Persistent Organochlorine Compounds Research Articles

КОНЦЕНТРАЦИИ РАДИОАКТИВНЫХ И ТОКСИЧНЫХ ХИМИЧЕСКИХ ВЕЩЕСТВ В ДОННЫХ ОТЛОЖЕНИЯХ КАРСКОГО МОРЯ

The paper presents the results of a comprehensive analysis of bottom sediment samples taken in 2020 during the Roshydromet marine scientific research in the Stepovoi and Litke bays of the Novaya Zemlya archipelago and in the coastal zone of the Kara Sea near Amderma village. All sediment samples were analyzed for the concentration of radionuclides 137Cs, 90Sr, 238Pu, 239 + 240Pu, and some samples were analyzed for the content of toxic chemicals: heavy metals, persistent organochlorine compounds, and aliphatic hydrocarbons. The analysis of the results showed that the levels of radionuclides and toxic chemicals in bottom sediments of the Stepovoi Bay are generally consistent with the data of similar surveys in previous years.

Levels of Persistent Organochlorine Compounds in Nile Tilapia (Oreochromis niloticus) from Three Cage Aquaculture Farms on the Volta Basin of Ghana: Implications for Human Health

Levels of Persistent Organochlorine Compounds in Nile Tilapia (Oreochromis niloticus) from Three Cage Aquaculture Farms on the Volta Basin of Ghana: Implications for Human Health

Are temporal trends of some persistent organochlorine and organobromine compounds in Swedish breast milk slowing down?

We investigated body burdens of persistent organic pollutants (POPs) in Swedish first-time mothers by measurements in breast milk, and followed up the temporal trends between 1996 and 2017. POPs were analysed in individual samples (n = 539) from participants from Uppsala county, Sweden. This made it possible to adjust temporal trends for age of the mother, pre-pregnancy BMI, weight gain during pregnancy, weight loss after delivery, and education, the main determinants for POP body burdens, apart from sampling year. We also compared observed body burdens with the body burdens determined to be safe from a health perspective in the risk assessment of dioxin-like polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), published by the European Food Safety Authority (EFSA). Declining temporal trends in breast milk of on average −4 to 14% per year were observed 1996–2017 for PCBs, PCDD/Fs, chlorinated pesticides, and brominated flame retardants, except for the polybrominated diphenyl ethers (PBDEs) BDE-153 and BDE-209. The toxic equivalents (TEQs) for PCDD declined faster than PCDF TEQs, −6.6% compared to −3.5% per year. For CB-169, CB-180, PCDDs, PCDFs, Total TEQ, and hexachlorobenzene (HCB), a change point year (CP) was observed around 2008–2009 and after that, the decline in levels has slowed down. If breast milk levels follows the exponential declining trend of total TEQ estimated for the entire period (−5.7% per year), 97.5% of first time mothers from the Uppsala area will have body burdens below the estimated safe level in year 2022. If instead it follows the estimated % decline after the CP in 2008 (−1.6% per year), it will take until 2045 before 97.5% is below the estimated safe level. It is important to proceed with the monitoring of POPs in breast milk from Swedish mothers in order to further observe if the levels are stabilizing or continue to decline.

Endocrine-disrupting organochlorine xenobiotics in fish products imported from Asia\u2014an assessment of human health risk

The sources of endocrine-disrupting persistent organochlorine compounds (OC) are environmental pollutants. Contaminated food is a direct result of environmental pollution, and fish are considered as the main source of OC in the human diet. This study aimed to analyze the contamination of imported fish fillets with organochlorine pesticides (OCPs) and polychlorinated biphenyl (PCB) congeners in the context of potential health risks of consumers in Poland in the light of the new tolerable weekly intake (TWI) values. The tested compounds in fish products were determined by liquid-liquid extraction and gas chromatography mass spectrometry (GS-MS) method. Despite the detection of almost all pesticides analyzed in the fish fillets tested, the risk factor (hazard quotient) was significantly lower than 1.0, ranging from 0.003 to 0.013. Considering the previous recommended TWI value (14 pg-TEQ/kg bw/week), the estimated weekly intake was lower at 43–53% of TWI. However, according to the new TWI values set by the EFSA in 2018, the estimated weekly intake was about three times higher than the TWI. This raises concerns regarding threats to consumer health.Graphical abstract

TW80 and GLDA-enhanced oxidation under electrokinetic remediation for aged contaminated-soil: Does it worth?

Soil from a former chemical plant was found to be contaminated with organochlorine compounds (OCs) from aged pesticide residues and underwent surfactant-enhanced electrokinetic remediation (EKR). Tween 80 (TW80) and N,N-Dicarboxymethyl glutamic acid tetrasodium (GLDA) were used to increase the availability of OCs and to enhance oxidation efficiency in the soil under EKR. The results indicate that flushing soil with TW80 increased the removal of persistent OCs from the soil, with 40%–80% removal efficiency. Further, incorporating TW80 with sodium persulfate significantly advanced oxidation and removed 60%–82% of OCs (in both absence and presence of the nZVI reactive barrier) within 10 days. Compared to control treatment, the addition of TW80 improved EKR by 20%–30%. The improvement was attributed to the ability of TW80 to solubilize hardly-soluble compounds and to sustain the activation of persulfate ions (S2O82−) by dissolving metal ions in the soil that would stimulate the production of sulfate radicals (SO4•−) and thus the degradation of pollutants (in the absence of nZVI reactive barrier). Differing from TW80, GLDA’s capacity to solubilize and extract OCs from the soil was much lower and less reliable, averaging around 10% compared to 60% OC-removal for TW80. However, in the absence of oxidant activators from an external source, GLDA was important for sustaining the Fenton reaction. Its inclusion increased pollutant removal from an average of 50%–60%. The addition of the nZVI reactive barrier did not significantly improve remediation within 7 days. These findings suggest that TW80 combined with EKR and advanced oxidation in the presence of the nZVI reactive barrier is the best in situ approach to remediate soils contaminated with OCs from chemical waste of industrial processes.

Assessment of persistent organochlorine compounds contamination on the Lake Victoria water and sediments: a case study in Tanzania

The current study was conducted to establish the levels of organochlorine pesticides (OCPs), its degradation products, and indicatory polychlorinated biphenyls (PCBs) in water and sediments from Lake Victoria in Tanzania. Seven indicator PCBs were identified in sediments, and five were identified in water. The PCBs loading ranged from lower than the limit of detection (LOD) to 10.28 µg kg−1 DW and 0.95 to 2.24 µg l−1 in sediments and water, respectively. PCBs, CB 138 and CB 153 dominated the load, because of their chemical stability and high degree of chlorination. In addition, ten OCPs were identified in sediments, and seven OCPs were identified in water. The levels of organochlorine compounds in sediments were higher than in water samples, implying that sediments may serve as a sink for these compounds. The presence of these compounds is probably as a result of either historical use, long-range environmental transport or environmental persistence. The levels of organochlorine compounds in the lake water and sediments are below the maximum residue limit set by EU and FAO, except for aldrin and dieldrin. Based on the Threshold Effect Concentration (TEC) for freshwater ecosystems, aldrin and dieldrin are the only OCPs that seem to be a threat to the lake environment.

Soil burden by persistent organochlorine compounds in the vicinity of a coal-fired power plant in Croatia: a comparison study with an urban-industrialized area.

The impact of a coal-fired Plomin Power Plant (PPP) in Croatia on PCB soil burden was examined by comparing the occurrence, levels, and profile of PCBs in soil from the PPP with the values determined in urban-industrialized soil (Varaždin, Croatia). Soil burden by organochlorine pesticides (OCPs) were also investigated at both locations. Topsoil samples were collected at five distances (100-800m) along a downwind pollution gradient from the PPP and across the city. The total content of PCBs in 100-m soil was nearly 20-fold the levels found in 800-m soil, which pointed to the PPP as a local source of soil contamination. The PPP soils were dominated by indicator PCB congeners, particularly hexa-homologs. A different profile and mass fraction range of PCBs in soils from PPP and Varaždin area indicated the different sources of contamination. Levels of total PCBs in PPP soils (0.25-19.07μgkg-1) were higher than PCB levels determined in soils from Varaždin (0.29-5.52μgkg-1), partially as a result of higher OC content in PPP soils. PPP soil burden by PCBs corresponded to a lower end of PCB level ranges reported for cities with high population and heavy industry. OCPs were detected at significantly higher levels in Varaždin soils than in PPP soils, with the highest contribution of the DDT-like compounds (DDX) detected in soils affected by river deposits. The p,p'-DDE/p,p'-DDT ratio in Varaždin soils indicated a fresh atmospheric input of p,p'-DDT. The PPP soil analysis detected a presence of only p,p'-DDE and HCB at levels corresponding to their global environmental presence.

Exhaustive Photocatalytic Lindane Degradation by Combined Simulated Solar Light-Activated Nanocrystalline TiO2 and Inorganic Oxidants

Organochlorine compounds (OCs) are very toxic, highly persistent, and ubiquitous contaminants in the environment. Degradation of lindane, a selected OC, by simulated solar light-activated TiO2 (SSLA-TiO2) photocatalysis was investigated. The film types of the TiO2 photocatalyst were prepared using a dip-coating method. The physical properties of the films were investigated using X-ray diffraction, transmission electron microscopy, and environmental scanning electron microscopy. The SSLA-TiO2 photocatalysis led to a lindane removal of 23% in 6 h, with 0.042 h−1 of an observed pseudo first-order rate constant (kobs). The SSLA-TiO2 photocatalysis efficiency was greatly enhanced by adding hydrogen peroxide (H2O2), persulfate (S2O82−), or both combined, corresponding to a 64%, 89%, and 99% lindane removal in the presence of 200 µM of H2O2, S2O82−, or equimolar H2O2-S2O82−, respectively. The hydroxyl and sulfate radicals mainly participated in lindane degradation, proven by the results of a radical scavenger study. The degradation kinetics were hindered in the presence of the water constituents, indicated by a 61%, 35%, 50%, 70%, 88%, and 91% degradation of lindane in 6 h, using a SSLA-TiO2/S2O82−/H2O2 photocatalysis system containing 1.0 mg L−1 humic acid (HA), or 1 mM of CO32−, HCO3−, NO3−, SO42−, and Cl−, respectively. The TiO2 film demonstrated high reusability during four runs of lindane decomposition experiments. The SSLA-TiO2/S2O82−/H2O2 photocatalysis is very effective for the elimination of a persistent OC, lindane, from a water environment.

Mobility of Some High Persistent Organochlorine Compounds from Soil to Mentha Piperita

The fate of organochlorine compounds in soil ecosystem is shaped by their physical-chemical properties and by environmental conditions. The high persistence of polychlorobiphenyls (PCBs) in soil is given by a slow degradation which varies from months to years (the half-life of PCB 28 is 10.9 years, and PCB 52, 11.2 years). Due to high lipophilicity, these carcinogenic compounds can be easily uptaken by plants and transferred to the food chain. The widespread use of medicinal plant, Mentha Piperita, in pharmaceutical and food industry represents a risk of contamination and pollution. Through laboratory studies, we worked to identify the chemical behavior in soil and plants of some PCB congeners: 28, 52, 138, 153 and 180). The compounds mobility from soil to the roots and then through plant was monitored for 5 weeks. By optimizing the analytical method the contaminants were determined from soil and plant with good recoveries and with reduced limit of detection, below 0.01 mg/kg. It was reported that usually are uptaken into the plant high chlorinated PCBs like PCB 153 and PCB 180 but this study shows that after 5 weeks of PCB application, the concentration of PCB 28, a trichlorobiphenyl, is increasing. Fortunately, calculating the bioconcentration factor (BCF) of the selected PCBs in roots, it was shown that is similar to BCF of other plants like poplar and zucchini. The obtained value of 0.2 is assessed as being low.

Persistent Organochlorine Compounds Levels in Selected Fish Species from Lake Victoria and Associated Human Health Risks

Nile perch (<i>L. niloticus </i>) and Nile tilapia (<i>O. niloticus</i>) are the major commercial fish species in Lake Victoria region of Tanzania. This study was conducted to assess the levels of persistent organochlorine compounds, namely PCBs and OCPs in these two fish species and the probable human health risks associated with the consumption of these two fish species from Lake Victoria. Fish samples were collected between May and August 2016 and the necessary anthropometric measurements such as length and weight were taken. The extraction was done using a modified QuEChERS method and the identification and quantification of the chemicals were done using GC/ECDs. The results of this study revealed that fish species sampled were undersize, which was an indication of overfishing and abuse of bylaws. Among the 19 OCPs which were considered, only four (β- HCH, HCB, Aldrin and Dieldrin) were detected at measurable quantities. β- HCH ranged from <0.24 to 1.19µg/kg. The mean concentrations were 0.77±0.43µg/kg and 0.56±0.16µg/kg for <i>L. niloticus</i> and <i>O. niloticus</i> respectively. HCB levels ranged from <0.18 to 0.59µg/kg in <i>L. niloticus</i> and <0.18µg/kg in <i>O. niloticus</i>. Aldrin ranged from <0.14 to 0.34µg/kg in <i>L. niloticus</i> whereas it was not detected in <i>O. niloticus</i>. Moreover, Dieldrin residues ranged from <0.17 to 1.06µg/kg in <i>O. niloticus</i> but were not detected in <i>L. niloticus</i>. Generally, there were slightly higher levels of the detected OCPs in <i>L. niloticus</i> than the corresponding levels in <i>O. niloticus</i> mainly due to their differences in trophic levels and feeding habits. The indicator PCBs were not detected in all the investigated fish samples. The levels of all the detected organochlorines were far below the MRL set for fish and fishery products suggesting that the fresh fish from Lake Victoria are safe for human consumption. Low levels of the detected residues and non- detection of many organochlorines considered indicate that contamination in Lake Victoria has not reached alarming levels. The human health risk assessment of the detected organochlorines showed cancer risk from 8.6E-06 to 3.2E-05 for children and from 7.8E-06 to 1.3E-05 for adults indicating that there is a low cancer risk for both age groups. The non- cancer risks (HI) on the other hand, were 5.7E-02 for children and 4.7E-02 for adults, which is an indication of an insignificant risk.

Non‐traditional atrazine degradation induced by zero‐valent‐copper: process optimization by the Doehlert experimental design, intermediates detection and toxicity assessment

AbstractBACKGROUNDOver recent years, several studies exploring new technologies capable of degrading persistent organochlorine compounds have been published. Special attention has been dedicated to atrazine (ATZ), due to its ecotoxicological relevance together with its frequent detection in the environment. Degradation of organochlorines via zero‐valent metals has gained great importance given its practicality and versatility, zero‐valent‐iron (ZVI) being the most applied metal for this purpose. Alternatively, zero‐valent‐copper (ZVCu) was proved to exhibit higher reactivity against chlorinated aromatics, therefore deserving further investigation.RESULTSThe optimum degradation conditions for ATZ removal with ZVCu were explored through a Doehlert experimental design. The same conditions were tested for the traditional ZVI, which confirmed that ZVCu was more reactive. The analysis of the degradation products suggests that both reductive and oxidative pathways coexist in the studied process.CONCLUSIONSZVCu was effective in ATZ degradation, both by reductive and oxidation pathways, within a wide range of pH values, although faster in acidic media. The resulting solution from the experiment that promoted the fastest degradation is less toxic than ATZ against microalgae Chlorella vulgaris, which is a positive output regarding the application of this process as a pre‐treatment step of ATZ‐contaminated water matrices. © 2018 Society of Chemical Industry

Genome-wide gene expression changes associated with exposure of rat liver, heart, and kidney cells to endosulfan

Endosulfan was once the most commonly used pesticide in agriculture and horticulture. It is an environmentally persistent organochlorine compound with the potential to bioaccumulate as it progresses through the food chain. Its acute and chronic toxicity to mammals, including humans, is well known, but the molecular mechanisms of its toxicity are not fully understood. To gain insight to these mechanisms, we examined genome-wide gene expression changes of rat liver, heart, and kidney cells induced by endosulfan exposure. We found that among the cell types examined, kidney and liver cells were the most sensitive and most resilient, respectively, to endosulfan insult. We acquired RNA sequencing information from cells exposed to endosulfan to identify differentially expressed genes, which we further examined to determine the cellular pathways that were affected. In kidney cells, exposure to endosulfan was uniquely associated with altered expression levels of genes constituting the hypoxia-inducible factor-1 (HIF-1) signaling pathway. In heart and liver cells, exposure to endosulfan altered the expression levels of genes for many members of the extracellular matrix (ECM)-receptor interaction pathway. Because both HIF-1 signaling and ECM-receptor interaction pathways directly or indirectly control cell growth, differentiation, proliferation, and apoptosis, our findings suggest that dysregulation of these pathways is responsible for endosulfan-induced cell death.

Organochlorine pesticides and polychlorinated biphenyls in human adipose tissue from northern Tunisia: Current extent of contamination and contributions of socio-demographic characteristics and dietary habits

The aims of the present study were to investigate the current exposure levels of persistent organochlorine compounds (OCs) in adipose tissues intraoperatively collected from 40 patients over 20 years undergoing non-cancer-related surgery residing in Northern region of Tunisia (Bizerte), which constitutes an exemplary case, and examined association between levels of contamination and both socio-demographic characteristics and dietary habits. Concentration of hexachlorobenzene (HCB), hexachlorocyclohexane isomers (α-HCH, β-HCH, γ-HCH and δ-HCH), dichlorodiphenyltrichloroethane isomers (p,p′-DDT and o,p′-DDT) and metabolites (p,p′-DDE, o,p′-DDE, p,p′-DDD and o,p′-DDD) and 12 polychlorinated biphenyls (PCBs) congeners were measured using capillary gas chromatography with electron capture detector. Overall, residue levels of OCs followed the decreasing order of DDTs > PCBs > HCB > HCHs. DDTs levels ranged from 74.49 to 1834.76ngg−1 lipid and contributing to more than 90% to the sum of organochlorine pesticides (OCPs). p,p′-DDE was the most abundant in all samples and the p,p′-DDT/p,p′-DDE ratio (range between 1.85% and 58.45%) suggesting recent and ongoing exposure to banned commercial DDT products. PCB concentrations varied from 29.27 to 322.58ngg−1 lipid and PCB-180, PCB-153 and PCB-138 were the dominant congeners accounting for 70% of total PCBs. We did not find significant correlations between OC exposure levels and sex, parity, habitat areas and smoking habits. In females, the adipose tissue concentrations of DDTs, HCB and PCB-118 were positively correlated with age. There was statistically significant relationship between body mass index (BMI) changes and the adipose tissue levels of HCB and HCHs. No association was found between OCPs levels and dietary factors. However, our study suggests that fish consumption may be an important contributor of PCBs adipose tissue content of PCBs in Tunisian people. The presented work is highly significant, being the first study pointing out the chronic exposure to OCs in Bizerte.

Influence of parasitism in dogs on their serum levels of persistent organochlorine compounds and polycyclic aromatic hydrocarbons

Persistent organochlorine pollutants (POPs) are toxic chemicals, which accumulate in humans and animals, as only few species have the capability of eliminating them. However, some authors have pointed to the possibility that certain species of invertebrates (i.e. nematodes) could metabolize this type of compounds. As certain species of nematodes act as parasites of vertebrates, this research was designed to explore the influence of some of the most common parasites of the dogs in their serum levels of 56 common POPs. The study included three groups of dogs (n=64), which were prospectively recruited in the island of Gran Canaria (Canary Islands, Spain): a) control animals, non-parasitized (serologically tested negative, n=24); b) dogs tested positive for intestinal parasites and negative for other parasites (n=24); and c) dogs tested positive for heartworm disease (Dirofilaria immitis) and negative for other parasites (n=16). The presence of Dirofilaria immitis was strongly associated with lower serum levels of a wide range of pollutant in their hosts (PCB congeners 28, 52, 118, 138, 153, and 180; hexachlorobenzene, lindane, aldrin, dieldrin, anthracene and pyrene). We also found an inverse association between the hosts' serum levels of PCBs and intestinal parasites. We did not find any association with DDT or its metabolites, but this might be explained by the recently suggested ability of dogs for the efficient metabolization of these compounds. According to the results of this study certain forms of parasitism would reduce the bioavailability of the major classes of POPs in dogs. However, further studies are needed to elucidate whether this phenomenon is due to a competence between parasites and hosts or could respond to a possible capability of parasitic nematodes for the metabolization of these POPs.

Protective effect of Camellia sinensis against-HCH-induced reproductive toxicity in Wistar rats

A wide number of pesticides, including highly persistent organochlorine compounds, such as gamma-Hexachlorocyclohexane (γ-HCH), have deteriorative effect on fauna and flora by inducing oxidative stress. Camellia sinensis, popularly known as green tea rich in polyphenols content, plays an important role in human health by virtue of its antioxidant properties. In the present study, protective effects of C. sinensis against the toxic effects of γ-HCH on sexually mature Wistar rats were investigated. The rats were divided in four groups viz. control (untreated), γ-HCH (20mg/kg bwt), γ-HCH (20mg/kg bwt) plus C. sinensis (100mg/kg bwt) and C. sinensis alone (100mg/kg bwt). γ-HCH-induced gross and microscopic alterations in testes were characterized by atrophy, distorted seminiferous tubules, disorganized spermatogonia, spermatocyte cells, sparse leydig cells, loss of spermatozoa (oligospermia) and interstitial edema. These changes were restored near to normalcy by C. sinensis. The results suggested that C. sinensis has protective effect against γ-HCH induced reproductive toxicity.

Residual archives on organochlorine insecticides in the core sediment of a tropical estuary, India

A comprehensive evaluation of the residual levels of Organochlorine insecticides (OCIs) in the sediment cores of Cochin Estuarine System (CES) is highlighted in this research article. It assessed the distribution pattern and impact of these xenobiotics in this environmental niche. Fifteen persistent organochlorine compounds (OCs) were quantitatively analysed in the six sediment core samples collected from specific sites of CES, during November 2009. Among these contaminants, residual levels of HCH, Cyclodienes and DDT were the dominant entities. According to the sediment quality guidelines (SQGs), the higher concentration of these persistent toxicants found in the CES was enough to pose ecological risk to the bottom dwelling consumers. This study provides a better understanding of these trace organics in the environment and could develop more effective strategies for protecting this vulnerable ecosystem from further pollution. Further, sediment screening bioassays can also be conducted for both sediment quality evaluation and identification of existing potent toxicants.

Blood concentrations and risk assessment of persistent organochlorine compounds in newborn boys in Turkey. A pilot study.

Even early life in utero cannot provide a safe place for newborns. The first acquaintance with chemicals takes place in utero and/or with mother's milk after delivery. Besides legislations and bans to persistent organic pollutants (POPs), these chemicals are still affecting the general population especially the children as they are one of the populations most susceptible to chemicals, and also the health problems may arise in the future. Our objective is to collect the first data in newborns in Turkey to determine baseline levels of POPs in the general population and estimate the potential cancer risk related to exposure. Twenty-nine organochlorine pesticides (OCPs) and 18 polychlorinated biphenyl (PCB) congeners in blood samples of newborn boys (0-1 month old) who were born in İstanbul, Turkey, in 2010-2012 were evaluated with high-resolution gas chromatography-high-resolution mass spectrometry (HRGC/HRMS). Results for analyzed chlorinated compounds are as follows: hexachlorocyclohexane (ΣHCH) 1828 ± 3650 pg/g lipid, dichlorodiphenyltrichloroethane (ΣDDT) 10,000 ± 15,398 pg/g lipid, and ΣPCB 1068 ± 1823 pg/g lipid. 4,4'-DDT, 4,4'-dichlorodiphenyldichloroethylene (4,4'-DDE), hexachlorobenzene, and PCB 138 and 153 are the major contaminants. New POPs as lindane 61 ± 268 pg/g lipid, pentachlorobenzene 13 ± 74 pg/g lipid, and endosulfan 29 ± 106 pg/g lipid are also detected in blood. Estimated total risk for lifetime PCB exposure is less than 1 × 10(-5), an acceptable risk. Blood concentration levels will be important base data in the assessment of health concerns of newborns as well as for studies about how endocrine disruptors affect humans.

Current data on the background burden to the persistent organochlorine pollutants HCB, p,p'-DDE as well as PCB 138, PCB 153 and PCB 180 in plasma of the general population in Germany.

Despite their long-term ban, persistent organochlorine compounds like hexachlorobenzene (HCB), p,p'-dichlorodiphenylethylene (DDE) as well as polychlorinated biphenyls (PCBs) are still of environmental concern. For the evaluation of potential occupational or environmental exposures to these substances, it is essential to know the current background burden of the general population. As representative and up-to-date information is missing for Germany, we have analysed a large dataset generated in studies on potential exposure to lower chlorinated PCBs to fill this gap for the levels of HCB, DDE as well as PCB 138, PCB 153 and PCB 180. We have investigated n=2750 plasma samples of persons of the general population living in North Rhine-Westfalia and Hesse aged 6-65 years and sampled between September 2010 and March 2014. For evaluation of the age-dependent accumulation in the general population we have generated seven age groups in the collective. Our laboratory used a validated and quality controlled procedure using GC/MS for quantification of the organochlorine compounds in plasma (LOQ: 0.01μg/L). The median (95th percentile) levels for ∑ PCB 138+PCB 153+PCB 180 were 0.14 (0.73); 0.30 (0.82); 0.38 (0.88); 0.50 (1.14); 0.92; 1.58 (3.54) and 2.41 (4.82)μg/L plasma in the age groups 6-10 years (n=102), 11-17 years (n=499), 18-25 years (n=157), 26-35 years (n=710), 36-45 years (n=400), 46-55 years (n=525) and 56-65 years (n=357), respectively. Similarly, the median (95th percentile) levels of p,p'-DDE were 0.18 (1.24); 0.18 (0.74); 0.24 (0.85); 0.30 (1.20); 0.45 (1.74); 0.64 (3.25) and 0.94 (4.7)μg/L plasma. Finally, the median (95th percentile) of HCB in plasma in these age groups was 0.05 (0.10); 0.06 (0.11); 0.08 (0.15); 0.08 (0.15); 0.11 (0.22); 0.14 (0.42) and 0.20 (0.68)μg/L plasma. Our results prove an overall substantial reduction in the body burden to organochlorine compounds in Germany compared to earlier studies. However, 15% and 3.6% of the examined collective exceeded the HBM-I- and HBM-II-values for PCBs established by the German Human Biomonitoring Commission. Due to a large sample size and a collection period from 2010 to 2014, our data might be suitable for the evaluation of additional exposures to these POPs and may serve as reference values.

Disruption of the Thyroid System by the Thyroid-Disrupting Compound Aroclor 1254 in Juvenile Japanese Flounder (Paralichthys olivaceus)

Polychlorinated biphenyls (PCBs) are a group of persistent organochlorine compounds that have the potential to disrupt the homeostasis of thyroid hormones (THs) in fish, particularly juveniles. In this study, thyroid histology, plasma TH levels, and iodothyronine deiodinase (IDs, including ID1, ID2, and ID3) gene expression patterns were examined in juvenile Japanese flounder (Paralichthys olivaceus) following 25- and 50- day waterborne exposure to environmentally relevant concentrations of a commercial PCB mixture, Aroclor 1254 (10, 100, and 1000 ng/L) with two-thirds of the test solutions renewed daily. The results showed that exposure to Aroclor 1254 for 50 d increased follicular cell height, colloid depletion, and hyperplasia. In particular, hypothyroidism, which was induced by the administration of 1000 ng/L Aroclor 1254, significantly decreased plasma TT4, TT3, and FT3 levels. Profiles of the changes in mRNA expression levels of IDs were observed in the liver and kidney after 25 and 50 d PCB exposure, which might be associated with a reduction in plasma THs levels. The expression level of ID2 mRNA in the liver exhibited a dose-dependent increase, indicating that this ID isotype might serve as sensitive and stable indicator for thyroid-disrupting chemical (TDC) exposure. Overall, our study confirmed that environmentally relevant concentrations of Aroclor 1254 cause significant thyroid disruption, with juvenile Japanese flounder being suitable candidates for use in TDC studies.

In vitro exposure of Leydig cells to an environmentally relevant mixture of organochlorines represses early steps of steroidogenesis.

Leydig cell steroidogenesis is mainly regulated by LH via increased cAMP production leading to STAR protein activation. STAR is essential for cholesterol shuttling inside mitochondria where steroidogenesis is initiated. Accumulating evidence suggest that persistent organochlorine compounds disrupt testicular function, but the mechanism of action remains poorly characterized. Here we report that in vitro exposure of MA-10 and MLTC-1 Leydig cells to an environmentally relevant mixture of 15 organochlorines impairs steroidogenesis. While having no effect on cell viability and basal steroid production, the organochlorine mixture caused a 50% decrease in cAMP-induced progesterone production. The mixture also reduced cAMP-induced 30 kDa STAR protein by 50% while having no effect on basal STAR protein. Basal or cAMP-induced Star mRNA levels and promoter activity were unaffected by the mixture, indicating that the organochlorine mixture acted at the translational/posttranslational level. Further supporting this is the fact that in COS-7 cells overexpressing STAR, the organochlorine mixture caused a decrease in the 30 kDa form of STAR and an accumulation of the 37 kDa forms. In addition to STAR, we found that the organochlorine mixture also decreases the levels of CYP11A1 and ADXR, two proteins essential for the conversion of cholesterol into pregnenolone. In conclusion, our data show that organochlorine exposure disrupts Leydig cell function by targeting different components of the steroidogenic pathway.