Animals ; Dioxins ; toxicity ; Humans ; Liver ; drug effects ; Polychlorinated Dibenzodioxins ; toxicity

OBJECTIVEThe toxicology of TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) has been studied mainly with regard to the carcinogenicity of its metabolites, but its phototoxicity is not well understood. Although some studies have indicated the lethal phototoxicity of TCDD, this study was designed to investigate its effect on SPC-A1 cells.

METHODSSPC-A1 cells were cultured in 1640 medium and treated with 10 nmol/L, 0.1 micromol/L, 1 micromol/L TCDD for either 24 h or 96 h at each concentration. SPC-A1 cells were co-cultured with TCDD at different concentrations. Then the cell morphology, DNA fragment electrophoresis, and cell cycle were analyzed by flow cytometry, and enzyme assays were used to observe the effect of TCDD on the morphology, growth rate, and enxyme change of SPC-A1 cells.

RESULTSWith the increasing concentrations of TCDD and prolongation of culture time, the morphology of SPC-A1 cells was changed from round shape to spindle, and the ability of SPC-A1 cells to adhere to wall was decreased. With debris emitted around the cells, the morphologic changes included reduction in cell volume. Nuclear chromatin condensation and PI were observed. With the increasing concentrations of TCDD, DNA ladder occurred. After treatment with TCDD, extraction of cancer cells exhibited typical DNA fragmentation, and flow cytometry analysis showed apoptosis in a dose-dependent manner. As the concentration of TCDD rose from 10 nmol/L to 1 micromol/L, the ratio of apoptotic cells increased from 10.76% to 21.82%.

CONCLUSIONSTCDD has in vitro cytotoxicity on SPC-A1 cells, and the cytotoxicity is positively related to its concentration and culture time. TCDD may inhibit the growth and proliferation of SPC-A1 cells through the pathway of apoptosis introduction.

Cell Line, Tumor ; DNA Fragmentation ; Environmental Pollutants ; toxicity ; Humans ; Polychlorinated Dibenzodioxins ; toxicity

Cell Proliferation ; drug effects ; Cells, Cultured ; Epidermis ; cytology ; drug effects ; Humans ; Polychlorinated Dibenzodioxins ; pharmacology

Objective: To explore the molecular mechanism of cleft palate in mice induced by 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD). Methods: The pregnant mice were randomly divided into TCDD-treated group (n=42) and control group (n=42). TCDD-treated group was given by gavage a single dose of TCDD (64 μg/kg) at 8: 00 AM on gestation day 10 (GD10) and the control group was given by gavage the isopyknic corn oil. At GD13-GD15, the fetal mice palate development was observed by HE staining. The mouse embryonic palatal mesenchymal cell proliferation was detected by 5-bromo-2-deoxyuridine (BrdU) immunofluorescence. The localization and expression of maternally expressed gene3 (MEG3) in mouse embryonic palatal mesenchymal cells was detected by situ hybridization and real-time PCR (RT-PCR). The key protein expressions of transforming growth factor-β (TGF-β)/Smad signaling pathway in mouse embryonic palatal mesenchyme were analyzed by Western blotting. The interaction of MEG3 and TGF-β receptor Ⅰ (TGF-βRⅠ) was examined by RNA binding protein immunoprecipitation (RIP). Results: At GD13 and GD14, compared with the control group, the ratio of BrdU-positive cells in the palatal mesenchyme of TCDD-treated fetuses decreased significantly (GD13, t=6.66, P=0.003; GD14, t=6.56, P=0.003). However, at GD15, the ratio of BrdU-positive cells was significantly increased (t=-5.98, P=0.004). MEG3 was mainly expressed in the nuclei of fetal mouse palatal mesenchymal cells, and the expression of MEG3 in TCDD group was significantly increased at GD13, GD14 and GD15(GD13, t=39.28, P=0.012; GD14, t=18.75, P=0.042; GD15, t=28.36, P=0.045). At GD14, TCDD decreased the levels of p-Smad2 and Smad4 in embryonic palate mesenchymal cells (p-Smad2, t=9.48, P=0.001;Smad4, t=63.10, P=0.001), whereas the expression of Smad7 was significantly increased at GD14 (t=30.77, P<0.001). The results of the RIP experiment showed that the amount of TGF-βRⅠ-bound MEG3 in mouse embryonic palatal mesenchymal cells in the TCDD group (23.940±1.301) was higher than that in the control group (8.537±1.523)(t=24.55, P<0.001). Conclusions: MEG3 is involved in the suppression of mouse embryonic palatal mesenchymal cell proliferation, functioning at least in part via interacting with the TGF-βRⅠ protein and thereby suppressing Smad signaling in the context of TCDD induced cleft palate.
Animals ; Bromodeoxyuridine ; Cleft Palate/genetics* ; Female ; Mice ; Mice, Inbred C57BL ; Palate/metabolism* ; Polychlorinated Dibenzodioxins/toxicity* ; Pregnancy

OBJECTIVETo establish the methods of Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) compounds determination by isotope dilution HRGC/HRMS simultaneously in human placenta tissue from mothers, and assess the human exposure risk to dioxins and PBDEs in study.

METHODSConcentrations of 17 PCDD/Fs and 12 dioxin-like PCBs as well as 7 PBDEs were measured in human placenta tissue samples by isotope dilution HRGC/HRMS. SigmaTEQ (PCDD + PCDFs + PCBs) concentration using WHO-TEF factor and PBDEs concentration was calculated respectively. Risk assessment of mother exposure to dioxins and PBDEs was evaluated.

RESULTSMedian of SigmaTEQ (PCDD + PCDFs + PCBs) concentration for six samples was 18.15 WHO-TEQ pg/g lipid, ranging from 5.14 - 67.01 WHO-TEQ pg/g lipid. Although the median of SigmaTEQ (PCDD + PCDFs + PCBs) was lower than that of human blood of EU and Japan, and close to that of Korea and Taiwan non-exposure as reported in the literatures, the highest SigmaTEQ (PCDD + PCDFs + PCBs) concentration of placenta sample exceeded the value of high dioxins exposure area subjects in Taiwan. The dominant contributor congener for WHO-TEQ were 2, 3, 4, 7, 8-PeCDF, 1, 2, 3, 7, 8-PeCDD, PCB126, totally accounted for 65 percent of SigmaWHO-TEQ. Median and average of PBDE concentration for six samples were 2.73 ng/g lipid and 7.17 ng/g lipid, respectively, ranging from 0.95 - 25.99 ng/g lipid. BDE47 was the dominant contributor congener for the total concentration, accounted for 35 percent.

CONCLUSIONThe methods of PCDD/Fs, PCBs and PBDEs compounds determined by isotope dilution HRGC/HRMS simultaneously in human placenta tissue from mothers were established successfully, and the human exposure risk to PCDD/Fs, PCBs and PBDEs should be surveyed for the donor with the highest SigmaTEQ (PCDD + PCDFs + PCBs) and PBDEs concentration of placenta sample in the future.

Benzofurans ; analysis ; Female ; Halogenated Diphenyl Ethers ; analysis ; Humans ; Maternal Exposure ; Placenta ; chemistry ; Polychlorinated Biphenyls ; analysis ; Polychlorinated Dibenzodioxins ; analogs & derivatives ; analysis ; Pregnancy

Objective: To analyze the level of PCDD/Fs exposure of occupational workers in the waste incineration industry and explore the risk of occupational exposure. Methods: In September 2021, literature on environmental PCDD/Fs exposure in waste incineration plants published from the establishment of the database to February 10, 2021 was retrieved from CNKI database. A total of 1365 literatures were retrieved, and 7 met the criteria for inclusion. The US Environmental Protection Agency (EPA) inhalation risk model was used to assess and analyze carcinogenic and non-carcinogenic risks of PCDD/Fs exposure among occupational workers in the waste incineration industry. Results: A total of 86 sampling sites were included in incineration plants in 7 regions. The study of Wuhan area showed that the concentration of working environment near the waste incinerator in the same factory was the highest, followed by the rest and office area in the factory. The concentration of PCDD/Fs in waste incinerators was the highest in Southwest China (4880.00-24880.00 pg TEQ/m(3)), and the lowest in Shenzhen (0.02-0.44 pg TEQ/m(3)). According to the cancer risk assessment, with the increase of exposure years, the risk of cancer increased. The highest risk of cancer was found in the waste incineration plants in Southwest China. When the exposure period was 1 year, the risk was moderate (22.40×10(-6)-114.20×10(-6)). When the exposure time was more than 5 years, the risk of cancer was high. In Jinan, workers working near the incinerator had a moderate risk of cancer after five years of exposure. In Zhejiang, workers were at medium risk of cancer after exposure for more than 20 years. Workers in Wuhan, Shanghai, Zhejiang Province, Shenzhen and the Pearl River Delta were still at low risk of cancer after 40 years of occupational exposure. HQ>1 of workers working near the waste incinerators in Jinan, Zhejiang Province and Southwest China, and the qualitative evaluation results showed that the non-carcinogenic risk was unacceptable. Conclusion: There are great differences in PCDD/Fs of occupational exposure in waste incineration industry, and the occupational exposure exceeding the occupational exposure limit has higher carcinogenic and non carcinogenic risks.
Humans ; Dibenzofurans ; Polychlorinated Dibenzodioxins/analysis* ; Air Pollutants/analysis* ; Incineration ; Dibenzofurans, Polychlorinated/analysis* ; China/epidemiology* ; Benzofurans ; Occupational Exposure/analysis* ; Carcinogens ; Risk Assessment ; Neoplasms ; Environmental Monitoring/methods*

OBJECTIVETo study the influence of lactational dioxin exposure (2, 3, 7, 8-tetrachlorodibenzo-p-dixon, TCDD) on development of alveolar bone in SD rat offspring.

METHODSThe rats of TCDD exposure group and control group were sacrificed and the alveolar bone with molars of PD60 rats in the two groups were embedded in resin. The sections were observed by fluorescent microscope. The alveolar bone formation was evaluated by histological examination, tetracycline fluorescence marker and quantitative histomorphometry. The indices of quantitative histomorphometry were compared.

RESULTSThe trabecular structure of alveolar bone was looser in TCDD exposure group than in the control group. The tetracycline fluorescence markers were more disorganized in TCDD group. The indices of quantitative histomorphometry of alveolar bone between two groups showed significantly different.

CONCLUSIONSLactational 2,3,7,8-TCDD exposure decreased the quality and quantity of alveolar bone in SD rat offspring. It is suggested that dioxins exposure may interrupt the spatial configuration.

Animals ; Female ; Lactation ; Maternal Exposure ; Polychlorinated Dibenzodioxins ; toxicity ; Pregnancy ; Rats ; Rats, Sprague-Dawley ; Tooth Socket ; drug effects ; growth & development ; pathology

OBJECTIVETo investigate the effect of 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin (OCDD) on the testicular gene expression profile in the testis of mice.

METHODSTwenty male C57BL/6j mice were randomly divided into normal control group (fed with maize oil) and 3 OCDD groups treated with OCDD by gavage for 30 days at low-, moderate-, and high doses of 1.25×10(-6), 1.25 ×10(-5), and 1.25×10(-4) g/mL, respectively (8 mL/kg daily). The testicular gene expression profiles of the mice were investigated using gene chip technique and compared between OCDD-exposed groups and the control group.

RESULTSCompared with the control group, the mice in low-dose OCDD group showed 1133 differentially expressed genes, including 659 up-regulated and 474 down-regulated ones; in the moderate-dose OCDD group, 978 genes were differentially expressed, including 487 up-regulated and 491 down-regulated ones; in the high-dose group, 895 genes were differentially expressed, including 424 up-regulated and 471 down-regulated ones.

CONCLUSIONThe effect of sub-chronic exposure to OCDD on testicular gene expression profiles in male C57BL/6j mice indicates that the testis is probably the target organ of OCDD.

Animals ; Male ; Mice ; Mice, Inbred C57BL ; Oligonucleotide Array Sequence Analysis ; Polychlorinated Dibenzodioxins ; toxicity ; Testis ; drug effects ; metabolism ; Transcriptome

OBJECTIVETo investigate the levels of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-p-furans (PCDD-Fs) in human breast milk of the mothers who lived in non-directly persistent organic pollutants (POPs) polluted area in Shenzhen, and the correlation of exposure risk factor was analyzed.

METHODSFrom July to November in 2007, 60 primiparas by vaginal delivery after parturition 3 weeks to 2 months were sampled for breast milk who aged from 20 - 34 years old and has lived in Shenzhen non-directly POPs polluted areas over 5 years. PCDD-Fs were extracted from the frozen-dried samples with accelerated solvent extraction (ASE), cleaned up by fluid management system (FMS) and quantified by high-resolution gas chromatography-high resolution mass spectrometry (HRGC-HRMS) using isotope dilution methodology. TEQ were calculated. The correlation relationship among infant's birth weight and length, participatory's dietary, age, inhabitation period, environment and the body burden of PCDD-Fs in mother was statistically analyzed by SPSS 13.0.

RESULTSThe participants aged from 20 - 34 years old (28 years on average) and lived in Shenzhen for 5 - 29 years (10 years on average). The concentration of PCDD-Fs in 60 breast milk samples were 26.957 143 - 669.583 333 pg/g fat (mean: 7.224 817 pg/g fat, median: 84.176 062 pg/g fat), and TEQ-PCDD-Fs in samples were 2.420 793 - 29.014 277 pg/g fat (mean: 8.645 992 pg/g fat, median: 7.751 804 pg/g fat). 2, 3, 4, 7, 8-PeCDF, 1, 2, 3, 7, 8-PeCDD, 2, 3, 7, 8-TCDD were the dominant contributors to the total TEQ, which were 3.691 654 pg/g fat (42.689 378%), 2.478 315 pg/g fat (28.652 356%), and 0.980 995 pg/g fat (11.343 995%) respectively. Significant positive correlations were found among age (r = 0.26, P < 0.05), inhabitation period (r = 0.49, P < 0.05), the consumption of fish (r = 0.37, P < 0.05) and the concentrations of TEQ-PCDD-Fs in the study.

CONCLUSIONThe levels of dioxin chemicals in the breast milk samples in non-directly POPs polluted areas of Shenzhen are high. Significant positive correlations were found among age, inhabitation period, the consumption of fish and the concentration of PCDD-Fs.

Adult ; China ; Dioxins ; analysis ; Environmental Exposure ; Female ; Humans ; Milk, Human ; chemistry ; Mothers ; Polychlorinated Dibenzodioxins ; analogs & derivatives ; analysis ; Risk Assessment ; Young Adult

Animals ; Cell Differentiation ; drug effects ; Cell Proliferation ; drug effects ; Epidermis ; cytology ; drug effects ; Humans ; Mice ; Polychlorinated Dibenzodioxins ; adverse effects ; toxicity ; Rats ; Skin Diseases ; chemically induced