found in all samples (up to 3000 pg/g wet weight), whereas TBBPA was detected in 17 of 60 serum samples (up to 950 pg/g wet weight). The concentrations of TriBP, TBBPA and 6-OH-BDE47 were not correlated to those of PenCP or 4-OH-PCB187 in either age group, suggesting the different kinetics on exposure routes and fate between these brominated and chlorinated POCs.

Separation and fragmentation study of isocoproporphyrin derivatives by UHPLC-ESI-exact mass MS/MS and identification of a new isocoproporphyrin sulfonic acid metabolite

Isocoproporphyrin and its derivatives are commonly used as biomarkers of porphyria cutanea tarda, heavy metal toxicity and hexachlorobenzene (HCB) intoxication in humans and animals. However, most are isobaric with other porphyrins and reference materials are unavailable commercially. The structural characterisation of these porphyrins is important but very little data is available. We report here the separation and characterisation of isocoproporphyrin, deethylisocoproporphyrin, hydroxyisocoproporphyrin and ketoisocoproporphyrin, isolated in the faeces of rats fed with a diet containing HCB, by ultra high performance liquid chromatography-exact mass tandem mass spectrometry (UHPLC-MS/MS). Furthermore, we report the identification and characterisation of a previously unreported porphyrin metabolite, isocoproporphyrin sulfonic acid isolated in the rat faeces. The measured mass-to-charge ratio (m/z) of the precursor ion was m/z 735.2338, corresponding to a molecular formula of C36H39N4O11S with an error of 0.3 ppm from the calculated m/z 735.2336. The MS/MS data was consistent with an isocoproporphyrin sulfonic acid structure, derived from dehydroisocoproporphyrinogen by sulfonation of the vinyl group. The metabolite was present in a greater abundance than other isocoproporphyrin derivatives and may be a more useful biomarker for HCB intoxication.

Exposure to priority organochlorine contaminants in the Italian general population. Part 1. Eight priority organochlorinated pesticides in blood serum

Despite extensive use of organochlorinated pesticides (OCPs) such as dichlorodiphenyltrichloroethane (DDT) in Italy in the 1940s to 1970s, especially for public health control of malaria mosquitoes, information on their exposure levels among the general population is limited. These OCPs can be a source of health risk to human. A total of 137 blood samples were collected from residents of the general population of three Italian towns, Novafeltria, Pavia and Milan, to determine the levels of eight OCPs in blood serum. The concentrations of beta-hexachlorocyclohexane, hexachlorobenzene (HCB), 1,1-dichloro-2-( o-chlorophenyl)-2-( p-chlorophenyl)ethylene, 1,1-dichloro-2,2-bis( p-chlorophenyl)-ethylene ( p, p' -DDE), 1,1-dichloro-2-( o-chlorophenyl)-2-( p-chlorophenyl)ethane, 1,1-dichloro-2,2-bis (4-chlorophenyl)ethane, 1,1,1-trichloro-2-( o-chlorophenyl)-2-( p-chlorophenyl)-ethane and 1,1,1-trichloro-2,2-bis( p-chlorophenyl) ethane were measured by gas chromatography–mass spectrometry. Variations in serum concentrations of OCPs with respect to place of residence, gender, age and body mass index (BMI) were evaluated by non-parametric tests. p, p' -DDE and HCB were the most abundant and major contributors of total OCP concentration. Their levels differed significantly between the three towns with a trend Milan > Novafeltria > Pavia (  p < 0.0001). Females had significantly higher concentrations of HCB and p, p'-DDE than males in the overall population sample. HCB concentrations were significantly higher in females than in males of Milan ( p = 0.029). We observed positive correlations of p, p'-DDE and HCB with age in Novafeltria subjects ( r = 0.468, p = 0.004). Total OCP concentrations differed significantly across BMI categories ( p = 0.018) in overall population. We have demonstrated a clear pattern of the main OCPs in a fairly large population. Generally, our study provides information on OCPs exposure among the Italian general population and provides indications for further investigations.

Organohalogenated contaminants in domestic cats' plasma in relation to spontaneous acromegaly and type 2 diabetes mellitus: a clue for endocrine disruption in humans?

It was recently hypothesized that pets may serve as sentinels to explore human exposure to organohalogenated chemicals (OHCs) via indoor environments and adverse health effects. The current study investigates OHCs contamination in domestic cats suffering from diabetes mellitus (DM), particularly DM induced by acromegaly and a form of DM akin to human type 2 DM (T2DM). Plasma from three groups of domestic cats was analyzed: acromegaly induced DM, T2DM and age matched control cats without DM. Analytes targeted included organochlorine pesticides, polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs), together with their hydroxylated (HO-) metabolites. Similar PCB profiles were measured in cat plasma compared to humans, while the PBDE profile (dominated by BDE-99 (48%-55%) and BDE-47 (19%-25%)), the PCB and PBDE metabolite profiles were different in cat plasma than found in humans. Significantly higher OHC concentrations were recorded in plasma of acromegalic cats compared to the other two groups. Group differences in the PCBs/HO-PCBs ratios suggest that acromegalic cats have a lower capacity to metabolize persistent OHCs, like PCBs, than diabetic cats or cats without an endocrinopathy. As pituitary tumorigenesis in animals can be induced by estrogens, and PCBs may act as xenoestrogens, further investigation into whether there could be a causative link with the induction of feline acromegaly is warranted. Interestingly, BDE-47/BDE-99 ratios in cats were similar to the ratios in house dust. The results of this study suggest that domestic cats may represent a good model to assess human exposure to chemicals present in indoor dust.

Action of hexachlorobenzene on tumor growth and metastasis in different experimental models

Hexachlorobenzene (HCB) is a widespread organochlorine pesticide, considered a possible human carcinogen. It is a dioxin-like compound and a weak ligand of the aryl hydrocarbon receptor (AhR). We have found that HCB activates c-Src/HER1/STAT5b and HER1/ERK1/2 signaling pathways and cell migration, in an AhR-dependent manner in MDA-MB-231 breast cancer cells. The aim of this study was to investigate in vitro the effect of HCB (0.005, 0.05, 0.5, 5μM) on cell invasion and metalloproteases (MMPs) 2 and 9 activation in MDA-MB-231 cells. Furthermore, we examined in vivo the effect of HCB (0.3, 3, 30mg/kg b.w.) on tumor growth, MMP2 and MMP9 expression, and metastasis using MDA-MB-231 xenografts and two syngeneic mouse breast cancer models (spontaneous metastasis using C4-HI and lung experimental metastasis using LM3). Our results show that HCB (5μM) enhances MMP2 expression, as well as cell invasion, through AhR, c-Src/HER1 pathway and MMPs. Moreover, HCB increases MMP9 expression, secretion and activity through a HER1 and AhR-dependent mechanism, in MDA-MB-231 cells. HCB (0.3 and 3mg/kg b.w.) enhances subcutaneous tumor growth in MDA-MB-231 and C4-HI in vivo models. In vivo, using MDA-MB-231 model, the pesticide (0.3, 3 and 30mg/kg b.w.) activated c-Src, HER1, STAT5b, and ERK1/2 signaling pathways and increased MMP2 and MMP9 protein levels. Furthermore, we observed that HCB stimulated lung metastasis regardless the tumor hormone-receptor status. Our findings suggest that HCB may be a risk factor for human breast cancer progression.

The relationships between pesticide metabolites and neurobehavioral test performance in the third National Health and Nutrition Examination Survey

Regression analysis was used to estimate and test for relationships between urinary pesticide metabolites and neurobehavioral test performance in adults, 20 to 59 years old, participating in the third National Health and Nutrition Examination Survey. The 12 pesticide metabolites included 2 naphthols, 8 phenols, a phenoxyacetic acid, and a pyridinol. The 3 neurobehavioral tests included in the survey were simple reaction time, symbol-digit substitution, and serial digit learning. As the 2,4-dichlorophenol, 2,5-dichlorophenol, and the pentachlorophenol concentrations increased, performance on the serial digit learning test improved. As the 2,5-dichlorophenol concentration increased, performance on the symbol-digit substitution test improved. At low concentrations, the parent compounds of these metabolites may act at acetylcholine and γ-aminobutyric acid synapses in the central nervous system to improve neurobehavioral test performance.

Changes in serum concentrations of polychlorinated biphenyls (PCBs), hydroxylated PCB metabolites and pentachlorophenol during pregnancy

We studied pregnancy-related changes in serum concentrations of five polychlorinated biphenyls (PCBs, CB 118, CB 138, CB 153, CB 156, CB 180), three hydroxylated PCB metabolites (4-OH-CB107, 4-OH-CB146, 4-OH-CB187), and pentachlorophenol (PCP). Median serum lipid content increased 2-fold between early (weeks 9-13) and late pregnancy (weeks 35-36) (N=10), whereas median PCB levels in serum lipids decreased 20-46%, suggesting a dilution of PCB concentrations in serum lipids. Nevertheless, strong positive intra-individual correlations (Spearman's r=0.61-0.99) were seen for PCBs during the whole study period. Thus, if samples have been collected within the same relative narrow time window during pregnancy, PCB results from one single sampling occasion can be used in assessment of relative differences in body burdens during the whole pregnancy period. Concentrations of OH-PCBs in blood serum tended to decline as pregnancy progressed, although among some women the concentrations increased at the end of pregnancy. Positive intra-individual correlations (r=0.66-0.99) between OH-PCB concentrations were observed during the first and second trimester, whereas correlations with third trimester concentrations were more diverging (r=-0.70-0.85). No decline in PCP concentrations was observed during pregnancy and no significant correlations were found between concentrations at different sampling periods. Our results suggest that for both OH-PCBs and PCP, sampling has to be more specifically timed depending on the time period during pregnancy that is of interest. The differences in patterns of intra- and inter-individual variability of the studied compounds may be due to a combination of factors, including lipid solubility, persistence of the compounds, distribution in blood, metabolic formation, and pregnancy-related changes in body composition and physiological processes.

Activation of c-Src/HER1/STAT5b and HER1/ERK1/2 signaling pathways and cell migration by hexachlorobenzene in MDA-MB-231 human breast cancer cell line

Hexachlorobenzene (HCB) is a widespread environmental pollutant. It is a dioxin-like compound and a weak ligand of the aryl hydrocarbon receptor (AhR) protein. HCB is a tumor cocarcinogen in rat mammary gland and an inducer of cell proliferation and c-Src kinase activity in MCF-7 breast cancer cells. This study was carried out to investigate HCB action on c-Src and the human epidermal growth factor receptor (HER1) activities and their downstream signaling pathways, Akt, extracellular-signal-regulated kinase (ERK1/2), and signal transducers and activators of transcription (STAT) 5b, as well as on cell migration in a human breast cancer cell line, MDA-MB-231. We also investigated whether the AhR is involved in HCB-induced effects. We have demonstrated that HCB (0.05μM) produces an early increase of Y416-c-Src, Y845-HER1, Y699-STAT5b, and ERK1/2 phosphorylation. Moreover, our results have shown that the pesticide (15 min) activates these pathways in a dose-dependent manner (0.005, 0.05, 0.5, and 5μM). In contrast, HCB does not alter T308-Akt activation. Pretreatment with a specific inhibitor for c-Src (4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo[3,4-d]pyrimidine [PP2]) prevents Y845-HER1 and Y699-STAT5b phosphorylation. AG1478, a specific HER1 inhibitor, abrogates HCB-induced STAT5b and ERK1/2 activation, whereas 4,7-orthophenanthroline and α-naphthoflavone, two AhR antagonists, prevent HCB-induced STAT5b and ERK1/2 phosphorylation. HCB enhances cell migration evaluated by scratch motility and transwell assays. Pretreatment with PP2, AG1478, and 4,7-orthophenanthroline suppresses HCB-induced cell migration. These results demonstrate that HCB stimulates c-Src/HER1/STAT5b and HER1/ERK1/2 signaling pathways in MDA-MB-231. c-Src, HER1, and AhR are involved in HCB-induced increase in cell migration. The present study makes a significant contribution to the molecular mechanism of action of HCB in mammary carcinogenesis.

Biomonitoring equivalents for hexachlorobenzene

Recent efforts worldwide have resulted in a growing database of measured concentrations of chemicals in blood and urine samples taken from the general population. However, few tools exist to assist in the interpretation of the measured values in a health risk context. Biomonitoring equivalents (BEs) are defined as the concentration or range of concentrations of a chemical or its metabolite in a biological medium (blood, urine, or other medium) that is consistent with an existing health-based exposure guideline. This study reviews available health-based exposure guidance values for hexachlorobenzene (HCB) from Health Canada, the United States Environmental Protection Agency (US EPA), the US Agency for Toxic Substances and Disease Registry (ATSDR) and World Health Organization (WHO). HCB liver tissue concentrations in chronic rodent bioassays and information on human elimination rates and tissue distribution of HCB were extrapolated to estimate serum lipid-adjusted HCB concentrations that are consistent with the exposure guidance values for HCB. Estimated serum lipid-adjusted HCB concentrations ranging from 16 to 250 ng/g lipid were consistent with non-cancer-based exposure guidance values from various agencies. Concentrations associated with cancer risk-specific doses at target risk levels of interest were also estimated. These BE values may be used as screening tools for evaluation of population biomonitoring data for HCB in a risk assessment context and can assist in prioritization of the potential need for additional risk assessment efforts for HCB relative to other chemicals.

Hexachlorobenzene induces cell proliferation and IGF-I signaling pathway in an estrogen receptor alpha-dependent manner in MCF-7 breast cancer cell line

Hexachlorobenzene (HCB) is an organochlorine pesticide widely distributed in the biosphere. ERalpha regulates the expression of genes involved in growth and development, and plays an important role in breast cancer. The present study focuses attention on the effect of HCB (0.005, 0.05, 0.5, 5 microM) on cell proliferation in estrogen receptor alpha (ERalpha)(+) MCF-7, and ERalpha(-) MDA-MB-231 breast cancer cell lines. We also studied the insulin growth factor-I (IGF-I) signaling pathway in MCF-7 cells. HCB (0.005 and 0.05 microM) stimulated cell proliferation in MCF-7, but not in MDA-MB-231 cells. The pesticide increased apoptosis in MCF-7, at HCB (0.5 and 5 microM). At these doses, HCB induced the expression of the aryl hydrocarbon receptor (AhR)-regulated gene cytochrome P4501A1. MCF-7 cells exposed to HCB (0.005 and 0.05 microM) overexpressed IGF-IR and insulin receptor (IR). IRS-1-phosphotyrosine content was increased in a dose dependent manner. ICI 182,780 prevented HCB-induced cell proliferation and IGF-I signaling in MCF-7 cells incubated in phenol-red free media. In addition, HCB (0.005 microM) increased c-Src activation, Tyr537-ERalpha phosphorylation and ERalpha down-regulation. Taken together, our data indicate that HCB stimulation of cell proliferation and IGF-I signaling is ERalpha dependent in MCF-7 cells.

Correcting serum concentrations of organochlorine compounds by lipids: alternatives to the organochlorine/total lipids ratio

INTRODUCTION

When studying the effects of organochlorine compounds (OCs) on human health it is common to correct serum concentrations of OC by total lipids (TL). However, the relationship between serum OCs and serum TL is far from established in many diseases, including several cancers. Our aim was to analyze the relationship between serum OC and TL in patients with pancreatic ductal adenocarcinoma (PDA), and to explore several alternatives to perform the OC lipid correction.

METHODS

Incident cases of PDA were interviewed and had blood drawn soon around hospital admission (n=144). Serum concentrations of OCs were analysed by high-resolution gas chromatography with electron-capture detection.

RESULTS

Most patients with high TL had moderate or low concentrations of OCs. By contrast, the variability of OC values among patients with normal TL was large. Correlations were of a similar magnitude between OC and TL and between OC and total cholesterol; while these correlations were weak (all Spearman's rho<0.3 and R(2)<0.11), no OC were significantly correlated with triglycerides. Although all alternatives to the OC/TL linear ratio were statistically significant for at least one OC, their R(2) was always below 10%.

CONCLUSIONS

In patients with severe diseases as PDA, linear correction of OC by TL as commonly performed in epidemiologic studies may be inappropriate. Results contribute to the scant literature on the rationale to correct serum concentrations of OC by lipids. They suggest that it is unwarranted to routinely correct OC by TL, offer ways to assess such need, and present alternatives as no TL correction, correction by total cholesterol only or use of different statistical models.

A physiologically based pharmacokinetic model for the assessment of infant exposure to persistent organic pollutants in epidemiologic studies

BACKGROUND

It has been suggested that pre- and postnatal exposure to persistent organic pollutants (POPs) can promote several adverse effects in children, such as altered neurodevelopment. Epidemiologic studies to date have relied on the analysis of biological samples drawn pre- or post-natally for exposure assessment, an approach that might not capture some key events in the toxicokinetics of POPs.

OBJECTIVES

We aimed to build a generic physiologically based pharmacokinetic (PBPK) modeling framework for neutral POPs to assess infant toxicokinetic profiles and to validate the model using data on POP levels measured in mothers and infants from a Northern Québec Inuit population.

METHODS

The PBPK model developed herein was based upon a previously published model to which an infant submodel was added. Using the model and maternal blood levels at the time of delivery, exposure to 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE), 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (p,p'-DDT), hexachlorobenzene (HCB), beta-hexachlorocyclohexane (beta-HCH), 2,2',3,4,4',5'-hexachlorobiphenyl (PCB-138), 2,2',4,4',5,5'-hexachlorobiphenyl (PCB-153), and 2,2',3,4,4',5,5'-heptachlorobiphenyl (PCB-180) in mothers was estimated to subsequently simulate infant blood, breast milk, and cord blood POP concentration. Simulations were then compared with corresponding measured levels through Spearman correlation analyses.

RESULTS

Predictions were highly correlated with measured concentrations for PCB-153, PCB-180, PCB-138, HCB, and p,p'-DDE (r = 0.83-0.96). Weaker correlations were observed for p,p'-DDT and beta-HCH for which levels were near the limits of detection.

CONCLUSION

This is the first study to validate a PBPK model of POPs in infants on an individual basis. This approach will reduce sampling efforts and enable the use of individualized POP toxicokinetic profiles in the epidemiologic studies of POP adverse effects on child development.

Exposure to hexachlorobenzene during pregnancy increases the risk of overweight in children aged 6 years

AIM

To determine whether prenatal exposure to hexachlorobenzene (HCB) has potential adverse effects on child's weight and body mass index (BMI) in a general population with no local pollution sources.

METHODS

Starting from mid 1997, all mothers presenting for antenatal exposure in Menorca were recruited. Subsequently, 482 children were enrolled. HCB was measured in cord blood. Weight and height were measured at birth and at age 6.5 years.

RESULTS

Children with HCB levels higher than 1.03 ng/mL in cord blood were 1.14 kg (0.38) heavier and had a higher BMI (beta= 0.80 (0.34)) than children with HCB levels lower than 0.46 ng/mL. No statistically significant associations were found in height. Children in the higher exposure group of HCB had an increased risk of 2.5 and 3.0 of being overweight and obese. Children from normal weight mothers also presented an increased risk of having higher BMI with increasing concentrations of HCB in cord serum.

CONCLUSION

Prenatal exposure to HCB is associated with an increase in BMI and weight at age 6.5 years. Further studies with larger samples and longer follow-up are needed to confirm these results.

Pentachlorobenzene, hexachlorobenzene, and pentachlorophenol in children's serum from industrial and rural populations after restricted use

The study of a population of 4-year-old children born between 1997 and 1999 in an urban area under strong inputs of pentachlorobenzene (PeCB) and hexachlorobenzene (HCB) suggested that the measured concentrations of pentachlorophenol (PCP) in serum may essentially result from metabolism of these chlorinated hydrocarbons. In contrast, examination of a rural population of children where the same compounds were present at relatively low levels points to other inputs besides transformation of PeCB and HCB being responsible for the measured PCP concentrations. In both populations, the results showed that a major proportion of the organochlorine compounds present in these children's serum at 4 years of age was incorporated during the lactation period.

Pentachlorophenol and other chlorinated phenols are substrates for human hydroxysteroid sulfotransferase hSULT2A1

Pentachlorophenol (PCP) is a persistent chemical contaminant that has been extensively investigated in terms of its toxicology and metabolism. Similar to PCP, other chlorinated phenol derivatives are also widely present in the environment from various sources. Even though some of the chlorine-substituted phenols, and particularly PCP, are well-known inhibitors of phenol sulfotransferases (SULTs), these compounds have been shown to undergo sulfation in humans. To investigate the enzymatic basis for sulfation of PCP in humans, we have studied the potential for PCP as well as the mono-, di-, tri-, and tetra-chlorinated phenols to serve as substrates for human hydroxysteroid sulfotransferase, hSULT2A1. Our results show that all of these compounds are substrates for this isoform of sulfotransferase, and the highest rates of sulfation are obtained with PCP, trichlorophenols, and tetrachlorophenols. Much lower rates of sulfation were obtained with isomers of monochlorophenol and dichlorophenol as substrates for hSULT2A1. Thus, the sulfation of polychlorinated phenols catalyzed by hSULT2A1 may be a significant component of their metabolism in humans.

Urinary deoxynivalenol is correlated with cereal intake in individuals from the United kingdom

BACKGROUND

Deoxynivalenol (DON) is a toxic fungal metabolite that frequently contaminates cereal crops. DON is toxic to animals, but the effects on humans are poorly understood, in part because exposure estimates are of limited precision.

OBJECTIVES

In this study we used the U.K. adult National Diet and Nutrition Survey to compare 24-hr urinary DON excretion with cereal intake.

METHODS

One hundred subjects were identified for each of the following cereal consumption groups: low (mean, 107 g cereal/day; range, 88-125), medium (mean, 179 g/day; range, 162-195) and high (mean, 300 g/day; range, 276-325). DON was analyzed in 24-hr urine samples by liquid chromatography-mass spectrometry after purification on immunoaffinity columns.

RESULTS

DON was detected in 296 of 300 (98.7%) urine samples. Cereal intake was significantly associated with urinary DON (p < 0.0005), with the geometric mean urinary levels being 6.55 microg DON/day [95% confidence interval (CI), 5.71-7.53]; 9.63 microg/day (95% CI, 8.39-11.05); and 13.24 microg/day (95% CI, 11.54-15.19) for low-, medium-, and high-intake groups, respectively. In multivariable analysis, wholemeal bread (p < 0.0005), white bread (p < 0.0005), "other" bread (p < 0.0005), buns/cakes (p = 0.003), high-fiber breakfast cereal (p = 0.016), and pasta (p = 0.017) were significantly associated with urinary DON. Wholemeal bread was associated with the greatest percent increase in urinary DON per unit of consumption, but white bread contributed approximately twice as much as wholemeal bread to the urinary DON levels because it was consumed in higher amounts.

CONCLUSION

The majority of adults in the United Kingdom appear to be exposed to DON, and on the basis of the urinary levels, we estimate that some individuals may exceed the European Union (EU) recommended maximum tolerable daily intake of 1,000 ng DON/kg (bw). This exposure biomarker will be a valuable tool for biomonitoring as part of surveillance strategies and in etiologic studies of DON and human disease risk.

The influence of lipid and lifestyle factors upon correlations between highly prevalent organochlorine compounds in patients with exocrine pancreatic cancer

We aimed to analyse the influence of cholesterol and triglycerides, and of tobacco, coffee and alcohol consumption upon correlations between serum concentrations of organochlorine compounds (OCs) in patients with exocrine pancreatic cancer (EPC). Incident cases of EPC diagnosed in eastern Spain were prospectively identified (N=144). OCs were analysed by high-resolution gas chromatography with electron-capture detection. A strong correlation was observed between hexachlorobenzene (HCB) and beta-hexachlorocyclohexane (beta-HCH) (Spearman's rho=0.758). beta-HCH showed rho>0.4 with p,p'-DDT, p,p'-DDE, PCB138 and PCB153 (all p<0.001). Some correlations among compounds were slightly affected by tobacco, coffee or alcohol consumption. We observed a striking diversity of correlation patterns by strata of cholesterol and triglycerides. Most correlations were higher in the lowest category of triglycerides than in the lowest category of cholesterol. Most coefficients above 0.7 were seen in the lowest category of triglycerides (e.g., OC pairs p,p'-DDT and HCB, p,p'-DDT and beta-HCH, p,p'-DDE and beta-HCH, or HCB and beta-HCH). Correlations among OCs may be stronger when concentrations of triglycerides are low than when they are high. This is compatible with a dilution in the early phases of cancer and with a concentration effect as triglycerides become lower in the advanced phases of the disease.

Exposure to hexachlorobenzene during pregnancy and children's social behavior at 4 years of age

BACKGROUND

Hexachlorobenzene (HCB) is an organochlorine chemical that has been used in agriculture and industrial processes. Behavioral impairment after HCB exposure has been described in animal models, but little information is available in humans.

OBJECTIVES

Our goal was to study the association of prenatal exposure to HCB with the social behavior of preschool children.

METHODS

Two birth cohorts in Ribera d'Ebre and Menorca (Spain) were set up between 1997 and 1999 (n = 475). The California Preschool Social Competence Scale and the Attention-Deficit Hyperactivity Disorder (ADHD) were scored by each 4-year-old child's teacher. Organochlorine compounds were measured in cord serum. Children's diet and parental sociodemographic information were obtained through questionnaire.

RESULTS

Children with concentrations of HCB > 1.5 ng/mL at birth had a statistically significant increased risk of having poor Social Competence [relative risk (RR) = 4.04; 95% confidence interval (CI), 1.76-9.58] and ADHD (RR = 2.71; 95% CI, 1.05-6.96) scores. No association was found between HCB and the cognitive and psychomotor performance of these children.

CONCLUSIONS

Prenatal exposure to current concentrations of HCB in Spain is associated with a decrease in the behavioral competence at preschool ages. These results should be considered when evaluating the potential neurotoxicologic effects of HCB.

An observational study of the potential exposures of preschool children to pentachlorophenol, bisphenol-A, and nonylphenol at home and daycare

The Children's Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants (CTEPP) study investigated the potential exposures of 257 preschool children, ages 1 1/2-5 yr, and their primary adult caregivers to more than 50 anthropogenic chemicals. Field sampling took place in selected counties in North Carolina (NC) and Ohio (OH) in 2000-2001. Over a 48-h period in each child's daycare center and/or home, food, beverages, indoor air, outdoor air, house dust, soil, participants' hand surfaces and urine were sampled. Additional samples-transferable residues, food preparation surface wipes, and hard floor surface wipes-were collected in the approximately 13% of the homes that had pesticide applications within the 7 days prior to field sampling. Three phenols were among the measured chemicals: pentachlorophenol (PCP), bisphenol-A [2,2-bis(4-hydroxyphenyl)propane], and nonylphenol (4-n-nonylphenol). Nonylphenol (NP) was detected in less than 11% of the samples in any medium. Among samples that were collected at all participants' homes and daycare centers, PCP was detected in >50% of indoor air, outdoor air, house dust, and urine samples; bisphenol-A (BPA) was detected in >50% of indoor air, hand wipe, solid food, and liquid food samples. The concentrations of the phenols in the sampled media were measured, and the children's potential exposures and potential absorbed doses resulting from intake through the inhalation, dietary ingestion, and indirect ingestion routes of exposure were estimated. The children's potential exposures to PCP were predominantly through inhalation: 78% in NC and 90% in OH. In contrast, their potential exposures to BPA were predominantly through dietary ingestion: 99%, for children in both states. The children's estimated exposures to PCP, calculated from the amounts excreted in their urine, exceeded their estimated maximum potential intake, calculated from the multimedia PCP concentrations, by a factor greater than 10. This inconsistency for PCP highlights the need for further research on the environmental pathways and routes of PCP exposure, investigation of possible exposures to other compounds that could be metabolized to PCP, and on the human absorption, metabolism, and excretion of this phenol over time periods longer than 48 h.

Potential of Gas Chromatography Coupled To Triple Quadrupole Mass Spectrometry for Quantification and Confirmation of Organohalogen Xenoestrogen Compounds in Human Breast Tissues

The potential of gas chromatography coupled to tandem mass spectrometry (GC/MS/MS) with a triple quadrupole analyzer (QqQ) has been investigated for the accurate and sensitive determination of xenoestrogens in human breast tissues. Special emphasis has been given to the confirmation of the identity of compounds detected in the samples analyzed in order to avoid the reporting of false positives. The work has been focused on the determination of approximately 30 organochlorine compounds (PCBs and pesticides) and organobromine compounds (polybrominated diphenyl ethers) in adipose breast tissue and in tumoral fragment. Analytes were extracted by dissolving the samples in hexane, and the extracts were purified by automated normal-phase HPLC prior to GC/MS/MS analysis. Three isotopically labeled standards were added before extraction as surrogates for the quality control of the analyses. Accuracy and precision were evaluated by means of recovery experiments using adipose breast tissue spiked at three concentration levels, with satisfactory results for most analytes. The excellent selectivity and sensitivity of QqQ in selected reaction monitoring mode allowed us satisfactory quantification and confirmation at levels as low as 5-25 ng/g, i.e., the lowest concentration level for which the method was fully validated. Two MS/MS transitions were selected for each analyte, using the concentration ratio obtained from them as a confirmatory parameter. The developed methodology was applied to the analysis of 51 breast samples (26 adipose tissues and 25 tumoral fragments), giving as a result the detection and confirmation of several organochlorine compounds in both types of samples. Due to its adequate analytical characteristics, the optimized method fits with the requirements of accurate quantification and reliable confirmation of the identity of compounds detected according to the most recent European Guidelines. As an ultimate unequivocal confirmation, several selected samples were reanalyzed by gas chromatography coupled to mass spectrometry with a time-of-flight (TOF) analyzer. Confirmation of analytes present at higher concentrations was successful with mass error less than 5 mDa. However, confirmation by TOF MS was not possible al low concentrations (i.e., at the few ng/g level) as a consequence of its lower sensitivity compared with that of triple quadrupole in selected reaction monitoring mode.