Exposure to Organochlorine Pesticides and Female Breast Cancer Risk According to Molecular Receptors Expression: a Systematic Review and Meta-analysis of Epidemiological Evidence

PURPOSE OF REVIEW

Organochlorine pesticides (OCP) have been proposed as potential mammary carcinogens since they interact with steroid signaling pathways. However, the epidemiological results are not conclusive. Most studies have evaluated breast cancer (BC) as a single entity without considering the different molecular expressions, including estrogen receptor (ER), progesterone receptor (PR), and HER2, that could differ in their association with these contaminants. Hence, we assessed the association between biological concentration of OCP and BC, according to its molecular receptor expression, based on a systematic review and meta-analysis.

RECENT FINDINGS

Of the 141 articles eligible for full-text review, nine met the inclusion criteria. The way in which molecular expression was reported was heterogeneous; therefore, the inclusion of studies in the meta-analysis was limited to eight articles. A negative association was identified for β-hexachlorocyclohexane and trans-nonachlor with ER + tumors and between hexachlorobenzene and ER - tumors. No associations were observed for p,p'-dichlorodiphenyldichloroethylene, cis-nonachlor, and dieldrin, and it was not possible to evaluate the associations between OCP with HER2 expression or triple-negative tumors due to lack of data. The results suggest that some OCP might be associated with BC depending on the expression of ER. However, the evidence is not conclusive due to the scarce data. We identified several methodological aspects to fill the gaps in knowledge and increase the comparability among studies.

Associations between persistent organic pollutants and type 1 diabetes in youth

BACKGROUND

Diabetes affects millions of people worldwide with a continued increase in incidence occurring within the pediatric population. The potential contribution of persistent organic pollutants (POPs) to diabetes in youth remains poorly known, especially regarding type 1 diabetes (T1D), generally the most prevalent form of diabetes in youth.

OBJECTIVES

We investigated the associations between POPs and T1D in youth and studied the impacts of POPs on pancreatic β-cell function and viability in vitro.

METHODS

We used data and plasma samples from the SEARCH for Diabetes in Youth Case Control Study (SEARCH-CC). Participants were categorized as Controls, T1D with normal insulin sensitivity (T1D/IS), and T1D with insulin resistance (T1D/IR). We assessed plasma concentrations of polychlorinated biphenyls (PCBs) and organochlorine pesticides and estimated the odds of T1D through multivariable logistic regression. In addition, we performed in vitro experiments with the INS-1E pancreatic β-cells. Cells were treated with PCB-153 or p,p'-DDE at environmentally relevant doses. We measured insulin production and secretion and assessed the mRNA expression of key regulators involved in insulin synthesis (Ins1, Ins2, Pdx1, Mafa, Pcsk1/3, and Pcsk2), glucose sensing (Slc2a2 and Gck), and insulin secretion (Abcc8, Kcnj11, Cacna1d, Cacna1b, Stx1a, Snap25, and Sytl4). Finally, we assessed the effects of PCB-153 and p,p'-DDE on β-cell viability.

RESULTS

Among 442 youths, 112 were controls, 182 were classified with T1D/IS and 148 with T1D/IR. The odds ratios (OR) of T1D/IS versus controls were statistically significant for p,p'-DDE (OR 2.0, 95% confidence interval (CI) 1.0, 3.8 and 2.4, 95% CI 1.2, 5.0 for 2nd and 3rd tertiles, respectively), trans-nonachlor (OR 2.5, 95% CI 1.3, 5.0 and OR 2.3, 95% CI 1.1, 5.1 for 2nd and 3rd tertiles, respectively), and PCB-153 (OR 2.3, 95% CI 1.1, 4.6 for 3rd tertile). However, these associations were not observed in participants with T1D/IR. At an experimental level, treatment with p,p'-DDE or PCB-153, at concentrations ranging from 1 × 10^-15 M to 5 × 10^-6 M, impaired the ability of pancreatic β-cells to produce and secrete insulin in response to glucose. These failures were paralleled by impaired Ins1 and Ins2 mRNA expression. In addition, among different targeted genes, PCB-153 significantly reduced Slc2a2 and Gck mRNA expression whereas p,p'-DDE mainly affected Abcc8 and Kcnj11. While treatment with PCB-153 or p,p'-DDE for 2 days did not affect β-cell viability, longer treatment progressively killed the β-cells.

CONCLUSION

These results support a potential role of POPs in T1D etiology and demonstrate a high sensitivity of pancreatic β-cells to POPs.

Associations between cigarette smoking and total mortality differ depending on serum concentrations of persistent organic pollutants among the elderly

There are substantial variations of relative risks (RR) in smoking-related mortality by country and time. We hypothesized the RRs in smoking-related mortality might differ depending on serum concentrations of persistent organic pollutants (POPs). We evaluated the associations of cigarette smoking with total mortality in 610 elderly (aged ≥ 70 yr) (702 elderly for organochlorine pesticides [OCPs]) after stratification by serum concentration of POPs, in the National Health and Nutrition Examination Survey (NHANES) 1999-2004 followed through 2006. Summary measures of POPs subclasses showed significant or marginally significant interaction with cigarette smoking on the risk of total mortality. P values for interaction were 0.069 for polychlorinated dibenzo-p-dioxins (PCDDs), 0.008 for polychlorinated biphenyls (PCBs), and 0.024 for OCPs. The effect of smoking on total mortality showed different patterns according to the serum concentration of some POPs. Former or current smokers had 1.4 to 2.9 times higher mortality rates compared with never smokers among participants with higher serum concentrations of POPs (2nd or 3rd tertiles). However, when the level of PCBs or OCPs were low (1st tertile), there were little positive associations between smoking and mortality. Our study suggests that the background exposure to several POPs may be related to variability in smoking-related total mortality.