Comparison of proposed frameworks for grouping polychlorinated biphenyl congener data applied to a case-control pilot study of prostate cancer

Endocrine Disrupting Chemicals Influence Hub Genes Associated with Aggressive Prostate Cancer

Prostate cancer (PCa) is one of the most frequently diagnosed cancers among men in the world. Its prevention has been limited because of an incomplete understanding of how environmental exposures to chemicals contribute to the molecular pathogenesis of aggressive PCa. Environmental exposures to endocrine-disrupting chemicals (EDCs) may mimic hormones involved in PCa development. This research aims to identify EDCs associated with PCa hub genes and/or transcription factors (TF) of these hub genes in addition to their protein-protein interaction (PPI) network. We are expanding upon the scope of our previous work, using six PCa microarray datasets, namely, GSE46602, GSE38241, GSE69223, GSE32571, GSE55945, and GSE26126, from the NCBI/GEO, to select differentially expressed genes based on |log2FC| (fold change) ≥ 1 and an adjusted p-value < 0.05. An integrated bioinformatics analysis was used for enrichment analysis (using DAVID.6.8, GO, KEGG, STRING, MCODE, CytoHubba, and GeneMANIA). Next, we validated the association of these PCa hub genes in RNA-seq PCa cases and controls from TCGA. The influence of environmental chemical exposures, including EDCs, was extrapolated using the chemical toxicogenomic database (CTD). A total of 369 overlapping DEGs were identified associated with biological processes, such as cancer pathways, cell division, response to estradiol, peptide hormone processing, and the p53 signaling pathway. Enrichment analysis revealed five up-regulated (NCAPG, MKI67, TPX2, CCNA2, CCNB1) and seven down-regulated (CDK1, CCNB2, AURKA, UBE2C, BUB1B, CENPF, RRM2) hub gene expressions. Expression levels of these hub genes were significant in PCa tissues with high Gleason scores ≥ 7. These identified hub genes influenced disease-free survival and overall survival of patients 60-80 years of age. The CTD studies showed 17 recognized EDCs that affect TFs (NFY, CETS1P54, OLF1, SRF, COMP1) that are known to bind to our PCa hub genes, namely, NCAPG, MKI67, CCNA2, CDK1, UBE2C, and CENPF. These validated differentially expressed hub genes can be potentially developed as molecular biomarkers with a systems perspective for risk assessment of a wide-ranging list of EDCs that may play overlapping and important role(s) in the prognosis of aggressive PCa.

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.

Combined Effects of Different Endocrine-Disrupting Chemicals (EDCs) on Prostate Gland

Endocrine-disrupting chemicals (EDCs) belong to a heterogeneous class of environmental pollutants widely diffused in different aquatic and terrestrial habitats. This implies that humans and animals are continuously exposed to EDCs from different matrices and sources. Moreover, pollution derived from anthropic and industrial activities leads to combined exposure to substances with multiple mechanisms of action on the endocrine system and correlated cell and tissue targets. For this reason, specific organs, such as the prostate gland, which physiologically are under the control of hormones like androgens and estrogens, are particularly sensitive to EDC stimulation. It is now well known that an imbalance in hormonal regulation can cause the onset of various prostate diseases, from benign prostate hyperplasia to prostate cancer. In this review, starting with the description of normal prostate gland anatomy and embryology, we summarize recent studies reporting on how the multiple and simultaneous exposure to estrogenic and anti-androgenic compounds belonging to EDCs are responsible for an increase in prostate disease incidence in the human population.

Endocrine disrupting-chemicals and biochemical recurrence of prostate cancer after prostatectomy: A cohort study in Guadeloupe (French West Indies)

Previous studies have suggested that exposure to environmental chemicals with hormonal properties, also called endocrine disrupting chemicals, may be involved in the occurrence of prostate cancer (PCa). Such exposure may also influence the treatment outcome as it is still present at the time of diagnosis, the beginning of therapy, and beyond. We followed 326 men in Guadeloupe (French West Indies) who underwent radical prostatectomy as primary treatment of localized PCa. We analyzed the relationship between exposure to the estrogenic chlordecone, the antiandrogenic dichlorodiphenyldichloroethylene (DDE, the main metabolite of the insecticide DDT), and the nondioxin-like polychlorinated biphenyl congener 153 (PCB-153) with mixed estrogenic/antiestrogenic properties and the risk of biochemical recurrence (BCR) after surgery. After a median follow-up of 6.1 years after surgery, we found a significant increase in the risk of BCR, with increasing plasma chlordecone concentration (adjusted hazard ratio = 2.51; 95% confidence interval: 1.39-4.56 for the highest vs. lowest quartile of exposure; p trend = 0.002). We found no associations for DDE or PCB-135. These results shown that exposure to environmental estrogens may negatively influence the outcome of PCa treatment.

Polychlorinated biphenyls influence on autism spectrum disorder risk in the MARBLES cohort

BACKGROUND

Autism spectrum disorder (ASD) is suspected to have environmental and genetic contributions. Polychlorinated biphenyls (PCBs) are environmental risk factors of interest due to their potential as neurodevelopmental toxicants and environmental persistence despite a US production ban in the 1970s.

METHODS

Participants were mother-child pairs from MARBLES, a high-risk pregnancy cohort that enrolls families who have one child diagnosed with ASD and are planning to have another child. PCB concentrations were measured in maternal blood at each trimester of pregnancy using gas chromatography coupled with triple quadruple mass spectrometry. Concentrations were summed into total PCB and two categories based on function/mechanisms of action: dioxin-like (DL), and ryanodine receptor (RyR)-activating PCBs. Multinomial logistic regression assessed risk of clinical outcome classification of ASD and non-typical development (Non-TD) compared to typically developing (TD) in the children at 3 years old.

RESULTS

A total of 104 mother-child pairs were included. There were no significant associations for total PCB; however, there were borderline significant associations between DL-PCBs and decreased risk for Non-TD outcome classification (adjusted OR: 0.41 (95% CI 0.15-1.14)) and between RyR-activating PCBs and increased risk for ASD outcome classification (adjusted OR: 2.63 (95% CI 0.87-7.97)).

CONCLUSION

This study does not provide strong supporting evidence that PCBs are risk factors for ASD or Non-TD. However, these analyses suggest the need to explore more deeply into subsets of PCBs as risk factors based on their function and structure in larger cohort studies where non-monotonic dose-response patterns can be better evaluated.

Hypersensitive assessment of aryl hydrocarbon receptor transcriptional activity using a novel truncated cyp1a promoter in zebrafish

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a persistent organic pollutant (POP), an unintentional byproduct of various industrial processes, and a human carcinogen. The expression of the cytochrome P450 1A (cyp1a) gene is upregulated in the presence of TCDD through activating the aryl hydrocarbon receptor pathway in a dose-dependent manner. Several essential response elements, including the 8 potential xenobiotic response elements in the cyp1a promoter region, have been identified to be the main functional parts for the response to TCDD. Thus, we aimed to develop a convenient and sensitive biomonitoring tool to examine the level of POPs in the environment and evaluate its potential human health risks by TCDD. Here, we established a transgenic zebrafish model with a red fluorescent reporter gene ( mCherry) using the truncated cyp1a promoter. Under exposure to TCDD, the expression pattern of mCherry in the reporter zebrafish mirrored that of endogenous cyp1a mRNA, and the primary target tissues for TCDD were the brain vessels, liver, gut, cloaca, and skin. Our results indicated that exposure of the embryos to TCDD at concentrations as low as 0.005 nM for 48 h, which did not elicit morphologic abnormalities in the embryos, markedly increased mCherry expression. In addition, the reporter embryos responded to other POPs, and primary liver cell culture of zebrafish revealed that Cyp1a protein was mainly expressed in the cytoplasm of liver cells. Furthermore, our transgenic fish embryos demonstrated that TCDD exposure can regulate the expression levels of several tumor-related factors, including epidermal growth factor, TNF-α, C-myc, proliferating cell nuclear antigen, TGF-β, serine/threonine kinase (Akt), and phosphorylated Akt, suggesting that our transgenic fish can be used as a sensitive model to evaluate the carcinogenicity induced by TCDD exposure.-Luo, J.-J., Su, D.-S., Xie, S.-L., Liu, Y., Liu, P., Yang, X.-J., Pei D.-S. Hypersensitive assessment of aryl hydrocarbon receptor transcriptional activity using a novel truncated cyp1a promoter in zebrafish.

Persistent Threats by Persistent Pollutants: Chemical Nature, Concerns and Future Policy Regarding PCBs-What Are We Heading For?

Polychlorinated biphenyl (PCB)-contaminated sites around the world affect human health for many years, showing long latency periods of health effects. The impact of the different PCB congeners on human health should not be underestimated, as they are ubiquitous, stable molecules and reactive in biological tissues, leading to neurological, endocrine, genetic, and systemic adverse effects in the human body. Moreover, bioaccumulation of these compounds in fatty tissues of animals (e.g., fish and mammals) and in soils/sediments, results in chronic exposure to these substances. Efficient destruction methods are important to decontaminate polluted sites worldwide. This paper provides an in-depth overview of (i) the history and accidents with PCBs in the 20th century, (ii) the mechanisms that are responsible for the hazardous effects of PCBs, and (iii) the current policy regarding PCB control and decontamination. Contemporary impacts on human health of historical incidents are discussed next to an up to date overview of the health effects caused by PCBs and their mechanisms. Methods to decontaminate sites are reviewed. Steps which lead to a policy of banning the production and distribution of PCBs are overviewed in a context of preventing future accidents and harm to the environment and human health.

Polychlorinated biphenyls: New evidence from the last decade

Millions of pounds of polychlorinated biphenyl (PCB) compounds have been produced in multiple countries for industrial applications over the last several decades. PCB exposure induces various adverse health effects in animals and humans. Environmental and occupational exposures to PCBs have been associated with liver, kidney, endocrine, and neurodevelopmental adverse effects. We have collected and reviewed animal and human data cited in the US National Library of Medicine from 2000 to 2010. In brief, our review shows new evidence, that is, in animal studies, exposure to one of the PCBs, A1221, induces a significant alteration of serum luteinizing hormone. The effects were more profound in the F2 generation, particularly with respect to fluctuations in hormones and reproductive tract tissues across the estrous cycle. Morphological analyses of brain tissue from rats exposed to A1254 confirmed the results of an earlier work which showed that the relative size of the intra- and infrapyramidal (II-P) mossy fibers was smaller than that in the controls and also reduction in growth was selective for the II-P mossy fibers. PCB exposure increased anogenital distance and prostate size but decreased epididymal weight, epididymal sperm count, and motile epididymal sperm count. No effects were observed on testicular weight or size. The epidemiological data showed an association between diabetes mellitus prevalence and elevated concentrations of PCB 153. Additionally, prenatal PCB exposure studies were associated with a smaller thymic index at birth and could adversely affect immune responses to childhood vaccinations and resistance to respiratory infections. PCB exposure was also reported to adversely affect enamel development in children in a dose-dependent manner. Because PCBs and their metabolites are potential health hazards, understanding the risk factors associated with individual PCBs, PCB mixtures, and PCB metabolites is important. PCB exposures of vulnerable populations (pregnant women, fetuses, infants, and children) are of particular concern because of heightened sensitivity during this period of brain development.

Exposure to polychlorinated biphenyls and prostate cancer: population-based prospective cohort and experimental studies

Polychlorinated biphenyls (PCBs) are highly persistent environmental pollutants and are undesirable components of our daily food. PCBs are classified as human carcinogens, but the evidence for prostate cancer is limited and available data are inconsistent. We explored the link between non-dioxin-like PCB and grade of prostate cancer in a prospective cohort as well as in cell experiments. A population-based cohort of 32496 Swedish men aged 45-79 years was followed prospectively through 1998-2011, to assess the association between validated estimates of dietary PCB exposure and incidence of prostate cancer by grade (2789 cases, whereof 1276 low grade, 756 intermediate grade, 450 high grade) and prostate cancer mortality (357 fatal cases). In addition, we investigated a non-dioxin-like PCB153-induced cell invasion and related markers in normal prostate stem cells (WPE-stem) and in three different prostate cancer cell lines (PC3, DU145 and 22RV1) at exposure levels relevant to humans. After multivariable-adjustment, dietary PCB exposure was positively associated with high-grade prostate cancer, relative risk (RR) 1.35 [95% confidence interval (CI): 1.03-1.76] and with fatal prostate cancer, RR 1.43 (95% CI: 1.05-1.95), comparing the highest tertile with the lowest. We observed no association with low or intermediate grade of prostate cancer. Cell invasion and related markers, including MMP9, MMP2, Slug and Snail, were significantly increased in human prostate cancer cells as well as in prostate stem cells after exposure to PCB153. Our findings both from the observational and experimental studies suggest a role of non-dioxin-like PCB153 in the development of high-grade and fatal prostate cancer.

Prediagnostic Serum Organochlorine Concentrations and Metastatic Prostate Cancer: A Nested Case-Control Study in the Norwegian Janus Serum Bank Cohort

BACKGROUND

Organochlorine (OC) insecticides and polychlorinated biphenyls (PCBs) have been shown to have estrogenic, antiestrogenic, or antiandrogenic properties; as a result, the impact of exposure to these compounds and risk of hormonal cancers, such as prostate cancer, is a concern.

OBJECTIVES

We conducted a nested case-control study, using prospectively collected serum, to estimate associations between OC exposures and metastatic prostate cancer in a population-based cohort from Norway.

METHODS

Sera from 150 cases and 314 controls matched on date of blood draw, age at blood draw, and region was used to determine concentrations of 11 OC pesticide metabolites and 34 PCB congeners. Odds ratios (ORs) and 95% confidence intervals (95% CIs) for quartiles of lipid-corrected metabolite levels were calculated using conditional logistic regression.

RESULTS

Metastatic prostate cancer was two times as likely among men with serum concentrations of oxychlordane in the highest quartile compared with those in the lowest quartile (OR = 2.03; 95% CI: 1.03, 4.03; p-trend 0.05). Elevated but nonsignificant ORs were estimated for the highest versus lowest quartile of heptachlor epoxide, HCB, and mirex, although these exposures were correlated with oxychlordane. Findings for specific PCB congeners showed a significant inverse association between natural log-transformed lipid-adjusted PCB 44 and metastatic prostate cancer (OR = 0.74; 95% CI: 0.56, 0.97; p-trend = 0.02).

CONCLUSIONS

Our study highlights the importance of estimating associations with specific OC chemicals and suggests a possible role of OC insecticides and PCBs in the etiology of metastatic prostate cancer.

CITATION

Koutros S, Langseth H, Grimsrud TK, Barr DB, Vermeulen R, Portengen L, Wacholder S, Beane Freeman LE, Blair A, Hayes RB, Rothman N, Engel LS. 2015. Prediagnostic serum organochlorine concentrations and metastatic prostate cancer: a nested case-control study in the Norwegian Janus Serum Bank cohort. Environ Health Perspect 123:867-872; http://dx.doi.org/10.1289/ehp.1408245.

Body concentrations of persistent organic pollutants and prostate cancer: a meta-analysis

There have been some concerns that persistent organic pollutants (POPs) may be associated with the risk of prostate cancer. Meta-analyses have not yet investigated the association between human-biomonitoring data for POPs and prostate cancer risk. The purpose of this study was to assess the association between body concentration of individual compounds or mixtures of POPs and prostate cancer risk in the general population by performing a meta-analysis. A literature search was performed using PubMed, EMBASE, and KoreaMed from the period 1950 through 2014. The odds ratio (OR) and its 95% confidence interval (CI) of prostate cancer associated with POPs were estimated using fixed-effects model or random-effects model where appropriate. Dose-response relationships were assessed by using the generalized least-squares method for trend estimation. A total of eight (six case-control, one cross-sectional, one nested case-control) studies including 1158 prostate cancer cases among 6932 subjects were selected for the meta-analysis. Total POPs of interest showed positive associations with statistical significance on prostate cancer (OR 1.31, 95% CI 1.13, 1.57). In dose-response meta-analysis, 1 μg/g lipid of PCBs was found to be associated with a 49% increased risk of prostate cancer (OR 1.49, 95% CI 1.07, 2.06). One nanogram per gram (1000 μg/g) lipid of trans-nonachlor was found to be associated with approximately 2% increased risk of prostate cancer (OR = 1.02/1 ng/g lipid of trans-nonachlor, 95% CI 1.00, 1.03). The available evidence suggests that body concentrations of POPs are positively associated with prostate cancer risk, which implies valuable evidence for prostate cancer prevention.

Associations of plasma concentrations of dichlorodiphenyldichloroethylene and polychlorinated biphenyls with prostate cancer: a case-control study in Guadeloupe (French West Indies)

BACKGROUND

Long-term exposure to persistent pollutants with hormonal properties (endocrine-disrupting chemicals; EDCs) may contribute to the risk of prostate cancer (PCa). However, epidemiological evidence remains limited.

OBJECTIVES

We investigated the relationship between PCa and plasma concentrations of universally widespread pollutants, in particular p,p'-dichlorodiphenyl dichloroethene (DDE) and the non-dioxin-like polychlorinated biphenyl congener 153 (PCB-153).

METHODS

We evaluated 576 men with newly diagnosed PCa (before treatment) and 655 controls in Guadeloupe (French West Indies). Exposure was analyzed according to case-control status. Associations were assessed by unconditional logistic regression analysis, controlling for confounding factors. Missing data were handled by multiple imputation.

RESULTS

We estimated a significant positive association between DDE and PCa [adjusted odds ratio (OR) = 1.53; 95% CI: 1.02, 2.30 for the highest vs. lowest quintile of exposure; p trend = 0.01]. PCB-153 was inversely associated with PCa (OR = 0.30; 95% CI: 0.19, 0.47 for the highest vs. lowest quintile of exposure values; p trend < 0.001). Also, PCB-153 was more strongly associated with low-grade than with high-grade PCa.

CONCLUSIONS

Associations of PCa with DDE and PCB-153 were in opposite directions. This may reflect differences in the mechanisms of action of these EDCs; and although our findings need to be replicated in other populations, they are consistent with complex effects of EDCs on human health.

Exposure to endocrine disrupting chemicals and male reproductive health

Endocrine disrupting chemicals (EDCs) can interfere with normal hormonal balance and may exert adverse consequences on humans. The male reproductive system may be susceptible to the effects of such environmental toxicants. This review discusses the recent progress in scientific data mainly from epidemiology studies on the associations between EDCs and male reproductive health and our understanding of possible mechanisms associated with the effects of EDCs on male reproductive health. Finally, the review provides recommendations on future research to enhance our understanding of EDCs and male reproductive health. The review highlights the need for (1) well-defined longitudinal epidemiology studies, with appropriately designed exposure assessment to determine potential causal relationships; (2) chemical and biochemical approaches aimed at a better understanding of the mechanism of action of xenoestrogens with regard to low-dose effects, and assessment of identify genetic susceptibility factors associated with the risk of adverse effects following exposure to EDCs.

The relevance of serum levels of long chain omega-3 polyunsaturated fatty acids and prostate cancer risk: A meta-analysis

OBJECTIVE

Our objective was to systematically analyze the evidence for an association between serum level long chain omega-3 polyunsaturated fatty acid (n-3 PUFA) and prostate cancer risk from human epidemiological studies. STUDY PROCEDURES: We searched biomedical literature databases up to November 2011 and included epidemiological studies with description of long chain n-3 PUFA and incidence of prostate cancer in humans. Critical appraisal was done by two independent reviewers. Data were pooled using the general variance-based method with random-effects model; effect estimates were expressed as risk ratio with 95% confidence interval (CI). Heterogeneity was assessed by Chi(2) and quantified by I(2), publication bias was also determined.

RESULTS

In total, 12 studies were included. Significant negative association was noted between high serum level of n-3 PUFA doc-osapentaenoic acid (DPA) and total prostate cancer risk (RR:0.756; 95% CI 0.599, 0.955; p = 0.019). Likewise, a positive association between high blood level of fish oil contents, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and high-grade prostate tumour incidence (RR:1.381; 95% CI 1.050, 1.817; p = 0.021) was noted; however, this finding was evident only after adjustment was done on interstudy variability through the removal of a lower quality study from the pool.

CONCLUSIONS

High serum levels of long chain n-3 PUFA DPA is associated with reduced total prostate cancer risk. While high blood level of EPA and DHA is possibly associated with increased high-grade prostate tumour risk.

Blood level omega-3 Fatty acids as risk determinant molecular biomarker for prostate cancer

Previous researches involving dietary methods have shown conflicting findings. Authors sought to assess the association of prostate cancer risk with blood levels of omega-3 polyunsaturated fatty acids (n-3 PUFA) through a meta-analysis of human epidemiological studies in available online databases (July, 2012). After critical appraisal by two independent reviewers, Newcastle-Ottawa Quality Assessment Scale (NOQAS) was used to grade the studies. Six case control and six nested case control studies were included. Results showed nonsignificant association of overall effect estimates with total or advanced prostate cancer or high-grade tumor. High blood level of alpha-linolenic acid (ALA) had nonsignificant positive association with total prostate cancer risk. High blood level of docosapentaenoic acid (DPA) had significant negative association with total prostate cancer risk. Specific n-3 PUFA in fish oil, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) had positive association with high-grade prostate tumor risk only after adjustment of interstudy variability. There is evidence that high blood level of DPA that is linked with reduced total prostate cancer risk and elevated blood levels of fish oils, EPA, and DHA is associated with high-grade prostate tumor, but careful interpretation is needed due to intricate details involved in prostate carcinogenesis and N-3 PUFA metabolism.

Polychlorinated biphenyls and cancer: an epidemiological assessment

Polychlorinated biphenyls (PCBs) are toxic and persistent chemicals produced between 1930s and 1980s primarily for insulating fluids in heavy-duty electrical equipment in power plants, industries, and large buildings. They persist in the environment and accumulate in plants and animals, and have been classified as probable carcinogens to humans. We performed a systematic review and meta-analysis of scientific literature on the relationship between PCB exposure and human cancer. Two cohorts of people highly exposed to PCBs through ingestion of contaminated rice oil and some cohorts of occupationally exposed workers failed to show a definite increase in total cancer mortality and provided inconsistent results regarding single cancers. Several cohort and case-control studies investigated the association between PCBs and specific cancers, showing an association between PCB serum levels and non-Hodgkin lymphomas (NHL), with a summary odds ratio of 1.5 (95% confidence interval: 1.1-1.7), but no consistent results for the other cancer sites and types. In conclusion, this review provides some evidence for the role of PCBs in the development of NHL, although the inconsistent results of studies performed on highly polluted people and occupationally exposed workers do not allow a firm conclusion to be drawn.

Differential gene expression and a functional analysis of PCB-exposed children: understanding disease and disorder development

The goal of the present study is to understand the probable molecular mechanism of toxicities and the associated pathways related to observed pathophysiology in high PCB-exposed populations. We have performed a microarray-based differential gene expression analysis of children (mean age 46.1 months) of Central European descent from Slovak Republic in a well-defined study cohort. The subset of children having high blood PCB concentrations (>75 percentile) were compared against their low PCB counterparts (<25 percentile), with mean lipid-adjusted PCB values of 3.02±1.3 and 0.06±0.03 ng/mg of serum lipid, for the two groups, respectively (18.1±4.4 and 0.3±0.1 ng/ml of serum). The microarray was conducted with the total RNA from the peripheral blood mononuclear cells of the children using an Affymetrix platform (GeneChip Human genome U133 Plus 2.0 Array) and was analyzed by Gene Spring (GX 10.0). A highly significant set of 162 differentially expressed genes between high and low PCB groups (p value <0.00001) were identified and subsequently analyzed using the Ingenuity Pathway Analysis tool. The results indicate that Cell-To-Cell Signaling and Interaction, Cellular Movement, Cell Signaling, Molecular Transport, and Vitamin and Mineral Metabolism were the major molecular and cellular functions associated with the differentially altered gene set in high PCB-exposed children. The differential gene expressions appeared to play a pivotal role in the development of probable diseases and disorders, including cardiovascular disease and cancer, in the PCB-exposed population. The analyses also pointed out possible organ-specific effects, e.g., cardiotoxicity, hepatotoxicity and nephrotoxicity, in high PCB-exposed subjects. A few notable genes, such as BCL2, PON1, and ITGB1, were significantly altered in our study, and the related pathway analysis explained their plausible involvement in the respective disease processes, as mentioned. Our results provided insight into understanding the associated molecular mechanisms of complex gene-environment interactions in a PCB-exposed population. Future endeavors of supervised genotyping of pathway-specific molecular epidemiological studies and population biomarker validations are already underway to reveal individual risk factors in these PCB-exposed populations.

Common classification schemes for PCB congeners and the gene expression of CYP17, CYP19, ESR1 and ESR2

BACKGROUND

Reliable techniques to measure polychlorinated biphenyl (PCB) congeners make the clearer definition of their effects on human health possible. Given that PCBs are classified as endocrine disrupters, we sought to explore the expression of some key genes involved in sex steroid metabolism.

OBJECTIVES

To examine common classification schemes of PCB congeners and determine whether exposure to groups classified by mechanism of action alter the gene expression (GE) of CYP17, CYP19, and ESR1 and ESR2.

METHODS

GE and exposure to various classifications of lipid-adjusted PCB congeners were examined in 139 daughters of the Michigan Fisheaters' Cohort. Using mixed models analyses and adjusting for age, menopausal status, and current use of oral contraceptives and hormone replacement therapy, GE data were regressed on exposure to PCB congener groupings based on mechanism of action.

RESULTS

Three novel findings are elucidated: first, that up-regulation of CYP19 expression is associated with exposure to PCB groupings containing dioxin-like, potentially anti-estrogenic, immunotoxic congeners, including PCB IUPAC #74, #105, #118, #138, #156, #157, #158, #167, and #170 from this cohort. Second, that exposure to similar congeners (PCB IUPAC #105, #156, #157, #158, and #167 in this cohort) but using a classification based solely on hormonal mechanisms of action is associated with increased expression of ESR2. Third, that increased expression of CYP17 is of borderline significance when associated with exposure to PCB IUPAC #118, #138, and #156.

CONCLUSIONS

These findings are both counter-intuitive and intriguing. Rather than exhibiting anti-estrogenic effects alone, they suggest that these congeners up-regulate the major enzyme involved in estrogen synthesis and tend to confirm previous findings of links between AhR and ER signaling pathways. Replication of these findings, expansion of the number of genes examined, exploration of mixtures of environmental chemicals, and subsequent study of health outcomes in a larger cohort are future priorities.

2-(4-Chlorophenyl)benzo-1,4-quinone induced ROS-signaling inhibits proliferation in human non-malignant prostate epithelial cells

Polychlorinated biphenyls (PCBs) and their metabolites are environmental chemical contaminants which can produce reactive oxygen species (ROS) by auto-oxidation of di-hydroxy PCBs as well as the reduction of quinones and redox-cycling. We investigate the hypothesis that 2-(4-chlorophenyl)benzo-1,4-quinone (4-Cl-BQ), a metabolite of 4-chlorobiphenyl (PCB3), induced ROS-signaling inhibits cellular proliferation. Monolayer cultures of exponentially growing asynchronous human non-malignant prostate epithelial cells (RWPE-1) were incubated with 0-6 μM of 4-Cl-BQ and harvested at the end of 72 h of incubation to assess antioxidant enzyme expression, cellular ROS levels, cell growth, and cell cycle phase distributions. 4-Cl-BQ decreased manganese superoxide dismutase (MnSOD) activity, protein, and mRNA levels. 4-Cl-BQ treatment increased dihydroethidium (DHE) fluorescence, which was suppressed in cells pretreated with polyethylene glycol conjugated superoxide dismutase (PEG-SOD). The increase in ROS levels was associated with a decrease in cell growth, and an increase in the percentage of S-phase cells. These effects were suppressed in cells pretreated with PEG-SOD. 4-Cl-BQ treatment did not change the protein levels of phosphorylated H2AX at the end of 72 h of incubation, suggesting that the inhibition in cell growth and accumulation of cells in S-phase at the end of the treatments were probably not due to 4-Cl-BQ induced DNA double strand break. These results demonstrate that MnSOD activity and ROS-signaling perturb proliferation in 4-Cl-BQ treated in vitro cultures of human prostate cells.

Protective effects of selenium against DNA adduct formation in Inuit environmentally exposed to PCBs

Dietary habits that expose populations to potential toxicants as well as protective agents simultaneously are a realistic scenario where a meaningful assessment of the interactions and net benefit or damage can be made. A group of Inuit from Salluit, Northern Canada are exposed to high levels of PCBs and selenium, both present in the Inuit traditional foods such as blubber from sea mammals and fatty fish. Blood samples were collected from 83 Inuit, 22-70 years old. Blood selenium and PCB levels were determined previously and ranged from 227 to 2069µg/L and 1.7 to 143µg/L, respectively. DNA isolated from white blood cells were analyzed by modified (32)P-postlabeling adductomics technology that detects a multitude of highly polar to lipophilic adducts. The levels of 8-oxodG adducts ranged from 470 to 7400 adducts/10(9) nucleotides. Other as yet unidentified polar adducts showed a 30 to 800-fold inter-individual variability. Adduct levels were negatively associated with PCB and selenium levels. The subjects were classified into high and low ratio groups, with respect to selenium/PCB. In the high ratio group, the coefficient of selenium is significantly negatively correlated with 8-oxodG (r = -0.38, p = 0.014) and total adducts (r = -0.41, p = 0.009) while there was no correlation within the low selenium/PCB group. This study suggests that increasing selenium has mitigating effect in reducing DNA adducts and therefore, possible negative effects of PCB were not seen. A protective effect of selenium is highlighted.

Toxicology mechanism of the persistent organic pollutants (POPs) in fish through AhR pathway

With the development of industry and agriculture, the cases of cancer and tumor have been increasing gradually in the last 30 years, and quite a few cases are caused by persistent organic pollutants (POPs), some of them belonging to environmental endocrine disruptors, and they have become ubiquitous in the environment, especially in the aquatic ecosystem; so this issue has aroused the extensive attention of the world. The mechanism of POPs toxicology is very complicated, but it is mainly mediated by the aryl hydrocarbon receptor (AhR) pathway in fish. In order to gain a comprehensive understanding of the AhR pathway, the present paper focuses on reviewing it from four major steps, including formation of cytosolic complex, translocation of AhR, heterodimerization of AhR, and induction of CYP1A. This study summarized the isoform numbers of AhR pathway genes and the expression patterns in the regulation process of POPs toxicology in zebrafish.

Chlordecone Exposure and Risk of Prostate Cancer

Purpose

Determining whether environmental estrogens are associated with the risk of prostate cancer may have important implications for our general understanding of this disease. The estrogenic insecticide chlordecone was used extensively in the French West Indies, contaminating the population for more than 30 years. We analyzed the relationship between exposure to chlordecone and the risk of prostate cancer.

Patients and Methods

We investigated 623 men with prostate cancer and 671 controls. Exposure was analyzed according to case-control status, using either current plasma concentration or a cumulative exposure index based on years of exposure. We genotyped two single-nucleotide polymorphisms (rs3829125 and rs17134592) in the gene encoding chlordecone reductase.

Results

We found a significant increase in the risk of prostate cancer with increasing plasma chlordecone concentration (odds ratio [OR], 1.77; 95% CI, 1.21 to 2.58 for the highest tertile of values above the limit of detection [LD]; P trend = .002) and for cumulative exposure index (OR, 1.73; 95% CI, 1.04 to 2.88 for the highest quartile; P trend = .004). Stronger associations were observed among those with a positive family history of prostate cancer and among those who had lived in a Western country. The rs3829125 and rs17134592 allele variants were in complete linkage disequilibrium and were found at low frequency (0.04). Among subjects with plasma chlordecone concentrations above the LD, carriers of the allele variants had a higher risk of prostate cancer (OR, 5.23; 95% CI, 0.82 to 33.32).

Conclusion

These findings support the hypothesis that exposure to environmental estrogens increases the risk of prostate cancer.

Plasma organochlorines and subsequent risk of prostate cancer in Japanese men: a nested case-control study

BACKGROUND

Although accumulating evidence suggests that exposure to organochlorine pesticides and polychlorinated biphenyls (PCBs) may contribute to the development of prostate cancer, few investigations have used biological samples to classify exposure to specific organochlorines. To our knowledge, this is the first prospective study to investigate the association between blood levels of organochlorines and prostate cancer risk.

METHODS

We conducted a nested case-control study using data from the Japan Public Health Center-based Prospective (JPHC) Study. A total of 14,203 men 40-69 years old who returned the baseline questionnaire and who provided blood samples were followed from 1990 to 2005. Using a mean follow-up period of 12.8 years, we identified 201 participants who were newly diagnosed with prostate cancer. Two matched controls for each case were selected from the cohort. We used a conditional logistic regression model to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) for prostate cancer in relation to plasma levels of nine organochlorines: PCBs, dichlorodiphenyltrichloroethane (DDT), hexachlorobenzene (HCB), beta-hexachlorocyclohexane (beta-HCH), trans- and cis-nonachlor, oxychlordane, and mirex.

RESULTS

No statistically significant association with total prostate cancer was seen for any plasma organochlorine, although we did observe an insignificant inverse association for plasma HCB and beta-HCH. Total PCB in plasma was also inversely associated with advanced prostate cancer but without statistical significance.

CONCLUSION

Our results suggest that no overall association exists between prostate cancer and organochlorines at the levels measured in our study population.

Background levels of polychlorinated biphenyls in the U.S. population

BACKGROUND

Polychlorinated biphenyl (PCB) exposures are encountered by the general public by eating contaminated food or living near a previously operating PCB factory or hazardous waste site. PCBs affect the immune, reproductive, nervous, and endocrine systems and are carcinogens. PCBs were banned in the United States in 1977. For public health, it is important to be able to estimate individual risk, especially for vulnerable populations, to monitor the decline in risk over time and to alert the public health community if spikes occur in PCB exposures, by measuring serum PCB levels. The historical decline in PCB exposures cannot be documented within a repeatedly tested general population, since there is no such population. Therefore, our aim was to model serum PCB levels in the US general population over time using published data.

METHODS

Models were developed based on 45 publications providing 16,914 background PCB levels in sera collected 1963-2003. Multiple linear regression and exponential decay were used to model the summary PCB levels.

RESULTS

Background levels of higher-chlorinated PCBs (five or more chlorines) in sera increased before 1979 and decreased after 1979; a quadratic model was the best fit. However, the exponential decay model explained better the low PCB serum levels still seen in the general population. For lower-chlorinated serum PCBs, no increase or decrease was shown (1.7ppb for all years).

CONCLUSIONS

Limitations for both models were lack of repeated measures, non-randomly selected study participants, selected years, concentration on geographic areas centered on PCB waste sites, lack of adjustment for BMI or for laboratory methods. Despite the limitations, this analysis shows that background PCB levels in the general population are still of concern. Future work should focus on uncertainties governing how to interpret the levels with respect to possible long term health effects.

Omega-3 fatty acids, genetic variants in COX-2 and prostate cancer

Dietary intake of fish and omega-3 polyunsaturated fatty acids (omega-3 PUFAs) may decrease the risk of prostate cancer development and progression to advanced stage disease. This could reflect the anti-inflammatory effects of PUFAs, possibly through mediation of cyclooxygenase (COX), a key enzyme in fatty acid metabolism and inflammation. Despite promising experimental evidence, epidemiological studies have reported somewhat conflicting results regarding the effects of fish/PUFAs on prostate cancer development and progression. The literature suggests that fish, and particularly long-chain omega-3 PUFAs, may have a more pronounced protective effect on biologically aggressive tumors or on their progression, and less on early steps of carcinogenesis. Moreover, the impact of LC omega-3 PUFAs may be modified by variation of the COX-2 gene. Overall, results to date support the hypothesis that long-chain omega-3 PUFAs may impact prostate inflammation and carcinogenesis via the COX-2 enzymatic pathway.

Polychlorinated biphenyls in bile of patients with biliary tract cancer

BACKGROUND

Polychlorinated biphenyls (PCBs) are anthropogenic, organic compounds. Although banned in the 1970s, PCBs are poorly biodegradable and hence ubiquitous in the environment. They accumulate in adipose tissue and are implicated various malignancies, including breast and pancreatic cancer. The hepatobiliary system is the main excretory route for such xenobiotic toxins. Incidence rates of intrahepatic biliary tract cancer are increasing worldwide. Measurement and comparison of PCB levels in bile from human patients with benign and malignant bile duct disease has not previously been done.

OBJECTIVES

To compare PCB concentrations in bile from patients with malignant (n=8) and non-malignant (n=7) biliary disease.

METHODS AND RESULTS

Fifteen human bile samples, collected endoscopically, were analysed using gas chromatography mass spectrometry for seven target PCB congeners (28, 52, 101, 118, 153, 138, and 180), known to occur in the environment and food. Amongst males, total PCB concentrations in bile ranged from 6 ng mL(-1) (aged 73 years) to 49 ng mL(-1) (aged 90 years); and in females between 8 ng mL(-1) (aged 33 years) to 43 ng mL(-1) (aged 67 years) bile. Although there was no overall difference in mean PCB levels between non-cancer and cancer patients, levels of congener 28 were significantly higher in patients with biliary tract cancer (p<0.05).

CONCLUSIONS

Despite the banning of PCBs over 30 years ago, these xenobiotics are present in the bile of patients with biliary disease. PCB levels tend to increase with age, suggesting chronic bioaccumulation. Further research is necessary to investigate the relevance of increased levels of congener 28 in bile in biliary tract cancer.

Paradoxical increases in serum levels of highly chlorinated PCBs in aged women in clear contrast to robust decreases in dietary intakes from 1980 to 2003 in Japan

OBJECTIVE

Exposure to polychlorinated biphenyls (PCBs) is considered to have culminated between 1950 and 1970 in Japan, and exposure through diet, the major exposure route, has decreased significantly over the last 10 years. The primary goal of the present study was to investigate the long-term trends and congener profiles of serum and dietary levels of PCBs using historical samples.

METHODS

Using banked samples collected in 1980, 1995, and 2003 surveys, we determined the daily intakes and serum concentrations of 13 PCB congeners (#74, #99, #118, #138, #146, #153, #156, #163, #164, #170, #180, #182, and #187) in women.

RESULTS

The total daily PCB intake [ng/day, geometric mean (geometric standard deviation)] decreased significantly from 523 (2.5) in 1980 to 63 (3.2) in 2003. The serum total PCB level (ng/g lipid) in women <40 years of age decreased significantly from 185 (1.8) in 1980 to 68 (1.8) in 2003. In contrast, the level in women >50 years of age increased significantly from 125 (1.7) in 1980 to 242 (1.7) in 2003. Specifically, the serum concentrations of hexa (#138, #146, #153, #156, #163, and #164) and hepta (#170, #180, #182, and #187) congeners increased significantly. A comparison of the serum PCB levels of women born from 1940 to 1953 revealed that their serum total PCB level was significantly higher in the 2003 survey [242 (1.7), n = 9] than in the 1995 [128 (2.0), n = 17] surveys. This increase in the total PCB level was attributable to increases in the hepta congener groups.

CONCLUSION

Present results suggest a decreased rate of elimination of hepta congeners with aging in females, rather than a birth-generation phenomenon.

Environmental exposures and gene regulation in disease etiology

Health or disease is shaped for all individuals by interactions between their genes and environment. Exactly how the environment changes gene expression and how this can lead to disease are being explored in a fruitful new approach to environmental health research, representative studies of which are reviewed here. We searched Web of Science and references of relevant publications to understand the diversity of gene regulatory mechanisms affected by environmental exposures with disease implications. Pharmaceuticals, pesticides, air pollutants, industrial chemicals, heavy metals, hormones, nutrition, and behavior can change gene expression through a broad array of gene regulatory mechanisms. Furthermore, chemically induced changes in gene regulation are associated with serious and complex human diseases, including cancer, diabetes and obesity, infertility, respiratory diseases, allergies, and neurodegenerative disorders such as Parkinson and Alzheimer diseases. The reviewed studies indicate that genetic predisposition for disease is best predicted in the context of environmental exposures. And the genetic mechanisms investigated in these studies offer new avenues for risk assessment research. Finally, we are likely to witness dramatic improvements in human health, and reductions in medical costs, if environmental pollution is decreased.

PCBs enhance collagen I expression from human peritoneal fibroblasts

OBJECTIVE

To test the effect of four polychlorinated biphenyl congeners (PCB-77, PCB-105, PCB 153, and PCB 180) on expression of three adhesion markers (transforming growth factor [TGF] beta1, vascular endothelial growth factor [VEGF], and type I collagen) in normal human peritoneal and adhesion fibroblasts.

DESIGN

Cell culture study.

SETTINGS

University research laboratory.

PATIENT(S)

Primary cultures of normal peritoneal and adhesion fibroblasts were established from three patients.

INTERVENTION(S)

Fibroblasts were treated with PCB-77, PCB-105, PCB-153, or PCB-180 at 20 ppm for 24 hours. Total RNA was extracted from each treatment and subjected to real-time reverse transcriptase polymerase chain reaction (RT-PCR). MAIN OUTCOME AND MEASURE(S): The mRNA levels of type I collagen, VEGF, and TGF-beta1.

RESULT(S)

Normal human peritoneal fibroblasts expressed type I collagen, VEGF, and TGF-beta1. Exposure of normal human fibroblasts to PCB-77, PCB-105, PCB-153, or PCB-180 did not affect mRNA levels of beta-actin, the housekeeping gene used to normalized RNA levels for the real-time RT-PCR, nor did it affect cell viability as assessed by trypan blue exclusion. The PCB treatments, compared with control, resulted in no significant change for TGF-beta1 or VEGF mRNA levels in normal peritoneal and adhesion fibroblasts. In marked contrast, type I collagen mRNA levels were markedly increased in response to the brief 24 hours' exposure to each PCB treatment in both cell types.

CONCLUSION(S)

The finding that PCB-77, PCB-105, PCB-153, and PCB-180 increased the expression of type I collagen in human normal peritoneal and adhesion fibroblasts is the first demonstration of involvement of organochlorines in the pathogenesis of tissue fibrosis. This may implicate organochlorine exposure as an etiologic factor in a wide variety of previously unlinked human ailments characterized by fibrosis.

[Environmental pollutants and prostate cancer: epidemiological data]

Prostate cancer is the most frequent cancer affecting men in most Western countries. Certain risk factors have been identified (age, family history, ethnic origin), but the aetiology of this cancer remains largely unknown. However, a role for environmental factors is strongly suspected. Questions have been raised concerning the role of the chemical substances generated by human activities in the occurrence of this disease. Diverse studies have consistently demonstrated a higher risk of prostate cancer in agricultural populations than in the general population. The hypothesis that this higher risk is linked to the use of pesticides has been tested in a number of studies, mostly in North America and Europe. However, to date, with a few possible exceptions, it has been impossible to demonstrate a significant association between exposure to pesticides or a chemical family of pesticides and prostate cancer. Studies have also been carried out on the role of exposure to trace metals, such as cadmium, or to pollutants from industry, such as polychlorobiphenyls. However, no firm conclusions have been drawn. Finally, the effect of chemical substances with endocrine disruptor activity on the occurrence of prostate cancer remains largely unexplored in epidemiological studies. In the face of these uncertainties, rigorous studies are required, with objective measurements of exposure, taking into account confounding factors and individual risk factors, making it possible to assess gene-environment interactions.

Environmental exposures and gene regulation in disease etiology

OBJECTIVE

Health or disease is shaped for all individuals by interactions between their genes and environment. Exactly how the environment changes gene expression and how this can lead to disease are being explored in a fruitful new approach to environmental health research, representative studies of which are reviewed here.

DATA SOURCES

We searched Web of Science and references of relevant publications to understand the diversity of gene regulatory mechanisms affected by environmental exposures with disease implications.

DATA SYNTHESIS

Pharmaceuticals, pesticides, air pollutants, industrial chemicals, heavy metals, hormones, nutrition, and behavior can change gene expression through a broad array of gene regulatory mechanisms. Mechanisms include regulation of gene translocation, histone modifications, DNA methylation, DNA repair, transcription, RNA stability, alternative RNA splicing, protein degradation, gene copy number, and transposon activation. Furthermore, chemically induced changes in gene regulation are associated with serious and complex human diseases, including cancer, diabetes and obesity, infertility, respiratory diseases, allergies, and neurodegenerative disorders such as Parkinson and Alzheimer diseases. One of the best-studied areas of gene regulation is epigenetics, especially DNA methylation. Our examples of environmentally induced changes in DNA methylation are presented in the context of early development, when methylation patterns are initially laid down. This approach highlights the potential role for altered DNA methylation in fetal origins of adult disease and inheritance of acquired genetic change.

CONCLUSIONS

The reviewed studies indicate that genetic predisposition for disease is best predicted in the context of environmental exposures. Second, the genetic mechanisms investigated in these studies offer new avenues for risk assessment research. Finally, we are likely to witness dramatic improvements in human health, and reductions in medical costs, if environmental pollution is decreased.

A prospective study on dietary fat and incidence of prostate cancer (Malmö, Sweden)

OBJECTIVE

To study the associations between intake of various types of fat and risk of prostate cancer (PCa) in a population-based cohort.

METHODS

We have studied 10,564 initially cancer-free men of the Malmö Diet and Cancer cohort, aged 45-73 years. Diet was assessed by a modified diet history method. Cases and clinical characteristics were ascertained via national and regional registry data.

RESULTS

During a mean follow-up of 11.0 years, 817 incidental PCa cases were diagnosed. Out of these, 281 were classified as advanced. There were 202 cases occurring before 65 years of age. After adjustment for age and energy intake, there was no association between intake of any types of fat and risk of PCa, or between fat intake and advanced PCa or PCa occurring in persons aged <65 years. However, we observed positive associations between intakes of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and risk of PCa. After adjustment for multiple confounders, the latter associations were weakened, but the results were otherwise virtually unchanged.

CONCLUSIONS

This large study, with high-validity dietary data, does not support an association between intake of total, saturated, or mono-unsaturated fat and PCa risk. The observed associations between EPA/DHA intakes and PCa are difficult to interpret.

Occupational exposure to organochlorine insecticides and cancer incidence in the Agricultural Health Study

Organochlorine (OC) insecticides have been regulated as possible human carcinogens primarily on the basis of animal studies. However, the epidemiologic evidence is inconsistent. We investigated the relationship between cancer incidence and OC insecticide use among pesticide applicators enrolled in the Agricultural Health Study, a prospective cohort study of 57,311 licensed applicators in Iowa and North Carolina enrolled between 1993 and 1997. Information on ever use of 7 OC insecticides (aldrin, chlordane, DDT, dieldrin, heptachlor, lindane, toxaphene) was collected from a self-administered questionnaire at enrollment. Lifetime exposure-days to OC insecticides were calculated using additional data from a take-home questionnaire completed by 25,291 participants (44% of total). We found no clear evidence of an association between use of OC insecticides and incident cancers (N = 1,150) ascertained through December, 2002. When we focused on individual insecticides and structurally similar groups (aldrin and dieldrin; chlordane and heptachlor), significantly increased relative risks of some cancers were observed for use of some chemicals (rectal cancer and chlordane, lung cancer and dieldrin, non-Hodgkin lymphoma (NHL) and lindane, melanoma and toxaphene, leukemia and chlordane/heptachlor). Some significant decreased relative risks were also observed (colon cancer and aldrin; overall cancer and heptachlor). In conclusion, we did not observe any clear relationship between cancer risk and the use of OC insecticides. Our chemical-specific findings are based on small numbers and multiple comparisons, and should be interpreted with caution; however, some observed associations (lindane and NHL, chlordane/heptachlor and leukemia) are supported by previous evidence.

Understanding population and individual risk assessment: the case of polychlorinated biphenyls

Decisions about how to improve or protect the public health can be, and sometimes necessarily are, made on imprecise science. The regulation of potential human carcinogens in the environment entails a population-risk assessment process intended to reduce risks to less than one additional cancer in 100,000 or 1,000,000 persons. These risk assessment processes, however, may be miscommunicated or misinterpreted in the context of individual cancer risks by scientists, regulators, the lay media, and the public. This commentary will review methods for establishing a causal relationship between carcinogen exposures and cancer risk. It will use the case of polychlorinated biphenyls (PCB) as an example of how to place scientific data into the context of human exposure and cancer risk. PCBs are widespread environmental contaminants and most people have detectable levels of PCBs in their bodies. The primary source for exposure in the general population is through the diet. PCBs are carcinogens in experimental animal models, but how this information can be extrapolated to human risk remains uncertain. PCB experimental studies provide data that are used to regulate and control human exposure, although the epidemiologic evidence fails to establish PCBs as human carcinogens. Thus, what is used for population-risk assessment may not be appropriate for individual-risk assessment or concluding that a causal relationship exists between PCB exposure and cancer risk. The hazards from a carcinogen designated by regulatory and review agencies as a "probable" human carcinogen is often misunderstood out of context about the magnitude of the risk and in what settings. How scientists communicate their results in scientific articles can strongly influence how others interpret their data. Misunderstandings from both the use of regulatory and review-agency opinions and the conclusions espoused by scientists occur in the media, among private physicians counseling their patients about cancer risk, and in the legal settings where plaintiffs seek compensation for exposure and alleged harm (or future harm). This can lead to false conclusions about what caused a cancer in a specific patient, undue anxiety about future cancer risk, inappropriate cancer screening, and attendant increased morbidity due to increased uses of the medical system and complication rates from medical procedures. The communication of research findings by scientists must be presented with caution, resisting the temptation to extrapolate, inappropriately, research data to the general population.

Adipose Tissue Concentrations of Persistent Organic Pollutants and the Risk of Prostate Cancer

OBJECTIVE

We sought to study the concentrations of certain persistent organic pollutants with endocrine-disrupting properties in cases with prostate cancer and controls with benign prostate hyperplasia.

METHODS

Adipose tissue was obtained from 58 cases and 20 controls.

RESULTS

The median concentration among controls was used as cut-off in the statistical analysis. In the total material, a greater-than median concentration of PCB congener 153 yielded an odds ratio (OR) of 3.15 and 95% confidence interval (CI) of 1.04-9.54 and one chlordane type, trans-chlordane, yielded OR 3.49 (95% CI = 1.08-11.2). In the group of case subjects with PSA levels greater than the median level of 16.5 ng/mL, PCB 153 was OR 30.3 (95% CI = 3.24-284), hexachlorobenzene OR = 9.84 (95% CI = 1.99-48.5), trans-chlordane OR = 11.0 (95% CI = 1.87-64.9), and the chlordane-type MC6 OR = 7.58 (95% CI = 1.65-34.9). The grouping of PCBs according to structural and biological activity was found to produce significantly increased risks for enzyme and phenobarbital-inducing PCBs and lower chlorinated PCBs in the case group with PSA levels greater than 16.5 ng/mL.

CONCLUSIONS

These chemicals might be of etiologic significance but need to be further investigated. The biological relevance of the arbitrary cut-off point of PSA is unclear.

Polychlorinated biphenyls (PCBs): routes of exposure and effects on human health

The polychlorinated biphenyls (PCBs) are synthetic organochlorine chemicals that were useful industrial products in the past, but their production was ended because they persist in both the environment and living organisms. The PCBs are mixtures of up to 209 different components (congeners), depending on the number and position of chlorines around the biphenyl ring. The PCBs are fat-soluble substances to which everyone is exposed through ingesting animal fats, inhalation, or dermal contact. Exposure to PCBs suppresses the immune system, thereby increasing the risk of acquiring several human diseases. Both ortho-substituted and coplanar (dioxin-like) congeners are tumor promoters that enhance the effects of other carcinogenic substances. PCB exposure, especially during fetal and early life, reduces IQ and alters behavior. The PCBs alter thyroid and reproductive function in both males and females and increase the risk of developing cardiovascular and liver disease and diabetes. Women are at high risk of giving birth to infants of low birth weight, who are at high lifetime risk for several diseases. As knowledge of their toxic effects has grown faster than environmental levels have declined, PCBs remain dangerous contaminants.