A Correlation Study of Organochlorine Levels in Serum, Breast Adipose Tissue, and Gluteal Adipose Tissue among Breast Cancer Cases in India

Partitioning of Persistent Organic Pollutants between Adipose Tissue and Serum in Human Studies

Blood is the most widely used matrix for biomonitoring of persistent organic pollutants (POPs). It is assumed that POPs are homogenously distributed within body lipids at steady state; however, the variability underlying the partitioning of POPs between fat compartments is poorly understood. Hence, the objective of this study was to review the state of the science about the relationships of POPs between adipose tissue and serum in humans. We conducted a narrative literature review of human observational studies reporting concentrations of POPs in paired samples of adipose tissue with other lipid-based compartments (e.g., serum lipids). The searches were conducted in SCOPUS and PUBMED. A meta-regression was performed to identify factors responsible for variability. All included studies reported high variability in the partition coefficients of POPs, mainly between adipose tissue and serum. The number of halogen atoms was the physicochemical variable most strongly and positively associated with the partition ratios, whereas body mass index was the main biological factor positively and significantly associated. To conclude, although this study provides a better understanding of partitioning of POPs to refine physiologically based pharmacokinetic and epidemiological models, further research is still needed to determine other key factors involved in the partitioning of POPs.

Serum concentrations of organochlorine pesticides, biomarkers of oxidative stress, and risk of breast cancer

Studies have documented that exposure to organochlorine pesticides (OCPs) is linked with breast cancer, but the underlying biological mechanisms are still unknown. This study included 313 women diagnosed with breast cancer and 313 controls in Wuhan, China, and measured 18 OCPs in serum and 3 oxidative stress biomarkers in urine. Multivariable adjusted regression models were used to evaluate the associations among OCPs, oxidative stress biomarkers, and breast cancer. The mediating effect of oxidative stress was assessed by mediation analysis. We observed that most OCPs were positively associated with risk of breast cancer (all FDR-P values < 0.05 or 0.10). Moreover, we found that p,p'-DDT, p,p'-DDD, dieldrin, heptachlor, and heptachlor epoxide were positively associated with 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA) and 8-iso-prostaglandin F_2α (8-isoPGF_2α), which in turn were positively associated with risk of breast cancer. Mediation analysis indicated that HNE-MA and 8-isoPGF_2ɑ mediated the positive associations between these OCPs and risk of breast cancer, with mediating proportion ranging from 6.23% to 19.9%. Our results suggest that lipid peroxidation may mediate the positive associations between OCP exposures and risk of breast cancer.

Adipose to serum ratio and mixtures of persistent organic pollutants in relation to endometriosis: Findings from the ENDO Study

BACKGROUND

Endometriosis is an estrogen-dependent disease. Endocrine disrupting chemicals (EDCs) and their mixtures may play an etiologic role.

OBJECTIVES

We evaluated an adipose-to-serum ratio (ASR) of lipophilic EDCs and their mixtures associated with incident endometriosis.

METHODS

We quantified 13 polychlorinated biphenyl (PCB) congeners, 6 polybrominated diphenyl ether (PBDE) congeners, and 11 organochlorine pesticides (OCPs) in serum and omental fat among women from the ENDO Study (2007-2009) aged 18-44 years diagnosed with (n=190) or without (n=283) surgically-visualized incident endometriosis. Odds ratios (OR) and 95% confidence intervals (CI) between ASR and endometriosis were estimated using logistic regression models adjusted for age (years), body mass index (kg/m²), serum cotinine (ng/ml), and breastfeeding conditional on parity. Bayesian hierarchical models (BHM) compared estimated associations for adipose and ASR to serum. Bayesian kernel machine regression (BKMR) estimated change in latent health and 95% posterior intervals (PI) between chemical mixtures and endometriosis.

RESULTS

Select ASR for estrogenic PCBs and OCPs were associated with an increased odds of an endometriosis diagnosis, but not for anti-estrogenic PCBs or PBDEs. Across all chemicals, BHMs generated ORs that were on average 14% (95% PI: 6%, 22%) higher for adipose and 20% (95% PI: 12%, 29%) higher for ASR in comparison to serum. ORs from BHMs were greater for estrogenic PCBs and OCPs, with no differences for PBDEs. BKMR models comparing the 75th to 25th percentile were moderately associated with endometriosis for estrogenic PCBs [adipose 0.27 (95% PI: 0.18, 0.72) and ASR 0.37 (95% PI: 0.06, 0.80)] and OCPs [adipose 0.17 (95% PI: 0.21, 0.56) and ASR 0.26 (95% PI: 0.05, 0.57)], but not for antiestrogenic PCBs and PBDEs.

DISCUSSION

ASR added little insight beyond adipose for lipophilic chemicals. BKMR results supported associations between ASR and adipose estrogenic PCB and OCP mixtures and incident endometriosis. These findings underscore the importance of choice of biospecimen and considering mixtures when assessing exposure-disease relationships.

Polychlorinated biphenyls and risk of hepatocellular carcinoma in the population living in a highly polluted area in Italy

Polychlorinated biphenyls (PCBs) are human carcinogens, based on sufficient evidence for melanoma and limited evidence for non-Hodgkin lymphoma and breast cancer. Few data are available for liver cancer, although PCBs cause it in rats and determined liver damage in poisoned people. We investigated the association between PCB serum levels and hepatocellular carcinoma (HCC) with a case-control study in a PCB-polluted area in North Italy. We enrolled prospectively 102 HCC incident cases and 102 age and gender-matched hospital controls. Serum concentrations of 33 PCB congeners were determined by a gas chromatograph coupled to mass spectrometry. Of 102 HCC cases, 62 who had lost < 3 kg of body weight in past 3 years were included in the analysis (67.7% males, mean age 68 years). The odds ratio (OR) for HCC for 3rd compared to 1st tertile of PCB distribution was 1.76 (95% confidence interval 0.62-5.03) for total PCB, adjusting for socio-demographic variables and risk factors for HCC by logistic regression. For most PCB congeners, ORs > 1.5 or 2 were found, although the 95% CIs included the null value for almost all of them. This preliminary study suggests that PCBs might play a role in HCC development.

Exposure to polychlorinated biphenyls and organochlorine pesticides and thyroid cancer in connecticut women

BACKGROUND

Thyroid cancer incidence has increased substantially over the past decades, and environmental risk factors have been suggested to play a role. Polychlorinated biphenyls (PCB) and organochlorine pesticides (OCP) are established thyroid hormone disruptors, but their relationship to thyroid cancer is not known.

METHODS

We investigated the relationship between serum PCB and OCP concentrations and papillary thyroid cancer (PTC) in 250 incident female PTC cases and 250 female controls frequency-matched on age, all residing in Connecticut. Interviews and serum samples were collected from 2010 to 2013. Samples were analyzed for 32 different chemicals using gas chromatography with isotope dilution high resolution mass spectrometry. We calculated odds ratios (OR) and 95% confidence intervals (CI) using single pollutant logistic regression models for concentrations (per interquartile range) of individual PCB/OCP and summed groups of structurally or biologically similar PCB/OCP, adjusted for education, family history of cancer, alcohol consumption, age, and body mass index. Sub-analyses included stratification by tumor size (≤ and >1 cm) and birth before or during peak PCB production (born in 1960 or earlier and born after 1960), as exposures during early life may be important. We also applied three multi-pollutant approaches (standard multi-pollutant regression, hierarchical Bayesian modeling, principal components regression analysis) to investigate associations with co-exposures to multiple PCB/OCPs.

RESULTS

No PCB/OCPs were positively associated with PTC in primary analyses. Statistically significant associations were observed for 9 of the 32 chemicals and 3 summed groups of similar chemicals in the those born during peak production based on single-pollutant models. Multi-pollutant analyses suggested null associations overall.

CONCLUSIONS

Our results using single and multi-pollutant modeling do not generally support an association between PCB or OCP exposure and PTC, but some associations in those born during peak production suggest that additional investigation into early-life exposures and subsequent thyroid cancer risk may be warranted.

Bioaccumulation of pesticide contaminants in tissue matrices of dogs suffering from malignant canine mammary tumors in Punjab, India

The unprecedented application of pesticides in Punjab, India during green revolution has lead to an environmental crisis due to the accumulation of persistent organic and pesticide pollutants in the environment and biota of this region. The present study aimed at estimating the abundance of pesticide contaminants in three biological matrices of 36 dogs suffering from malignant canine mammary tumor (mCMT) and 6 tumor free control dogs from Punjab, India. Presence of individual and total pesticides in canine biological samples, age and bodyweight of canine patients was assessed as a potential risk factor for mCMT using logistic regression analysis. Chi-square test was employed to determine tissue-specific accumulations of individual pesticides. Spearman's correlation coefficient was estimated to determine the association between the levels of total pesticides in different tissue matrices and with age and bodyweight of mCMT cases. Gas chromatography-ECD analysis of serum, mammary tissue and adjoining mammary adipose tissue revealed fourteen different pesticides including γ-HCH, α-HCH, dieldrin, aldrin, heptachlor, butachlor, p,p-DDT, o,p-DDT, p,p-DDD, p,p-DDE, L-cyhalothrin, permethrin, fipronil, and fenitrothion. Heptachlor, γ-HCH, aldrin and p,p-DDT were more frequently detected, whereas, p,p-DDE and o,p-DDT were the least common. Differential accumulation of pesticides in tissue matrices, particularly between serum and mammary tissue/adipose tissue was observed. We could not find any association between the total pesticide concentrations among serum, mammary tissue and mammary adipose tissue in mCMT cases. We found that the odds for individual pesticide for serum, mammary tissue and adipose tissue were associated with high uncertainties; however, the total pesticide concentration in mammary tissue was near non-significantly associated with higher risk of mCMT with low uncertainty. Statistically non-significant higher odds of CMT occurrence with increase in age was noticed No association between the concentration of total pesticides in different matrices and age and bodyweight of canine subjects was found.

Serum concentrations of DDE, PCBs, and other persistent organic pollutants and mammographic breast density in Triana, Alabama, a highly exposed population

INTRODUCTION

Although some persistent organic pollutants (POPs) are considered human carcinogens, results from studies evaluating exposures and breast cancer risk have been inconsistent, potentially related to varying ages at exposure. Additionally, few studies evaluated the association between POPs exposure and mammographic breast density (MBD), an intermediate biomarker of breast cancer risk. We carried out a cross-sectional study to investigate associations between serum POPs concentrations and MBD measured in 1998 in female residents of Triana, Alabama, in a predominately African American population with high POPs exposures, particularly to p,p'-DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane).

METHODS

We measured lipid-adjusted serum concentrations (ng/g lipid) of p,p'-DDT and its main metabolite p,p'-DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene), polychlorinated biphenyls (PCBs), β-hexachlorocyclohexane (β-HCCH), heptachlor epoxide, oxychlordane, trans-nonachlor, mirex, and aldrin for each woman in our study (n = 210). We also measured two MBD metrics, percent MBD (%MBD) and area of MBD (aMBD). Using adjusted Spearman correlation coefficients (rs) we evaluated correlations between %MBD and aMBD with individual POPs in the overall population and by age group (19-40, 41-54, and 55-91 years) and also estimated adjusted mean measures of MBD with 95% confidence intervals across tertiles of analytes using generalized linear models (GLM). We calculated p-values for multiplicative interaction by age group using GLM. Additional analyses excluded women with current hormone replacement therapy (HRT) use and evaluated early-life exposure (prior to age 18) during the heaviest contamination period in Triana (1947-90).

RESULTS

Among all women, we found no correlation between p,p'-DDE and %MBD, but after age stratification and exclusion of HRT users, there was a suggestion of a difference by age group, with younger women having a weak positive correlation (rs = 0.12, p = 0.37) and older women having a weak negative correlation (rs = -0.12, p = 0.43); pinteraction = 0.06. In contrast, PCBs were weakly positively correlated with %MBD among all women, with the correlation magnitudes increasing after excluding current HRT users (rs-total PCBs = 0.17, p = 0.03). After age stratification and exclusion of HRT users, correlations for PCBs were higher among younger and middle-age women, with only a handful of these correlations being statistically significant. For β-HCCH, the strongest finding was a negative correlation among older women (rs = -0.26, p = 0.07). Correlations were positive predominantly in the younger age group for heptachlor epoxide (rs = 0.27, p = 0.04), oxychlordane (rs = 0.35, p = 0.006), and trans-nonachlor (rs = 0.37, p = 0.003), and largely null for the middle and older age groups; pinteraction range: 0.03-0.05. Similar patterns were found in GLM analyses using tertiles of exposure and aMBD as the metric for MBD. Women exposed during the heaviest chemical contamination period in Triana prior to age 18 had positive correlations between %MBD and PCBs, heptachlor epoxide, mirex, oxychlordane, and trans-nonachlor.

CONCLUSIONS

In this population, despite high exposures to p,p'-DDT and thus high serum concentrations of its main metabolite, p,p'-DDE, we did not find strong evidence of a positive association with MBD. In fact, there was some evidence of a negative association among older women for p,p'-DDE; a similar pattern was found for β-HCCH. However, younger women with higher serum levels of PCBs, heptachlor epoxide, oxychlordane, and trans-nonachlor, who were likely exposed in early life, had higher MBD. These findings should be replicated in larger studies.

Longitudinal changes in persistent organic pollutants (POPs) from 2001 to 2009 in a sample of elderly Swedish men and women

BACKGROUND

Prospective cohort studies evaluating the temporal trends of background-level persistent organic pollutants (POPs) and their potential negative health effects in humans are needed.

OBJECTIVE

The objectives of this study are to examine the five year longitudinal trend in chlorinated and brominated (Cl/Br) POP concentrations in a sample of elderly individuals and to investigate the relationship between gender, changes in body weight, plasma lipid levels and POP concentrations.

METHODS

In the population-based Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study, plasma samples were collected from the same individuals over a 5 year period. Originally 992 subjects (all aged 70) were sampled between 2001 and 2004 and 814 returning subjects (all aged 75) were sampled again from 2006 to 2009. Plasma concentrations of 16 polychlorinated biphenyls (PCBs), 5 organochlorine pesticides (OCPs), octachlorinated dibenzo-p-dioxin (OCDD), and one polybrominated diphenylether (BDE 47) were determined using high-throughput 96-well plate solid phase extraction and gas chromatography-high resolution mass spectrometry (GC-HRMS).

RESULTS

During the 5-year follow-up, plasma concentrations of all POPs significantly decreased (p < 0.00001). Median reductions ranged from 4% (PCB105) to 45% (PCB 99), with most reductions being in the 30-40% range. For most POPs, a larger decline was seen in men than in women. The relationship between the weight change and change in POP concentrations was generally negative, but a positive relationship between lipid levels and POP concentrations when expressed as wet-weight was observed. In general, similar changes in POP concentrations and their relationships to body weight were observed regardless of using either wet-weight (pg/mL) or lipid-normalized (ng/g lipid) concentrations.

CONCLUSION

In this longitudinal cohort study, gender and minor, but varying changes in body weight and lipid levels greatly influenced the individual-based changes in POP concentrations. In general, our findings suggest that men and women with larger decreases in body weight and greater increases in lipid levels have the slowest decline in body burden of POPs. Based on the results from this study, either wet-weight or lipid normalized concentrations can be used to determine the percent change in POP concentrations and their relationships to physiological changes and differences.

Plasma levels of polychlorinated biphenyls and risk of cutaneous malignant melanoma: A hospital-based case-control study

Polychlorinated biphenyls (PCB) have been classified by the International Agency for Research on Cancer (IARC) in Group 1 as carcinogenic to human, based on sufficient evidence in humans of an increased risk of cutaneous malignant melanoma (CMM), however few studies have been done in the general population. This study examined the relationship between PCB plasma levels and risk of CMM adjusting for sun sensitivity and sun exposure in a province of Northern Italy (Brescia), where a chemical factory produced PCBs from 1938 to 1984 causing human contamination. A case-control study of 205 CMM patients and 205 control subjects was conducted. Cases and controls were assayed for plasma levels of 33 PCB congeners. No associations was found between risk of CMM and plasma levels of total PCB (OR = 0.81; 95% CI: 0.34-1.96 for highest vs lowest quartile) or specific congeners. The study confirmed the association with light skin colour (OR = 3.00; 95% CI: 1.91-4.73), cumulative lifetime UV exposure (OR = 2.56; 95% CI: 1.35-4.85) and high level of education (OR = 1.45; 95% CI: 1.03-2.05). This case-control study does not support the hypothesis of an association between current plasma levels of PCBs and CMM development in the general population.

Receptor activities of persistent pollutant serum mixtures and breast cancer risk

Studies on associations between persistent organic pollutants (POPs) and breast cancer risk are inconclusive. The majority of studies have evaluated the effect of single compounds, without considering multiple exposures to and interactions between different POPs. The present study aimed at evaluating breast cancer risk related to combined effects of serum POP mixtures on cellular receptor functions. Data on breast cancer cases (n = 77) and controls (n = 84) were collected among Greenlandic Inuit women. Serum mixtures of lipophilic POPs (lipPOPs), perfluoroalkyl acids (PFAAs) and dioxin-like POPs were extracted. The effect of the mixture extracts on the estrogen receptor (ER), androgen receptor (AR) and aryl hydrocarbon receptor (AhR) was determined using cell culture reporter gene assays. The serum mixtures were analyzed alone and upon co-exposure with natural receptor ligands to determine agonistic and antagonistic/competitive activity. We found that the frequency of lipPOP mixtures eliciting no, decreasing, or agonizing xenoandrogenic effect differed by breast cancer status. Using lipPOP mixtures with no effect on AR as reference, the mixtures with decreasing effects reduced breast cancer risk (OR: 0.30 (0.12; 0.76)). The AhR-toxic equivalent of serum mixtures was significantly lower in cases than in controls, and a reduced breast cancer risk was found when comparing the third tertile to the first (OR: 0.34 (0.14; 0.83)). We found no association between the xenoestrogenic activities of lipPOPs or PFAAs and breast cancer risk. Serum lipPOP mixtures are hormone disruptive and may influence breast cancer risk, whereas PFAAs seem to influence breast cancer risk through other pathways.

The effect of follicullar fluid pesticides and polychlorinated biphenyls concentrations on intracytoplasmic sperm injection (ICSI) embryological and clinical outcome

OBJECTIVES

The present study evaluated the correlation between the concentrations of polychlorinated biphenyls (PCBs) and pesticides in the follicular fluid (FF) obtained during intracytoplasmic sperm injection (ICSI) with the ovarian response, endometrial thickness, and embryological and clinical outcomes.

DESIGN

Cross-sectional observational study.

MATERIALS AND METHODS

Women aged 20 to 38 years (300 infertile couples) presenting to a university-affiliated fertility center were approached to participate in the study. Only 150 couples that underwent ICSI for male factor infertility agreed to participate, and 94 of them had retrieved enough FF samples suitable for laboratory testing. The FF sample was obtained, centrifuged, and stored in liquid nitrogen. Two organochlorine pesticides (OCPs), Lindane and DDT;three organophosphates (OPs);chlorpyrifos;Diazinon; malathion; one Chloroacetanilide (Pretilachlor);two pyrethroids(Bioallethrin and β-cyfluthrin); and the concentrations of four PCBs, 28, 52, 138, 180, were estimated in the obtained FF samples by using gas chromatography/mass spectrometry. SPSS statistical analysis program (version 17) was used for analysis. Multiple regression analysis was used to correlate the PCBs and pesticides with ICSI outcomes.

RESULTS

There were significant negative correlations between FF concentrations of the eight examined pesticides and the four PCBs on the endometrial thickness. However, Pretilachlor, chlorpyrifos, β-cyfluthrin, and Diazinon were the only toxic agents that negatively correlated with the number of the oocytes retrieved. Fertilization and early embryo cleavage rates were negatively correlated with Pretilachlor and β-cyfluthrin. Moreover, high concentrations of Lindane,DDT, Diazinon,and chlorpyrifos were significantly associated lower implantation rate. PCB 28 and 180 concentration in the FF was associated with a lower number of retrieved oocytes and fertilization rate, respectively. The number of implanted embryos was negatively correlated with PCB 52 FF concentration. However, the clinical pregnancy rate did not reach the level of significance.

CONCLUSION

Higher concentrations of any studied PCBs and pesticides are associated with thinner endometrial thickness. The higher the level of Pretilachlor, β-cyfluthrin, PCB 28 and 180, the lower the retrieval, fertilization, and embryo cleavage rates. High PCB and pesticide concentrations in the FF adversely affected embryological ICSI outcomes. However, more data are needed to evaluate their effect on the clinical outcome.

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.

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.

Serum and adipose tissue as matrices for assessment of exposure to persistent organic pollutants in breast cancer patients

The aim of this study was to assess differences between two biological matrices (serum and breast adipose tissue) in the evaluation of persistent organic pollutant (POP) exposure in breast cancer patients. The study population consisted of 103 women undergoing surgery for newly diagnosed breast carcinoma in a public hospital in Granada, Southern Spain. Independent variables were gathered from questionnaires and clinical records. POP concentrations were quantified in breast adipose tissue and serum samples. Spearman correlation tests were performed between pairs of POP concentrations and stepwise multivariable linear regression analyses were conducted to assess predictors of concentrations in the two matrices. p,p'- Dichlorodiphenyldichloroethylene (p,p'-DDE) showed the the highest median concentration in both matrices (194.34 and 173.84 ng/g lipid in adipose tissue and serum, respectively). Median wet-basis adipose tissue:serum ratios ranged from 109.34 to 651.62, while lipid-basis ratios ranged from 0.88 to 4.34. In general, we found significant positive correlation coefficients between pairs of POPs in adipose tissue and in serum, which were always higher in adipose tissue. We found positive and statistically significant correlations between serum and adipose tissue concentrations of p,p'-DDE and hexachlorobenzene (HCB) but not of polychlorinated biphenyls (PCBs). Age was positively associated with most POPs in adipose tissue and serum, while the body mass index was positively associated with adipose tissue HCB concentrations and negatively associated with serum PCB-153 and PCB-138 concentrations. Recent weight loss was inversely associated with POP residues in adipose tissue and positively associated with POP residues in serum. Serum HCB and PCB-180 concentrations were lower in patients who had received preoperative chemotherapy. According to our results, serum and adipose tissue POP concentrations in breast cancer patients may be differentially affected by external predictors. Taken together, these findings indicate the need to take account of the individual POP(s) under study and the biological matrix used when relating internal POP exposure to breast cancer disease and to make a careful selection of covariates for adjusting the model.

Circulating persistent organic pollutants and body fat distribution: Evidence from NHANES 1999-2004

OBJECTIVE

To evaluate and compare the correlations of various circulating persistent organic pollutants (POPs) with fat mass percentages (FM%) of trunk, leg, and whole body measured by dual-energy X-ray absorptiometry.

METHODS

This study included 2358 adults (≥20 years) in the National Health and Nutrition Examination Survey 1999-2004. Partial Pearson correlation coefficients were calculated, after adjusting for major confounders, including age, smoking status, and history of lactation and parity. Wolfe's method was used to compare correlation coefficients derived from the same participants.

RESULTS

Twelve POPs showed significantly different correlations with fat depots in trunk and leg regions. β-hexachlorocyclohexane, heptachlorodibenzo-p-dioxin, octachlorodibenzo-p-dioxin, and polychlorinated biphenyl (PCB)-126 showed stronger positive correlations with trunk FM% than with leg FM%, whereas PCBs with ≥6 chlorines were more inversely correlated with trunk FM% than leg FM%. Age-stratified analysis showed stronger inverse correlations between POPs and trunk FM% mainly in participants <40 years, whereas stronger positive correlations between POPs and trunk FM% were observed in older participants.

CONCLUSIONS

Stronger associations between POPs and trunk fat as compared to leg fat possibly indicated a more important role of trunk fat in the pharmacokinetics of POPs, or a stronger effect of POPs, as endocrine disruptors, on trunk fat metabolism.

The integrative role of leptin, oestrogen and the insulin family in obesity-associated breast cancer: potential effects of exercise

Obesity is an established risk factor for postmenopausal breast cancer. The mechanisms through which obesity influences the development and progression of breast cancer are not fully elucidated; however, several factors such as increased oestrogen, concentrations of various members of the insulin family and inflammation that are associated with adiposity are purported to be important factors in this relationship. Emerging research has also begun to focus on the role of adipokines, (i.e. adipocyte secreted factors), in breast cancer. Leptin secretion is directly related to adiposity and is believed to promote breast cancer directly and independently, as well as through involvement with the oestrogen and insulin signalling pathways. As leptin is secreted from white adipose tissue, any intervention that reduces adiposity may be favourable. However, it is also important to consider that energy expenditure through exercise, independent of fat loss, may improve leptin regulation. The purpose of this narrative review was to explore the role of leptin in breast cancer development and progression, identify key interactions with oestrogen and the insulin family, and distinguish the potential effects of exercise on these interactions.

Polychlorinated biphenyls and polybrominated biphenyl ethers in adipose tissue and matched serum from an E-waste recycling area (Wenling, China)

To Date, the knowledge on relationship between PCBs/PBDEs exposure and thyroid hormones (THs) levels during pregnancy still needs to be extended. Meanwhile, studies on congener-specific adipose-serum ratios for PCBs/PBDEs were limited. This study reports the levels of PCBs/PBDEs in serum-adipose tissue samples (n = 64) from expectant women living surrounding e-waste recycling sites in Wenling, China. Their concentrations varied from several to hundreds of ng g(-1) lipid. Maternal exposure to PCBs was associated with lower TSH during pregnancy, suggesting possible implication for maternal health and fetal development. The compound levels between the adipose tissue and matched serum samples were highly correlated (p < 0.001), generating a predicted adipose-serum partitioning relationship for individual PCB congener and PBDE congener. Molecular characteristics, such as Kow value, molecular weight and molecular volume, may play a key role in the variable partitioning of some compounds between serum and adipose tissue.

Elevated serum pesticide levels and risk for Alzheimer disease

IMPORTANCE

The causes of late-onset Alzheimer disease (AD) are not yet understood but likely include a combination of genetic, environmental, and lifestyle factors. Limited epidemiological studies suggest that occupational pesticide exposures are associated with AD. Previously, we reported that serum levels of dichlorodiphenyldichloroethylene (DDE), the metabolite of the pesticide dichlorodiphenyltrichloroethane (DDT), were elevated in a small number of patients with AD (n=20).

OBJECTIVE

To evaluate the association between serum levels of DDE and AD and whether the apolipoprotein E (APOE) genotype modifies the association.

DESIGN, SETTING, AND PARTICIPANTS

A case-control study consisting of existing samples from patients with AD and control participants from the Emory University Alzheimer's Disease Research Center and the University of Texas Southwestern Medical School's Alzheimer's Disease Center. Serum levels of DDE were measured in 79 control and 86 AD cases.

MAIN OUTCOMES AND MEASURES

Serum DDE levels, AD diagnosis, severity of AD measured by the Mini-Mental State Examination score, and interaction with APOE4 status.

RESULTS

Levels of DDE were 3.8-fold higher in the serum of those with AD (mean [SEM], 2.64 [0.35] ng/mg cholesterol) when compared with control participants (mean [SEM], 0.69 [0.1] ng/mg cholesterol; P < .001). The highest tertile of DDE levels was associated with an odds ratio of 4.18 for increased risk for AD (95% CI, 2.54-5.82; P < .001) and lower Mini-Mental State Examination scores (-1.605; range, -3.095 to -0.114; P < .0001). The Mini-Mental State Examination scores in the highest tertile of DDE were -1.753 points lower in the subpopulation carrying an APOE ε4 allele compared with those carrying an APOE ε3 allele (P interaction = .04). Serum levels of DDE were highly correlated with brain levels of DDE (ρ = 0.95). Exposure of human neuroblastoma cells to DDT or DDE increased levels of amyloid precursor protein.

CONCLUSIONS AND RELEVANCE

Elevated serum DDE levels are associated with an increased risk for AD and carriers of an APOE4 ε4 allele may be more susceptible to the effects of DDE. Both DDT and DDE increase amyloid precursor protein levels, providing mechanistic plausibility for the association of DDE exposure with AD. Identifying people who have elevated levels of DDE and carry an APOE ε4 allele may lead to early identification of some cases of AD.

Mechanism and kinetic properties of NO3-initiated atmospheric degradation of DDT

In this article, the NO3 radical-initiated atmospheric oxidation degradation of DDT was theoretically investigated using molecular orbital theory calculations. All the calculations of intermediates, transition states and products were performed at the MPWB1K/6-311+G(3df,2p)//MPWB1K/6-31+G(d,p) level of theory. Several energetically favorable reaction pathways were revealed. The formation mechanisms of secondary pollutants were presented and discussed. The rate constants were deduced over the temperature range of 273-333 K using canonical variational transition-state (CVT) theory with the small curvature tunneling (SCT) method. Our study shows that H abstraction from the alkyl group and NO3 addition to the C3 atom of the benzene ring are the dominant reaction pathways. The rate-temperature formula of the overall rate constants is k(T)(DDT+NO3) = (7.21 × 10(-15))exp(-153.81/T) cm(3)/(molsec) over the possible atmospheric temperature range of 273-333 K. The atmospheric lifetime of DDT determined by NO3 radical is about 52.5 days, which indicates that it can be degraded in the gas phase within several months.

Environmental toxicants and autism spectrum disorders: a systematic review

Although the involvement of genetic abnormalities in autism spectrum disorders (ASD) is well-accepted, recent studies point to an equal contribution by environmental factors, particularly environmental toxicants. However, these toxicant-related studies in ASD have not been systematically reviewed to date. Therefore, we compiled publications investigating potential associations between environmental toxicants and ASD and arranged these publications into the following three categories: (a) studies examining estimated toxicant exposures in the environment during the preconceptional, gestational and early childhood periods; (b) studies investigating biomarkers of toxicants; and (c) studies examining potential genetic susceptibilities to toxicants. A literature search of nine electronic scientific databases through November 2013 was performed. In the first category examining ASD risk and estimated toxicant exposures in the environment, the majority of studies (34/37; 92%) reported an association. Most of these studies were retrospective case-control, ecological or prospective cohort studies, although a few had weaker study designs (for example, case reports or series). Toxicants implicated in ASD included pesticides, phthalates, polychlorinated biphenyls (PCBs), solvents, toxic waste sites, air pollutants and heavy metals, with the strongest evidence found for air pollutants and pesticides. Gestational exposure to methylmercury (through fish exposure, one study) and childhood exposure to pollutants in water supplies (two studies) were not found to be associated with ASD risk. In the second category of studies investigating biomarkers of toxicants and ASD, a large number was dedicated to examining heavy metals. Such studies demonstrated mixed findings, with only 19 of 40 (47%) case-control studies reporting higher concentrations of heavy metals in blood, urine, hair, brain or teeth of children with ASD compared with controls. Other biomarker studies reported that solvent, phthalate and pesticide levels were associated with ASD, whereas PCB studies were mixed. Seven studies reported a relationship between autism severity and heavy metal biomarkers, suggesting evidence of a dose-effect relationship. Overall, the evidence linking biomarkers of toxicants with ASD (the second category) was weaker compared with the evidence associating estimated exposures to toxicants in the environment and ASD risk (the first category) because many of the biomarker studies contained small sample sizes and the relationships between biomarkers and ASD were inconsistent across studies. Regarding the third category of studies investigating potential genetic susceptibilities to toxicants, 10 unique studies examined polymorphisms in genes associated with increased susceptibilities to toxicants, with 8 studies reporting that such polymorphisms were more common in ASD individuals (or their mothers, 1 study) compared with controls (one study examined multiple polymorphisms). Genes implicated in these studies included paraoxonase (PON1, three of five studies), glutathione S-transferase (GSTM1 and GSTP1, three of four studies), δ-aminolevulinic acid dehydratase (one study), SLC11A3 (one study) and the metal regulatory transcription factor 1 (one of two studies). Notably, many of the reviewed studies had significant limitations, including lack of replication, limited sample sizes, retrospective design, recall and publication biases, inadequate matching of cases and controls, and the use of nonstandard tools to diagnose ASD. The findings of this review suggest that the etiology of ASD may involve, at least in a subset of children, complex interactions between genetic factors and certain environmental toxicants that may act synergistically or in parallel during critical periods of neurodevelopment, in a manner that increases the likelihood of developing ASD. Because of the limitations of many of the reviewed studies, additional high-quality epidemiological studies concerning environmental toxicants and ASD are warranted to confirm and clarify many of these findings.

Associations of organochlorine pesticides and polychlorinated biphenyls in visceral vs. subcutaneous adipose tissue with type 2 diabetes and insulin resistance

Background exposure to organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs) has been linked to type 2 diabetes. As OC pesticides and PCBs mainly accumulate in adipose tissue and there are physiological and clinical differences between visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT), we explored if there were associations of OC pesticides and PCBs in VAT or SAT with type 2 diabetes and insulin resistance. Participants were 50 patients with or without type 2 diabetes who underwent surgery for either cancer or benign liver or gallbladder lesions. We analyzed 14 OC pesticides and 22 PCB congeners in both VAT and SAT. Insulin resistance was estimated using homeostasis model assessment (HOMA). Although concentrations of OC pesticides and PCBs were strongly correlated between VAT and SAT, absolute concentrations differed substantially between them. In particular, concentrations of all PCBs were consistently about 5-10 times higher in VAT than SAT, but these patterns were independent of diabetes status. Some OC pesticides or PCBs, such as dichlorodiphenyltrichloroethanes (DDTs), chlordanes, and PCBs with 5 or less chlorides showed significant associations with diabetes or insulin resistance. For example, when tertiles of concentration-based summary measures were used, adjusted ORs were 1.0, 2.3, and 9.0 (P trend=0.02) for DDTs in VAT and 1.0, 2.1, and 5.7 (P trend=0.08) for PCBs with 5 or less chlorides. This study generally confirmed previous findings using serum concentrations. It would be useful to study pharmacodynamics of POPs in VAT and SAT further.

Polychlorinated biphenyls in serum, liver and adipose tissue of subjects with hepatocellular carcinoma living in a highly polluted area

Brescia (North Italy) is located in a highly industrialized area with diffuse environmental pollution by polychlorinated biphenyls (PCBs) and with a high incidence of hepatocellular carcinoma (HCC). We aimed to investigate the concentration of PCBs congeners in serum, liver and adipose tissue of patients with HCC living in this area. We enrolled prospectively 101 HCC incident cases. Lipid-adjusted PCBs concentration of single congeners and total PCBs concentration, computed as the sum of 24 PCBs congeners, were measured in the serum of all subjects and in the liver and abdominal fat of 59 HCC cases undergoing surgery. A high correlation was found between PCBs serum and liver (Spearman r=0.79), serum and fat (r=0.91), and liver and fat (r=0.75) concentrations. Serum PCBs concentration in HCC patients did not vary according to demographical, clinical or epidemiological variables, apart from age, as PCBs concentration increased linearly with the subject's age. This study confirms that serum lipid-adjusted PCBs concentration is a valid measure of PCBs body storage and is highly correlated with PCBs concentration detected in other biological samples.

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.

Brain organochlorines and Lewy pathology: the Honolulu-Asia Aging Study

Although organochlorines have been reported more frequently in Parkinson's disease (PD) brains than in controls, the association with brain Lewy pathology is unknown. Honolulu-Asia Aging Study (HAAS) participants, exposed to organochlorines from a variety of sources during midlife, represent a population well suited to determining the relationship of brain organochlorines with Lewy pathology in decedents from the longitudinal HAAS. The study design included the measurement of 21 organochlorine levels in frozen occipital lobe samples from HAAS decedents. Alpha-synuclein immunostaining performed on 225 brains was used to identify Lewy bodies and Lewy neurites. With the potential for spurious associations to appear between Lewy pathology and 17 organochlorine compounds found in at least 1 brain, initial assessments identified heptachlor epoxide isomer b, methoxychlor, and benzene hexachloride b as being most important. The prevalence of Lewy pathology was 75% (6 of 8) among brains with any 2 of the 3 compounds, 48.8% (79 of 162) among those with 1, and 32.7% (18 of 55) for those with neither (P = .007 test for trend). Although findings persisted after removing cases with PD and dementia with Lewy bodies and after adjustment for age at death, body mass index, pack-years of cigarette smoking, and coffee intake (P = .013), the results were insignificant when correcting for multiple testing. Although consistent with earlier accounts of an association between organochlorines and clinical PD, associations with Lewy pathology warrant further study.

Toxicity assessment and vitellogenin expression in zebrafish (Danio rerio) embryos and larvae acutely exposed to bisphenol A, endosulfan, heptachlor, methoxychlor and tetrabromobisphenol A

Organochlorine pesticides and brominated flame retardants, such as tetrabromobisphenol A and polybrominated diphenyl ethers, pose an environmental hazard owing to their persistence, low solubility and estrogenic effects, and concerns have been raised regarding their effects on aquatic biota. In the present study, zebrafish embryos and larvae were used as a model to investigate the sublethal and lethal effects of three different organochlorine pesticides, namely methoxychlor, endosulfan and heptachlor, as well as the flame retardant tetrabromobisphenol A, and its precursor compound bisphenol A. Preliminary data for chemical exposure tests were obtained by determining the 96 h median effective concentration EC50 (hatching rate) and 96 h median lethal concentration LC50 . Quantitative polymerase chain reaction was used to investigate the gene expression levels of the biomarker vitellogenin (vtg1) after 96 h exposures to 10, 25, 50 and 75% of the 96 h EC50 value for embryos and 96 h LC50 value for larvae. The use of vtg1 mRNA induction in zebrafish embryos and larvae was found to be a sensitive biomarker of exposure to these organic compounds, and was helpful in elucidating their adverse effects and setting water quality guidelines.

Association of hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (DDT), and dichlorodiphenyldichloroethylene (DDE) with in vitro fertilization (IVF) outcomes

BACKGROUND

Hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (DDT), and dichlorodiphenyldichloroethylene (DDE) are persistent chlorinated pesticides with endocrine activity that may adversely affect the early stages of human reproduction.

OBJECTIVE

Our goal was to determine the association of serum levels of HCB, DDT, and DDE with implantation failure, chemical pregnancy, and spontaneous abortion in women undergoing in vitro fertilization (IVF) from 1994 to 2003.

METHODS

Levels of HCB and congeners of DDT and DDE were measured in serum collected during the follicular phase. Multivariable-adjusted statistical models accommodating multiple outcomes and multiple cycles per woman were used to estimate the relation between serum pesticide levels and IVF outcomes.

RESULTS

A total of 720 women with a mean ± SD age 35.4 ± 4.2 years at enrollment contributed 774 IVF cycles. All samples had detectable levels of HCB, DDT, and DDE, with median levels of 0.087 ng/g serum for HCB, 1.12 ng/g serum for total DDT, and 1.04 ng/g serum for p,p´-DDE. Compared with the lowest quartile (Q1) of HCB, the lipid- and multivariable-adjusted odds ratio (OR) for failed implantation was significantly elevated for those with higher HCB quartiles [Q2-Q4; adjusted ORs: for Q2, 1.71; 95% confidence interval (CI): 1.03, 2.82; for Q3, 2.30; 95% CI: 1.39, 3.81; for Q4, 2.32; 95% CI: 1.38, 3.90] and showed a significantly increasing trend (p = 0.001). No statistically significant associations were observed between DDT/DDE and IVF outcomes or between HCB and chemical pregnancy or spontaneous abortion.

CONCLUSIONS

Serum HCB concentrations were on average lower than that of the general U.S. population and associated with failed implantation among women undergoing IVF.

Concentrations of organochlorine pesticides and polychlorinated biphenyls in human serum and adipose tissue from Bolivia

Organochlorine pesticides and polychlorinated biphenyls (PCBs) are synthetic chemicals that are highly resistant to biodegradation and have proven adverse health effects. The objectives of this study were to determine concentrations of three selected organochlorine pesticides (p,p'-DDT, p,p'-DDE, HCB) and three specific PCB congeners (PCB 138, 153, 180) in adipose tissue and serum samples from an urban adult population (n=112) in the city of Santa Cruz de la Sierra, Bolivia, and to investigate their relationships within and between the two matrices and with selected socio-demographic characteristics. The percentages of samples positive for these compounds ranged from 40% for PCB 180 to 100% for p,p'-DDE in adipose tissue, and from 21% for HCB to 93% for p,p'-DDE in serum. Median number of residues per sample was five for adipose tissue and three for serum. Geometric mean concentrations indicate a considerable historical and recent exposure to organochlorine pesticides and PCBs in this population. Adipose tissue:serum ratios ranged from 149.3 to 590.3 (wet basis) and from 0.9 to 3.5 (lipid basis). We found positive and statistically significant correlations between adipose tissue and serum concentrations only in p,p'-DDE and HCB. This novel study in Bolivia underlines the need for human biomonitoring to assess exposure to environmental pollutants in South America.

PCB congener specific oxidative stress response by microarray analysis using human liver cell line

In this study we have examined the effect of exposure to different congeners of PCBs and their role in oxidative stress response. A metabolically competent human liver cell line (HepG2) was exposed with two prototype congeners of PCBs: coplanar PCB-77 and non-coplanar PCB-153. After the predetermined times of exposure (0-24h) at 70 μM concentration, the HepG2 cells showed significant apoptotic changes by fluorescent microscopy after 12h of exposure. Gene set enrichment analysis (GSEA) identified oxidative stress as the predominant enrichment. Further, paraquat assay showed that PCB congeners lead to oxidative stress to different extents, PCB-77 being more toxic. This study, with emphasis on all recommended microarray quality control steps, showed that apoptosis was one of the most significant cellular processes as a result of oxidative stress, but each of these congeners had a unique signature gene expression, which was further validated by Taqman real time PCR and immunoblotting. The pathways involved leading to the common apoptotic effect were completely different. Further in-silico analysis showed that PCB-153 most likely acted through the TNF receptor, leading to oxidative stress involving metallothionein gene families, and causing apoptosis mainly by the Fas receptor signaling pathway. In contrast, PCB-77 acted through the aryl hydrocarbon receptor. It induced oxidative stress through the involvement of cytochrome P450 (CYP1A1) leading to apoptosis through AHR/ARNT pathway.

Multivariate models to predict human adipose tissue PCB concentrations in Southern Spain

The use of Polychlorinated biphenyls (PCBs) has been severely restricted due to their high toxicity and persistency in the environment. However, the presence of PCBs in human tissues nowadays is still been reported worldwide. Background exposure predictors of the human PCB body burden require more precise understanding. In the present study, PCB congeners 138, 153, and 180 were quantified in adult adipose tissue samples (n=387) from Granada Province (Southern Spain) and data on potential predictors of PCB concentrations were gathered by questionnaire. Chemical analysis of the selected congeners was done by gas chromatography and mass spectrometry, and multivariate analyses were performed stratifying by gender. PCB residues were quantified in 92% (PCB 153), 90% (PCB 180), and 86% (PCB 138) of the population. Geometric mean concentrations were 161.65+/-4.41 ng/g lipid for PCB 153, 111.62+/-6.27 ng/g lipid for PCB 180, and 38.41+/-8.61 ng/g lipid for PCB 138. Multivariate models explained 30-36% of the variability in PCB concentrations. Age and body mass index (BMI) predicted exposure in both males and females and were positively correlated with the concentration of the three PCB congeners. Occupation and diet predicted exposure in the males, whereas only dietary predictors were observed in the females. Further in-depth studies are required to investigate the influence of dietary habits on the bioaccumulation of PCBs and to evaluate the impact of policies aimed at reducing human exposure.

Dioxin-like PCBs and endometriosis

A recent survey in the United States identified 287 different chemicals in human cord blood, demonstrating the significant exposure of women and their children to a wide array of environmental toxicants. While reducing contamination and exposure should be an international priority, it is equally appropriate to develop an understanding of the health consequences of increasing world-wide industrialization. Endometriosis, a disease of the female reproductive tract, has emerged as a disease potentially related to environmental exposures. While a number of population-based studies have suggested that a woman's exposure to dioxin-like polychlorinated biphenyls may affect her risk of developing this disease, other studies have failed to find such evidence. In the current manuscript, we will review the limited data regarding polychlorinated biphenyl congeners and endometriosis with a focus on dioxin-like toxicants. We will also discuss the potential importance of early life exposures to these toxicants on the subsequent development of endometriosis.

Maternal levels of organochlorines in two communities in southern Vietnam

Some pesticides and PCBs continue to be reported as environmental problems in some areas of Vietnam. In 2005, a study among delivering women took place in two communities in south-central Vietnam (Khanh Hoa Province), namely the coastal city of Nha Trang and the rural district of Dien Khanh located about 10 km inland. The main findings in plasma (n=189) were relatively high mean concentrations of p,p'-DDE (12.2 microg/l in Nha Trang and 11.4 microg/l in Dien Khanh) and p,p'-DDT (1.2 microg/l in Nha Trang and 1.1 microg/l in Dien Khanh) with no significant community differences. The ratio of p,p'-DDE/p,p'-DDT (11.5 in Nha Trang/12.7 in Dien Khanh) suggests, as in other Vietnamese OCs studies, a relatively recent use of this pesticide. Mean concentrations of PCB 153 (0.15 microg/l in Nha Trang and 0.10 microg/l in Dien Khanh) and other congeners were low in both communities. Age and parity (all compounds), as well as community of residence for PCB 153, were the most important predictors of plasma OCs concentrations.

Population physiologically based pharmacokinetic modeling for the human lactational transfer of PCB-153 with consideration of worldwide human biomonitoring results

BACKGROUND

One of the most serious human health concerns related to environmental contamination with polychlorinated biphenyls (PCBs) is the presence of these chemicals in breast milk.

OBJECTIVES

We developed a physiologically based pharmacokinetic model of PCB-153 in women, and predict its transfer via lactation to infants. The model is the first human, population-scale lactational model for PCB-153. Data in the literature provided estimates for model development and for performance assessment.

METHODS

We used physiologic parameters from a cohort in Taiwan and reference values given in the literature to estimate partition coefficients based on chemical structure and the lipid content in various body tissues. Using exposure data from Japan, we predicted acquired body burden of PCB-153 at an average childbearing age of 25 years and compared predictions to measurements from studies in multiple countries. We attempted one example of reverse dosimetry modeling using our PBPK model for possible exposure scenarios in Canadian Inuits, the population with the highest breast milk PCB-153 level in the world.

RESULTS

Forward-model predictions agree well with human biomonitoring measurements, as represented by summary statistics and uncertainty estimates.

CONCLUSION

The model successfully describes the range of possible PCB-153 dispositions in maternal milk, suggesting a promising option for back-estimating doses for various populations.

Polychlorinated biphenyls and thyroid hormone serum concentrations among people living in a highly polluted area: a cross-sectional population-based study

BACKGROUND

Polychlorinated biphenyls (PCBs) may interact with several thyroid functions. Severe environmental pollution by PCBs has been observed in Brescia, Italy, due to the presence of a factory that produced these compounds until 1984.

OBJECTIVES

We aimed to investigate the correlation between serum levels of total PCBs and PCB 153 and thyroid hormone serum levels in adults in a cross-sectional population-based study.

METHODS

A total of 527 subjects were enrolled; they were face-to-face interviewed about their history of thyroid disease and provided a blood sample under fasting conditions. The serum levels of free and total triiodothyronine (FT3 and TT3), thyroxine (FT4 and TT4) and thyroid-stimulating hormone (TSH), anti-thyroperoxidase (anti-TPO) and anti-thyroglobulin (anti-TGA), and lipid-adjusted total PCBs and PCB 153 were determined.

RESULTS

There was no statistically significant difference in total PCB and PCB 153 concentrations in subjects with and without thyroid disease. Inverse, weak, statistically significant correlations were found between total PCBs and FT3 (Spearman's r=-0.09) and between total PCBs and PCB 153 and TSH (Spearman's r=-0.16 and -0.12, respectively). However, multiple regression analysis with FT3 and TSH serum levels as dependent variables and total PCBs and PCB 153 serum levels as predictors, including age, gender and BMI, showed a positive, rather than negative, association of PCBs and PCB 153 with FT3 and no association with TSH.

CONCLUSIONS

This study does not support the hypothesis that relatively high PCB environmental exposure can determine substantial alterations in thyroid function among adult people.

Global DNA hypomethylation is associated with high serum-persistent organic pollutants in Greenlandic Inuit

BACKGROUND

Persistent organic pollutants (POPs) may influence epigenetic mechanisms; therefore, they could affect chromosomal stability and gene expression. DNA methylation, an epigenetic mechanism, has been associated with cancer initiation and progression. Greenlandic Inuit have some of the highest reported POP levels worldwide.

OBJECTIVE

Our aim in this study was to evaluate the relationship between plasma POPs concentrations and global DNA methylation (percent 5-methylcytosine) in DNA extracted from blood samples from 70 Greenlandic Inuit. Blood samples were collected under the Arctic Monitoring and Assessment Program and previously analyzed for a battery of POPs.

METHODS

We used pyrosequencing to estimate global DNA methylation via Alu and LINE-1 assays of bisulfite-treated DNA. We investigated correlations between plasma POP concentrations and global DNA methylation via correlation coefficients and linear regression analyses.

RESULTS

We found inverse correlations between percents methylcytosine and many of the POP concentrations measured. Linear regressions, adjusting for age and cigarette smoking, showed statistically significant inverse linear relationships mainly for the Alu assay for p,p'-DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane; beta = -0.26), p,p'-DDE [1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene; beta = -0.38], beta-hexachlorocyclohexane (beta = -0.48), oxychlordane (beta = -0.32), alpha-chlordane (beta = -0.75), mirex (beta = -0.27), sum of polychlorinated biphenyls (beta = -0.56), and sum of all POPs (beta = -0.48). Linear regressions for the LINE-1 assay showed beta estimates of similar magnitudes to those using the Alu assay, however, none was statistically significant.

CONCLUSIONS

This is the first study to investigate environmental exposure to POPs and DNA methylation levels in a human population. Global methylation levels were inversely associated with blood plasma levels for several POPs and merit further investigation.

Reactive oxygen species from the uncoupling of human cytochrome P450 1B1 may contribute to the carcinogenicity of dioxin-like polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) are classified by the International Agency for Research on Cancer as probable human carcinogens. A subset of PCBs are described as 'dioxin like' because of similarities to 2,3,7,8-tetrachlorodibenzo-p-dioxin. Dioxin-like PCBs have been shown to tightly bind the active site of cytochrome P450 (CYP) 1A isoforms, primarily CYP1A1, resulting in inhibition of CYP activity and the generation of reactive oxygen species (ROS) as a result of uncoupling of the catalytic cycle. Human CYP1B1 (hCYP1B1) is an extrahepatic CYP closely related to hCYP1A1 and is overexpressed in the lungs of smokers. Moreover, hCYP1B1 has been found to be overexpressed in cancers derived from a number of tissue types, as well as in pre-malignant prostate tumours, implicating overexpression of hCYP1B1 as a risk factor for extrahepatic carcinogenesis. It has been demonstrated previously that hCYP1B1 is inhibited by dioxin-like PCBs, but whether or not it is uncoupled has not been investigated. In the current study, the ability of three dioxin-like PCBs 3,3',4,4'-tetrachlorobiphenyl, 3,3',4,4',5-pentachlorobiphenyl and 3,3',4,4',5,5'-hexachlorobiphenyl (PCB169) to inhibit hCYP1B1 and stimulate the formation of ROS in V79MZ cells (which lack endogenous CYPs) expressing hCYP1B1 was demonstrated. Moreover, the generation of ROS was also associated with increases in parameters of oxidative stress related to genotoxicity (DNA oxidation and lipid peroxidation). For PCB169, these effects were time and concentration dependent. These data identify a novel mechanism of genotoxicity for dioxin-like PCBs, as well as providing further evidence that overexpression of hCYP1B1 is a risk factor for extrahepatic carcinogenesis.

Exposure of mother-child and postpartum woman-infant pairs to DDT and its metabolites in Tianjin, China

1,1,1-trichloro-2,2'-bis(4-chlorophenyl)ethane (DDT) exhibits its long persistence in the environment, unusual bioaccumulation, effects on wildlife, and the possibility of long-term adverse effects on human health, especially reproductive toxicity. Despite the prohibition of most persistent organochlorine pesticides in China, the presence of organochlorine residue, including DDT, has been widely indicated in environmental substance. However, scarce information is available about accumulative levels of DDT in human tissues in China. To evaluate levels of DDT and its potential effects on women and children's health in a Chinese pesticide-exposed area, we recruited 50 pairs of mother-child and 50 postpartum women, and determined the levels of total DDT and its four main metabolites (p,p'-DDE, p,p'-DDT, p,p'-DDD, o,p'-DDT) in venous blood, breast milk and umbilical blood cord by gas chromatography. Accordingly, data on reproductive outcomes of mothers and postpartum women and healthy status of children and infants were gathered through a questionnaire and medical examinations. Furthermore, we also assayed the DDT levels of some environmental samples (soil, food, milk, et al.). The levels of DDT in children's blood were higher than that in the women's. As compared to breast milk, the umbilical blood cord and the ventral fat individually demonstrated a significantly lower and higher level of DDT in the postpartum women. DDT was lower in milk and crucian carp than in the soil near the chemical plant. p,p'-DDT and p,p'-DDE were the main metabolites of DDT. Our findings suggested the cumulative effect of DDT in human body in Tianjin, China.

Endocrine disrupting pesticides: implications for risk assessment

Endocrine disrupting (ED) chemicals are compounds that alter the normal functioning of the endocrine system, potentially causing disease or deformity in organisms and their offspring. Pesticides are used widely to kill unwanted organisms in crops, public areas, homes and gardens and medicinally to kill parasites. Many are proven or suspected to be EDs. Ancient physiological similarities between different vertebrate groups suggest that disorders observed in wildlife may indicate risks to humans. This makes accurate risk assessment and effective legislation difficult. In this paper, the hazardous properties of pesticides which are known to have ED properties are reviewed in order to assess the implications for risk assessment. As well as data on sources of exposure in the United Kingdom (UK) an assessment of the evidence on the health effects of ED pesticides is also included. In total, 127 have been identified from the literature and their effects and modes of action are listed in this paper. Using the UK as a case study, the types and quantities of pesticides used, and their methods of application are assessed, along with their potential pathways to humans. In the UK reliable data are available only for agricultural use, so non-agricultural routes of pesticide exposure have been poorly quantified. The exposure of people resident in or visiting rural areas could also have been grossly under-estimated. Material links between ED pesticide use and specific illnesses or deformities are complicated by the multifactorial nature of disease, which can be affected by factors such as diet. Despite these difficulties, a large body of evidence has accumulated linking specific conditions to ED pesticides in wildlife and humans. A more precautionary approach to the use of ED pesticides, especially for non-essential purposes is proposed.

Serum organochlorines and breast cancer: a case-control study among African-American women

This population-based case-control study of African-American women (355 breast cancer case patients, 327 controls) examined the association between breast cancer and circulating levels of PCBs and dichlorodiphenyldichloroethene (DDE), a metabolite of DDT. Case patients were diagnosed with invasive breast carcinoma and interviewed between June 1995 and July 1998, and control subjects were identified by random digit dialing methods. Serum levels of DDE and total PCBs were adjusted for total lipid content. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable unconditional logistic regression methods. Effect modification by tumor receptor status and cancer treatment was investigated. Breast cancer risk was not associated with increasing quintiles of lipid-adjusted PCBs or DDE (highest versus lowest quintile adjusted for age, body mass index (BMI) and breastfeeding for DDE: OR = 1.02, 95% CI = (0.61, 1.72), p-trend = 0.74; for PCBs: OR = 1.01, 95% CI = (0.63, 1.63), p-trend = 0.56). Risk did not differ by strata of BMI, breastfeeding, parity, menopausal status or tumor receptor status. This study, the largest study of African-American women to date, does not support a role of DDE and total PCBs in breast cancer risk at the levels measured.

Association of serum concentration of organochlorine pesticides with dietary intake and other lifestyle factors among urban Chinese women

Concerns about the carcinogenic and endocrine-disrupting characteristics of organochlorine pesticides (OCPs) have led to a global ban on OCP use. However, OCPs persist in the environment for decades because of their long half-life. We evaluated serum levels of OCPs and their correlations with usual dietary intake and other lifestyle factors among 250 healthy women who participated as controls in the Shanghai Breast Cancer Study. Serum levels of hexachlorocyclohexane isomers (alpha-HCH, beta-HCH, gamma-HCH), dichloro-di-phenyl-trichloroethane (DDT) isomers (p,p'-DDE and p,p'-DDT), hexachlorobenzene (HCB), trans-nonachlor (TNC), and eight polychlorinated biphenyls (PCB) congeners (IUPAC no. 74, 118, 138, 153, 170, 180, 183, and 187) were measured. Lifestyle factors and usual dietary habits over the past 5 years were assessed through an in-person interview. With the exception of PCB, total OCP levels in our study population were significantly higher than those observed in other countries. Age, income, body mass index, waist-to-hip ratio, number of pregnancies, and/or total duration of breastfeeding were all significantly correlated with all types of OCPs. Of the 20 food groups evaluated, correlations with serum total OCPs were observed for eggs (r=0.13), fresh beans (r=-0.17), tea (r=0.14), and animal fat (r=0.18). Multiple regression analyses showed that age and animal fat intake were positively associated with serum total level OCPs, while leafy vegetable and fresh bean consumption was negatively associated with OCPs level. Our study suggests that dietary intake may be an important contributor of serum levels of OCPs in Chinese women.

Organochlorines and risk of non-Hodgkin lymphoma

Organochlorine chemicals and polychlorinated biphenyls (PCBs) have been suspected as possible risk factors for non-Hodgkin lymphoma (NHL). We investigated PCBs and organochlorine pesticides and risk of NHL in a population-based case-control study in British Columbia, Canada. Congeners of PCBs (including dioxinlike congeners) and pesticides or pesticide metabolites were measured in plasma of 422 pretreatment cases and 460 control subjects. This is so far the largest study to examine organochlorines in plasma to date. Several dioxin-like PCB congeners were associated with increased risk of NHL, including dioxin-like PCB nos. 118 and 156 with odds ratios (OR) for the highest versus lowest quartile between 1.6 and 1.8. Several non-dioxin-like congeners also showed significant associations. The PCB congener with the strongest association was no. 180 with an OR for the highest versus the lowest quartile of 1.83 (95% confidence interval = 1.18-2.84). Six pesticide analytes also showed a significant association with NHL; beta-hexachlorocyclohexane, p,p'-DDE, hexachlorobenzene, mirex, oxychlordane and trans-nonachlor. The strongest association was found for oxychlordane, a metabolite of the pesticide chlordane (highest vs. lowest quartile OR = 2.68, 95% confidence interval = 1.69-4.24). Our results provide further evidence that organochlorines contribute to NHL risk.

SPE-HPLC purification of endocrine-disrupting compounds from human serum for assessment of xenoestrogenic activity

Assessment of xenoestrogenic activity in human serum samples requires the removal of endogenous sex hormones to assure that the activity measured originates from xenobiotic compounds only. Serum samples representing high, medium and lower accumulation of persistent organic pollutants (POPs) were extracted using solid-phase extraction (SPE) followed by normal-phase high-performance liquid chromatography (NP-HPLC) for separation of POPs from endogenous hormones. The recovery of polychlorinated biphenyl (PCB) congeners in spiked serum samples was up to 86 %, making the extraction method suitable for the study. MVLN cells, stably transfected with an estrogen receptor (ER) luciferase reporter vector (estrogen response element chemically activated luciferase expression, ERE-CALUX), were exposed to the reconstituted SPE-HPLC extracts for determination of the integrated estrogenic activity. The effects of PCBs were analyzed by direct in vitro exposure of PCBs (nos. 138, 153, 180) and by ex vivo analysis of SPE-HPLC extracts from serum spiked with the PCBs. Similar effects on ER transactivation were observed for the direct in vitro and the ex vivo analysis experiments. The ER transactivation responses determined for actual serum samples were in the linear range of the dose-response curve. 17beta-Estradiol titrations showed that the xenoestrogenic effects were mediated via ER. Moreover, our SPE-HPLC-ERE-CALUX assay was demonstrated to elicit high interlaboratory correlation. In the present study the combination of SPE-HPLC purification and the ex vivo estrogenic responses measured by ERE-CALUX was validated and considered to be a valuable tool to assess the combined ER effect of lipophilic serum POPs where additive/synergistic and agonistic/antagonistic effects are integrated giving an overall estimate of exposure and bioactivity.

Persistent Organochlorine Chemicals in Plasma and Risk of Non-Hodgkin's Lymphoma

Polychlorinated biphenyls (PCB) have been suspected as possible contributors to increasing non-Hodgkin's lymphoma incidence during the latter half of the 20th century based on their toxicologic properties and provocative epidemiologic reports. We investigated PCBs and other organochlorines and risk of non-Hodgkin's lymphoma in a population-based case-control study in the United States. Congeners of PCBs (including coplanar congeners), dioxins, furans and pesticides or pesticide metabolites were measured in plasma of 100 untreated cases and 100 control subjects. We used a multiple imputation procedure to fill in missing values of levels determined to be below the detection limits. Risks of non-Hodgkin's lymphoma associated with each analyte were estimated using conditional logistic regression for the continuous measure, exposure quartiles, trend across quartile categories, and exposures above the 95th percentile. Certain PCB congeners were associated with increased risk of non-Hodgkin's lymphoma, including coplanar PCBs 156, 180, and 194, with odds ratios for the highest versus lowest quartile ranging from 2.7 to 3.5, and significant trends. Each of the furan congeners was associated with risk of non-Hodgkin's lymphoma, as were total furans, with 3.5-fold increased risk for the highest versus lowest quartile and a significant trend across quartiles (P = 0.006). The toxic equivalency quotient (TEQ), a summed metric that weights congeners by their dioxin-like potency, was associated with non-Hodgkin's lymphoma, with 35% increased risk per 10 TEQ pg/g lipid (95% confidence interval, 1.02-1.79). Our results add to existing literature, which suggests that exposure to organochlorines contributes to non-Hodgkin's lymphoma risk; these risks were most apparent for certain PCBs and furans.