Urinary Phthalate Metabolite Concentrations and Breast Cancer Incidence and Survival following Breast Cancer: The Long Island Breast Cancer Study Project

Novel insights into the causal relationship between endocrine-disrupting chemicals and breast cancer mediated by circulating metabolites

The relationship between Endocrine-disrupting chemicals (EDCs) and breast cancer has not been extensively investigated. Although EDCs can disrupt human endocrine system, the underlying mechanism of EDCs on breast cancer requires further exploration. This study aimed to investigate the causal relationship between EDCs and breast cancer through Mendelian randomization (MR) and Generalised Summary-data-based Mendelian Randomization (GSMR) approach. Our results demonstrated that Bisphenol F was associated with increased risk of breast cancer [odds ratio (OR) = 1.018 (95% CI 1.004-1.031), P = 0.010)]. Mono-(2-ethyl-5-carboxypentyl) phthalate (MECPP) was associated with lower breast cancer risk (OR = 0.894, 95%CI = 0.819-0.975, P = 0.012). In addition, we identified 4 EDCs (bisphenol F, MECPP, Mono-ethyl phthalate, and Methyl paraben) significantly associated with ER+ breast cancer. Furthermore, 3-bromo-5-chloro-2,6-dihydroxybenzoic acid mediated 10.9% of the influence of MECPP on breast cancer. In addition, enrichment analysis was used to identify the pathways related to EDCs. MR-Phenome Wide Association Study (PheWAS) analysis was used to explore potential treatable diseases and adverse outcomes of EDCs. These findings shed light on the potential impact of EDCs exposure on breast cancer, which offer novel perspectives for future mechanistic and clinical research of EDCs and breast cancer.

Effects of endocrine disrupting chemicals, blood metabolome, and epigenetics on breast cancer risk: A multi-dimensional mendelian randomization study

Current research on the relationship between environmental endocrine disrupting chemicals (EDCs) and breast cancer remains insufficient, with limited evidence and inconsistent conclusions. Mendelian randomization (MR) is a robust method for establishing causality, as it reduces biases from confounding factors and reverse causation. This study uses MR to investigate the effects of three types of EDCs, including bisphenols, parabens, and phthalates, on the risk of overall breast cancer and its subtypes-Luminal A, Luminal B, triple negative, human epidermal growth factor receptor 2-enriched, and estrogen receptor-positive/negative. The study also examines the 1400 blood metabolome as potential mediators and explores EDCs-associated DNA methylation changes as potential factors, with a focus on European populations. Our results shows that n-butyl paraben (n-BuP) is positively associated with Luminal A, mono-methyl phthalate is negatively associated with Luminal B, and mono-iso-butyl phthalate (MiBP) is positively associated with triple negative breast cancer (TNBC). Mediation analysis reveals that blood metabolites, such as caffeic acid sulfate and the caffeine-to-paraxanthine ratio, mediate the effect of n-BuP on Luminal A, while methylsuccinate mediate the effect of MiBP on TNBC. Epigenetic analysis shows associations between EDCs exposure-related DNA methylation changes at specific CpG sites (cg26325335, cg08537847, cg27454300) and different breast cancer risks. These findings not only suggest potential biomarkers for early detection and intervention but also underscore the imperative for further research to rigorously validate these associations.

Impact of Structural Racism and Social Determinants of Health on Disparities in Breast Cancer Mortality

The striking ethnic and racial disparities in breast cancer mortality are not explained fully by pathologic or clinical features. Structural racism contributes to adverse conditions that promote cancer inequities, but the pathways by which this occurs are not fully understood. Social determinants of health, such as economic status and access to care, account for a portion of this variability, yet interventions designed to mitigate these barriers have not consistently led to improved outcomes. Based on the current evidence from multiple disciplines, we describe a conceptual model in which structural racism and racial discrimination contribute to increased mortality risk in diverse groups of patients by promoting adverse social determinants of health that elevate exposure to environmental hazards and stress; these exposures in turn contribute to epigenetic and immune dysregulation, thereby altering breast cancer outcomes. Based on this model, opportunities and challenges arise for interventions to reduce racial and ethnic disparities in breast cancer mortality.

Contamination levels and ecological risk assessment of phthalate esters (PAEs) in the aquatic environment of Chaohu Lake

Phthalate esters (PAEs), widely recognized as synthetic organic compounds with extensive production and utilization, are known to disrupt physiological processes in both animals and humans, even at low environmental concentrations. This study investigated the occurrence, distribution, and potential ecological risk of five representative PAEs (DMP, Dimethyl phthalate; DEP, Diethyl phthalate; DBP, Dibutyl phthalate; DiBP, Diisobutyl phthalate; DEHP, Bis(2-ethylhexyl) phthalate) in a typical lake (Chaohu Lake, China). It was found that PAEs were detected in both the aqueous (1.09-6.402 µg/L) and solid phases (0.827-6.602 µg/g) of Chaohu Lake. Notably, DiBP and DBP were the predominant PAEs in the water, and DiBP and DEHP were the most prevalent in the sediments. The concentrations of PAEs exhibited significant seasonal variations in the aqueous phases, with total PAEs in summer being nearly twice those in winter. Toxicity assessments revealed that DEHP, DBP, and DiBP posed high risks to the survival of three indicator organisms (algae, Daphnia, and fish) in the aqueous phase. In the solid phase, the exceeding rate of DiBP was as high as 92.9%. On the other hand, DBP and DEHP generally presenting moderate risk, although some sites were identified as high-risk. This study's analysis of PAEs concentrations in Chaohu Lake reveals a discernible increasing trend when compared with historical data. These findings underscore the urgent need for interventions to mitigate the ecological threats posed by PAEs in Chaohu Lake.

Ecotoxicity assessment of additives in commercial biodegradable plastic products: Implications for sustainability and environmental risk

Biodegradable plastics have gained popularity as environmentally friendly alternatives to conventional petroleum-based plastics, which face recycling and degradation challenges. Although the biodegradability of these plastics has been established, research on their ecotoxicity remains limited. Biodegradable plastics may still contain conventional additives, including toxic and non-degradable substances, to maintain their functionality during production and processing. Despite degrading the polymer matrix, these additives can persist in the environment and potentially harm ecosystems and humans. Therefore, this study aimed to assess the potential ecotoxicity of biodegradable plastics by analyzing the phthalate esters (PAEs) leaching out from biodegradable plastics through soil leachate. Sixteen commercial biodegradable plastic products were qualitatively and quantitatively analyzed using gas chromatography-mass spectrometry to determine the types and amounts of PAE used in the products and evaluate their ecotoxicity. Among the various PAEs analyzed, non-regulated dioctyl isophthalate (DOIP) was the most frequently detected (ranging from 40 to 212 μg g-1). Although the DOIP is considered one of PAE alternatives, the detected amount of it revealed evident ecotoxicity, especially in the aquatic environment. Other additives, including antioxidants, lubricants, surfactants, slip agents, and adhesives, were also qualitatively detected in commercial products. This is the first study to quantify the amounts of PAEs leached from biodegradable plastics through water mimicking PAE leaching out from biodegradable plastics to soil leachate when landfilled and evaluate their potential ecotoxicity. Despite their potential toxicity, commercial biodegradable plastics are currently marketed and promoted as environmentally friendly materials, which could lead to indiscriminate public consumption. Therefore, in addition to improving biodegradable plastics, developing eco-friendly additives is significant. Future studies should investigate the leaching kinetics in soil leachate over time and toxicity of biodegradable plastics after landfill disposal.

Exposure to di-2-ethylhexyl phthalate and breast neoplasm incidence: A cohort study

BACKGROUND

Phthalates are ubiquitous environmental endocrine disruptors. As the predominant phthalate, di-2-ethylhexyl phthalate (DEHP) has been considered possibly carcinogenic to humans but large-scale longitudinal evidence is needed to further clarify its carcinogenicity.

OBJECTIVES

To examine the association between DEHP exposure and incidence of breast malignant neoplasm, carcinoma in situ and benign neoplasm.

METHODS

A total of 273,295 women from UK Biobank cohort were followed up for a median of 13.5 years. Disease information was collected from National Health Service Cancer Registry and National Death Index. Baseline and yearly-average level of DEHP exposure were estimated for each individual by linking chemical monitoring record of European Environment Agency with home address of the participants by Kriging interpolation model. Cox proportional hazard model was employed to estimate the association between DEHP exposure and breast neoplasms.

RESULTS

The median (IQR) of baseline and yearly-average DEHP concentration were 8000.25 (interquartile range: 6657.85-11,948.83) and 8000.25 (interquartile range: 1819.93-11,359.55) μg/L. The highest quartile of baseline DEHP was associated with 1.11 fold risk of carcinoma in situ (95 % CI, 1.00, 1.23, p < 0.001) and 1.27 fold risk of benign neoplasm (95 % CI, 1.05, 1.54, p < 0.001). As for yearly-average exposure, each quartile of DEHP was positively associated with higher risk of malignant neoplasm (HR, 1.05; 95 % CI, 1.03, 1.07, p < 0.001), carcinoma in situ (HR, 1.08; 95 % CI, 1.04, 1.11, p < 0.001) and benign neoplasm (HR, 1.13; 95 % CI, 1.07, 1.20, p < 0.001). Stratification analysis showed no significant modification effects on the DEHP-neoplasm relationship by menopausal status or ethnicity but a suggestive higher risk in younger women and those who underwent oral contraceptive pill therapy. In sensitivity analysis, the associations remained when excluding the cases diagnosed within 2 years post baseline.

CONCLUSIONS

Real-world level of DEHP exposure was associated with higher risk of breast neoplasms. Because of the health risks associated with DEHP, its release to the environment should be managed.

Association between urinary phthalates and phthalate metabolites and cancer risk: A systematic review and meta-analysis

Phthalates, widely utilized in industrial products, are classified as endocrine-disrupting chemicals (EDCs). Although certain phthalate and their metabolites have been implicated in cancer development, the reported findings have exhibited inconsistencies. Therefore, we conducted the comprehensive literature search to assess the association between phthalate and their metabolites and cancer risk by identifying original studies measuring phthalates or their metabolites and reporting their correlation with cancer until July 4, 2023. The Odds Ratios (ORs) and corresponding 95% confidence intervals (CIs) were extracted and analyzed to estimate the risk. Pooled data from eleven studies, including 3101 cancer patients and 6858 controls, were analyzed using a fixed- or random-effects model based on heterogeneity tests. When comparing extreme categories of different phthalates and their metabolites, we observed a significant association between urinary phthalates and phthalate metabolites (MEHHP, MECPP, DBP and MBzP) and cancer risk. The findings of our meta-analysis reinforce the existing evidence that urinary phthalates and phthalate metabolites is strongly associated with cancer development. Further investigations are warranted to elucidate the underlying mechanisms of this association. These results may offer novel insights into cancer development.

Personal Care Product Use during Puberty and Incident Breast Cancer among Black, Hispanic/Latina, and White Women in a Prospective US-Wide Cohort

BACKGROUND

Some personal care products (PCPs) contain endocrine-disrupting chemicals that may affect breast cancer (BC) risk. Patterns of use vary by race and ethnicity. Use often starts in adolescence, when rapidly developing breast tissue may be more susceptible to environmental carcinogens. Few studies have examined associations of BC with PCP use during this susceptible window.

OBJECTIVES

We characterized race and ethnicity-specific patterns of PCP use at 10-13 years of age and estimated associations of use with incident BC.

METHODS

At enrollment (2003-2009), Sister Study participants (n = 4,049 Black, 2,104 Latina, and 39,312 White women) 35-74 years of age reported use of 37 "everyday" PCPs during the ages of 10-13 y (did not use, sometimes, or frequently used). We conducted race and ethnicity-specific latent class analyses to separately identify groups of women with similar patterns of beauty, hair, and skincare/hygiene product use. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for associations of identified PCP classes and single products with incident BC using Cox proportional hazards regression.

RESULTS

During a mean follow-up time of 10.8 y, 280 Black, 128 Latina, and 3,137 White women were diagnosed with BC. Classes of adolescent PCP use were not clearly associated with BC diagnosis among Black, Latina, or White women. HRs were elevated but imprecise for frequent nail product and perfume use in Black women (HR = 1.34; 95% CI: 0.85, 2.12) and greater hair product use in Black (HR = 1.28; 95% CI: 0.91, 1.80) and Latina (HR = 1.42; 95% CI: 0.81, 2.48) women compared with lighter use. In single-product models, we observed higher BC incidence associated with frequent use of lipstick, nail products, pomade, perfume, makeup remover, and acne/blemish products in at least one group.

DISCUSSION

This work provides some support for the hypothesis that PCP use during puberty is associated with BC risk. More research is needed to confirm these novel findings. https://doi.org/10.1289/EHP13882.

The adverse role of endocrine disrupting chemicals in the reproductive system

Reproductive system diseases pose prominent threats to human physical and mental well-being. Besides being influenced by genetic material regulation and changes in lifestyle, the occurrence of these diseases is closely connected to exposure to harmful substances in the environment. Endocrine disrupting chemicals (EDCs), characterized by hormone-like effects, have a wide range of influences on the reproductive system. EDCs are ubiquitous in the natural environment and are present in a wide range of industrial and everyday products. Currently, thousands of chemicals have been reported to exhibit endocrine effects, and this number is likely to increase as the testing for potential EDCs has not been consistently required, and obtaining data has been limited, partly due to the long latency of many diseases. The ability to avoid exposure to EDCs, especially those of artificially synthesized origin, is increasingly challenging. While EDCs can be divided into persistent and non-persistent depending on their degree of degradation, due to the recent uptick in research studies in this area, we have chosen to focus on the research pertaining to the detrimental effects on reproductive health of exposure to several EDCs that are widely encountered in daily life over the past six years, specifically bisphenol A (BPA), phthalates (PAEs), polychlorinated biphenyls (PCBs), parabens, pesticides, heavy metals, and so on. By focusing on the impact of EDCs on the hypothalamic-pituitary-gonadal (HPG) axis, which leads to the occurrence and development of reproductive system diseases, this review aims to provide new insights into the molecular mechanisms of EDCs' damage to human health and to encourage further in-depth research to clarify the potentially harmful effects of EDC exposure through various other mechanisms. Ultimately, it offers a scientific basis to enhance EDCs risk management, an endeavor of significant scientific and societal importance for safeguarding reproductive health.

Occurrence, ecological and health risk assessment of phthalates in a polluted urban river used for agricultural land irrigation in central Mexico

The escalating global concern on phthalate esters (PAEs) stems from their status as emerging contaminants, marked by their toxicity and their potential to harm both the environment and human health. Consequently, this study aimed to evaluate the occurrence, spatial distribution, and ecological and health risks associated with PAEs in the Atoyac River, an urban waterway in central Mexico that receives untreated and poorly treated urban and industrial wastewater. Of the 14 PAEs analyzed in surface water samples collected along the river mainstream, nine were detected and quantified by GC-MS. The concentration of each detected PAE ranged from non-detected values to 25.7 μg L-1. Di (2-ethylhexyl) phthalate (DEHP) and di-n-hexyl phthalate (DnHP) were detected in all sampling sites, with concentrations ranging from 8.1 to 19.4 μg L-1 and from 6.3 to 15.6 μg L-1, respectively. The cumulative Σ9PAEs concentrations reached up to 81.1 μg L-1 and 96.0 μg L-1 in sites downstream to high-tech industrial parks, pinpointing industrial wastewater as the primary source of PAEs. Given that the river water is stored in a reservoir and used for cropland irrigation, this study also assessed the ecological and human health risks posed by PAEs. The findings disclosed a high ecological risk to aquatic organisms exposed to di-n-octyl phthalate (DOP), dicyclohexyl phthalate (DCHP), benzyl butyl phthalate (BBP), DEHP, and DnHP. Additionally, a high carcinogenic (CR > 10-4) and noncarcinogenic (HQ > 10) risk for the DEHP exposure through ingestion of crops irrigated with river water was identified for both children and adults. These data on PAEs provide valuable insights for the Mexican government's future strategies in regulating these pollutants in water bodies, thereby minimizing the environmental and human health risks that they pose.

Worldwide risk assessment of phthalates and bisphenol A in humans: The need for updating guidelines

Phthalates and bisphenol A (BPA) are compounds widely used as raw materials in the production of plastics, making them ubiquitous in our daily lives. This results in widespread human exposure and human health hazards. Although efforts have been conducted to evaluate the risk of these compounds in diverse regions around the world, data scattering may mask important trends that could be useful for updating current guidelines and regulations. This study offers a comprehensive global assessment of human exposure levels to these chemicals, considering dietary and nondietary ingestion, and evaluates the associated risk. Overall, the exposure daily intake (EDI) values of phthalates and BPA reported worldwide ranged from 1.11 × 10-7 to 3 700 µg kg bw-1 d-1 and from 3.00 × 10-5 to 6.56 µg kg bw-1 d-1, respectively. Nevertheless, the dose-additive effect of phthalates has been shown to increase the EDI up to 5 100 µg kg bw-1 d-1, representing a high risk in terms of noncarcinogenic (HQ) and carcinogenic (CR) effects. The worldwide HQ values of phthalates and BPA ranged from 2.25 × 10-7 to 3.66 and from 2.74 × 10-7 to 9.72 × 10-2, respectively. Meanwhile, a significant number of studies exhibit high CR values for benzyl butyl phthalate (BBP) and di(2-ethylhexyl) phthalate (DEHP). Moreover, DEHP has shown the highest maximum mean CR values for humans in numerous studies, up to 179-fold higher than BBP. Despite mounting evidence of the harmful effects of these chemicals at low-dose exposure on animals and humans, most regulations have not been updated. Thus, this article emphasizes the need for updating guidelines and public policies considering compelling evidence for the adverse effects of low-dose exposure, and it cautions against the use of alternative plasticizers as substitutes for phthalates and BPA because of the significant gaps in their safety.

Exposure to phenols, chlorophenol pesticides, phthalate and PAHs and mortality risk: A prospective study based on 6 rounds of NHANES

OBJECTIVES

Human exposure to various endocrine disrupting chemicals (EDCs) is widespread and long-lasting. The primary objective of this study was to prospectively evaluate the association of combined exposure of phenols, chlorophenol pesticides, phthalate and polycyclic aromatic hydrocarbons (PAHs) and mortality risk in a representative US population.

METHODS

The data on urinary levels of phenols, chlorophenol pesticides, phthalates, and PAH metabolites, were collected from participants aged ≥20 years in six rounds of the National Health and Nutrition Examination Survey (NHANES) (2003-2014). NHANES-linked death records up to December 31, 2015 were used to ascertain mortality status and cause of death. Cox proportional hazards and competing risk models were mainly used for chemical and mortality risk association analysis. The weighted quantile sum (WQS) regression and the least absolute shrinkage and selection operator regression were employed to estimate the association between EDC co-exposure and mortality risk.

RESULTS

High levels of mono-n-butyl phthalate, monobenzyl phthalate, and 1-napthol were significantly associated with increased risk of all cause, cardiovascular disease (CVD) and cancer mortality among all participants. WQS index was associated with the risks of all-cause (hazard ratio [HR] = 1.389, 95%CI: 1.155-1.669) and CVD mortality (HR = 1.925, 95%CI: 1.152-3.216). High co-exposure scores were associated with elevated all-cause (HR = 2.842, 95% CI: 1.2.094-3.858), CVD (HR = 1.855, 95% CI: 1.525-2.255), and cancer mortality risks (HR = 2.961, 95% CI: 1.468-5.972). The results of subgroup analysis, competing risk model, and sensitivity analysis were generally consistent with the findings from the main analyses, indicating the robustness of our findings.

CONCLUSIONS

This study provided the first epidemiological evidence that co-exposure to EDC at fairly low levels contributed to elevated mortality risk among US adults. The underlying mechanisms for the effects of EDC co-exposure on human health are worthy of future exploration.

Urinary parabens and breast cancer risk: Modification by LINE-1 and LUMA global DNA methylation, and associations with breast cancer defined by tumor promoter methylation status

Parabens are a group of alkyl esters of p-hydroxybenzoic acid added to consumer products to prevent the growth of harmful bacteria and molds. Parabens are hypothesized to increase the risk of breast cancer (BC); however, no study has examined the interactions between parabens, global DNA methylation (DNAm), and BC risk. We examined the modifying effects of DNAm on the associations between parabens and BC, and whether parabens were associated with BC defined by tumor promoter methylation status. Participants included 708 cases and 598 controls from the Long Island Breast Cancer Study Project. Methylparaben (MPB), propylparaben, and butylparaben levels were measured in spot urine samples. Global DNAm was measured by analysis of long interspersed elementes-1 (LINE-1) and the luminometric methylation assay (LUMA). The promoter methylation status of 13 genes was measured in tumor samples from 509 cases. We used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between parabens and BC stratified by LINE-1/LUMA, and between parabens and gene-specific promoter methylation-defined BC. Outcome heterogeneity was evaluated using ratios of ORs (RORs). We assessed the joint effects of the multiple parabens using quantile g-computation. The highest versus lowest tertile of MPB and a one-quantile increase in all parabens were associated with ORs of 1.46 (95% CI = 0.96-2.23) and 1.32 (95% CI = 1.02-1.71), respectively, among women with hypomethylated LINE-1. A one-ln unit increase in MPB was associated with a 25% increase in the odds of hypomethylated (vs. hypermethylated) CCND2 promoter-defined BC (ROR = 1.25, 95% CI = 1.06-1.48), and a one-quantile increase in all parabens was associated with a 55% increase in the odds of hypomethylated (vs. hypermethylated) CCND2 promoter-defined BC (ROR = 1.55, 95% CI = 1.04-2.32). Exposure to parabens may increase the risk of BC among women with hypomethylated global DNAm and may increase the risk of tumors with gene-specific hypomethylated promoter regions.

Di-(2-ethylhexyl) phthalate exposure links to inflammation and low bone mass in premenopausal and postmenopausal females: Evidence from ovariectomized mice and humans

OBJECTIVE

Phthalates induce inflammation and are ubiquitously used in daily life. We aim to study the impact of di-(2-ethylhexyl) phthalate (DEHP) exposure on inflammation and osteoporosis in premenopausal and postmenopausal females.

METHODS

Female 8-week-old C57BL/6JNarl mice received an ovariectomy (OVX) or a sham operation and were fed with DEHP or vehicle by oral gavage for 4 or 8 weeks. Their femurs were isolated for micro-computed tomography, and their serum was collected for inflammatory cytokine assays. Correlations between urinary phthalate metabolites and the lumbar spine bone mineral density (BMD) in premenopausal and postmenopausal volunteers were performed.

RESULTS

Among the OVX mice treated for 4 weeks, significant lower bone volume, bone volume/tissue volume, and trabecular number but significant higher trabecular bone pattern factor and structure model index were identified in the mice treated with DEHP than with vehicle. The OVX mice treated with DEHP for 4 weeks had significantly higher serum interleukin (IL)-1β, IL-10, IL-17A, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and Dickkopf-1 levels than those treated with vehicle. The sham mice treated with DEHP for 8 weeks showed an impaired femur trabecular microstructure and had significantly higher serum IL-1β, IL-6, IL-10, IL-17A, IFN-γ, and TNF-α than those treated with vehicle. DEHP metabolites were inversely correlated with the BMD of premenopausal women and the T-score of postmenopausal women.

CONCLUSION

DEHP treatment in OVX and sham mice results in osteoporosis and impairs the microstructure of the femur trabecula through inflammation. Phthalate exposure negatively affects the bone mass in both premenopausal and postmenopausal women. Thus, long-term avoidance is suggested.

Urinary concentration of endocrine-disrupting phthalates and breast cancer risk in Indian women: A case-control study with a focus on mutations in phthalate-responsive genes

BACKGROUND

Phthalates are known endocrine-disrupting chemicals used indiscriminately as constituents in consumer products including food processing, and packaging, cosmetics, personal care and household items. Although, few studies have assessed the risk of breast cancer on exposure to phthalates, their association with breast cancer risk in Indian women have not yet been evaluated.

METHODS

We conducted a case-control study involving 171 participants. Urinary concentrations of six phthalate dieters; DMP (Dimethyl phthalate), DEP (Diethyl phthalate), DBP (Dibutyl phthalate), BBP (benzyl butyl phthalate), DEHP (Di-2-ethyl-hexyl phthalate), DINOP (Di-n-octyl phthalate) were estimated by GC-MS and geometric means were calculated. Univariate and multivariable logistic regression was performed to assess breast cancer risk on exposure to phthalates. Genes responsive to phthalates were identified through literature search and matched with NGS data, and gene-enrichment analysis was performed.

RESULTS

Significant associations were observed between urinary phthalate concentrations and increased risk of breast cancer for di-butyl phthalate (OR=1.5, 95% CI; 1.06, 2.11, p = 0.002) and di-2-ethyl-hexyl phthalate (>median vs ≤ median; OR=2.97, 95% CI; 1.18, 7.47, p = 0.005) in multivariable analyses. We also found several phthalate-responsive gene mutations in paired breast tumor tissues, which include PTPRD (76.19%), AR (42.86%), CYP1A1 (42.86%), CYP19A1 (23.81%), AHRR (19.05%), PIK3CA (19.05%), CYP1B1 (9.52%), RB1 (9.52%) and MMP9 (9.52%). Gene-enrichment analysis revealed that these genes form a major part of ER/PR, PPAR and HIF-1α-TGF-β signaling cascades involved in breast cancer CONCLUSION: Although the sample size is small, in this first case-control study from India, DBP and DEHP were found to be associated with increased risk of invasive breast cancer and tumor tissues revealed mutations in several phthalate-responsive genes. It is, therefore suggested that human biomonitoring in India and larger studies evaluating the early life genetic and epigenetic alterations on phthalates exposure are required to establish their role in breast carcinogenesis.

Skin models for dermal exposure assessment of phthalates

Phthalates are a class of compounds that have found widespread use in industrial applications, in particular in the polymer, cosmetics and pharmaceutical industries. While ingestion, and to a lesser degree inhalation, have been considered as the major exposure routes, especially for higher molecular weight phthalates, dermal exposure is an important route for lower weight phthalates such as diethyl phthalate (DEP). Assessing the dermal permeability of such compounds is of great importance for evaluating the impact and toxicity of such compounds in humans. While human skin is still the best model for studying dermal permeation, availability, cost and ethical concerns may preclude or restrict its use. A range of alternative models has been developed over time to substitute for human skin, especially in the early phases of research. These include ex vivo animal skin, human reconstructed skin and artificial skin models. While the results obtained using such alternative models correlate to a lesser or greater degree with those from in vivo human studies, the use of such models is nevertheless vital in dermal permeation research. This review discusses the alternative skin models that are available, their use in phthalate permeation studies and possible new avenues of phthalate research using skin models that have not been used so far.

Association between recurrent breast cancer and phthalate exposure modified by hormone receptors and body mass index

The association between phthalate exposure and breast cancer remains controversial. We performed a prospective patient cohort design to explore the interaction between creatinine-corrected urinary phthalate metabolites and hormone receptors as well as body mass index (BMI) on recurrent breast cancer. In this follow-up study, 636 female breast cancer patients and 45 new recurrent cases diagnosed for a total of 1576.68 person-years of follow-up were recruited. Mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) was negatively associated with breast cancer recurrence, with adjusted hazard ratio (aHR) 3rd vs. 1st quartile of 0.15 (95% CI 0.04–0.51). The MEOHP presented as a non-monotonic dose–response (NMDR) curve, being U-shaped. In the stratification of hormone receptors, MEOHP still exhibited a U-shaped dose–response curve. The third quartile of MEOHP showed significant lowest recurrent risk in the status of ER-positive (aHR 0.18, 95% CI 0.05–0.66), PR-negative (aHR 0.14, 95% CI 0.03–0.63), and HER2-negative (aHR 0.24, 95% CI 0.08–0.76). Whether in BMI < 25 or in BMI ≥ 25, the third quartile of MEOHP was negatively associated with recurrent breast cancer, and there was a negative interaction on an additive scale between MEOHP and BMI (p_interaction = 0.042). The association between MEOHP and recurrent breast cancer was modified by hormone receptors and BMI.

Elevated levels of perfluoroalkyl substances in breast cancer patients within the Greater Manila Area

Several studies have reported exposure of humans to various endocrine disrupting chemicals (EDCs) worldwide. However, there is a lack of data regarding EDC exposures in humans living in Southeast Asian countries, such as the Philippines. Hence, this study measured levels of 41 EDCs in women residing in the Greater Manila Area, home to the second largest city in Southeast Asia. Urine samples from women with versus without breast cancer were analyzed for 11 phthalate metabolites, 8 environmental phenols, and 10 bisphenols, while serum samples were analyzed for 12 perfluoroalkyl substances (PFAS). Out of the four groups of EDCs analyzed, PFAS were significantly associated with breast cancer (adjusted OR = 13.63, 95% CI: 3.24-94.88 p-trend = 0.001 for PFDoA; adjusted OR = 9.26, 95% CI 2.54-45.10, p-trend = 0.002 for PFDA; and adjusted OR = 2.66, 95% CI: 0.95-7.66, p-trend = 0.004 for PFHxA). Long-chain PFAS levels were positively correlated with age and were significantly higher in women from Region IV-A, a heavily industrialized region, than from the National Capital Region. Overall, this study showed baseline information regarding the level of EDCs in Filipinas, providing a glimpse of EDC exposure in women living in a megalopolis city in Southeast Asia.

Phthalates and Phenols, Leukocyte Telomere Length, and Breast Cancer Risk and Mortality in the Long Island Breast Cancer Study Project

BACKGROUND

Phthalates and phenols from the environment have been inconsistently associated with breast cancer risk or mortality. Studies on the potential modifying role of leukocyte telomere length (LTL), a biomarker of biological aging, on these associations are lacking.

METHODS

We included 1,268 women from the Long Island Breast Cancer Study Project with available data on phthalate and phenol analytes and LTL measurements. Twenty-two phthalate and phenol analytes were measured in spot urines and LTL was measured in blood. The modifying effect of LTL on the associations of individual analyte with breast cancer risk as well as mortalities was estimated using interaction terms between LTL and urinary concentrations of analyte in logistic regression and Cox regression models, respectively. ORs, HRs, and corresponding 95% confidence intervals for a one-unit (ln μg/g creatinine) increase of urinary phthalate/phenol level were estimated at 10th, 50th, and 90th percentiles of LTL.

RESULTS

LTL significantly (P < 0.05) modified associations between 11 of 22 of urinary phthalate/phenols analytes and breast cancer risk. An inverse association between phthalate/phenols analytes and breast cancer risk at shorter LTL and a positive association at longer LTL was generally suggested. No modifying effect was found for LTL on the association between these phthalate/phenols analytes and breast cancer mortalities.

CONCLUSIONS

LTL may modify the associations between phthalate and phenol exposures and breast cancer risk.

IMPACT

This study is the first study that determined the modifying effect of biological aging in the association between environmental chemical exposure and breast cancer risk.

Role of Notch pathway in effect of mono-2-ethylhexyl phthalate on the proliferation and cell cycle of SH-SY5Y cell

Neuroblastoma (NB) is an estrogen-dependent tumor. Mono-2-ethylhexyl phthalate (MEHP) has an estrogen-like effect. However, the effects of MEHP on the progression of NB are not well illustrated. This study was to clarify the effect of Notch pathway on proliferation and cell cycle of SH-SY5Y cell induced by MEHP. The viability of SH-SY5Y and BE2C cells were detected by CCK8; cell cycle and apoptosis were detected by flow cytometry; the protein expression levels of Notch pathway and cell cycle related proteins were detected by Western-blot. Results show that MEHP exposure can promote cell proliferation and altered the cell cycle. MEHP exposure can up-regulate the expression of C-MYC, Cyclin D1, Bcl-2 and affected the Notch pathway. In conclusion, MEHP exposure can promote NB cell proliferation and affect the cell cycle and apoptosis. Notch pathway plays a critical role in accelerating the cell cycle and inhibiting the apoptosis of SH-SY5Y cells caused by MEHP.

Hair product use and breast cancer incidence in the Black Women's Health Study

Hair relaxers and leave-in conditioners and oils, commonly used by Black/African American women, may contain estrogens or estrogen-disrupting compounds. Thus, their use may contribute to breast cancer risk. Results of the few previous studies on this topic are inconsistent. We assessed the relation of hair relaxer and leave-in conditioner use to breast cancer incidence in the Black Women's Health Study, a nationwide prospective study of Black women. Among 50 543 women followed from 1997 to 2017, 2311 incident breast cancers occurred. Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using Cox proportional hazards regression for breast cancer overall and by estrogen receptor (ER) status. For heavy use (≥15 years of use for ≥7 times/year) of hair relaxers relative to never/light use (<4 years, no more than 1-2 times/year), the multivariable HR for breast cancer overall was 1.13 (95%CI: 0.96-1.33). Duration, frequency, age at first use and number of scalp burns were not associated with overall breast cancer risk. For heavy use of hair relaxers containing lye, the corresponding HR for ER+ breast cancer was 1.32 (95% CI: 0.97, 1.80); there was no association for non-lye products. There was no association of conditioner use and breast cancer. Results of this study were largely null, but there was some evidence that heavy use of lye-containing hair relaxers may be associated with increased risk of ER+ breast cancer. Consistent results from several studies are needed before it can be concluded that use of certain hair relaxers impacts breast cancer development.

Intermittent fasting ameliorates di-(2-ethylhexyl) phthalate-induced precocious puberty in female rats: A study of the hypothalamic-pituitary-gonadal axis

Di-(2-ethylhexyl) phthalate has been reported to interfere with the development and function of animal reproductive systems. However, hardly any studies provide methods to minimize or prevent the adverse effects of DEHP on reproduction. The energy balance state of mammals is closely related to reproductive activities, and the reproductive axis can regulate reproductive activities according to changes in the body's energy balance state. In this study, the effects of every other day fasting (EODF), as a way of intermittent fasting, on preventing the precocious puberty induced by DEHP in female rats was studied. EODF significantly improved the advancement of vaginal opening age (as the markers of puberty onset) and elevated serum levels of luteinizing hormone and estradiol (detected by ELISA) induced by 5 mg kg^-1 DEHP exposure (D5). The mRNA and western blot results showed that the EODF could minimized the increase of gonadotropin-releasing hormone expression induced by DEHP exposure. The administration of DEHP could elevate the levels of kisspeptin protein and the number of kisspeptin-immunoreactive neurons in anteroventral periventricular nucleu, and this increase was diminished considerably by EODF treatment. In contrast, the D5 and D0 groups showed no remarkable difference in the level of Kiss1 expression in arcuate nucleus, whereas the D5 + EODF group had a remarkable decrease in kisspeptin expression as compared with the other two groups. Our results indicated that EODF might inhibit the acceleration of puberty onset induced by DEHP exposure via HPG axis.

Urinary phthalate exposures and risk of breast cancer: the Multiethnic Cohort study

BACKGROUND

The epidemiologic evidence from observational studies on breast cancer risk and phthalates, endocrine disrupting chemicals, has been inconsistent. In the only previous study based on pre-diagnostic urinary phthalates and risk of breast cancer, results were null in mostly white women.

METHODS

We examined the association between pre-diagnostic urinary phthalates and breast cancer in a nested case-control study within the Multiethnic Cohort (MEC) study, presenting the first data from five major racial/ethnic groups in the USA. We measured 10 phthalate metabolites and phthalic acid, using a sensitive liquid chromatography mass spectrometry assay on 1032 women with breast cancer (48 African Americans, 77 Latinos, 155 Native Hawaiians, 478 Japanese Americans, and 274 Whites) and 1030 matched controls. Conditional logistic regression was used to examine risk with individual metabolites and ratios of primary (MEHP, mono-2-ethylhexyl-phthalate) to secondary (MEHHP, mono(2-ethyl-5-hydroxyhexyl); MEOHP, mono(2-ethyl-5-oxohexy)) metabolites of di-2-ethylhexyl phthalate (DEHP), a widely used plasticizer. In addition, we investigated risk associations with high (∑HMWP) and low molecular weight (∑LMWP) phthalates, as well as total phthalates which included high and low molecular weight phthalates with phthalic acid (∑LMHMPA) or without phthalic acid in molar ratios (∑LMHMmolar) and adjusted for creatinine and potential confounders.

RESULTS

Among all women, breast cancer risk was higher for those in tertile 2 and tertile 3 of primary to secondary metabolites of DEHP (MEHP/(MEHHP + MEOHP)) in comparison to those in tertile 1; the respective odds ratios were 1.32 (95% CI 1.04-1.68) and 1.26 (95% CI 0.96-1.66) (Ptrend = 0.05). Risk among Native Hawaiian women increased with exposures to eight of ten individual phthalates and total phthalates (∑LMHMPA ORT3 vs T1 = 2.66, 95% CI 1.39-5.12, Ptrend = 0.001). In analysis by hormone receptor (HR) status, exposure above the median of ∑LMWP was associated with an increased risk of HR-positive breast cancer (OR = 1.30, 95% CI 1.05-1.60) while above the median exposure to phthalic acid was associated with an increased risk of HR-negative breast cancer (ORabove vs below median = 1.59, 95% CI 1.01-2.48).

CONCLUSIONS

Further investigations of suggestive associations of elevated breast cancer risk with higher ratios of primary to secondary metabolites of DEHP, and differences in risk patterns by race/ethnicity and HR status are warranted.

Endocrine disrupting chemicals and breast cancer: a systematic review of epidemiological studies

BACKGROUND

Endocrine-disrupting compounds (EDCs) are ubiquitous substances that are found in our everyday lives, including pesticides, plasticizers, pharmaceutical agents, personal care products, and also in food products and food packaging. Increasing epidemiological evidence suggest that EDCs may affect the development or progression of breast cancer and consequently lead to lifelong harmful health consequences, especially when exposure occurs during early life in humans. Yet so far no appraisal of the available evidence has been conducted on this topic.

OBJECTIVE

To systematically review all the available epidemiological studies about the association of the levels of environmental exposures of EDCs with breast cancer risk.

METHODS

The search was performed in accordance with the PRISMA guidelines. We retrieved articles from PubMed (MEDLINE) until 10 March 2021. The key words used in this research were: "Endocrine disruptor(s)" OR "Endocrine disrupting chemical(s)" OR any of the EDCs mentioned below AND "Breast cancer" to locate all relevant articles published. We included only cohort studies and case-control studies. All relevant articles were accessed in full text and were evaluated and summarized in tables.

RESULTS

We identified 131 studies that met the search criteria and were included in this systematic review. EDCs reviewed herein included pesticides (e.g. p,p'-dichlorodiphenyltrichloroethane (DDT), p,p'-dichlorodiphenyldichloroethylene (DDE), atrazine, 2,3,7,8-tetrachloridibenzo-p-dioxin (TCDD or dioxin)), synthetic chemicals (e.g. bisphenol A (BPA), phthalates, per- and polyfluoroalkyl substances (PFAS), parabens, polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), contraceptive pills), phytoestrogens (e.g. genistein, resveratrol), and certain mycotoxins (e.g. zearalenone). Most studies assessed environmental EDCs exposure via biomarker measurements.

CONCLUSION

We identified certain EDC exposures could potentially elevate the risk of breast cancer. As majority of EDCs are highly persistent in the environment and bio-accumulative, it is essential to assess the long-term impacts of EDC exposures, especially multi-generational and transgenerational. Also, since food is often a major route of exposure to EDCs, well-designed exposure assessments of potential EDCs in food and food packing are necessary and their potential link to breast cancer development need to be carefully evaluated for subsequent EDC policy making and regulations.

The Association of Bisphenol A and Phthalates with Risk of Breast Cancer: A Meta-Analysis

Background: Breast cancer is the most common cancer and the second leading cause of cancer-related death amongst American women. Endocrine-disrupting chemicals (EDCs), especially bisphenol A (BPA) and phthalates, have adverse effects on human health. However, the association of BPA and phthalates with breast cancer remains conflicting. This study aims to investigate the association of BPA and phthalates with breast cancer. Methods: Correlative studies were identified by systematically searching three electronic databases, namely, PubMed, Web of Sciences, and Embase, up to November 2020. All data were analyzed using Stata 15.0. Results: A total of nine studies, consisting of 7820 breast cancer cases and controls, were included. The urinary phthalate metabolite mono-benzyl phthalate (MBzP) and mono-2-isobutyl phthalate (MiBP) were negatively associated with breast cancer (OR = 0.73, 95% CI: 0.60–0.90; OR = 0.75, 95% CI: 0.58–0.98, respectively). However, the overall ORs for BPA, mono-ethyl phthalate (MEP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono-2-ethylhexyl phthalate (MEHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), mono-(3-carboxypropyl) phthalate (MCPP), and mono-butyl phthalate (MBP) were 0.85 (95% CI: 0.69–1.05), 0.96 (95% CI: 0.62–1.48), 1.12 (95% CI: 0.88–1.42), 1.13 (95% CI: 0.74–1.73), 1.01 (95% CI: 0.74–1.40), 0.74 (95% CI: 0.48–1.14), and 0.80 (95% CI: 0.55–1.15), respectively, suggesting no significant association. The sensitivity analysis indicated that the results were relatively stable. Conclusion: Phthalate metabolites MBzP and MiBP were passively associated with breast cancer, whereas no associations were found between BPA, MEP, MEHHP, MEHP, MEOHP, MCPP, and MBP and breast cancer. More high-quality case-control studies or persuasive cohort studies are urgently needed to draw the best conclusions.

Incidence of uterine leiomyoma in relation to urinary concentrations of phthalate and phthalate alternative biomarkers: A prospective ultrasound study

BACKGROUND

Numerous studies suggest that some phthalates have adverse reproductive effects. However, literature on the association between phthalates and incidence of uterine leiomyomata (UL) is limited and inconsistent, with no existing prospective studies.

OBJECTIVES

We examined the association of urinary concentrations of phthalate and phthalate alternative biomarkers with UL incidence.

METHODS

We conducted a case-cohort analysis within a subgroup of 754 participants in the Study of the Environment, Lifestyle, and Fibroids (SELF), a prospective cohort of premenopausal Black women aged 23-35 years who were recruited during 2010-2012. We quantified fourteen phthalates and two phthalate alternative [1,2-cyclohexane dicarboxylic acid, diisononyl ester (DINCH)] biomarkers in urine collected at baseline, 20 months, and 40 months. Transvaginal ultrasounds identified UL at baseline and every 20 months during 60 months of follow-up. We evaluated the individual biomarkers, molar sum of di(2-ethylhexyl) phthalate [ΣDEHP] and potency-weighted sum of anti-androgenic [WΣAA] biomarkers. We used Cox proportional hazards regression to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between biomarkers and UL incidence. We then used quantile g-computation to examine joint associations of multiple phthalate biomarkers with UL incidence.

RESULTS

Most individual biomarkers showed weak-to-moderate inverse associations with UL incidence. HRs comparing highest vs. lowest quartiles of mono-isobutyl phthalate (MiBP) and mono-hydroxyisobutyl phthalate (MHiBP) concentrations were 0.63 (95% CI: 0.40, 1.01) and 0.61 (95% CI: 0.38, 0.96), respectively. Inverse associations for specific phthalates were stronger among women with BMI ≥ 30 kg/m². HRs comparing detectable vs. nondetectable concentrations of DINCH biomarkers were 0.92 (95% CI: 0.62, 1.35) for cyclohexane-1,2-dicarboxylic acid mono hydroxyisononyl ester (MHNCH) and 0.68 (95% CI: 0.38, 1.18) for cyclohexane-1,2-dicarboxylic acid mono carboxyisoocytl ester (MCOCH). For the DEHP metabolite of mono(2-ethylhexyl) phthalate (MEHP), we observed weak-to-moderate positive associations. HRs comparing highest vs. lowest quartiles for MEHP and ΣDEHP were 1.29 (95% CI: 0.82, 2.06) and 0.96 (95% CI: 0.61, 1.50), respectively. In the mixtures analysis, the HR for a joint quartile increase in phthalate biomarker concentrations was 0.90 (95% CI: 0.73, 1.08).

DISCUSSION

In this prospective ultrasound study of reproductive-aged Black women, urinary concentrations of phthalate and DINCH biomarkers were not appreciably associated with higher risk of UL, either individually or jointly.

SGLT2 inhibitors and thiazide enhance excretion of DEHP toxic metabolites in subjects with type 2 diabetes: A randomized clinical trial

OBJECTIVE

Phthalates are non-persistent pollutants related to impaired metabolism and high cardiovascular risk. Their toxic metabolites are eliminated through urine and feces. Prevention policies are considered by the governments, although no therapeutic strategy to facilitate their elimination from the human body has been proposed so far. Aim of the present study was to verify, for the first time in humans, whether diuretics might be able to enhance phthalates' toxic metabolites urinary output.

DESIGN AND METHODS

We conducted a two-armed, parallel-design, randomized clinical trial. Thirty patients with type 2 diabetes and hypertension received a four week-treatment with Dapagliflozin 10 mg or Hydrochlorothiazide 12.5 mg. 24-hours urine were collected to measure urinary excretion of three major 2-ethylhexyl-phthalate (DEHP) metabolites, i.e. mono 2-ethylhexyl phthalate (MEHP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP) and mono 2-ethyl-5-hydroxyhexyl phthalate (MEHHP).

RESULTS

24-h urinary excretion of DEHP and MEHP was increased (+44%, p = 0.036; +49%, p = 0.0016) while MEOHP e MEHHP showed only a positive trend (+25%, p = 0.016; +36%, p = 0.062). Irrespective of the specific treatment, induced variations of daily urinary eliminations of MEHP metabolites were related with the 24-h urinary sodium (r = 0.42, p = 0.0226) and potassium (r = 0.54, p = 0.0026) excretion. Also, DEHP and MEOHP were related to sodium (r = 0·43, p = 0.0205; r = 0·44, p = 0.0168 respectively) but not to potassium.

CONCLUSIONS

Urinary phthalates excretion seems to occur mainly through sodium- and potassium-related mechanisms, apparently independent from the different diuretic effect. Both thiazide diuretics and SLGT2 inhibitors are effective into the removal of phthalates metabolites from the human body, reducing the human tissues' exposure to their toxicity.

Testing the low dose mixtures hypothesis from the Halifax project

In 2013, 60 scientists, representing a larger group of 174 scientists from 26 nations, met in Halifax, Nova Scotia to consider whether - using published research - it was logical to anticipate that a mixture of chemicals, each thought to be non-carcinogenic, might act together in that mixture as a virtual carcinogen. The group identified 89 such chemicals, each one affecting one or more Hallmark(s) - collectively covering all Hallmarks of Cancer - confirming the possibility that a chemical mixture could induce all the Hallmarks and function as a virtual carcinogen, thereby supporting the concern that chemical safety research that does not evaluate mixtures, is incomplete. Based on these observations, the Halifax Project developed the Low-Dose Carcinogenesis Hypothesis which posits "…that low-dose exposures to [mixtures of] disruptive chemicals that are not individually carcinogenic may be capable of instigating and/or enabling carcinogenesis." Although testing all possible combinations of over 80,000 chemicals of commerce would be impractical, prudence requires designing a methodology to test whether low-dose chemical mixtures might be carcinogenic. As an initial step toward testing this hypothesis, we conducted a mini review of published empirical observations of biological exposures to chemical mixtures to assess what empirical data exists on which to base future research. We reviewed studies on chemical mixtures with the criteria that the studies reported both different concentrations of chemicals and mixtures composed of different chemicals. We found a paucity of research on this important question. The majority of studies reported hormone related processes and used chemical concentrations selected to facilitate studying how mixtures behave in experiments that were often removed from clinical relevance, i.e., chemicals were not studied at human-relevant concentrations. New research programs must be envisioned to enable study of how mixtures of small doses of chemicals affect human health, starting, when at all possible, from non-malignant specimens when studies are done in vitro. This research should use human relevant concentrations of chemicals, expand research beyond the historic focus on endocrine endpoints and endocrine related cancers, and specifically seek effects that arise uniquely from exposure to chemical mixtures at human-relevant concentrations.

Gene expression profiles for low-dose exposure to diethyl phthalate in rodents and humans: a translational study with implications for breast carcinogenesis

Phthalates are commonly included as ingredients in personal care products such as cosmetics, shampoos and perfumes. Diethyl phthalate (DEP) has been found to be anti-androgenic and linked with adverse reproductive effects on males, but effects on females are poorly understood. We designed an integrative and translational study to experimentally examine the effects of DEP exposure at a human-equivalent dose on the mammary transcriptome in rats and to subsequently examine the DEP gene signature in breast tissues (both pre-malignant and tumor) from a population study. In Sprague-Dawley rats treated orally with DEP from birth to adulthood, we identified a signature panel of 107 genes predominantly down-regulated by DEP exposure. Univariate analysis of this 107 DEP gene signature in pre-malignant breast tissues revealed that six genes (P4HA1, MPZL3, TMC4, PLEKHA6, CA8, AREG) were inversely associated with monoethyl phthalate (MEP; the urinary metabolite of DEP) concentration (p < 0.05) among postmenopausal women; all six genes loaded on to one of seven factors identified by factor analysis. Transcription factor enrichment analysis revealed that genes in this factor were enriched for androgen receptor binding sites. These six genes were also significantly down-regulated in pre-malignant adjacent tissues compared to the corresponding tumor tissues in pair-wise analyses (p < 0.05). Results from our translational study indicate that low level exposure to diethyl phthalate results in measurable genomic changes in breast tissue with implications in breast carcinogenesis.

Phthalate exposure and prostate cancer in a population-based nested case-control study

BACKGROUND

Phthalic acid esters are established as endocrine disruptors. The study aimed to evaluate the association between urinary phthalate metabolites and prostate cancer occurrence.

METHODS

The study was based on the Taiwan Community-Based Cancer Screening Program, which was set up in 1991-1992 and followed periodically. By 2010, 80 incident prostate cancer cases were identified in the 12,020 men. For each case, 2 controls were randomly selected, matched by age (±3 years), urine collection date (±3 months), and residential township. Frequently used phthalate metabolites from the urine samples were quantified by liquid chromatography/electrospray ionization tandem mass spectrometry. Logistic regression was conducted to assess the association between the exposure levels and prostate cancer occurrence.

RESULTS

Exposure to di (2-ethylhexyl), butyl-benzyl and di-isobutyl phthalates (DEHP, BBzP, DiBP) was positively associated with prostate cancer in men with waist circumference (WC) ≥90 cm but not in the leans. Odds ratio for the DEHP metabolite summary score (upper tertile compared to the rest) and prostate cancer were 7.76 (95% CI = 1.95-30.9) for WC ≥ 90 cm.

CONCLUSIONS

DEHP, BBzP, and DiBP exposure were associated with prostate cancer occurrence in abdominally obese men. The main limitation remains the lack of mechanistic experiments and comparable toxicological data.

Use of skincare products and risk of cancer of the breast and endometrium: a prospective cohort study

BACKGROUND

Concerns have been raised that extensive use of personal care products that contain endocrine disrupting compounds increase the risk of hormone sensitive cancers.

OBJECTIVE

To assess the effect of skincare product use on the risk of pre- and postmenopausal breast cancer, estrogen receptor positive (ER+) and negative (ER-) breast cancer and cancer of the endometrium.

METHODS

We used data from 106,978 participants in the population-based Norwegian Women and Cancer cohort. Participants were categorized into non-, light, moderate, frequent and heavy users of skincare products based on self-reported use of hand and facial cream and body lotion. Cancer incidence information from the Cancer Registry of Norway was linked to individual data through the unique identity number of Norwegian citizens. Multivariable Cox proportional hazard regression was used to assess the effect of skincare product use on the risk of cancer of the breast and endometrium. We used multiple imputation by chained equations to evaluate the effect of missing data on observed associations.

RESULTS

We found no associations between use of skincare products and incidence of premenopausal breast cancer (frequent/heavy versus non-/light use: hazard ratio [HR] =1.10, 95% confidence interval [CI]: 0.92-1.32), postmenopausal breast cancer (heavy versus light use: HR = 0.87, 95% CI: 0.65-1.18, frequent versus light use: HR = 0.97, 95% CI: 0.88, 1.07) or endometrial cancer (frequent/heavy versus non-/light use: HR = 0.97, 95% CI: 0.79-1.20). Use of skincare products did not increase the risk of ER+ or ER- breast cancer and there was no difference in effect across ER status (0.58 ≤ pheterogeneity ≤ 0.99). The magnitude and direction of the effect estimates based on complete case analyses and multiple imputation were similar.

CONCLUSION

Heavy use of skincare products, i.e. creaming the body up to two times per day during mid-life, did not increase the risk of cancer of the breast or endometrium.

Urinary concentrations of environmental phenols and their associations with breast cancer incidence and mortality following breast cancer

BACKGROUND

Environmental phenols, compounds used widely in personal care and consumer products, are known endocrine disruptors. Few epidemiologic studies have examined the association of phenol biomarkers with breast cancer incidence and, to our knowledge, none have considered associations with mortality following breast cancer. We examined seven urinary phenol biomarkers in association with breast cancer incidence and subsequent mortality, and examined effect measure modification by body mass index (BMI).

METHODS

Participants included 711 women with breast cancer and 598 women without breast cancer who were interviewed for the population-based Long Island Breast Cancer Study Project. Among women with breast cancer, phenol biomarkers were quantified in spot urine samples collected on average within three months of a first diagnosis of primary in situ or invasive breast cancer in 1996-1997. Women with breast cancer were monitored for vital status using the National Death Index. After a median follow-up of 17.6 years, we identified 271 deaths, including 98 deaths from breast cancer. We examined creatinine-corrected phenol concentrations and the sum of parabens (Σparabens) in association with breast cancer incidence using logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs), and with mortality using Cox regression to estimate hazard ratios (HRs) and 95% CIs. We evaluated multiplicative effect measure modification using cross-product terms in nested models.

RESULTS

The highest (vs lowest) quintiles of urinary methylparaben, propylparaben, and Σparabens were associated with risk of breast cancer with ORs ranging from 1.31 to 1.50. Methylparaben, propylparaben, and Σparabens were also associated with all-cause mortality HRs ranging from 0.68 to 0.77. Associations for breast cancer incidence were more pronounced among women with BMI < 25.0 kg/m2 than among women with BMI ≥ 25.0 kg/m2; however, associations for mortality were more pronounced among women with BMI ≥ 25 kg/m2 than among women with BMI < 25 kg/m2.

CONCLUSIONS

Select parabens may have differential associations with risk of developing breast cancer and mortality following breast cancer.

Di(2-ethylhexyl) phthalate (DEHP) increases proliferation of epithelial breast cancer cells through progesterone receptor dysregulation

The di(2-ethylhexyl) phthalate (DEHP) is a plasticizer incorporated to plastic matrices of widely used consumer products. However, it is gradually released from these products, resulting in a chronic exposure for humans. Although DEHP, similar to other members of the phthalates family, is generally considered as an endocrine disruptor, the mechanisms implicated in its toxicity are yet poorly understood. Our objective was to determine the effects of an exposure to DEHP and to one of its major metabolite, the mono(2-ethylhexyl) phthalate (MEHP) on markers involved in breast carcinogenesis. T-47D cells were exposed to environmentally relevant and higher doses of DEHP and MEHP (0.1-10 000 nM) for 4 days. Our results showed that an exposure to 10 000 nM of DEHP and 0.1 nM of MEHP significantly increased the proliferation of T-47D cells, without inducing apoptosis. In addition, a significant increase in the protein levels of the isoform A of the progesterone receptor (PR) and of nuclear levels of PR were observed in T-47D cells exposed to 10 000 nM of DEHP. Importantly, the increased proliferation and nuclear levels of PR were totally and partially inhibited, respectively, by Mifepristone, a PR antagonist. These results suggest that an exposure to DEHP or MEHP increase cell proliferation by activating PR signaling, which could potentially increase the risks to develop breast cancer. The mechanism of activation of the progesterone pathway by DEHP and the long-term consequences of this activation remained to be elucidated.

Plasma levels of dichlorodiphenyldichloroethene (DDE) and dichlorodiphenyltrichloroethane (DDT) and survival following breast cancer in the Carolina Breast Cancer Study

OBJECTIVES

To examine plasma levels of dichlorodiphenyldichloroethene (DDE) and dichlorodiphenyltrichloroethane (DDT) in association with survival among women with breast cancer who participated in a population-based case-control study.

METHODS

Participants included 456 white and 292 black women from the Carolina Breast Cancer Study Phase I who were diagnosed with primary invasive breast cancer from 1993 to 1996, and who had available DDE/DDT and lipid measurements from blood samples obtained on average 4.1 months after diagnosis. Using the National Death Index, we identified 392 deaths (210 from breast cancer) over a median follow-up of 20.6 years. We used Cox regression to estimate covariate-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and breast cancer-specific 5-year mortality, and 20-year mortality conditional on 5-year survival, for lipid-standardized DDE and DDT levels. Associations stratified by race and estrogen receptor (ER) status were also examined.

RESULTS

The highest versus lowest DDE tertile and the highest vs non-detectable DDT quantile were associated with HRs of 1.95 (95% CI = 1.31-2.92) and 1.64 (95% CI = 1.10-2.44), respectively, for 20-year conditional all-cause mortality. DDE levels above versus below the median were associated with a HR of 1.69 (95% CI = 1.06-2.68) for 20-year conditional breast cancer-specific mortality among women overall, and HRs were 2.36 (95% CI = 1.03-5.42) among black women and 1.57 (95% CI = 0.86-2.89) among white women (PInteraction = 0.42), and 3.24 (95% CI = 1.38-7.58) among women with ER- tumors and 1.29 (95% CI = 0.73-2.28) among women with ER+ tumors (PInteraction = 0.03).

CONCLUSION

Exposure to DDE/DDT may adversely impact overall and breast cancer-specific survival. DDE exposure may contribute to the racial disparities in breast cancer survival.

Predictors of urinary phthalate biomarker concentrations in postmenopausal women

BACKGROUND

Phthalates are ubiquitous endocrine disrupting chemicals present in a wide variety of consumer products. However, the personal characteristics associated with phthalate exposure are unclear.

OBJECTIVES

We sought to describe personal, behavioral, and reproductive characteristics associated with phthalate metabolite concentrations in an ongoing study nested within the Women's Health Initiative (WHI).

MATERIALS AND METHODS

We measured thirteen phthalate metabolites in two or three archived urine samples collected in 1993-2001 from each of 1257 WHI participants (2991 observations). We fit multivariable generalized estimating equation models to predict urinary biomarker concentrations from personal, behavioral, and reproductive characteristics.

RESULTS

Older age was predictive of lower concentrations of monobenzyl phthalate (MBzP), mono-carboxyoctyl phthalate (MCOP), mono-3-carboxypropyl phthalate (MCPP), and the sum of di-n-butyl phthalate metabolites (ΣDBP). Phthalate metabolite concentrations varied by race/region, with generally higher concentrations observed among non-Whites and women from the West region. Higher neighborhood socioeconomic status predicted lower MBzP concentrations, and higher education predicted lower monoethyl phthalate (MEP) and higher concentrations of the sum of metabolites of di-isobutyl phthalate (ΣDiBP). Overweight/obesity predicted higher MBzP, MCOP, monocarboxynonyl phthalate (MCNP), MCPP, and the sum of metabolites of di(2-ethylhexyl) phthalate (ΣDEHP) and lower MEP concentrations. Alcohol consumption predicted higher concentrations of MEP and ΣDBP, while current smokers had higher ΣDBP concentrations. Better diet quality as assessed by Healthy Eating Index 2005 scores predicted lower concentrations of MBzP, ΣDiBP, and ΣDEHP.

CONCLUSION

Factors predictive of lower biomarker concentrations included increased age and healthy behaviors (e.g. lower alcohol intake, lower body mass index, not smoking, higher quality diet, and moderate physical activity). Racial group (generally higher among non-Whites) and geographic regions (generally higher in Northeast and West compared to South regions) also were predictive of phthalate biomarker concentrations.

Urinary Phthalate Biomarker Concentrations and Postmenopausal Breast Cancer Risk

BACKGROUND

Growing laboratory and animal model evidence supports the potentially carcinogenic effects of some phthalates, chemicals used as plasticizers in a wide variety of consumer products, including cosmetics, medications, and vinyl flooring. However, prospective data on whether phthalates are associated with human breast cancer risk are lacking.

METHODS

We conducted a nested case-control study within the Women's Health Initiative (WHI) prospective cohort (n = 419 invasive case subjects and 838 control subjects). Control subjects were matched 2:1 to case subjects on age, enrollment date, follow-up time, and WHI study group. We quantified 13 phthalate metabolites and creatinine in two or three urine samples per participant over one to three years. Multivariable conditional logistic regression analysis was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for breast cancer risk associated with each phthalate biomarker up to 19 years of follow-up.

RESULTS

Overall, we did not observe statistically significant positive associations between phthalate biomarkers and breast cancer risk in multivariable analyses (eg, 4th vs 1st quartile of diethylhexyl phthalate, OR = 1.03, 95% CI = 0.91 to 1.17). Results were generally similar in analyses restricted to disease subtypes, to nonusers of postmenopausal hormone therapy, stratified by body mass index, or to case subjects diagnosed within three, five, or ten years.

CONCLUSIONS

In the first prospective analysis of phthalates and postmenopausal breast cancer, phthalate biomarker concentrations did not result in an increased risk of developing invasive breast cancer.