Weight of Evidence Evaluation of Potential Human Cancer Risks from Exposure to Polychlorinated Biphenyls: An Update Based on Studies Published Since 2003

A mode of action-based probabilistic framework of dose-response assessment for nonmutagenic liver carcinogens: a case study of PCB-126

A main function of dose-response assessment is to estimate a "safe" dose in the target population to support chemical risk assessment. Typically, a "safe" dose is developed differently for cancer and noncancer effects based on a 2-step procedure, ie, point of departure (POD) derivation and low-dose extrapolation. However, the current dose-response assessment framework is criticized for its dichotomized strategy without integrating the mode of action (MOA) information. The objective of this study was, based on our previous work, to develop a MOA-based probabilistic dose-response framework that quantitatively synthesizes a biological pathway in a dose-response modeling process to estimate the risk of chemicals that have carcinogenic potential. 3,3',4,4',5-Pentachlorobiphenyl (PCB-126) was exemplified to demonstrate our proposed approach. There were 4 major steps in the new modeling framework, including (1) key quantifiable events (KQEs) identification and extraction, (2) essential dose calculation, (3) MOA-based POD derivation, and (4) MOA-based probabilistic reference dose (RfD) estimation. Compared with reported PODs and traditional RfDs, the MOA-based estimates derived from our approach were comparable and plausible. One key feature of our approach was the use of overall MOA information to build the dose-response relationship on the entire dose continuum including the low-dose region. On the other hand, by adjusting uncertainty and variability in a probabilistic manner, the MOA-based probabilistic RfDs can provide useful insights of health protection for the specific proportion of population. Moreover, the proposed framework had important potential to be generalized to assess different types of chemicals other than nonmutagenic carcinogens, highlighting its utility to improve current chemical risk assessment.

Meta-Analysis of Body Concentration of Polychlorinated Biphenyls and Prostate Cancer

Prostate Cancer (PCa) is the second most common hormone-sensitive neoplasm among men and the fifth cause of death due to malignancy in developed countries. Moreover, studies have shown the links between polychlorinated biphenyls (PCBs) and hormone-related cancers such as prostate cancer. Hence, we conducted a systematic review and meta-analysis to evaluate the potential relationship between the PCBs and developing PCa. In this meta-analysis study, the relevant databases such as Web of Science, PubMed, and Scopus were studied for English research. The Newcastle-Ottawa Scale was applied to evaluate the quality of the selected publications. The GRADE method was used to assess the risk of bias studies. After reviewing the relevant studies, a cohort and seven case-control studies entered the meta-analysis. These articles were published during 2003-2021 with 2989 participants and 1212 PCa cases. The heterogeneity among the studies was significant (p = 0.001, I² = 70.61). Using a random-effects model, the association between the serum and plasma levels of PCBs and the risk of PCa was not shown to be significant (OR = 1.12; 95% CI: 0.90-1.39). The results of Egger's test showed no trace of publication bias in the studies (P of bias = 0.573). This systematic review and meta-analysis was presented based on relatively strong evidence and has confirmed negatively significant associations between PCa risk and some PCBs congeners (PCB 44, 52, and 101). This study does not provide strong evidence that total PCB exposure is a risk factor for PCa development in humans.

Polychlorinated biphenyl quinone exposure promotes breast cancer aerobic glycolysis: An in vitro and in vivo examination

Polychlorinated biphenyls (PCBs) were classified as group I carcinogenic to humans, as their toxicological mechanisms have been associated with cancer initiation and promotion. However, whether PCBs have effects on cancer progression are still largely veiled. Here, we for the first time discovered that a PCB quinone-type metabolite, namely PCB29-pQ, exposure significantly promoted aerobic glycolysis, a hallmark property of metabolic reprogramming in cancer progression. PCB29-pQ exposure activated corresponding glucose transporter type 1 (GLUT1)/integrin β1/Src/focal adhesion kinase (FAK) signaling pathway in breast cancer MDA-MB-231 cells. Conversely, the inhibition of GLUT1 reversed this effect, as well as the ability of migration and invasion of MDA-MB-231 cells. In addition, PCB29-pQ-induced breast cancer metastasis in 4T1-luc cell inoculated nude mice is repressed by GLUT1 inhibition. Overall, our results demonstrated a novel mechanism that PCB29-pQ exposure promotes aerobic glycolysis in both in vitro and in vivo breast cancer models in a GLUT1-dependent fashion, which may provide a strategy to prevent breast cancer cell spread.

Effects of an environmentally relevant PCB-mixture on immune function, clinical chemistry, and thyroid hormone levels in adult female B6C3F1 mice

Polychlorinated biphenyls (PCBs) have been assessed for immunotoxicity; however, humans and wildlife are exposed to multiple PCBs environmentally. Therefore, the aim of this study was to examine the effects of a complex 37 PCB congener mixture identified in blubber specific to dolphins residing in the estuarine waters of Charleston, South Carolina. Immunotoxicity was determined in adult female B₆C₃F₁ mice by assessing lymphocyte proliferation, splenic and thymic immunophenotypes, and IgM production. Mice were exposed via oral gavage to the PCB-mixture (0, 1.8, 3.6, 7.1, or 14.3 mg/kg/day) for 28 days to yield a targeted total administered dose (TAD) 0, 50, 100, 200, or 400 mg/kg. Significant increased liver weight occurred at the highest treatment. IgM production was suppressed compared to control for all treatments. Numbers of thymic CD4+/CD8+, CD4-/CD8-, and CD4+/CD8- cells were not altered, but numbers of thymic CD4-/CD8+ cells were significantly increased in the highest treatment. Lymphocyte proliferation was not markedly affected by any treatment. The numbers of splenic CD4/CD8 T-cells or MHCII+ cells were not significantly changed. Humoral immunity using the plaque-forming cell assay for determining the specific IgM antibody-forming cell response appeared to be the most sensitive endpoint affected. As the lowest concentration tested resulted in decreased IgM production and total and free thyroxine (T₄) serum levels a NOAEL was not identified. The calculated ED₅₀ for suppression of IgM production was 2.4 mg/kg/day.

PCB levels in adipose tissue of dogs from illegal dumping sites in Campania region (Italy)

The aim of the study is to investigate the potential relationship between exposure to PCBs and cancer. In doing so we relied on a sample of dogs coming from a peculiar area of the Campania region (Italy), that has been suffering for illegal waste dumping and open air burning of plastic waste for many years. The latter determined the release of organic and inorganic pollutants, such as the PCBs. By comparing dogs with cancer and healthy dogs, we found much higher PCB concentrations in the former, with a significant difference (p < 0.05) for the non-indicator ∑10NDL-PCB and the DL-PCBs. A regression analysis, controlling for three potentially confounding factors, that are sex, age and weight, confirmed the higher ∑10NDL-PCB concentration in dogs with cancer. Hence, our evidence suggests a potential health hazard for animals and likewise people living in a risky area due to the presence of environmental organic pollutants.

Untangling the association between environmental endocrine disruptive chemicals and the etiology of male genitourinary cancers

Endocrine disrupting chemicals disrupt normal physiological function of endogenous hormones, their receptors, and signaling pathways of the endocrine system. Most endocrine disrupting chemicals exhibit estrogen/androgen agonistic and antagonistic activities that impinge upon hormone receptors and related pathways. Humans are exposed to endocrine disrupting chemicals through food, water and air, affecting the synthesis, release, transport, metabolism, binding, function and elimination of naturally occurring hormones. The urogenital organs function as sources of steroid hormones, are targeted end organs, and participate within systemic feedback loops within the endocrine system. The effects of endocrine disruptors can ultimately alter cellular homeostasis leading to a broad range of health effects, including malignancy. Human cancer is characterized by uncontrolled cell proliferation, mechanisms opposing cell-death, development of immortality, induction of angiogenesis, and promotion of invasion/metastasis. While hormonal malignancies of the male genitourinary organs are the second most common types of cancer, the molecular effects of endocrine disrupting chemicals in hormone-driven cancers has yet to be fully explored. In this commentary, we examine the molecular evidence for the involvement of endocrine disrupting chemicals in the genesis and progression of hormone-driven cancers in the prostate, testes, and bladder. We also report on challenges that have to be overcome to drive our understanding of these chemicals and explore the potential avenues of discovery that could ultimately allow the development of tools to prevent cancer in populations where exposure is inevitable.

Distribution of Organohalogen and Synthetic Musk Compounds in Breast Adipose Tissue of Breast Cancer Patients in Ulster County, New York, USA

We determined the concentrations of 98 halogenated organic compounds and synthetic musks in breast fat tissues of 50 breast cancer patients (age range: 34-77 years) collected during 1996-1998 in Ulster County, New York, USA. Polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated biphenyl 153 (PBB-153), polybrominated diphenyl ethers (PBDEs), and synthetic musk compounds (SMCs) were analyzed in breast fat tissues, and 46 analytes were found at a detection frequency of ≥ 65% and at concentrations in the decreasing order of OCPs > PCBs > SMCs > PBDEs > PBB-153. PCBs (median: 323 ng/g wet wt) and dichlorodiphenyltrichloroethanes (DDTs, median: 293 ng/g wet wt) were the major compounds found in breast fat tissues. Among PCB congeners, hexa- and hepta-chlorobiphenyls (60% of total PCBs) were the abundant ones. p,p'-DDE accounted for more than 99% of the total DDT concentrations. The concentrations of SMCs and PBDEs were 1-2 orders of magnitude lower than those of PCBs and DDTs. 1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-r-2-benzopyran (median: 33 ng/g wet wt) was the most abundant SMC, whereas BDE-47 (median: 4.5 ng/g wet wt) was the most dominant PBDE congener present in breast tissues. A significant correlation (p < 0.05) between women's age and concentrations of DDTs, chlordanes, hexachlorobenzene and PCBs in breast tissues was found. Concentrations of PCBs, PBDEs, OCPs, and SMCs were not significantly different between malignant and benign tumor cases. This study adds baseline information on target tissue burdens of persistent organic contaminants in breast cancer patients.

Occupational Risk Factors for Prostate Cancer: A Meta-analysis

Prostate cancer is the second most common cancer in men worldwide. There are many occupational factors that have been suggested to cause prostate cancer. Our aim was to evaluate the evidence for causality by a literature review of occupational factors. We searched literature in Medline and SCOPUS from 1966 to June 30, 2015 to identify occupational risk factors for prostate cancer. The following risk factors were selected: farmers/agricultural workers, pesticides - whole group, and separately organophosphate and organochlorine pesticides, carbamates and triazines, cadmium, chromium, cutting fluids, acrylonitrile, rubber manufacturing, whole body vibration, shift work, flight personnel, ionizing radiation, and occupational physical activity. For each factor a literature search was performed and presented as meta-analysis of relative risk and heterogeneity (Q and I2 index). A total of 168 original studies met the inclusion criteria with 90,688 prostate cancer cases. Significantly increased risks were observed for the following occupational exposures: pesticides (metaRR = 1.15, 95% confidence interval [CI] = 1.01-1.32; I2 = 84%), and specifically group of organochlorine pesticides (meta relative risk [metaRR] = 1.08, 95% CI = 1.03-1.14; I2 = 0%), chromium (metaRR = 1.19, 95% CI = 1.07-1.34; I2 = 31%), shift work (metaRR = 1.25, 95% CI = 1.05-1.49; I2 = 78%) and pilots (metaRR = 1.41, 95% CI = 1.02-1.94; I2 = 63%) and occupational physical activity in cohort studies (metaRR = 0.87, 95% CI = 0.81-0.94; I2 = 0%). The literature review supports a causal association for a few of the previously suggested factors.

Functional and structural liver abnormalities in former PCB exposed workers - analyses from the HELPcB cohort

The effects of polychlorinated biphenyls (PCB) on liver function and structure are still under debate. Although higher transaminase activity and tumor promoting potential of PCB reported for animal and human studies was suggested, these studies were not able to provide definitive evidence on the ability of these chemicals to affect liver function and contribution to tumor development. The aim of this study was to determine the influence of PCB on liver function and morphology in a cohort of former PCB exposed workers. Over 5 years, a longitudinal analysis of the association between PCB concentration and hepatic transaminases such as alanine transaminase (ALT) aspartate amino transaminase (AST) and gamma glutamyltransferase (γGT), as well as liver size and structure was undertaken. Data demonstrated a significant inverse association between PCB concentration and γGT activity levels but there was no marked relationship with AST and ALT activities. Regarding sonographic examination, a significant association was found between liver size and PCB concentration. This association remained, even after adjusting for alcohol consumption, liver affecting drugs, timespan of internal exposure, or age. No marked correlation was noted between PCB concentration and liver structure changes. In summary, an association was observed between PCB concentration and γGT activity levels as well as liver size in humans. The long-term health consequences attributed to PCB on liver and in particular in tumorigenesis are not foreseeable in our cohort thus far, but remain a focus in further ongoing surveillance.

Association of colorectal polyps and cancer with low-dose persistent organic pollutants: A case-control study

BACKGROUND

Low-dose persistent organic pollutants (POPs) have recently been linked to immunosenescence, a key mechanism in carcinogenesis, as well as many aging-related chronic diseases. Since feces are the main excretion route of POPs, the large intestine is a potential target organ for these pollutants. We performed a case-control study to evaluate whether exposure to low-dose POPs is related to the risk of colorectal polyps and cancer.

METHODS

A total of 277 participants were recruited from one hospital: 99 cancer patients, 102 polyp patients, and 76 control subjects. As typical examples of POPs, we measured the serum concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs).

RESULTS

Across the tertiles of the summary measure of POPs, the adjusted odds ratios (ORs) of colorectal polyps and cancer were 2.8 (1.2-6.8) (Ptrend = 0.01) and 3.0 (1.0-8.8) (Ptrend = 0.02), respectively, for subjects in the highest tertile. When OCPs and PCBs were analyzed separately, OCPs were linked to an increased risk of both polyps and cancer; the adjusted ORs were 2.3 (0.9-5.7) (Ptrend = 0.05) for polyps and 3.6 (1.1-11.8) (Ptrend< 0.01) for cancer. However, PCBs were only significantly associated with a high risk of polyps but not cancer; the adjusted OR was 2.8 (1.2-6.6) (Ptrend = 0.01).

CONCLUSION

Chronic exposure to low-dose POPs may be associated with an increased risk of colorectal polyps and cancer. Our findings suggest the carcinogenic potential of strong lipophilic chemical mixtures such as POPs which are accumulated in adipose tissue, released to circulation, and eliminated through feces.

Embryonic effects of an environmentally relevant PCB mixture in the domestic chicken

Studies were conducted to develop methods to assess the effects of a complex mixture of polychlorinated biphenyls (PCBs) in the domestic chicken (Gallus domesticus). Treatments were administered by egg injection to compare embryonic effects of an environmentally relevant PCB congener mixture in the domestic chicken over a range of doses. Chicken eggs were injected with the PCB mixture with a profile similar to that found in avian eggs collected on the upper Hudson River, New York, USA, at doses that spanned 0 to 98 μg/g egg. Eggs were hatched in the laboratory to ascertain hatching success. In the domestic chicken, the median lethal dose was 0.3 μg/g. These data demonstrate adverse effects of an environmentally relevant PCB mixture and provide the basis for further work using in vitro and other models to characterize the potential risk to avian populations. Environ Toxicol Chem 2018;37:2513-2522. © 2018 SETAC.

PCB exposure and potential future cancer incidence in Slovak children: an assessment from molecular finger printing by Ingenuity Pathway Analysis (IPA®) derived from experimental and epidemiological investigations

The risk of cancer due to PCB exposure in humans is highly debated. In eastern Slovakia, high exposure of the population to organochlorines (especially PCBs) was associated with various disease and disorder pathways, viz., endocrine disruption, metabolic disorder & diabetes, and cancer, thereby disturbing several cellular processes, including protein synthesis, stress response, and apoptosis. We have evaluated a Slovak cohort (45-month children, at lower and higher levels of PCB exposure from the environment) for disease and disorder development to develop early disease cancer biomarkers that could shed new light on possible mechanisms for the genesis of cancers under such chemical exposures, and identify potential avenues for prevention.Microarray studies of global gene expression were conducted from the 45-month-old children on the Affymetrix platform followed by Ingenuity Pathway Analysis (IPA®) to associate the affected genes with their mechanistic pathways. High-throughput qRT-PCR TaqMan low-density array (TLDA) was performed to further validate the selected genes on the whole blood cells of the most highly exposed children from the study cohort (n = 71). TP53, MYC, BCL2, and LRP12 differential gene expressions suggested strong relationships between potential future tumor promotion and PCB exposure in Slovak children. The IPA analysis further detected the most important signaling pathways, including molecular mechanism of cancers, prostate cancer signaling, ovarian cancer signaling, P53 signaling, oncostatin M signaling, and their respective functions (viz., prostate cancer, breast cancer, progression of tumor, growth of tumor, and non-Hodgkin's disease). The results suggest that PCB exposures, even at the early age of these children, may have lifelong consequences for the future development of chronic diseases.

Evolutionarily adapted hormesis-inducing stressors can be a practical solution to mitigate harmful effects of chronic exposure to low dose chemical mixtures

Although the toxicity of synthetic chemicals at high doses is well known, chronic exposure to low-dose chemical mixtures has only recently been linked to many age-related diseases. However, it is nearly impossible to avoid the exposure to these low-dose chemical mixtures as humans are exposed to a myriad of synthetic chemicals as a part of their daily lives. Therefore, coping with possible harms due to low dose chemical mixtures is challenging. Interestingly, within the range of environmental exposure, disease risk does not increase linearly with increasing dose of chemicals, but often tends to plateau or even decrease with increasing dose. Hormesis, the over-compensation of various adaptive responses through cellular stresses, is one possible mechanism for this non-linearity. Although the hormetic effects of synthetic chemicals or radiation have long been debated in the field of toxicology, the hormesis concept has recently been generalized in the field of molecular biology; similar to responses to synthetic chemicals, mild to moderate intermittent stressors from any source can induce hormetic responses. Examples of stressors are exercise, calorie restriction, intermittent fasting, cognitive stimulation, and phytochemicals. Mitohormesis is hormesis induced by such stressors through mitochondrial retrograde signalling including the increased production of mild reactive oxygen species. Xenohormesis is phytochemical-induced hormesis, reflective of a mutualistic relationship between plant and animals. As humans had repeated exposure to all of these stressors during their evolution, the hormetic effects of these health behaviours may be considered to be evolutionarily adapted. Although hormesis induced by synthetic chemicals occurs in humans, such hormesis may not be recommended to the public due to unresolved issues on safety including the impossibility of control exposure. However, the use of personal health behaviors which enhance mitohormetic- or xenohormetic-stress can be readily incorporated into everyone's daily lives as a practical way to counteract harmful effects of unavoidable low-dose chemical mixtures.

Uptake of radiolabeled 3,3',4,4'-tetrachlorobiphenyl into Japanese quail egg compartments and embryo following air cell and albumen injection

The avian embryo is an excellent model for testing adverse developmental effects of environmental chemicals as well as uptake and movement of xenobiotics within the egg compartments. Before incubation at embryonic day 0, ¹⁴ C 3,3',4,4'-tetrachlorobiphenyl (¹⁴ C PCB 77) was injected into Japanese quail eggs either onto the air cell or into the albumen. All egg components were collected on embryonic day 1, 5, or 10, and concentrations of ¹⁴ C PCB 77 were measured in various egg components (shell, membrane, yolk, albumen, and embryo). The results showed measurable ¹⁴ C PCB 77 in all egg components, with changing concentrations in each egg component over the course of embryonic development. Specifically, concentrations in the shell content decreased between embryonic days 1 and 10, increased in albumen from embryonic days 1 to 5 and then decreased at embryonic day 10, and increased in both yolk and embryo from embryonic days 1 to 10. Vehicle and injection site both influenced ¹⁴ C PCB 77 allantoic fluid concentrations, with little effect on other egg components except for the inner shell membrane. The fatty acid vehicle injected into the albumen yielded the highest ¹⁴ C PCB 77 recovery. These findings demonstrate dynamic movement of toxicants throughout the egg components during avian embryonic development and a steady increase of relatively low levels of ¹⁴ C PCB 77 in the embryo compared with the yolk, albumen, and shell, suggesting that embryonic uptake (i.e., exposure) mirrors utilization of egg components for nutrition and growth during development. Environ Toxicol Chem 2018;37:126-135. © 2017 SETAC.

A role of low dose chemical mixtures in adipose tissue in carcinogenesis

The Halifax project recently hypothesized a composite carcinogenic potential of the mixture of low dose chemicals which are commonly encountered environmentally, yet which are not classified as human carcinogens. A long neglected but important fact is that adipose tissue is an important exposure source for chemical mixtures. In fact, findings from human studies based on several persistent organic pollutants in general populations with only background exposure should be interpreted from the viewpoint of chemical mixtures because serum concentrations of these chemicals can be seen as surrogates for chemical mixtures in adipose tissue. Furthermore, in conditions such as obesity with dysfunctional adipocytes or weight loss in which lipolysis is increased, the amount of the chemical mixture released from adipose tissue to circulation is increased. Thus, both obesity and weight loss can enhance the chance of chemical mixtures reaching critical organs, however paradoxical this idea may be when fat mass is the only factor considered. The complicated, interrelated dynamics of adipocytes and chemical mixtures can explain puzzling findings related to body weight among cancer patients, including the obesity paradox. The contamination of fat in human diet with chemical mixtures, occurring for reasons similar to contamination of human adipose tissue, may be a missing factor which affects the association between dietary fat intake and cancer. The presence of chemical mixtures in adipose tissue should be considered in future cancer research, including clinical trials on weight management among cancer survivors.

State of the evidence 2017: an update on the connection between breast cancer and the environment

BACKGROUND

In this review, we examine the continually expanding and increasingly compelling data linking radiation and various chemicals in our environment to the current high incidence of breast cancer. Singly and in combination, these toxicants may have contributed significantly to the increasing rates of breast cancer observed over the past several decades. Exposures early in development from gestation through adolescence and early adulthood are particularly of concern as they re-shape the program of genetic, epigenetic and physiological processes in the developing mammary system, leading to an increased risk for developing breast cancer. In the 8 years since we last published a comprehensive review of the relevant literature, hundreds of new papers have appeared supporting this link, and in this update, the evidence on this topic is more extensive and of better quality than that previously available.

CONCLUSION

Increasing evidence from epidemiological studies, as well as a better understanding of mechanisms linking toxicants with development of breast cancer, all reinforce the conclusion that exposures to these substances - many of which are found in common, everyday products and byproducts - may lead to increased risk of developing breast cancer. Moving forward, attention to methodological limitations, especially in relevant epidemiological and animal models, will need to be addressed to allow clearer and more direct connections to be evaluated.

Do polychlorinated biphenyls cause cancer? A systematic review and meta-analysis of epidemiological studies on risk of cutaneous melanoma and non-Hodgkin lymphoma

In 2015 a IARC Working Group upgraded the classification of PCBs to Group 1 "Carcinogenic to humans", also on the basis of evidence from epidemiological studies showing an excess risk for melanoma. Increased risks for non-Hodgkin lymphoma (NHL) and breast cancer were also reported though the evidence was limited. However, some recent reviews of studies on PCB exposure and risk of cancer provided discrepant findings. Therefore, we re-evaluated the association between exposure to PCBs and risk of melanoma and NHL by a systematic review and meta-analysis. We retrieved 11 independent cohort studies on occupationally exposed workers. About half of them showed increased standardized mortality or incidence ratios (SMRs or SIRs) for melanoma and none for NHL. The pooled SMRs were 1.32 (95% CI: 1.05-1.64) for melanoma and 0.94 (0.73-1.23) for NHL. Among population-based cohort and case-control studies with individual measures of PCB exposure, one only study was carried out on PCB exposure and melanoma, showing an odds ratio (OR) of 6.0 (2.0-18.2) for the highest compared to lowest quartile of PCB distribution. 13 cohort and case-control studies evaluated the association between NHL and PCB concentration in blood or subcutaneous fat, with summary OR = 1.5 (1.1-1.7) for the highest vs lowest quantile of PCB distribution. However, two cohort studies on people intoxicated by rice oil containing PCBs found no excess of deaths for skin cancer and inconsistent results for NHL. In conclusion, these findings do not provide a strong evidence that PCB exposure can increase the risk of melanoma and NHL in humans.

Serum levels of environmental pollutants is a risk factor for breast cancer in Inuit: a case control study

BACKGROUND

Environmental Persistent Organic Pollutants (POPs) can alter the hormone homeostasis by mimicking, interfering or blocking the function of hormones; moreover POPs are hypothesized to modify the risk of breast cancer. The association between POPs and breast cancer has been widely studied but the conclusions are inconsistent. The present study examined the associations between serum levels of POPs and breast cancer with focus on the highly exposed Greenlandic Inuit population.

METHODS

The study design was a case-control study of Inuit women from Greenland. The participants were asked to complete a questionnaire with information on reproductive history and lifestyle and to provide a blood sample. The sampling was carried out in two time periods (2000-2003 and 2011-2014). The serum levels were determined of 14 polychlorinated biphenyls (PCBs), 11 organochlorine pesticides (OCPs), 16 perfluoroalkyl acids (PFAAs), 1 polybrominated biphenyl (PBB), and 9 polybrominated diphenyl ethers (PBDEs). Independent samples t-test was used to compare differences between cases and controls and odds ratios (OR) adjusted for identified confounders were obtained using logistic regression.

RESULTS

The study population included 77 breast cancer cases and 84 controls. The majority of the measured compounds declined significantly from 2000 - 2003 to 2011-2014. However, for the perfluorinated carboxylic acids (PFCAs) an increase was observed. The serum levels were significantly higher in cases compared to controls for the majority of the compounds, and after adjusting for age the difference was maintained for ∑OCP, dichlorodiphenyldichloroethylene (p,p'-DDE), ∑PFAA, ∑perfluorinated sulfonic acids (PFSA), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS). For the lipophilic POPs, high serum levels (middel/highest vs. lowest tertile) of ∑PCB, ∑estrgoenicPCB, PCB99, PCB138, PCB153, PCB170, PCB170, and PCB183 was associated with breast cancer risk; for the amphiphilic PFAAs, high serum levels of ∑PFAA, ∑PFCA, ∑PFSA, perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), PFHxS, and PFOS were associated with breast cancer risk.

CONCLUSION

Significant, positive associations between breast cancer risk and PCBs and PFAAs were observed. The associations indicate that environmental exposure to POPs can be a factor increasing the risk for breast cancer in Inuit women.

Effects of structurally different noncoplanar and coplanar PCBs on HELF cell proliferation, cell cycle, and potential molecular mechanisms

Polychlorinated biphenyls (PCBs) are a group of chemicals that persist in the environment, indoors, and humans. Lung exposure to airborne and food contaminants, such as PCBs, may cause possible lung disorders, such as cancer. In the present study, we investigated the effects of structurally different lower chlorinated (≤4Cl), noncoplanar PCB40, and coplanar PCB77 on human lung fibroblast cell line (HELF) cell proliferation, cell cycle progression, and possible molecular mechanisms. Noncoplanar PCB40 and coplanar PCB77 exhibited concentration- and time-dependent biphasic dose-response effects on HELF cell proliferation. Noncoplanar PCB40 and coplanar PCB77 induced 23 and 45% cytotoxicity at higher concentrations than the control. The flow cytometry analysis showed that exposure to PCB40 caused a significant increase in time spent in the G1 phase but decreased length of the S phase in a concentration- and time-dependent manner, whereas PCB77 exposure decreased time spent in the G1 and S phases but increased time spent in the G2 phase. Western blot analysis indicated that PCB77 increased the expression of cyclin E, CDK2, p21, and caspase-9, while PCB40 decreased the expression of these proteins (except CDK2 and p21). An increase in CDK expression after exposure to PCB77 suggests that it may cause carcinogenic effects on HELF cells at higher doses. Our results also demonstrate that the different cytotoxic effects induced by coplanar and nonplanar PCBs were correlated with their structural characteristics; the coplanar congener was more cytotoxic than the nonplanar congener. The study elaborates threshold levels for these chemicals and suggests that the cytotoxicity mechanisms by which PCB congeners act on HELF cells depend on their planarity and chemical structures. Furthermore, the study will be important for developing antidotes to the adverse effects and risk assessment practices for PCBs. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1183-1190, 2017.

Prediagnostic plasma concentrations of organochlorines and risk of B-cell non-Hodgkin lymphoma in envirogenomarkers: a nested case-control study

BACKGROUND

Evidence suggests a largely environmental component to non-Hodgkin's lymphoma (NHL). Persistent organic pollutants (POPs) including polychlorinated biphenyls (PCBs), DDE and HCB have been repeatedly implicated, but the literature is inconsistent and a causal relationship remains to be determined.

METHODS

The EnviroGenoMarkers study is nested within two prospective cohorts EPIC-Italy and the Northern Sweden Health and Disease Study. Six PCB congeners, DDE and HCB were measured in blood plasma samples provided at recruitment using gas-chromatography mass spectrometry. During 16 years follow-up 270 incident cases of B-cell NHL (including 76 cases of multiple myeloma) were diagnosed. Cases were matched to 270 healthy controls by centre, age, gender and date of blood collection. Cases were categorised into ordered quartiles of exposure for each POP based on the distribution of exposure in the control population. Logistic regression was applied to assess the association with risk, multivariate and stratified analyses were performed to identify confounders or effect modifiers.

RESULTS

The exposures displayed a strong degree of correlation, particularly amongst those PCBs with similar degrees of chlorination. There was no significant difference (p < 0.05) in median exposure levels between cases and controls for any of the investigated exposures. However under a multivariate model PCB138, PCB153, HCB and DDE displayed significant inverse trends (Wald test p-value <0.05). Under stratified analyses these were determined to be driven by males and by the Diffuse Large B-Cell Lymphoma subtype. When considering those in the highest levels of exposure (>90^th percentile) the association was null for all POPs CONCLUSION: We report no evidence that a higher body burden of PCBs, DDE or HCB increased the risk of subsequent NHL diagnosis. Significantly inverse associations were noted for males with a number of the investigated POPs. We hypothesize these unexpected relationships may relate to the subtype composition of our population, effect modification by BMI or other unmeasured confounding. This study provides no additional support for the previously observed role of PCBs, DDE and HCB as risk factors for NHL.

Breast cancer and persistent organic pollutants (excluding DDT): a systematic literature review

Persistent organic pollutants (POPs) are a group of heterogeneous compounds of both natural and anthropogenic origin with highly persistent and bioaccumulative properties. They cause a range of adverse effects to human health and the environment around the world. There is growing concern that POPs may increase breast cancer risk due to their xenoestrogenic properties. The aim of this systematic literature review is to summarize and integrate the risks of breast cancer following environmental exposure to POPs (other than DDT) from primary epidemiological studies published between 2006 and 2015. After searching various databases, 14 case-control studies and one cohort study were included. Evidence of an association between increased breast cancer risk and environmental exposure to these chemicals is inconsistent and inadequate to conclude with certainty. However, most of the studies have examined exposure to the pollutants after diagnosis of breast cancer, overlooking exposure during critical windows of vulnerability. They have also largely focused on individual chemicals but ignored the combined effects of different chemicals. Therefore, major data gaps remain in examining exposure during critical windows of vulnerability and assessing combined effects of multiple chemicals. Development of better exposure assessment methods addressing these gaps is required for future research.

Polychlorinated biphenyls and breast cancer: A congener-specific meta-analysis

The incidence of breast cancer is related to various risk factors, especially that the environmental and lifestyle factors account for major contribution at the rate of 70% to 95% over all. However, there still remains some controversy over the epidemiological evidence regarding the effects of environmental carcinogens on the risk of breast cancer. We conducted a quantitative meta-analysis aiming at full evaluation of the effects of polychlorinated biphenyls (PCBs) on breast cancer in a congener-specific fashion. Four online literature databases were systematically searched before 1st January 2015, for studies stating correlation between PCB congeners and breast cancer. The Newcastle-Ottawa Scale was used to evaluate the quality of the studies that were included in our analysis. Sixteen studies were included in our final meta-analysis after screening based on the priori inclusion criteria. Nine PCB congeners were reported by more than two studies and they were presented in detail. The pooled Odds Ratios (ORs) showed a significant increase in the risk of breast cancer in individuals with higher plasma/fat levels of PCB 99 (OR: 1.36; 95% CI: 1.02 to 1.80), PCB 183 (OR: 1.56; 95% CI: 1.25 to 1.95) and PCB 187 (OR: 1.18; 95% CI: 1.01 to 1.39). Besides, the outcomes did not support a relationship between dioxin-like PCB congeners and the risk of breast cancer. The results of our meta-analysis imply that PCB 99, PCB 183 and PCB 187 would increase the risk of breast cancer. The mechanism of this increased risk may be by the induction of the CYP2B family in cytochrome P450 enzymes.

NADPH Oxidase Inhibitor Apocynin Attenuates PCB153-Induced Thyroid Injury in Rats

PCBs, widespread endocrine disruptors, cause the disturbance of thyroid hormone (TH) homeostasis in humans and animals. However, the exact mechanism of thyroid dysfunction caused by PCBs is still unknown. In order to clarify the hypotheses that NADPH oxidase (NOX) and subsequent NF-κB pathway may play roles in thyroid dysfunction, sixty Sprague-Dawley rats were randomly divided into four groups: control group, PCB153 treated (PCB) group, received apocynin with PCB153 treatment (APO + PCB) group, and drug control (APO) group. Serum thyroid hormone levels were evaluated. The morphological change of thyroid tissue was analyzed under the light and transmission electron microscopy. NOX2, 8-OHdG, and NF-κB expression in the thyroid tissue was evaluated by immune-histochemical staining. Oxidative stress and inflammatory cytokines were detected. The following results were reduced after apocynin treatment: (1) serum thyroid hormone, (2) thyroid pathological injuries, (3) thyroid MDA, (4) thyroid ultrastructural change, (5) serum inflammatory cytokines, and (6) thyroid expression of NOX2, 8-OHdG, and NF-κB. These results suggested that NOX inhibition attenuates thyroid dysfunction induced by PCB in rats, presumably because of its role in preventing ROS generation and inhibiting the activation of NF-κB pathway. Our findings may provide new therapeutic targets for PCBs induced thyroid dysfunction.

Methodological issues in human studies of endocrine disrupting chemicals

Possible harm from endocrine disrupting chemicals (EDCs) in humans is speculated based on two types of evidence; 1) increasing trends of suspected diseases in ecological studies of populations and 2) findings from traditional epidemiological studies of individuals. However, ecological findings are not regarded as direct human evidence of the relation between EDCs and disease, while the evidence among epidemiological studies of individuals is often inconsistent. Thus, a criticism is that linking EDCs and health in human is naively presumed without solid evidence. However, human studies of EDCs are methodologically complex and understanding methodological issues will help to interpret findings from existing human studies and to properly design optimal human studies. The key issues are low reliability of exposure assessment of EDCs with short half-lives, EDC mixtures, possibility of non-monotonic dose-response relationships, non-existence of an unexposed group, difficulties in measuring exposure during critical periods, and interactions with established risk factors. Furthermore, EDC mixtures may affect human health through other mechanisms than traditional endocrine disruption, for example glutathione depletion or mitochondrial dysfunction. Given this complexity, the most plausible scenario in humans is that exposure to EDC mixtures leads to increasing risk of related diseases at the ecological level, but inconsistent associations would be expected in traditional epidemiological studies. Although epidemiologists have long relied on Bradford Hill's criteria to objectively evaluate whether associations observed in epidemiology can be interpreted as causal, there are challenges to use these criteria for EDCs, particularly concerning consistency across studies and the findings of linear dose-response relationships. At the individual level, compared to EDCs with short half-lives, epidemiological studies of EDCs with long half-lives among populations with a relatively low exposure dose range of exposure can likely produce relatively more reliable results, because the measurement of EDCs with long half-lives likely represents typical long-term exposure and populations with exposure in the low range of doses are likely to have a reference group closer to non-exposure.

Abundance and distribution of polychlorinated biphenyls (PCBs) in breast tissue

Many environmental chemicals accumulate in human tissues and may contribute to cancer risk. Polychlorinated biphenyls (PCBs) are associated with adverse health effects, but relationships between PCB exposure and breast cancer are unclear. In this study, we sought to determine whether bioaccumulation of PCBs differs within regions of the human breast and whether PCB levels are associated with clinical and pathological characteristics in breast cancer patients. Tissue sections (n=245) were collected from breast quadrants from 51 women with a diagnosis ranging from disease-free to metastatic breast cancer. Ninety-seven PCB congeners were assayed by high resolution gas chromatography. ANOVA was used to examine PCB distribution within the breast and relationships with clinical/pathological variables. Pearson product-moment correlations assessed relationships between age at mastectomy and PCB levels. PCBs were abundant in breast tissues with a median concentration of 293.4ng/g lipid (range 15.4-1636.3ng/g). PCB levels in breast tissue were significantly different (p<0.001) among functional groupings of congeners defined by structure-activity properties: Group I (28.2ng/g), Group II (96.6ng/g), Group III (166.0ng/g). Total PCB concentration was highly correlated with age at mastectomy, but the distribution of PCBs did not differ by breast quadrant. PCB levels were not associated with patient status or tumor characteristics. In conclusion, PCB congeners with carcinogenic potential were present at high levels in the human breast, but were not associated with clinical or pathological characteristics in breast cancer patients.

Transcriptional profiling and biological pathway analysis of human equivalence PCB exposure in vitro: indicator of disease and disorder development in humans

BACKGROUND AND AIMS

Our earlier gene-expression studies with a Slovak PCBs-exposed population have revealed possible disease and disorder development in accordance with epidemiological studies. The present investigation aimed to develop an in vitro model system that can provide an indication of disrupted biological pathways associated with developing future diseases, well in advance of the clinical manifestations that may take years to appear in the actual human exposure scenario.

METHODS

We used human Primary Blood Mononuclear Cells (PBMC) and exposed them to a mixture of human equivalence levels of PCBs (PCB-118, -138, -153, -170, -180) as found in the PCBs-exposed Slovak population. The microarray studies of global gene expression were conducted on the Affymetrix platform using Human Genome U133 Plus 2.0 Array along with Ingenuity Pathway Analysis (IPA) to associate the affected genes with their mechanistic pathways. High-throughput qRT-PCR Taqman Low Density Array (TLDA) was done to further validate the selected 6 differentially expressed genes of our interest, viz., ARNT, CYP2D6, LEPR, LRP12, RRAD, TP53, with a small population validation sample (n=71).

RESULTS

Overall, we revealed a discreet gene expression profile in the experimental model that resembled the diseases and disorders observed in PCBs-exposed population studies. The disease pathways included endocrine system disorders, genetic disorders, metabolic diseases, developmental disorders, and cancers, strongly consistent with the evidence from epidemiological studies.

INTERPRETATION

These gene finger prints could lead to the identification of populations and subgroups at high risk for disease, and can pose as early disease biomarkers well ahead of time, before the actual disease becomes visible.

Molecular mechanisms of 2, 3', 4, 4', 5-pentachlorobiphenyl-induced thyroid dysfunction in FRTL-5 cells

Polychlorinated biphenyls (PCBs) can severely interfere with multiple animals and human systems. To explore the molecular mechanisms underlying 2, 3′, 4, 4′, 5- pentachlorobiphenyl (PCB118)-induced thyroid dysfunction, Fischer rat thyroid cell line-5(FRTL-5) cells were treated with either different concentrations of PCB118 or dimethyl sulfoxide (DMSO). The effects of PCB118 on FRTL-5 cells viability and apoptosis were assessed by using a Cell Counting Kit-8 assay and apoptosis assays, respectively. Quantitative real-time polymerase chain reaction was used to quantify protein kinase B (Akt), Forkhead box protein O3a (FoxO3a), and sodium/iodide symporter (NIS) mRNA expression levels. Western blotting was used to detect Akt, phospho-Akt (p-Akt), FoxO3a, phospho-FoxO3a (p-FoxO3a), and NIS protein levels. Luciferase reporter gene technology was used to detect the transcriptional activities of FoxO3a and NIS promoters. The effects of the constitutively active Akt (CA-Akt) and dominant-negative Akt (DN-Akt) plasmids on p-Akt, p-FoxO3a, and NIS levels were examined in PCB118-treated FRTL-5 cells. The effects of FoxO3a siRNA on FoxO3a, p-FoxO3a, and NIS protein levels were examined in the PCB118-treated FRTL-5 cells. The effects of pcDNA3 (plsmid vectors designed for high-level stable and transient expression in mammalian host)-FoxO3a on NIS promoter activity were examined in the PCB118-treated FRTL-5 cells. Our results indicated that relatively higher PCB118 concentrations can inhibit cell viability in a concentration- and time-dependent manner. Akt, p-Akt, and p-FoxO3a protein or mRNA levels increased significantly in PCB118-treated groups and NIS protein and mRNA levels decreased considerably compared with the control groups. FoxO3a promoter activity increased significantly, whereas NIS promoter activity decreased. These effects on p-FoxO3a and NIS could be decreased by the DN-Akt plasmid, enhanced by the CA-Akt plasmid, and blocked by FoxO3a siRNA. The overexpressed FoxO3a could reduce NIS promoter activity. Our results suggested that PCB118 induces thyroid cell dysfunction through the Akt/FoxO3a/NIS signaling pathway.

Molecular mechanisms of human thyrocyte dysfunction induced by low concentrations of polychlorinated biphenyl 118 through the Akt/FoxO3a/NIS pathway

Polychlorinated biphenyls (PCBs) are typical persistent organic pollutants that can interfere with multiple organ systems of humans. Previously, we concluded that persistent exposure to low doses of PCB118 could severely damage the thyroidal structure, dramatically decrease the concentration of serum thyroid hormones and inhibit the pivotal gene expressions such as sodium/iodide symporter (NIS) and thyroglobulin (Tg). To explore the molecular mechanisms of thyrocyte dysfunction induced by 2,3',4,4',5-pentachlorobiphenyl (PCB118), monolayer cultured human thyroid epithelial cells (HTECs) were treated with PCB118 or dimethyl sulfoxide (DMSO) as a control. Our results indicated that relatively higher concentrations of PCB118 could induce a loss in the viability of HTEC. In cultures with concentrations of PCB118 from 0.025 to 25 nM, which did not affect cell viability or apoptosis, concentrations of Tg and thyroxine (T(4)) were significantly decreased compared with those in the controls. In addition, mRNA and protein levels of Akt were increased significantly in the PCB118-treated groups, whereas FoxO3a expression did not show particular variation. Furthermore, exposure to PCB118 was associated with a significant increase of the protein levels of p-Akt and p-FoxO3a, and these effects were blocked by LY294002. In contrast, mRNA and protein expression levels of NIS were decreased significantly, and this effect was blocked by LY294002. Unlike control cells, a cytoplasmic shift of FoxO3a was observed in the PCB118-treated group. Our research suggests that PCB118 may induce thyrocyte dysfunction through the Akt/FoxO3a/NIS signalling pathway, which provides potential new insights for finding interventions to counteract the damage to the human body caused by PCBs.

Persistent organic pollutants and promoter hypermethylation of the O(6)-methylguanine-DNA methyltransferase gene

Promoter hypermethylation of the O(6)-methylguanine-DNA methyltransferase (MGMT) DNA repair gene is important during carcinogenesis. We explored whether organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), were associated with hypermethylation of the MGMT gene promoter in peripheral leukocytes among 368 Koreans without cancer. Hypermethylation decreased as OCPs increased (Ptrend = 0.02), while PCB concentrations showed an inverted U-shaped association (Pquadratic < 0.01). The prevalence of MGMT promoter hypermethylation was highest within the 2nd quintile of the PCB summary score (28.4%), while it was only 2.7% in the upper 10% score. Chronic exposure to these chemicals may affect methylation of the MGMT promoter, with possibly non-monotonic dose response relationships.

Cancer incidence in a cohort with high fish consumption

PURPOSE

Evidence suggests that fish-derived omega-3 polyunsaturated fatty acids inhibit cancer promotion and progression. On the other hand, fish may contain endocrine-disrupting and potentially carcinogenic environmental contaminants. Our objective was to describe cancer incidence among the Finnish professional fishermen and their wives who are presumed to eat a lot of fish, partly from the contaminated Baltic Sea. Additionally, we wanted to see whether occupational characteristics are reflected in the fishermen's cancer pattern.

METHODS

All Finnish fishermen during 1980-2002 were identified from the Professional Fishermen Register (n = 6,410) and their wives from the National Population Information System (n = 4,260). The cohort was linked with the Finnish Cancer Registry data until 2011, and the standardized incidence ratios (SIR) were calculated based on national incidence rates.

RESULTS

The total cancer incidence among the fishermen and their wives was the same as in the Finnish general population. Among the fishermen, the incidence was increased for lip (SIR 2.17, 95 % confidence interval 1.26-3.47) and testis (2.51, 1.15-4.75) and decreased for colon (0.72, 0.52-0.98) cancers.

CONCLUSIONS

We cannot exclude the possibility that the observed excess in testis cancer among the fishermen could reflect life-long high exposure to environmental contaminants. An excess in lip cancer has been repeatedly observed among outdoor workers due to high exposure to ultraviolet radiation, whereas high physical activity during fishing is the most likely explanation for the deficit in colon cancer.

Historical reconstruction of polychlorinated biphenyl (PCB) exposures for workers in a capacitor manufacturing plant

We developed a semiquantitative job exposure matrix (JEM) for workers exposed to polychlorinated biphenyls (PCBs) at a capacitor manufacturing plant from 1946 to 1977. In a recently updated mortality study, mortality of prostate and stomach cancer increased with increasing levels of cumulative exposure estimated with this JEM (trend p values = 0.003 and 0.04, respectively). Capacitor manufacturing began with winding bales of foil and paper film, which were placed in a metal capacitor box (pre-assembly), and placed in a vacuum chamber for flood-filling (impregnation) with dielectric fluid (PCBs). Capacitors dripping with PCB residues were then transported to sealing stations where ports were soldered shut before degreasing, leak testing, and painting. Using a systematic approach, all 509 unique jobs identified in the work histories were rated by predetermined process- and plant-specific exposure determinants; then categorized based on the jobs' similarities (combination of exposure determinants) into 35 job exposure categories. The job exposure categories were ranked followed by a qualitative PCB exposure rating (baseline, low, medium, and high) for inhalation and dermal intensity. Category differences in other chemical exposures (solvents, etc.) prevented further combining of categories. The mean of all available PCB concentrations (1975 and 1977) for jobs within each intensity rating was regarded as a representative value for that intensity level. Inhalation (in microgram per cubic milligram) and dermal (unitless) exposures were regarded as equally important. Intensity was frequency adjusted for jobs with continuous or intermittent PCB exposures. Era-modifying factors were applied to the earlier time periods (1946-1974) because exposures were considered to have been greater than in later eras (1975-1977). Such interpolations, extrapolations, and modifying factors may introduce non-differential misclassification; however, we do believe our rigorous method minimized misclassification, as shown by the significant exposure-response trends in the epidemiologic analysis.

Persistent organic pollutants distribution in lipoprotein fractions in relation to cardiovascular disease and cancer

Persistent organic pollutants (POPs) are lipophilic environmental toxins that have been associated with cardiovascular disease (CVD) and cancer. The aim of this study was to investigate the concentrations of POPs in human high and low/very low-density lipoproteins (HDL and LDL/VLDL) and the possible association with CVD and cancer occurrence in individuals living in a contaminated area. Lipoproteins from 28 individuals (7 healthy controls, 8 subjects with cancer, 13 subjects with CVD) were isolated and the fraction-specific concentration of 20 different POPs was analyzed by high resolution gas chromatography/high resolution mass spectrometry. The activity of Paraoxonase 1 (PON1), an anti-oxidant in HDL, was determined in plasma of these 28 subjects and additional 50 subjects from the same area excluding diseases other than cancer or CVD. Fourteen polychlorinated biphenyls (PCBs) and three organochlorine pesticides were detected, and especially highly chlorinated PCBs were enriched in lipoproteins. Significantly higher concentrations of POPs were found among individuals with CVD or cancer compared to controls. Principal component analyses showed that POP concentrations in HDL were more associated with CVD, while POP concentrations in LDL/VLDL were more associated with cancer. PON1 activity was negatively correlated to sumPCB and a co-variation between decreased arylesterase-activity, increased PCB concentrations and CVD was found. This study shows that POPs are present in lipoproteins and were more abundant in individuals with CVD or cancer compared to healthy controls. The results also indicate that PCB exposure is accompanied by reduced PON1 activity that could impair the HDL function to protect against oxidation.

Endocrine disruption of the epigenome: a breast cancer link

The heritable component of breast cancer accounts for only a small proportion of total incidences. Environmental and lifestyle factors are therefore considered to among the major influencing components increasing breast cancer risk. Endocrine-disrupting chemicals (EDCs) are ubiquitous in the environment. The estrogenic property of EDCs has thus shown many associations between ongoing exposures and the development of endocrine-related diseases, including breast cancer. The environment consists of a heterogenous population of EDCs and despite many identified modes of action, including that of altering the epigenome, drawing definitive correlations regarding breast cancer has been a point of much discussion. In this review, we describe in detail well-characterized EDCs and their actions in the environment, their ability to disrupt mammary gland formation in animal and human experimental models and their associations with exposure and breast cancer risk. We also highlight the susceptibility of early-life exposure to each EDC to mediate epigenetic alterations, and where possible describe how these epigenome changes influence breast cancer risk.

Epidemiological study of prostate cancer (EPICAP): a population-based case-control study in France

BACKGROUND

Prostate cancer is the most common cancer in male in most Western countries, including France. Despite a significant morbidity and mortality to a lesser extent, the etiology of prostate cancer remains largely unknown. Indeed, the only well-established risk factors to date are age, ethnicity and a family history of prostate cancer. We present, here, the rationale and design of the EPIdemiological study of Prostate CAncer (EPICAP), a population-based case-control study specifically designed to investigate the role of environmental and genetic factors in prostate cancer. The EPICAP study will particularly focused on the role of circadian disruption, chronic inflammation, hormonal and metabolic factors in the occurrence of prostate cancer.

METHODS/DESIGN

EPICAP is a population-based case-control study conducted in the département of Hérault in France. Eligible cases are all cases of prostate cancers newly diagnosed in 2012-2013 in men less than 75 years old and residing in the département of Hérault at the time of diagnosis. Controls are men of the same age as the cases and living in the département of Hérault, recruited in the general population.The sample will include a total of 1000 incident cases of prostate cancer and 1000 population-based controls over a 3-year period (2012-2014).The cases and controls are face-to-face interviewed using a standardized computed assisted questionnaire. The questions focus primarily on usual socio-demographic characteristics, personal and family medical history, lifestyle, leisure activities, residential and occupational history. Anthropometric measures and biological samples are also collected for cases and controls.

DISCUSSION

The EPICAP study aims to answer key questions in prostate cancer etiology: (1) role of circadian disruption through the study of working hours, chronotype and duration/quality of sleep, (2) role of chronic inflammation and anti-inflammatory drugs, (3) role of hormonal and metabolic factors through a detailed questionnaire, (4) role of individual genetic susceptibility of genes involved in biological pathways of interest. The EPICAP study will also allow us to study prognostic factors and tumor aggressiveness.Taken together, the EPICAP study will provide a comprehensive framework to go further in the understanding of prostate cancer occurrence and its prognosis.

Metabolomic approach assisted high resolution LC-ESI-MS based identification of a xenobiotic derivative of fenhexamid produced by Lactobacillus casei

Fenhexamid is a widely used fungicide with one of the highest maximum tolerance limits approved for fruits and vegetables. The goal of this study was to examine if fenhexamid is metabolized by a nontarget organism, a Lactobacillus species (Lactobacillus casei Shirota), a probiotic strain of the human gastrointestinal tract. The assignment of bacterial derivatives of the xenobiotic fenhexamid was substantially facilitated by a metabolomic software based approach optimized for the extraction of molecular features of chlorine-containing compounds from liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry data with an untargeted compound search algorithm. After validating the software with a set of seventeen chlorinated pesticides and manually verifying the result lists, eleven molecular features out of 4363 turned out to be bacterial derivatives of fenhexamid, revealing the O-glycosyl derivative as the most abundant one that arose from the fermentation medium of Lactobacillus casei Shirota in the presence of 100 μg/mL fenhexamid.

Breast cancer in the Arctic--changes over the past decades

The purpose of this study is to review the current literatures on breast cancer (BC) in the Arctic, especially the trends in incidence during the last decades and the possible explanations. The design of this study is a literature review. The scientific literature concerning BC were reviewed, especially focusing on the Arctic and the special conditions that exist in this region. Breast cancer incidence is increasing all over the world, including in the Arctic. The enormous transition in health conditions and lifestyle in the Arctic might be contributing to the known risk factors. In Greenland, the age at menarche has diminished by 3 years during the course of 100 years, and the number of children per women as well as the duration of breastfeeding is decreasing. Obesity and intake of saturated fat is increasing and the intake of traditional food rich in unsaturated fat and vitamin D decreasing. Smoking and alcohol consumption in the Arctic has been relatively high but is now decreasing. More focus on genetic susceptibility in relation to BC has identified the specific BRCA1 founder mutation in the Greenlandic population, which might appear to be an important risk factor. However, the known established risk factors alone cannot account for the increasing trend observed. Studies suggest that environmental contaminants such as persistent organic pollutants (POPs) including perfluorinated compounds increase the risk of BC possibly in conjunction with certain genetic polymorphisms involved in carcinogen activation. The lipophilic POPs such as polychlorinated biphenyls and organochlorine pesticides are found at very high levels in the Arctic population. Several factors can explain the increasing incidence of BC in the Arctic. The transition in lifestyle and health conditions unfortunately increases the known risk factors of BC. Moreover, the population of the Arctic might show up to be especially vulnerable because of the contemporary high burden of POPs and genetic susceptibility.

Current status of the epidemiologic evidence linking polychlorinated biphenyls and non-hodgkin lymphoma, and the role of immune dysregulation

BACKGROUND

Although case-control studies conducted to date have largely affirmed the relationship between polychlorinated biphenyls (PCBs) and non-Hodgkin lymphoma (NHL), occupational cohort studies of PCB-exposed workers have been generally interpreted as negative, thereby raising doubts about a potential causal association. A common theme of immune dysregulation unifies many of NHL's strongest risk factors, and several authors have posited that subclinical immune dysregulation may increase NHL risk by decreasing host resistance, reducing control of cellular proliferation and differentiation, and diminishing tumor surveillance mechanisms.

OBJECTIVES

The goals of this review were a) to evaluate the epidemiological research examining the association between PCB exposure and NHL and discuss the contribution to the weight of evidence of case-control studies and occupational cohort studies; and b) to summarize the evidence for immune dysregulation as a means by which PCBs may cause NHL.

METHODS

We performed a literature search using PubMed and seven additional online biomedical and toxicological referencing libraries to identify literature published through August 2011.

DISCUSSION AND CONCLUSIONS

Overall, we conclude that the weight of evidence supports a causal role of PCBs in lymphomagenesis. The strongest epidemiological evidence for the relationship between PCBs and NHL comes from case-control studies conducted among the general population. Epidemiological and toxicological data demonstrating immunosuppressive and inflammatory effects of PCBs further contribute to the weight of evidence by providing a plausible explanation for how PCBs can cause NHL through immune dysregulation.

Organochlorine compounds and testicular dysgenesis syndrome: human data

Cryptorchidism, hypospadias, subfertility and testicular germ-cell tumour have been suggested to comprise a testicular dysgenesis syndrome (TDS) based on the premise that each may derive from perturbations of embryonal programming and gonadal development during foetal life. Endocrine-disrupting chemicals have been hypothesized to be associated with these disorders, given the importance of sex steroid hormones in urogenital development and homeostasis. Organochlorines are one such set of compounds which are defined as containing between one and ten covalently bonded chlorine atoms. These compounds are persistent pollutants with long half-lives, accumulate in adipose tissue when ingested, bioaccumulate and biomagnify, and have complex and variable toxicological profiles. Examples of organochlorines include dichloro-diphenyl-trichloroethane and its metabolites, polychlorinated biphenyls, and chlordane. In this comprehensive review of human epidemiologic studies which have tested for associations between organochlorines and facets of TDS, we find evidence for associations between the exposures p,p'-DDE, cis-nonachlor and trans-nonachlor with testicular germ-cell tumour. The sum of the evidence from human epidemiological studies does not indicate any association between specific organochlorines studied and cryptorchidism, hypospadias or fertility. Many other endocrine-disrupting chemicals, including additional organochlorines, have yet to be assessed in relation to disorders associated with TDS, yet study of such chemicals has strong scientific merit given the relevance of such hypotheses to urogenital development.

Global gene expression and Ingenuity biological functions analysis on PCBs 153 and 138 induced human PBMC in vitro reveals differential mode(s) of action in developing toxicities

Several reports have indicated that low level of polychlorinated biphenyl (PCB) exposure can adversely affect a multitude of physiological disorders and diseases in in vitro, in vivo, and as reported in epidemiological studies. This investigation is focused on the possible contribution of two most prevalent PCB congeners in vitro in developing toxicities. We used PCBs 138 and 153 at the human equivalence level as model agents to test their specificity in developing toxicities. We chose a global approach using oligonucleotide microarray technology to investigate modulated gene expression for biological effects, upon exposure of PCBs, followed by Ingenuity Pathway Analysis (IPA), to understand the underlying consequence in developing disease and disorders. We performed in vitro studies with human peripheral blood mononuclear cells (PBMC), where PBMC cells were exposed to respective PCBs for 48 h. Overall, our observation on gene expression indicated that PCB produces a unique signature affecting different pathways, specific for each congener. While analyzing these data through IPA, the prominent and interesting disease and disorders were neurological disease, cancer, cardiovascular disease, respiratory disease, as well as endocrine system disorders, genetic disorders, and reproductive system disease. They showed strong resemblances with in vitro, in vivo, and in the epidemiological studies. A distinct difference was observed in renal and urological diseases, organisimal injury and abnormalities, dental disease, ophthalmic disease, and psychological disorders, which are only revealed by PCB 138 exposure, but not in PCB 153. The present study emphasizes the challenges of global gene expression in vitro and was correlated with the results of exposed human population. The microarray results give a molecular mechanistic insight and functional effects, following PCB exposure. The extent of changes in genes related to several possible mode(s) of action highlights the changes in cellular functions and signaling pathways that play major roles. In addition to understanding the pathways related to mode of action for chemicals, these data could lead to the identification of genomic signatures that could be used for screening of chemicals for their potential to cause disease and developmental disorders.

Polychlorinated biphenyls and non-Hodgkin's lymphoma: a case-control study in Northern Italy

BACKGROUND

Polychlorinated biphenyls (PCBs) have been hypothesized to increase the risk of non-Hodgkin lymphoma (NHL), although conclusive evidence is still lacking. High levels of PCBs were found in soil in some areas close to a PCB-producing factory in Brescia, North Italy. We conducted a population-based case-control study among residents of the town to investigate the possible association between PCB pollution and NHL in this area.

METHODS

We included both incident and deceased NHL cases, and a random sample of the town residents as controls, frequency matched to cases as regards age and gender. Exposure to PCBs was estimated on the basis of the lifetime residential history of cases and controls in four different areas of the town-A, B and C (polluted areas) and D (control area).

RESULTS

A total of 495 cases (287 incident cases) and 1467 controls were enrolled. Positive associations were found between NHL and having resided for at least 10 years in the area A, the most polluted area (odds ratio, OR=1.8; p=0.02) and for having resided in any of the polluted areas considered together (A+B+C) (OR=1.4; p=0.08). However, no associations were evident for having resided 20 years or longer in the polluted areas or when analyzing the association with each subject's main residence in his/her lifetime.

CONCLUSION

This study provides some evidence for an association between PCB exposure and NHL, though results should be considered with caution in the absence of individual biological measures of exposure.