A case-control study of perfluoroalkyl substances and the risk of breast cancer in Taiwanese women

Contributions of Synthetic Chemicals to Autoimmune Disease Development and Occurrence

PURPOSE OF REVIEW

Exposure to many synthetic chemicals has been linked to a variety of adverse human health effects, including autoimmune diseases. In this scoping review, we summarize recent evidence detailing the effects of synthetic environmental chemicals on autoimmune diseases and highlight current research gaps and recommendations for future studies.

RECENT FINDINGS

We identified 68 recent publications related to environmental chemical exposures and autoimmune diseases. Most studies evaluated exposure to persistent environmental chemicals and autoimmune conditions including rheumatoid arthritis (RA), systemic lupus (SLE), systemic sclerosis (SSc), and ulcerative colitis (UC) and Crohn's disease. Results of recent original research studies were mixed, and available data for some exposure-outcome associations were particularly limited. PFAS and autoimmune inflammatory bowel diseases (UC and CD) and pesticides and RA appeared to be the most frequently studied exposure-outcome associations among recent publications, despite a historical research focus on solvents. Recent studies have provided additional evidence for the associations of exposure to synthetic chemicals with certain autoimmune conditions. However, impacts on other autoimmune outcomes, particularly less prevalent conditions, remain unclear. Owing to the ubiquitous nature of many of these exposures and their potential impacts on autoimmune risk, additional studies are needed to better evaluate these relationships, particularly for understudied autoimmune conditions. Future research should include larger longitudinal studies and studies among more diverse populations to elucidate the temporal relationships between exposure-outcome pairs and to identify potential population subgroups that may be more adversely impacted by immune modulation caused by exposure to these chemicals.

Involvement of per- and polyfluoroalkyl compounds in tumor development

Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic persistent chemicals, which are used in many industrial and commercial applications. Hundreds of different PFAS have been identified in the environment and they are commonly found also in human blood. Due to the chemical stability and extensive use, PFAS pose a risk for human health and wildlife. Mounting evidence indicates that PFAS-exposure adversely affects many organs including liver, kidney, and reproductive tissues and induces tumors in laboratory rodents. Epidemiological studies show association between PFAS-exposure and some tumors also in humans. Effects of PFAS-exposure are complex and obviously do not depend only on the concentration and the structure of PFAS, but also on age and sex of the exposed individuals. It has been difficult to show a causal link between PFAS-exposure and tumors. Moreover, molecular mechanisms of the PFAS effects in different tissues are poorly understood. PFAS are not directly mutagenic and they do not induce formation of DNA binding metabolites, and thus are assumed to act more through non-genotoxic mechanisms. In this review, we discuss the involvement of PFAS-compounds in tumor development in tissues where PFAS exposure has been associated with cancer in epidemiological and animal studies (liver, kidney, testicle and breast). We will focus on molecular pathways and mechanisms related to tumor formation following PFAS-exposure.

Threats of per- and poly-fluoroalkyl pollutants to susceptible populations

Environmental exposure to per- and poly-fluoroalkyl substances (PFAS) has raised significant global health concerns due to potential hazards in healthy adults. However, the impact of PFAS on susceptible populations, including pregnant individuals, newborns, the older people, and those with underlying health conditions, has been overlooked. These susceptible groups often have physiological changes that make them less resilient to the same exposures. Consequently, there is an urgent need for a comprehensive understanding of the health risks posed by PFAS exposure to these populations. In this review, we delve into the potential health risks of PFAS exposure in these susceptible populations. Equally important, we also examine and discuss the molecular mechanisms that underlie this susceptibility. These mechanisms include the induction of oxidative stress, disruption of the immune system, impairment of cellular metabolism, and alterations in gut microbiota, all of which contribute to the enhanced toxicity of PFAS in susceptible populations. Finally, we address the primary research challenges and unresolved issues that require further investigation. This discussion aims to foster research for a better understanding of how PFAS affect susceptible populations and to pave the way for strategies to minimize their adverse effects.

Per- and polyfluoroalkyl substances, polychlorinated biphenyls, organochlorine pesticides, and polybrominated diphenyl ethers and dysregulation of MicroRNA expression in humans and animals-A systematic review

BACKGROUND

Persistent organic pollutants (POPs) are chemicals characterized by their environmental persistence. Evidence suggests that exposure to POPs, which is ubiquitous, is associated with microRNA (miRNA) dysregulation. miRNA are key regulators in many physiological processes. It is thus of public health concern to understand the relationships between POPs and miRNA as related to health outcomes.

OBJECTIVES

This systematic review evaluated the relationship between widely recognized, intentionally manufactured, POPs, including per- and polyfluoroalkyl substances (PFAS), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (dichlorodiphenyltrichloroethane [DDT], dichlorodiphenyldichloroethylene [DDE], hexachlorobenzene [HCB]), with miRNA expression in both human and animal studies.

METHODS

We used PubMed and Embase to systematically search the literature up to September 29th, 2023. Search results for human and animal studies were included if they incorporated at least one POP of interest in relation to at least one miRNA. Data were synthesized to determine the direction and significance of associations between POPs and miRNA. We utilized ingenuity pathway analysis to review disease pathways for miRNA that were associated with POPs.

RESULTS

Our search identified 38 eligible studies: 9 in humans and 29 in model organisms. PFAS were associated with decreased expression of miR-19, miR-193b, and miR-92b, as well as increased expression of miR-128, miR-199a-3p, and miR-26b across species. PCBs were associated with increased expression of miR-15a, miR-1537, miR-21, miR-22-3p, miR-223, miR-30b, and miR-34a, as well as decreased expression of miR-130a and let-7b in both humans and animals. Pathway analysis for POP-associated miRNA identified pathways related to carcinogenesis.

DISCUSSION

This is the first systematic review of the association of POPs with miRNA in humans and model organisms. Large-scale prospective human studies are warranted to examine the role of miRNA as mediators between POPs and health outcomes.

The association between per- and polyfluoroalkyl substances (PFASs) and brain, esophageal, melanomatous skin, prostate, and lung cancer using the 2003-2018 US National Health and Nutrition Examination Survey (NHANES) datasets

Introduction

The purpose of this study was to use the US National Health and Nutrition Examination Survey (NHANES) datasets to examine potential relationships between four per- and polyfluoroalkyl substance (PFAS) exposures and each type of cancer, specifically perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA).

Methods

A logistic regression analysis was performed. A directed acyclic graph was plotted to adjust for the potential confounders.

Results

The odds ratio (OR) of brain cancer for a one-unit increase in ln (PFHxS) was 8.16 (95 % confidence interval [CI] 2.98-68.89). The OR of esophageal cancer for one unit increase of ln (PFOA) and ln (PFOS) was 5.10 (95 % CI 1.18-17.34) and 3.97 (95 % CI 1.24-11.42), respectively. The OR of melanoma for one unit increase of ln (PFOA) and ln (PFHxS) was 1.65 (95 % CI 1.07-2.58) and 1.55 (95 % CI 1.07-2.25), respectively. The OR of prostate cancer for one unit increase of ln (PFOS) and ln (PFNA) was 1.21 (95 % CI 1.00-1.48) and 1.27 (95 % CI 1.00-1.62), respectively. The OR of lung cancer for one unit increase of ln (PFOS) and ln (PFNA) was 2.62 (95 % CI 1.24-5.83) and 2.38 (95 % CI 1.00-5.52), respectively.

Discussion

Considering that brain, esophageal, and melanomatous skin cancers have not been targets of epidemiologic studies regarding PFAS exposure, future studies could target these cancers as outcomes of interest.

Environment relevant exposure of perfluorooctanoic acid accelerates the growth of hepatocellular carcinoma cells through mammalian target of rapamycin (mTOR) signal pathway

Perfluorooctanoic acid (PFOA), a synthetic alkyl chain fluorinated compound, has emerged as a persistent organic pollutant of grave concern, casting a shadow over both ecological integrity and humans. Its insidious presence raises alarms due to its capacity to bioaccumulate within the human liver, potentially paving the treacherous path toward liver cancer. Yet, the intricate mechanisms underpinning PFOA's role in promoting the growth of hepatocellular carcinoma (HCC) remain shrouded in ambiguity. Here, we determined the proliferation and transcription changes of HCC after PFOA exposure through integrated experiments including cell culture, nude mice tests, and colony-forming assays. Based on our findings, PFOA effectively promotes the proliferation of HCC cells within the experimental range of concentrations, both in vivo and in vitro. The proliferation efficiency of HCC cells was observed to increase by approximately 10% due to overexposure to PFOA. Additionally, the cancer weight of tumor-bearing nude mice increased by 87.0% (p < 0.05). We systematically evaluated the effects of PFOA on HCC cells and found that PFOA's exposure can selectively activate the PI3K/AKT/mTOR/4E-BP1 signaling pathway, thereby playing a pro-cancer effect on HCC cells Confirmation echoed through western blot assays and inhibitor combination analyses. These insights summon a response to PFOA's dual nature as both an environmental threat and a promoter of liver cancer. Our work illuminates the obscured domain of PFOA-induced hepatoxicity, shedding light on its ties to hepatocellular carcinoma progression.

Association between exposure to per- and perfluoroalkyl substances (PFAS) and reproductive hormones in human: A systematic review and meta-analysis

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) is persistent endocrine disrupting chemicals. Previous evidence suggests that exposure to PFAS is associated with reproductive hormone levels, but the results of relevant studies are inconsistent. The objective of our study is to determine the association between exposure to PFAS and reproductive hormone levels in gender-specific general population.

METHOD

Based on scientific search strategies, we systematically searched PubMed, Web of Science, Embase, Medline, and Scopus to obtain the eligible studies published before January 21, 2023. The quality of the included articles was assessed using the Office of Health Assessment and Translation (OHAT) Risk of Bias tool. We combined the β coefficient and 95% confidence intervals (CI) using Stata.17 with random-effect model or fixed-effect model. We also performed subgroup analysis, sensitivity analysis, and Begger's and Egger's tests.

RESULTS

Eleven studies involving 7714 participants were included. Meta-analysis showed that PFHxS exposure was positively associated with estradiol (E2) levels in female [β = 0.030, 95% CI: (0.013, 0.046), P = 0.000]. A negative association was found between PFOA [β = -0.012, 95% CI: (-0.023, -0.002), P = 0.017] and PFOS [β = -0.011; 95% CI: (-0.021, -0.000), P = 0.042] exposure with male testosterone (TT) levels. In the subgroup analysis, there were stronger associations in children than in adults. And the high heterogeneity was mainly due to the cross-sectional studies. Publication bias was not found in most of the analyses.

CONCLUSION

Our study showed that PFAS exposure was significantly associated with reproductive hormone levels. Further related studies are needed to identify the association and potential mechanism in the future.

Case-Cohort Study of the Association between PFAS and Selected Cancers among Participants in the American Cancer Society's Cancer Prevention Study II LifeLink Cohort

BACKGROUND

Previous epidemiological studies found associations between exposure to per- and polyfluoroalkyl substances (PFAS) and some cancer types. Many studies considered highly exposed populations, so relevance to less-exposed populations can be uncertain. Additionally, many studies considered only cancer site, not histology.

OBJECTIVES

We conducted a case-cohort study within the American Cancer Society's prospective Cancer Prevention Study II (CPS-II) LifeLink cohort to examine associations between PFAS exposure and risk of selected cancers, considering histologic subtypes.

METHODS

Serum specimens were collected from cohort participants during the period 1998-2001. This study included a subcohort (500 men, 499 women) randomly selected from participants without prior cancer diagnoses at serum collection, and all participants with incident (after serum collection) first cancers of the breast (females only, n = 786 ), bladder (n = 401 ), kidney (n = 158 ), pancreas (n = 172 ), prostate (males only, n = 1,610 ) or hematologic system (n = 635 ). PFAS concentrations [perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA)] were measured in stored serum. We assessed associations between PFAS concentrations and incident cancers, by site and histologic subtype, using multivariable Cox proportional hazards models stratified by sex and controlling for age and year at blood draw, education, race/ethnicity, smoking, and alcohol use.

RESULTS

Serum PFOA concentrations were positively associated with renal cell carcinoma of the kidney among women [hazard ratio (HR) and 95% confidence interval (CI) per PFOA doubling: 1.54 (95% CI: 1.05, 2.26)] but not men. Among men, we observed a positive association between PFHxS concentrations and chronic lymphocytic leukemia/small lymphocytic lymphoma [CLL/SLL, HR and 95% CI per PFHxS doubling: 1.34 (95% CI: 1.02, 1.75)]. We observed some heterogeneity of associations by histologic subtype within sites.

DISCUSSION

This study supports the previously observed association between PFOA and renal cell carcinoma among women and suggests an association between PFHxS and CLL/SLL among men. Consideration of histologic subtypes might be important in future studies of PFAS-cancer associations. https://doi.org/10.1289/EHP13174.

Analytical methods employed in the identification and quantification of per- and polyfluoroalkyl substances in human matrices - A scoping review

Persistent organic pollutants (POPs) represent a possible hazard for the ecosystems, with adverse outcomes on wildlife and humans. POPs have always received interest from the scientific community, and they have also been subject to legal restrictions worldwide on their application and commercialization. Among the broad spectrum of POPs, per- and polyfluoroalkyl substances (PFASs) are considered emerging contaminants due to their potential effect on the ecosystem and human health. These contaminants are widely employed in countless applications, from surfactants and building materials to food packaging. On the other hand, their chemical structure gives them the ability to interact with the environment, causing possible toxic effects for humans and environment. Human biomonitoring is a necessary instrument to indagate the impact of PFASs on human health: in recent years several studies have found detectable levels of PFASs in several biological matrices in humans (blood, hair, nails, and urine). Here, we review the most recent scientific literature concerning analytical methods employed in the identification and quantification of PFASs focusing on biological matrices. It has been noted that liquid chromatography coupled with mass spectrometry is the main analytical instrumentation employed, while blood and/or serum samples are the main employed human matrices whereas the use of non-invasive matrices is still at the beginning. Various issues directly related to human metabolism of PFASs and the effective amount of PFAS absorbed from the environment still need to be investigated.

Exploratory profiles of phenols, parabens, and per- and poly-fluoroalkyl substances among NHANES study participants in association with previous cancer diagnoses

BACKGROUND

Some hormonally active cancers have low survival rates, but a large proportion of their incidence remains unexplained. Endocrine disrupting chemicals may affect hormone pathways in the pathology of these cancers.

OBJECTIVE

To evaluate cross-sectional associations between per- and polyfluoroalkyl substances (PFAS), phenols, and parabens and self-reported previous cancer diagnoses in the National Health and Nutrition Examination Survey (NHANES).

METHODS

We extracted concentrations of 7 PFAS and 12 phenols/parabens and self-reported diagnoses of melanoma and cancers of the thyroid, breast, ovary, uterus, and prostate in men and women (≥20 years). Associations between previous cancer diagnoses and an interquartile range increase in exposure biomarkers were evaluated using logistic regression models adjusted for key covariates. We conceptualized race as social construct proxy of structural social factors and examined associations in non-Hispanic Black, Mexican American, and other Hispanic participants separately compared to White participants.

RESULTS

Previous melanoma in women was associated with higher PFDE (OR:2.07, 95% CI: 1.25, 3.43), PFNA (OR:1.72, 95% CI: 1.09, 2.73), PFUA (OR:1.76, 95% CI: 1.07, 2.89), BP3 (OR: 1.81, 95% CI: 1.10, 2.96), DCP25 (OR: 2.41, 95% CI: 1.22, 4.76), and DCP24 (OR: 1.85, 95% CI: 1.05, 3.26). Previous ovarian cancer was associated with higher DCP25 (OR: 2.80, 95% CI: 1.08, 7.27), BPA (OR: 1.93, 95% CI: 1.11, 3.35) and BP3 (OR: 1.76, 95% CI: 1.00, 3.09). Previous uterine cancer was associated with increased PFNA (OR: 1.55, 95% CI: 1.03, 2.34), while higher ethyl paraben was inversely associated (OR: 0.31, 95% CI: 0.12, 0.85). Various PFAS were associated with previous ovarian and uterine cancers in White women, while MPAH or BPF was associated with previous breast cancer among non-White women.

IMPACT STATEMENT

Biomarkers across all exposure categories (phenols, parabens, and per- and poly- fluoroalkyl substances) were cross-sectionally associated with increased odds of previous melanoma diagnoses in women, and increased odds of previous ovarian cancer was associated with several phenols and parabens. Some associations differed by racial group, which is particularly impactful given the established racial disparities in distributions of exposure to these chemicals. This is the first epidemiological study to investigate exposure to phenols in relation to previous cancer diagnoses, and the first NHANES study to explore racial/ethnic disparities in associations between environmental phenol, paraben, and PFAS exposures and historical cancer diagnosis.

Systematic review and meta-analysis of breast cancer risks in relation to 2,3,7,8-tetrachlorodibenzo-p-dioxin and per- and polyfluoroalkyl substances

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and per- and polyfluoroalkyl substances (PFAS) are endocrine disrupting chemicals that may cause breast cancer. However, there lacks consistent research on the association between TCDD, PFAS exposure, and breast cancer. To this end, a meta-analysis was carried out in this review to explore the relationship between these two endocrine disruptors and breast cancer. Relevant literature was searched from 5 databases: Medline, Scopus, Embase, PubMed, and Web of Science. Odds ratios (OR) with 95% confidence intervals (CIs) were pooled by fixed-effects and random-effects meta-analysis models. A total of 17 publications were finally included for quantitative evaluation. Meta-analysis showed that TCDD (OR = 1.00, 95% CI = 0.89-1.12, I2 = 39.3%, P = 0.144), PFOA (OR = 1.07, 95% CI = 0.84-1.38, I2 = 85.9%, P < 0.001), PFOS (OR = 1.01, 95% CI = 0.95-1.08, I2 = 65.7%, P < 0.001), PFNA (OR = 0.89, 95% CI = 0.67-1.19, I2 = 74.4%, P < 0.001), and PFHxS (OR = 0.90, 95% CI = 0.72-1.13, I2 = 74%, P < 0.001) were not significantly correlated with breast cancer. Internal exposure, however, showed a significant positive correlation between TCDD and BC (OR = 2.85, 95% CI = 1.23-6.59, I2 = 0.0%, P = 0.882). No statistically significant association between TCDD, PFAS exposure, and breast cancer was observed in this meta-analysis.

Association between prenatal exposure to perfluoroalkyl substance mixtures and intrauterine growth restriction risk: A large, nested case-control study in Guangxi, China

Intrauterine growth restriction (IUGR) is an abnormal fetal growth pattern that can lead to neonatal morbidity and mortality. IUGR may be affected by prenatal exposure to environmental pollutants, including perfluoroalkyl substances (PFASs). However, research linking PFAS exposure to IUGR is limited, with inconsistent results. We aimed to investigate the association between PFAS exposure and IUGR by using nested casecontrol study based on Guangxi Zhuang Birth Cohort (GZBC), in Guangxi, China. A total of 200 IUGR cases and 600 controls were enrolled in this study. The maternal serum concentrations of nine PFASs were measured using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLCMS). The associations single and mixed effects of prenatal PFAS exposure on IUGR risk were assessed using conditional logistic regression (single-exposure), Bayesian kernel machine regression (BKMR) and quantile g-computation (qgcomp) models. In the conditional logistic regression models, the log10-transformed concentrations of perfluoroheptanoic acid (PFHpA, adjusted OR: 4.41, 95% CI: 3.03-6.41), perfluorododecanoic acid (PFDoA, adjusted OR: 1.94, 95% CI: 1.14-3.32), and perfluorohexanesulfonate (PFHxS, adjusted OR: 1.83, 95% CI: 1.15-2.91) were positively associated with risk of IUGR. In the BKMR models, the combined effect of PFASs was positively associated with IUGR risk. In the qgcomp models, we also found an increased IUGR risk (OR=5.92, 95% CI: 2.33-15.06) when all nine PFASs increased by one tertile as a whole, and PFHpA (43.9%) contributed the largest positive weights. These findings suggested prenatal exposure to single and mixtures of PFASs may increase IUGR risk, with the effect being largely driven by the PFHpA concentration.

Perfluoroalkyl substances promote breast cancer progression via ERα and GPER mediated PI3K/Akt and MAPK/Erk signaling pathways

Perfluoroalkyl substances (PFASs) are a classic environmental endocrine disruptor with carcinogenic risk. Epidemiological studies have shown that PFASs contamination is associated with breast cancer development, but the mechanism remains largely unknown. This study first obtained complex biological information about PFASs-induced breast cancer through the comparative toxicogenomics database (CTD). The Protein-Protein Interaction (PPI) network, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis were utilized to investigate molecular pathways. The ESR1 and GPER expression levels at different pathological stages and the prognosis of Breast Cancer patients were confirmed using the Cancer Genome Atlas (TCGA) database. Furthermore, we verified this by cellular experiments and the results showed breast cancer cell migration and invasion were promoted by PFOA. Two estrogen receptors (ER), ERα and G protein-coupled estrogen receptor (GPER), mediated the promoting effects of PFOA by activating MAPK/Erk and PI3K/Akt signaling pathways. These pathways were regulated by ERα and GPER in MCF-7 cells or independently by GPER in MDA-MB-231 cells. Overall, our study provides a better overview of the mechanisms associated with PFASs-induced breast cancer development and progression.

Urban-Rural Disparity in Birth Cohort Effects on Breast Cancer Incidence

Breast cancer is the most commonly diagnosed cancer among women worldwide. Studies have reported minimal birth cohort effects on the incidence rates of breast cancer in Western countries but have reported notable birth cohort effects in some Asian countries. The risks of breast cancer may also vary within a country. In the present study, we abstracted female invasive breast cancer data from the Taiwan Cancer Registry for the period 1997-2016. We used the age-period-cohort model to compare birth cohort effects on breast cancer incidence rates between urban and rural regions in Taiwan. We identified a notable urban-rural disparity in birth cohort effects on breast cancer incidence rates in women in Taiwan. The incidence rates in the urban regions were higher than those in the rural regions across all cohorts. However, the incidence rates rose faster in the rural regions than in the urban regions across the cohorts. The risks of breast cancer observed for women born in 1992 were approximately 22 and 11 times than those observed for women born in 1917 in rural and urban regions, respectively. The observed gap in breast cancer incidence rates between the urban and rural regions gradually disappeared across the cohorts. Accordingly, we speculate that urbanization and westernization in Taiwan may be the drivers of female breast cancer incidence rates across birth cohorts.

High-content analysis shows synergistic effects of low perfluorooctanoic acid (PFOS) and perfluorooctane sulfonic acid (PFOA) mixture concentrations on human breast epithelial cell carcinogenesis

Perfluoroalkyl substances (PFAS) have been associated with cancer, but the potential underlying mechanisms need to be further elucidated and include studies of PFAS mixtures. This mechanistic study revealed that very low concentrations (500 pM) of the binary PFOS and PFOA mixture induced synergistic effects on human epithelial breast cell (MCF-10A) proliferation. The cell proliferation was mediated by pregnane X receptor (PXR) activation, an increase in cyclin D1 and CDK6/4 levels, decrease in p21 and p53 levels, and by regulation of phosphor-Akt and β-catenin. The PFAS mixture also altered histone modifications, epigenetic mechanisms implicated in tumorigenesis, and promoted cell migration and invasion by reducing the levels of occludin. High-content screening using the cell painting assay, revealed that hundreds of cell features were affected by the PFAS mixture even at the lowest concentration tested (100 pM). The detailed phenotype profiling further demonstrated that the PFAS mixture altered cell morphology, mostly in parameters related to intensity and texture associated with mitochondria, endoplasmic reticulum, and nucleoli. Exposure to higher concentrations (≥50 µM) of the PFOS and PFOA mixture caused cell death through synergistic interactions that induced oxidative stress, DNA/RNA damage, and lipid peroxidation, illustrating the complexity of mixture toxicology. Increased knowledge about mixture-induced effects is important for better understanding of PFAS' possible role in cancer etiology, and may impact the risk assessment of these and other compounds. This study shows the potential of image-based multiplexed fluorescence assays and high-content screening for development of new approach methodologies in toxicology.

Critical review on phytoremediation of polyfluoroalkyl substances from environmental matrices: Need for global concern

Poly- and perfluoroalkyl substances (PFAS) are a class of emerging organic contaminants that are impervious to standard physicochemical treatments. The widespread use of PFAS poses serious environmental issues. PFAS pollution of soils and water has become a significant issue due to the harmful effects of these chemicals both on the environment and public health. Owing to their complex chemical structures and interaction with soil and water, PFAS are difficult to remove from the environment. Traditional soil remediation procedures have not been successful in reducing or removing them from the environment. Therefore, this review focuses on new phytoremediation techniques for PFAS contamination of soils and water. The bioaccumulation and dispersion of PFAS inside plant compartments has shown great potential for phytoremediation, which is a promising and unique technology that is realistic, cost-effective, and may be employed as a wide scale in situ remediation strategy.

Association between Perfluoroalkyl and Polyfluoroalkyl Substances and Women's Infertility, NHANES 2013-2016

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are widely used in consumer products. However, the role of PFAS in infertility is still poorly understood. A total of 788 women from the 2013-2016 nationally representative NHANES were included to explore the association between PFAS exposure and self-reported infertility. Six PFAS, including PFDE, PFNA, PFHxS, n-PFOA, n-PFOS, and Sm-PFOS, were detected by online SPE-HPLC-TIS-MS/MS. We used the generalized linear regression model (GLM), generalized additive models (GAM), and Bayesian kernel machine regression (BKMR) to assess the single effects, non-linear relationships, and mixed effects on women's infertility, respectively. The prevalence of self-reported infertility was 15.54% in this study. In GLM, n-PFOA showed a negative association with self-reported infertility in women for the Q3 (OR: 0.396, 95% CI: 0.119, 0.788) and Q4 (OR: 0.380, 95% CI: 0.172-0.842) compared with Q1 (p for trend = 0.013). A negative trend was also observed in n-PFOS and ∑PFOS (p for trend < 0.05). In GAM, a non-linear relationship was revealed in Sm-PFOS, which exhibits a U-shaped relationship. The BKMR model indicated that there might be a joint effect between PFAS and women's infertility, to which PFNA contributed the highest effect (PIP = 0.435). Moreover, age stratification analysis showed a different dose-response curve in under and above 35 years old. Women under the age of 35 have a more noticeable U-shaped relationship with infertility. Therefore, the relatively low level of mixed PFAS exposure was negatively associated with self-reported infertility in women in general, and the impact of PFAS on infertility may vary among women of different age groups. Further studies are needed to determine the etiological relationship.

Perfluoroalkyl substances (PFASs) as risk factors for breast cancer: a case-control study in Chinese population

BACKGROUND

Perfluoroalkyl substances (PFASs) are a large family of synthetic chemicals, some of which are mammary toxicants and endocrine disruptors. Recent studies have implicated exposure to PFASs as a risk factor for breast cancer in Europe and America. Little is known about the role of PFASs with respect to breast cancer in the Chinese population.

METHODS

Participants who were initially diagnosed with breast cancer at Tianjin Medical University Cancer Institute and Hospital between 2012 and 2016 were recruited as cases. The controls were randomly selected from the participants with available blood samples in the Chinese National Breast Cancer Screening Program (CNBCSP) cohort. Ultimately, we enrolled 373 breast cancer patients and 657 controls. Plasma PFASs were measured by an ultra-performance liquid chromatography (UPLC) system coupled to a 5500 Q-Trap triple quadrupole mass spectrometer. A logistic regression model with least absolute shrinkage and selection operator (LASSO) regularization was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) to assess the relationships between PFASs and breast cancer. The three most predictive variables in the LASSO model were selected from 17 PFASs, which was based on the optimal penalty coefficient (λ = 0.0218) identified with the minimum criterion. Additionally, Bayesian kernel machine regression (BKMR) and quantile g-computation models were applied to evaluate the associations between separate and mixed exposure to PFASs and breast cancer.

RESULTS

Perfluorooctanesulfonic acid (PFOS) exhibited the highest concentration in both the cases and controls. Perfluorooctanoic acid (PFOA) and perfluoro-n-decanoic acid (PFDA) were positively associated with breast cancer, and perfluoro-n-tridecanoic acid (PFTrDA) was negatively associated with breast cancer according to both the continuous-PFASs and the quartile-PFASs logistic regression models. Of note, PFOA was associated with the occurrence of estrogen receptor (ER)-, progesterone receptor (PR)-, and human epidermal growth factor receptor 2 (HER2)-positive breast cancer (OR_ER+  = 1.47, 95% CI: 1.19, 1.80; OR_PR+  = 1.36, 95% CI: 1.09, 1.69; OR_HER2 = 1.62, 95% CI: 1.19, 2.21).

CONCLUSIONS

Overall, we observed that PFASs were associated with breast cancer in Chinese women. Prospective cohort studies and mechanistic experiments are warranted to elucidate whether these associations are causal.

Mothers living with contamination of perfluoroalkyl substances: an assessment of the perceived health risk and self-reported diseases

Widespread contamination of the superficial, drinking, and groundwater by perfluoroalkyl substances (PFASs) was discovered in the Veneto Region (northeast of Italy) in 2013. Mothers from the contaminated area were concerned about the effects of PFAS on their own and their children's health. We determined the factors that influenced the perceived risk of PFAS and the presence of self-reported diseases by conducting a study with 384 mothers of children aged 1-13 years living in the contaminated area (Red Zone, Veneto, Italy). Information on demography, the sources of exposure, and the health condition of the mothers was collected through an online survey. The serum PFAS concentration was recorded for some of the participants. We determined the factors influencing the perceived risk, risk of health outcomes, and serum PFAS levels through regression analyses. The PFAS perceived risk of the mothers increased with an increase in the trust in scientific institutions and social media, and when many friends were present, trust in politics and full-time employment had a protective effect. The PFAS perceived risk increased the occurrences of self-reported and autoimmune diseases. Longer residence (> 20 years) in the most exposed area (Red Zone A) increased the frequency of some health outcomes. Serum PFAS concentrations decreased with breastfeeding, but increased with tap water consumption, residence in Red Zone A, and residence time. The PFAS perceived risk of the mothers was associated with many factors that influenced reporting of health issues. The association between PFAS exposure and health outcomes needs further investigation.

The association between blood PFAS concentrations and clinical biochemical measures of organ function and metabolism in participants of the Canadian Health Measures Survey (CHMS)

Per- and poly-fluoroalkyl substances (PFAS) are ubiquitous and may persist in human tissue for several years. Only a small proportion of PFAS have been studied for human health effects. We tested the association between human blood levels of six PFAS and several clinical measures of organ and metabolic function in a nationally representative sample of 6768 participants aged 3-79 years old who participated in the Canadian Health Measures Survey. Cross-sectional associations were assessed by generalized linear mixed models incorporating survey-specific sampling weights. An increase in perfluorooctanoic acid (PFOA) equivalent to the magnitude of its geometric mean (GM) of 2.0 μg/L was associated with percentage (95% CI) increases in serum enzymes reflecting liver function: aspartate aminotransferase (AST) 3.7 (1.1, 6.4), gamma-glutamyl transferase (GGT) 11.8 (2.5, 21.8), alanine aminotransferase (ALT) 3.2 (0.5, 5.9), and bilirubin 3.6 (2.7, 4.5). A GM increase in perfluorodecanoic acid (PFDA) of 0.2 μg/L was positively associated with percentage increases in GGT, triglycerides, low-density lipoprotein (LDL) cholesterol, total cholesterol, and calcium with respective increases of 15.5 (2.2, 30.4), 7.0 (1.0, 13.2), 10.7 (5.5, 16.1), 2.8 (0.2, 5.3), and 0.8 (0.3, 1.3). PFOA, perfluorooctane sulfonate (PFOS), PFDA and perfluorononanoic acid (PFNA) were positively associated with GGT. All six congeners were positively associated with at least one biomarker of lipid metabolism, and 5 of 6, PFOA, PFOS, PFDA, perfluorohexane sulfonate (PFHxS) and PFNA were positively associated with serum calcium. Exposure to selected PFAS is associated with clinical blood tests reflecting metabolism and the function of several organ systems. These relatively small changes may possibly indicate early pathology that is clinically inapparent and may possibly be of significance in a general population or in individuals exposed to very high levels of PFAS.

Associations between Polyfluoroalkyl Substances Exposure and Breast Cancer: A Meta-Analysis

Polyfluoroalkyl substances (PFASs) are persistent pollutants that may cause breast cancer. However, associations between exposure to PFASs and the risk of breast cancer are controversial. We retrieved studies on the association between PFASs—perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS), and perfluorooctane sulfonic acid (PFOS)—and breast cancer risk in women from PubMed, Embase, and the Web of Science. The pooled odds ratios (ORs) or relative risks (RRs) and their 95% confidence intervals (CIs) were extracted or calculated from provided data. Moreover, subgroup and metaregression analyses were performed to distinguish the potential sources of heterogeneity between studies. Lastly, eight original studies were included in the meta-analysis. PFOA and PFHxS were positively correlated with breast cancer risk, and the pooled ORs (and 95% CIs) were 1.32 (1.19 and 1.46) and 1.79 (1.51 and 2.11), respectively. PFNA was negatively correlated with breast cancer risk and the pooled OR (and 95% CIs) was 0.76 (0.6 and 0.96), and PFOS was shown to have no correlation with breast cancer risk and the pooled OR (and 95% CIs) was 1.01 (0.87 and 1.17). All results were merged in a random-effects model with significant heterogeneities (I2 > 90%, p < 0.001). The results demonstrated that PFASs might be potential risk factors for breast cancer, and the compounds in low exposure levels could have a more harmful impact on human health.

Exposure to Per- and Polyfluoroalkyl Substances and Mortality in U.S. Adults: A Population-Based Cohort Study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are widespread environmental contaminants associated with diseases such as cancer and dyslipidemia. However, few studies have investigated the association between PFAS mixture exposure and mortality in general populations.

OBJECTIVES

This study aimed to explore the association between PFAS mixture, perfluorooctanoic acid (PFOA), and perfluorooctane sulfonic acid (PFOS) and mortality in U.S. adults by a nationally representative cohort.

METHODS

Adults ≥18 years of age who were enrolled in the National Health and Nutrition Examination Survey (NHANES) (1999-2014) were included in our study. Baseline serum concentrations of seven PFAS were measured and individuals were followed up to 31 December 2015. Hazard ratios (HRs) and confidence intervals (CIs) were estimated using Cox proportional hazards models. Association between PFAS mixture exposure and mortality was analyzed using the k-means method by clustering PFAS mixtures into subgroups. Association between PFOA/PFOS exposure and mortality was subsequently analyzed in both continuous and categorical models.

RESULTS

During the follow-up period, 1,251 participants died. In the mixture analysis, the k-means algorithm clustered participants into low-, medium-, and high-exposure groups. Compared with the low-exposure group, participants in the high-exposure group showed significantly higher risks for all-cause mortality (HR=1.38; 95% CI: 1.07, 1.80), heart disease mortality (HR=1.58; 95% CI: 1.05, 2.51), and cancer mortality (HR=1.70; 95% CI: 1.08, 2.84). In single PFAS analysis, PFOS was found to be positively associated with all-cause mortality (third vs. first tertile HR=1.57; 95% CI: 1.22, 2.07), heart disease mortality (third vs. first tertile HR=1.65; 95% CI: 1.09, 2.57), and cancer mortality (third vs. first tertile HR=1.75; 95% CI: 1.10, 2.83), whereas PFOA exposure had no significant association with mortality. Assuming the observed association is causal, the number of deaths associated with PFOS exposure (≥17.1 vs. <7.9 ng/mL) was ∼382,000 (95% CI: 176,000, 588,000) annually between 1999 and 2015, and it decreased to 69,000 (95% CI: 28,000, 119,000) annually between 2015 and 2018. The association between PFOS and mortality was stronger among women and people without diabetes.

DISCUSSION

We observed a positive association between PFAS mixture exposure and mortality among U.S. adults. Limitations of this study include the potential for unmeasured confounding, selection bias, a relatively small number of deaths, and only measuring PFAS at one point in time. Further studies with serial measures of PFAS concentrations and longer follow-ups are necessary to elucidate the association between PFAS and mortality from specific causes. https://doi.org/10.1289/EHP10393.

In Vitro characterization of the endocrine disrupting effects of per- and poly-fluoroalkyl substances (PFASs) on the human androgen receptor

Per- and poly-fluoroalkyl substances (PFASs) are used extensively in a broad range of industrial applications and consumer products. While a few legacy PFASs have been voluntarily phased out, over 5000 PFASs have been produced as replacements for their predecessors. The potential endocrine disrupting hazards of most emerging PFASs have not been comprehensively investigated. In silico molecular docking to the human androgen receptor (hAR) combined with machine learning techniques were previously applied to 5206 PFASs and predicted 23 PFASs bind the hAR. Herein, the in silico results were validated in vitro for the five candidate AR ligands that were commercially available. Three manufactured PFASs namely (9-(nonafluorobutyl)- 2,3,6,7-tetrahydro-1 H,5 H,11 H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-11-one (NON), 2-(heptafluoropropyl)- 3-phenylquinoxaline (HEP), and 2,2,3,3,4,4,5,5,5-nonafluoro-N-(4-nitrophenyl)pentanamide (NNN) elicited significant antiandrogenic effects at relatively low concentrations. We further investigated the mechanism of AR inhibition and found that all three PFASs inhibited AR transactivation induced by testosterone through a competitive binding mechanism. We then examined the antiandrogenic effects of these PFASs on AR expression and its responsive genes. Consistently, these PFASs significantly decreased the expression of PSA and FKBP5 and increased the expression of AR, similar to the effects elicited by a known competitive AR inhibitor, hydroxyflutamide. This suggests they are competitive antagonists of AR activity and western blot analysis revealed these PFASs decreased intracellular AR protein in androgen sensitive human prostate cancer cells. Hence, the findings presented here corroborate our published in silico approach and indicate these emerging PFASs may adversely affect the human endocrine system.

Endocrine-Disrupting Chemicals and Breast Cancer: Disparities in Exposure and Importance of Research Inclusivity

Endocrine-disrupting chemicals (EDCs) are known contributors to breast cancer development. Exposures to EDCs commonly occur through food packaging, cookware, fabrics, and personal care products, as well as external environmental sources. Increasing evidence highlights disparities in EDC exposure across racial/ethnic groups, yet breast cancer research continues to lack the inclusion necessary to positively impact treatment response and overall survival in socially disadvantaged populations. Additionally, the inequity in environmental exposures has yet to be remedied. Exposure to EDCs due to structural racism poses an unequivocal risk to marginalized communities. In this review, we summarize recent epidemiological and molecular studies on 2 lesser-studied EDCs, the per- and polyfluoroalkyl substances (PFAS) and the parabens, the health disparities that exist in EDC exposure between populations, and their association with breast carcinogenesis. We discuss the importance of understanding the relationship between EDC exposure and breast cancer development, particularly to promote efforts to mitigate exposures and improve breast cancer disparities in socially disadvantaged populations.

Bioaccumulation of polyfluoroalkyl substances in the Lake Huron aquatic food web

Polyfluoroalkyl substances (PFAS) are a group of fluorinated organic chemicals that have been produced for industrial and commercial application since the 1950s. PFAS are highly persistent and ubiquitous in water, sediment, and biota. Toxic effects of PFAS on humans and the ecosystem have increased scientific and public concern. To better understand the distribution of PFAS in the Laurentian Great Lakes, carbon (¹²C and ¹³C) and nitrogen (¹⁴N and ¹⁵N) stable isotope enrichment, fatty acid profiles, and PFAS were measured in the Lake Huron (LH) aquatic food web. The trophic level of the organisms was estimated using δ¹⁵N and found to be a determinant of PFAS biomagnification. The δ¹³C and fatty acid profiles were used to assess the carbon/energy flow pathway and predator-prey relationships, respectively. The δ¹³C, δ¹⁵N, and fatty acids were used to elucidate the trophodynamics and understand the PFAS trophic transfer in the LH aquatic food web. Perfluorooctanesulfonic acid (PFOS) was the dominant PFAS observed, followed by C9 - C11 perfluorinated carboxylic acids (PFCA). The highest PFOS concentrations (45 ± 11 ng/g, wet weight (wwt)) were detected in lake trout (Salvelinus namaycush), while the highest total PFCA concentrations (sum of C4 - C16 PFCAs) were detected in deepwater sculpin (Myoxocephalus thompsonii). With the exception of perfluorooctanoic acid (PFOA), C8-C14 PFAS biomagnification factors (BMFs) were found to be generally greater than 1, suggesting PFAS biomagnification from prey to predator. Trophic magnification factors (TMFs) of C8-C14 PFCA were found to be independent of compound hydrophobicity.

Integration of Toxicogenomics and Physiologically Based Pharmacokinetic Modeling in Human Health Risk Assessment of Perfluorooctane Sulfonate

Toxicogenomics and physiologically based pharmacokinetic (PBPK) models are useful approaches in chemical risk assessment, but the methodology to incorporate toxicogenomic data into a PBPK model to inform risk assessment remains to be developed. This study aimed to develop a probabilistic human health risk assessment approach by integrating toxicogenomic dose-response data and PBPK modeling using perfluorooctane sulfonate (PFOS) as a case study. Based on the available human in vitro and mouse in vivo toxicogenomic data, we identified the differentially expressed genes (DEGs) at each exposure paradigm/duration. Kyoto Encyclopedia of Genes and Genomes and disease ontology enrichment analyses were conducted on the DEGs to identify significantly enriched pathways and diseases. The dose-response data of DEGs were analyzed using the Bayesian benchmark dose (BMD) method. Using a previously published PBPK model, the gene BMDs were converted to human equivalent doses (HEDs), which were summarized to pathway and disease HEDs and then extrapolated to reference doses (RfDs) by considering an uncertainty factor of 30 for mouse in vivo data and 10 for human in vitro data. The results suggested that the median RfDs at different exposure paradigms were similar to the 2016 U.S. Environmental Protection Agency's recommended RfD, while the RfDs for the most sensitive pathways and diseases were closer to the recent European Food Safety Authority's guidance values. In conclusion, genomic dose-response data and PBPK modeling can be integrated to become a useful alternative approach in risk assessment of environmental chemicals. This approach considers multiple endpoints, provides toxicity mechanistic insights, and does not rely on apical toxicity endpoints.

Cancer incidence in a Swedish cohort with high exposure to perfluoroalkyl substances in drinking water

BACKGROUND

The use of firefighting foams at a military airport resulted in high levels of perfluorinated substances (PFAS) in the drinking water distributed to one-third of households in the Swedish municipality of Ronneby between the mid-1980s and the end of 2013.

METHOD

The Ronneby Register Cohort, a large cohort comprising all individuals (N = 60,507) who ever lived in the Ronneby municipality during the period of drinking water contamination, was linked to the Swedish Cancer Register 1985-2016. Individual exposure was classified based on comprehensive data on yearly residential address and water distribution. External analysis explored standardized cancer incidence ratios (SIR) for residents never, or ever, residing in the contaminated water district, compared with those residing in other towns in the same county as reference population. Cox models provided hazard ratios (HR) for different exposure groups within the cohort.

RESULTS

5,702 individuals with cancer were identified. SIR for overall cancer was 1.04 for men (95%CI 0.96-1.12) and 0.89 for women (95%CI 0.82-0.96) who ever lived in the contaminated drinking water area. Kidney cancer, which was reported with increased risk in C8 study, showed somewhat elevated HR in this study (HR 1.27; 95%CI 0.85-1.89). The HR was modestly elevated for bladder cancer (HR 1.32; 95%CI 1.01-1.72), and reduced for prostate cancer (HR 0.83; 95%CI 0.71-0.98). In subjects who ever lived in the contaminated water area during 2005-2013, when exposure was estimated to be highest, higher risks for kidney cancer (HR 1.84; 95%CI 1.00-3.37) but lower for prostate cancer (HR 0.76; 95%CI 0.59-0.98) were observed.

CONCLUSION

Analysis of this large cohort exposed to high levels of PFAS, dominated by PFHxS and PFOS, revealed no evidence for an overall increased risk of cancer. A moderately increased risk of kidney cancer was observed, in accordance with previous findings after PFAS exposure dominated by PFOA.

Gestational Perfluoroalkyl Substance Exposure and DNA Methylation at Birth and 12 Years of Age: A Longitudinal Epigenome-Wide Association Study

BACKGROUND

DNA methylation alterations may underlie associations between gestational perfluoroalkyl substances (PFAS) exposure and later-life health outcomes. To the best of our knowledge, no longitudinal studies have examined the associations between gestational PFAS and DNA methylation.

OBJECTIVES

We examined associations of gestational PFAS exposure with longitudinal DNA methylation measures at birth and in adolescence using the Health Outcomes and Measures of the Environment (HOME) Study (2003-2006; Cincinnati, Ohio).

METHODS

We quantified serum concentrations of perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoate (PFNA), and perfluorohexane sulfonate (PFHxS) in mothers during pregnancy. We measured DNA methylation in cord blood (n=266) and peripheral leukocytes at 12 years of age (n=160) using the Illumina HumanMethylation EPIC BeadChip. We analyzed associations between log2-transformed PFAS concentrations and repeated DNA methylation measures using linear regression with generalized estimating equations. We included interaction terms between children's age and gestational PFAS. We performed Gene Ontology enrichment analysis to identify molecular pathways. We used Project Viva (1999-2002; Boston, Massachusetts) to replicate significant associations.

RESULTS

After adjusting for covariates, 435 cytosine-guanine dinucleotide (CpG) sites were associated with PFAS (false discovery rate, q<0.05). Specifically, we identified 2 CpGs for PFOS, 12 for PFOA, 8 for PFHxS, and 413 for PFNA; none overlapped. Among these, 2 CpGs for PFOA and 4 for PFNA were replicated in Project Viva. Some of the PFAS-associated CpG sites annotated to gene regions related to cancers, cognitive health, cardiovascular disease, and kidney function. We found little evidence that the associations between PFAS and DNA methylation differed by children's age.

DISCUSSION

In these longitudinal data, PFAS biomarkers were associated with differences in several CpGs at birth and at 12 years of age in or near genes linked to some PFAS-associated health outcomes. Future studies should examine whether DNA methylation mediates associations between gestational PFAS exposure and health. https://doi.org/10.1289/EHP10118.

Per-/polyfluoroalkyl substance concentrations in human serum and their associations with liver cancer

Per-/polyfluoroalkyl substances (PFASs) are widespread in global human blood, and have some toxic effects on liver. However, effects of PFAS exposure on human liver cancer (LC) risk are still not known. In this study, 203 LC patients and 203 controls were recruited, and their serum samples were collected between 2019 and 2021. We determined the residues of 12 PFASs in serum from all participants and quantified their association with LC incidence and tumor markers. PFOS (9.8 ng/mL) had the highest mean concentration in human serum, followed by PFOA (8.3 ng/mL) and 6:2 Cl-PFESA (3.9 ng/mL). We found that concentrations of PFOS and 6:2 Cl-PFESA in human serum were significantly correlated with the levels of alpha fetoprotein (AFP) (β_PFOS = 0.13, 95% confidence interval (CI_PFOS): 0.088, 0.17; β_{6:2 Cl-PFESA} = 0.070, CI_{6:2 Cl-PFESA}: 0.036, 0.10). A positive association of PFOS and 6:2 Cl-PFESA with odds ratios (OR) of LC (OR_PFOS = 0.609, CI_PFOS: 1.179, 4.029, P = 0.001; OR_{6:2 Cl-PFESA} = 1.844, CI_{6:2 Cl-PFESA}: 1.176, 2.512, P = 0.02) were found, after adjusting for different covariates. Moreover, serum PFOA concentrations were associated with carcinoembryonic antigen (CEA), but their correlation with the LC incidence was not statistically significant. This new finding supports the evidence for the positive associations among PFAS exposure, change of specific tumor marker, and LC risks.

Tumorigenic activity of alternative per- and polyfluoroalkyl substances (PFAS): Mechanistic in vitro studies

Environmental contaminants including long-chain per- and polyfluoroalkyl substances (PFAS) have been linked to cancer, which is a central cause of mortality in humans and many wildlife species. Today shorter-chain PFAS are extensively used as replacement compounds and commonly found in the environment. Mechanistic studies are important for a better understanding of their toxicological potential and possible role in cancer etiology. Here, we treated normal human breast epithelial cells (MCF-10A) with 500 pM to 500 μM of perfluorohexane sulfonate (PFHxS), undecafluorohexanoic acid (PFHxA), hexafluoropropylene oxide-dimer acid (GenX), perfluoro 3,6 dioxaoctanoic acid (PFO2OA), heptafluorobutyric acid (HFBA) and perfluorobutanesulfonic acid (PFBS) for 72 h to investigate potential effects on cell proliferation and neoplastic transformation. PFHxA, GenX, PFO2OA, HFBA and PFBS induced no alterations compared to controls at any of the concentrations tested. Exposure to 100 μM PFHxS on the other hand was shown to affect important regulatory cell-cycle proteins (cyclin D1, CDK6, p27, p53 and ERK) and induced cell proliferation, at least in part through activation of the constitutive androstane receptor (CAR) and the peroxisome proliferator-activated receptor alpha (PPARα). PFHxS also altered histone modifications and induced cell malignance by reducing the levels of adhesion proteins (E-cadherin and β-integrin) and promoting cell migration and invasion. These results demonstrate that five out of six alternative PFAS tested are clearly less harmful to MCF-10A cells than previously studied PFOS and PFOA, but raise concerns about PFHxS that also has been associated with breast cancer in epidemiological studies.

Per- and poly-fluoroalkyl substances (PFAS) and female reproductive outcomes: PFAS elimination, endocrine-mediated effects, and disease

Per- and poly-fluoroalkyl substances (PFAS) are widespread environmental contaminants frequently detected in drinking water supplies worldwide that have been linked to a variety of adverse reproductive health outcomes in women. Compared to men, reproductive health effects in women are generally understudied while global trends in female reproduction rates are declining. Many factors may contribute to the observed decline in female reproduction, one of which is environmental contaminant exposure. PFAS have been used in home, food storage, personal care and industrial products for decades. Despite the phase-out of some legacy PFAS due to their environmental persistence and adverse health effects, alternative, short-chain and legacy PFAS mixtures will continue to pollute water and air and adversely influence women's health. Studies have shown that both long- and short-chain PFAS disrupt normal reproductive function in women through altering hormone secretion, menstrual cyclicity, and fertility. Here, we summarize the role of a variety of PFAS and PFAS mixtures in female reproductive tract dysfunction and disease. Since these chemicals may affect reproductive tissues directly or indirectly through endocrine disruption, the role of PFAS in breast, thyroid, and hypothalamic-pituitary-gonadal axis function are also discussed as the interplay between these tissues may be critical in understanding the long-term reproductive health effects of PFAS in women. A major research gap is the need for mechanism of action data - the targets for PFAS in the female reproductive and endocrine systems are not evident, but the effects are many. Given the global decline in female fecundity and the ability of PFAS to negatively impact female reproductive health, further studies are needed to examine effects on endocrine target tissues involved in the onset of reproductive disorders of women.

Correlates of plasma concentrations of per- and poly-fluoroalkyl substances among reproductive-aged Black women

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals used in commercial and consumer goods. Black women are underrepresented in studies of PFAS exposure.

METHODS

We performed a cross-sectional analysis of correlates of plasma PFAS concentrations among 1499 Black women aged 23-35 participating in the Study of Environment, Lifestyle, and Fibroids (SELF), a Detroit-based cohort study. At baseline (2010-2012), participants provided questionnaire data on socio-demographics; behaviors; diet; and menstrual, contraceptive, and reproductive histories. Using mass spectrometry in non-fasting plasma samples collected at enrollment, we quantified several PFAS, including perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA), perfluoroundecanoate (PFUnDA), and 2-N-methyl-perfluorooctane sulfonamido acetate (MeFOSAA). We used linear regression to calculate percentage differences (%D) and 95 % confidence intervals (CIs) for associations between selected correlates and PFAS concentrations, adjusting for all other correlates.

RESULTS

PFHxS, PFOS, PFOA, and PFNA were detected in ≥97 % of women; PFDA in 86 %; MeFOSAA in 70 %; and PFUnDA in 52 %. Age, income, education, and intakes of water, alcohol, and seafood were positively associated with several PFAS. Current smoking was positively associated with MeFOSAA. Body mass index was inversely associated with most PFAS, except PFHxS. Strong inverse associations (%D; 95 % CI) were observed between parity (≥3 vs. 0 births) and PFHxS (-34.7; -43.0, -25.1) and PFOA (-33.1; -39.2, -26.3); breastfeeding duration (≥6 months vs. nulliparous) and PFOA (-31.1; -37.8, -23.7), PFHxS (-24.2; -34.5, -12.3), and PFOS (-18.4; -28.3, -7.1); recent birth (<2 years ago vs. nulliparous) and PFOA (-33.1; -39.6, -25.8), PFHxS (-29.3; -39.0, -18.1), PFNA (-25.2; -32.7, -16.8), and PFOS (-18.3; -28.3, -6.9); and intensity of menstrual bleed (heavy vs. light) and PFHxS (-18.8; -28.3, -8.2), PFOS (-16.4; -24.9, -7.1), PFNA (-10.5; -17.8, -2.6), and PFOA (-10.0; -17.2, -2.1). Current use of depot medroxyprogesterone acetate (DMPA) was positively associated with PFOS (20.2; 1.4, 42.5), PFOA (16.2; 1.5, 33.0), and PFNA (15.3; 0.4, 32.4).

CONCLUSIONS

Reproductive factors that influence PFAS elimination showed strong associations with several PFAS (reduced concentrations with parity, recent birth, lactation, heavy menstrual bleeding; increased concentrations with DMPA use).

Serum perfluoroalkyl substances and breast cancer risk in Japanese women: A case-control study

BACKGROUND

Perfluoroalkyl substances (PFASs) may contribute to causing breast cancer; however, associations between exposure to PFASs and risk of breast cancer are controversial.

OBJECTIVES

In the present study, we newly distinguished branched isomers of PFASs from their linear isomers and aimed to investigate the association between serum PFAS concentrations and breast cancer risk in Japanese women.

METHODS

We used a case-control design to study 405 eligible matched pairs attending four hospitals in Nagano Prefecture, Japan from May 2001 to September 2005. We used in-port arylation gas-chromatography mass spectrometry with negative chemical ionization to measure serum concentrations of 20 PFAS congeners. We calculated multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of breast cancer and its hormone-receptor subtypes by quartiles or tertiles of serum PFASs.

RESULTS

After multivariable adjustment for breast cancer risk factors, we found that serum concentrations of 20 PFAS congeners were significantly inversely associated with risk of breast cancer. Comparing the extreme quartiles of linear isomers of perfluorooctane sulfonate or perfluorooctanoic acid, ORs were 0.15 (95% CI: 0.07, 0.33 P for trend <0.0001) and 0.21 95% CI: 0.10, 0.44 P for trend <0.0001). Among postmenopausal women, whereas we found the linear isomer of perfluorotridecanoic acid to be inversely associated with breast cancer risk, a medium degree of exposure to the branched isomer of perfluorotridecanoic acid was associated with a marginally increased risk of breast cancer (OR [95% CI] = 1.74 [0.98, 3.09]).

DISCUSSION

In our case-control study, we found overall no association between serum PFAS concentrations and increased risk of breast cancer. Many inverse associations between serum PFAS concentrations and breast cancer risk were found.

Reproductive and environmental exposures and the breast cancer risk in Taiwanese women

Breast cancer (BC) incidence is increasing around the globe, including in Taiwan, though the cause of the increasing incidence is less clear. We followed up 11,296 Taiwanese females who did not have BC at baseline, and ascertained new invasive BC (N = 351) through data linkage to the National Cancer Registry from 1991 to 2018 to examine whether reproductive, lifestyle and environmental risk factors including polycyclic aromatic hydrocarbons (PAH) were associated with BC risk. We conducted a nested case–control study using baseline blood available from a total of 305 women with BC and 598 women without BC matched on time in cohort. We examined the association of PAH-albumin adducts and BC risk using conditional logistic regression models. Age at menarche (HR 0.6 (95% CI 0.5–0.9) for ≥ 15 vs. < 13 years) and multiparity were associated with BC risk (HR 2.0 (95% CI 1.4–2.8), 2.8 (1.9–4.2), and 2.4 (1.0–5.0) for 3–4, 1–2 and 0 live birth, compared with women ≥ 5 births). PAH-albumin adducts were not associated with BC risk. Given the increasing BC incidence in Taiwan, there is a need to identify environmental factors that are important to this population.

Per and polyfluoroalkyl substances scientific literature review: water exposure, impact on human health, and implications for regulatory reform

Among other emerging contaminants in water, per and polyfluoroalkyl substances (PFASs) have garnered international attention from the scientific community on a global scale. Some countries, such as the United States, have found that PFASs are present in humans on a wide scale. Although two PFASs have been widely studied-Perfluorooctanoic acid and Perfluorooctanesulfonic acid-many more PFASs are being created by industry and are either not known, not studied, or both. The objective of this literature review on PFASs is to give an overview of the information available about PFASs related to human exposure. The information from this literature review on the exposure of humans to PFASs through drinking water and the lack of many conventional drinking water treatment systems' ability to remove PFASs (particularly short-chain PFASs) suggests that current regulatory limits are insufficient to adequately protect humans. This is especially true for particularly vulnerable populations such as infants, young children, and developing children (pubescent). The gaps in the current knowledge and in current regulatory approaches could have long-term effects on human health.

Impact of kidney hyperfiltration on concentrations of selected perfluoroalkyl acids among US adults for various disease groups

Data from the National Health and Nutrition Examination Survey (N = 6141) for the years 2003-2016 for US adults were analyzed to evaluate the impact of glomerular hyperfiltration on the observed concentrations of perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorodecanoic acid, perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA) for several disease groups. Hyperfiltrators were defined as having an estimated glomerular filtration rate (eGFR) ≥ 110 mL/min/1.73 m², and normal filtrators were defined as those having an eGFR between 90 and 110 mL/min/1.73 m². The seven disease groups for which the data were analyzed were as follows: those (i) without any diseases; (ii) with hypertension only; (iii) with albuminuria only; (iv) with anemia only; (v) with diabetes only; (vi) with hypertension and one or more of diabetes, anemia, and albuminuria; and (vii) with two or more of diabetes, anemia, and albuminuria without hypertension. For almost every PFAA, for all seven disease groups except the albuminuria only group, hyperfiltrators had lower adjusted geometric means (AGM) than normal filtrators. For example, for the disease group with hypertension only, for PFOS, the AGMs for hyperfiltrators and normal filtrators were 8.3 and 10.6 ng/mL, respectively, for the total population. For the group with albuminuria only, normal filtrators were found to have higher AGMs than hyperfiltrators for the total population and males. For example, for PFHxS, the AGMs for normal and hyperfiltrators were 0.98 and 1.05 ng/mL, respectively, for the total population. For females, these AGMs for normal and hyperfiltrators were 0.96 and 0.86 ng/mL respectively. Males usually had higher AGMs than females, but the reverse was also true occasionally. Usually, male-female differences were substantially narrower for normal filtrators than hyperfiltrators. Irrespective of the filtration status, the disease group with hypertension only had the highest AGMs for every PFAA. AGMs for the anemia only group were the lowest for every PFAA as compared with other disease groups among hyperfiltrators.

PFAS and cancer, a scoping review of the epidemiologic evidence

BACKGROUND

The number of studies addressing per- and polyfluoroalkyl substances (PFAS) and cancer is increasing. Many communities have had water contaminated by PFAS, and cancer is one of the important community concerns related to PFAS exposure.

OBJECTIVES

We critically reviewed the evidence relating to PFAS and cancer from an epidemiologic standpoint to highlight directions for future research that would be the most likely to meaningfully increase knowledge.

METHODS

We conducted a search in PubMed for studies of cancer and PFAS (through 9/20/2020). We identified epidemiologic studies that provided a quantitative estimate for some measure of the association between PFAS and cancer. Here, we review that literature, including several aspects of epidemiologic study design that impact the usefulness of study results.

RESULTS

We identified 16 cohort (or case-cohort) studies, 10 case-control studies (4 nested within cohorts and 6 non-nested), 1 cross sectional study and 1 ecologic study. The cancer sites with the most evidence of an association with PFAS are testicular and kidney cancer. There are also some suggestions in a few studies of an association with prostate cancer, but the data are inconsistent.

DISCUSSION

Each study's design has strengths and limitations. Weaknesses in study design and methods can, in some cases, lead to questionable associations, but in other cases can make it more difficult to detect true associations, if they are present. Overall, the evidence for an association between cancer and PFAS remains sparse. A variety of studies with different strengths and weaknesses can be helpful to clarify associations between PFAS and cancer. Long term follow-up of large-sized cohorts with large exposure contrasts are most likely to be informative.

Endocrine disruption by PFAS: A major concern associated with legacy and replacement substances

Perand poly-fluorinated alkyl substances (PFAS) have been used for decades in a great variety of processes and products by virtue of their exceptional properties, versatility and chemical stability. Nevertheless, it is increasingly recognized that these substances can represent a serious hazard to human health and living organisms due to their persistence, long-range transport potential and tendency to accumulate in biota. For this reason, some efforts have been made across the EU to identify alternative molecules, with a shorter carbon chain and theoretically safer profile, that might replace the previous generation of legacy PFAS. Unfortunately, this strategy has not been entirely successful and serious concerns are still posed by PFAS in different human populations. Among others, an emerging aspect is represented by the adverse effects that both legacy and alternative PFAS can exert on the human endocrine system, with respect to vulnerable target subpopulations. In this review we will briefly summarize PFAS properties, uses and environmental fate, focusing on their effects on human reproductive capacity and fertility, body weight control and obesity as well as thyroid function.