Dioxins vs. PFAS: Science and Policy Challenges

BACKGROUND

Dioxin-like chemicals are a group of ubiquitous environmental toxicants that received intense attention in the last two decades of the 20th century. Through extensive mechanistic research and validation, the global community has agreed upon a regulatory strategy for these chemicals that centers on their common additive activation of a single receptor. Applying these regulations has led to decreased exposure in most populations studied. As dioxin-like chemicals moved out of the limelight, research and media attention has turned to other concerning contaminants, including per- and polyfluoroalkyl substances (PFAS). During the 20th century, PFAS were also being quietly emitted into the environment, but only in the last 20 years have we realized the serious threat they pose to health. There is active debate about how to appropriately classify and regulate the thousands of known PFAS and finding a solution for these "forever chemicals" is of the utmost urgency.

OBJECTIVES

Here, we compare important features of dioxin-like chemicals and PFAS, including the history, mechanism of action, and effective upstream regulatory strategies, with the objective of gleaning insight from the past to improve strategies for addressing PFAS.

DISCUSSION

The differences between these two chemical classes means that regulatory strategies for dioxin-like chemicals will not be appropriate for PFAS. PFAS exert toxicity by both receptor-based and nonreceptor-based mechanisms, which complicates mixtures evaluation and stymies efforts to develop inexpensive assays that accurately capture toxicity. Furthermore, dioxin-like chemicals were unwanted byproducts, but PFAS are useful and valuable, which has led to intense resistance against efforts to restrict their production. Nonetheless, useful lessons can be drawn from dioxin-like chemicals and applied to PFAS, including eliminating nonessential production of new PFAS and proactive investment in environmental remediation to address their extraordinarily long environmental persistence. https://doi.org/10.1289/EHP14449.

The Conflict between Regulatory Agencies over the 20,000-Fold Lowering of the Tolerable Daily Intake (TDI) for Bisphenol A (BPA) by the European Food Safety Authority (EFSA)

BACKGROUND

The European Food Safety Authority (EFSA) recommended lowering their estimated tolerable daily intake (TDI) for bisphenol A (BPA) 20,000-fold to 0.2  ng / kg  body weight  ( BW ) / day . BPA is an extensively studied high production volume endocrine disrupting chemical (EDC) associated with a vast array of diseases. Prior risk assessments of BPA by EFSA as well as the US Food and Drug Administration (FDA) have relied on industry-funded studies conducted under good laboratory practice protocols (GLP) requiring guideline end points and detailed record keeping, while also claiming to examine (but rejecting) thousands of published findings by academic scientists. Guideline protocols initially formalized in the mid-twentieth century are still used by many regulatory agencies. EFSA used a 21st century approach in its reassessment of BPA and conducted a transparent, but time-limited, systematic review that included both guideline and academic research. The German Federal Institute for Risk Assessment (BfR) opposed EFSA's revision of the TDI for BPA.

OBJECTIVES

We identify the flaws in the assumptions that the German BfR, as well as the FDA, have used to justify maintaining the TDI for BPA at levels above what a vast amount of academic research shows to cause harm. We argue that regulatory agencies need to incorporate 21st century science into chemical hazard identifications using the CLARITY-BPA (Consortium Linking Academic and Regulatory Insights on BPA Toxicity) nonguideline academic studies in a collaborative government-academic program model.

DISCUSSION

We strongly endorse EFSA's revised TDI for BPA and support the European Commission's (EC) apparent acceptance of this updated BPA risk assessment. We discuss challenges to current chemical risk assessment assumptions about EDCs that need to be addressed by regulatory agencies to, in our opinion, become truly protective of public health. Addressing these challenges will hopefully result in BPA, and eventually other structurally similar bisphenols (called regrettable substitutions) for which there are known adverse effects, being eliminated from all food-related and many other uses in the EU and elsewhere. https://doi.org/10.1289/EHP13812.

Does fluoride exposure affect thyroid function? A systematic review and dose-response meta-analysis

INTRODUCTION

Fluoride exposure may have various adverse health effects, including affecting thyroid function and disease risk, but the pattern of such relation is still uncertain.

METHODS

We systematically searched human studies assessing the relation between fluoride exposure and thyroid function and disease. We compared the highest versus the lowest fluoride category across these studies, and we performed a one-stage dose-response meta-analysis for aggregated data to explore the shape of the association.

RESULTS

Most retrieved studies (27 of which with a cross-sectional design) were conducted in Asia and in children, assessing fluoride exposure through its concentrations in drinking water, urine, serum, or dietary intake. Twenty-four studies reported data on thyroid function by measuring thyroid-related hormones in blood (mainly thyroid-stimulating-hormone - TSH), 9 reported data on thyroid disease, and 4 on thyroid volume. By comparing the highest versus the lowest fluoride categories, overall mean TSH difference was 1.05 μIU/mL. Dose-response curve showed no change in TSH concentrations in the lowest water fluoride exposure range, while the hormone levels started to linearly increase around 2.5 mg/L, also dependending on the risk of bias of the included studies. The association between biomarkers of fluoride exposure and TSH was also positive, with little evidence of a threshold. Evidence for an association between fluoride exposure and blood concentrations of thyroid hormones was less evident, though there was an indication of inverse association with triiodothyronine. For thyroid disease, the few available studies suggested a positive association with goiter and with hypothyroidism in both children and adults.

CONCLUSIONS

Overall, exposure to high-fluoride drinking water appears to non-linearly affect thyroid function and increase TSH release in children, starting above a threshold of exposure, and to increase the risk of some thyroid diseases.

Opportunities in Assessing and Regulating Organohalogen Flame Retardants (OFRs) as a Class in Consumer Products

BACKGROUND

In 2015, the U.S. Consumer Product Safety Commission (CPSC) received and then, in 2017, granted a petition under the Federal Hazardous Substances Act to declare certain groups of consumer products as banned hazardous substances if they contain nonpolymeric, additive organohalogen flame retardants (OFRs). The petitioners asked the CPSC to regulate OFRs as a single chemical class with similar health effects. The CPSC later sponsored a National Academy of Sciences, Engineering, and Medicine (NASEM) report in 2019, which ultimately identified 161 OFRs and grouped them into 14 subclasses based on chemical structural similarity. In 2021, a follow-up discussion was held among a group of scientists from both inside and outside of the CPSC for current research on OFRs and to promote collaboration that could increase public awareness of CPSC work and support the class-based approach for the CPSC's required risk assessment of OFRs.

OBJECTIVES

Given the extensive data collected to date, there is a need to synthesize what is known about OFR and how class-based regulations have previously managed this information. This commentary discusses both OFR exposure and OFR toxicity and fills some gaps for OFR exposure that were not within the scope of the NASEM report. The objective of this commentary is therefore to provide an overview of the OFR research presented at SOT 2021, explore opportunities and challenges associated with OFR risk assessment, and inform CPSC's work on an OFR class-based approach.

DISCUSSION

A class-based approach for regulating OFRs can be successful. Expanding the use of read-across and the use of New Approach Methodologies (NAMs) in assessing and regulating existing chemicals was considered as a necessary part of the class-based process. Recommendations for OFR class-based risk assessment include the need to balance fire and chemical safety and to protect vulnerable populations, including children and pregnant women. The authors also suggest the CPSC should consider global, federal, and state OFR regulations. The lack of data or lack of concordance in toxicity data could present significant hurdles for some OFR subclasses. The potential for cumulative risks within or between subclasses, OFR mixtures, and metabolites common to more than one OFR all add extra complexity for class-based risk assessment. This commentary discusses scientific and regulatory challenges for a class-based approach suggested by NASEM. This commentary is offered as a resource for anyone performing class-based assessments and to provide potential collaboration opportunities for OFR stakeholders. https://doi.org/10.1289/EHP12725.

Fluoride Exposure and Skeletal Fluorosis: a Systematic Review and Dose-response Meta-analysis

PURPOSE OF REVIEW

We performed a systematic review and meta-analysis on the relation between fluoride exposure and skeletal fluorosis (SF) using a novel statistical methodology for dose-response modeling.

RECENT FINDINGS

Skeletal fluorosis, a major health issue that is endemic in some regions, affects millions of people worldwide. However, data regarding the dose-response relation between fluoride exposure and SF are limited and outdated. We included twenty-three studies in the meta-analysis. When comparing the highest versus the lowest fluoride category, the summary risk ratio (RR) for SF prevalence was 2.05 (95% CI 1.60; 2.64), with a value of 2.73 (95% CI 1.92; 3.90) for drinking water and 1.40 (95% CI 0.90; 2.17) for urinary fluoride. The RR by the risk of bias (RoB) was 2.37 (95% CI 1.56; 3.58) and 1.78 (95% CI 1.34; 2.36) for moderate and high RoB studies, respectively. The dose-response curve based on a one-stage cubic spline regression model showed an almost linear positive relation between exposure and SF occurrence starting from relatively low concentrations up to 5 mg/L and 2.5 mg/L, respectively, for water and urinary fluoride, with no substantial increase above this threshold. The RR for developing moderate-severe forms increases at 5.00 mg/L and 2.5 mg/L of water and urinary fluoride, respectively. Better-quality studies are needed to confirm these results, but greater attention should be given to water fluoride levels to prevent SF, in addition to the other potential adverse effects of fluoride exposure.

European Medicines Agency Conflicts With the European Food Safety Authority (EFSA) on Bisphenol A Regulation

The European Food Safety Authority (EFSA) has revised their estimate of the toxicity of bisphenol A (BPA) and, as a result, have recommended reducing the tolerable daily intake (TDI) by 20 000-fold. This would essentially ban the use of BPA in food packaging such as can liners, plastic food containers, and in consumer products. To come to this conclusion, EFSA used a systematic approach according to a pre-established protocol and included all guideline and nonguideline studies in their analysis. They found that Th-17 immune cells increased with very low exposure to BPA and used this endpoint to revise the TDI to be human health protective. A number of regulatory agencies including the European Medicines Agency (EMA) have written formal disagreements with several elements of EFSA's proposal. The European Commission will now decide whether to accept EFSA's recommendation over the objections of EMA. If the Commission accepts EFSA's recommendation, it will be a landmark action using knowledge acquired through independent scientific studies focused on biomarkers of chronic disease to protect human health. The goal of this Perspective is to clearly articulate the monumental nature of this debate and decision and to explain what is at stake. Our perspective is that the weight of evidence clearly supports EFSA's proposal to reduce the TDI by 20 000-fold.

Effective communications strategies to increase the impact of environmental health research

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are the subject of a growing body of research with the potential to positively impact public and ecological health. However, to effect positive change, findings must be communicated beyond the scientific community.

OBJECTIVE

We sought to (a) evaluate the relationships between communications strategy, media attention, and scholarly citations of PFAS research and (b) offer guidance for researchers and communications professionals who would like to publicize future work and increase its impact.

METHODS

We analyzed 273 peer-reviewed epidemiological studies on PFAS human health impacts with publication years 2018-2020, as collected by a pre-existing database. We investigated whether a press release was issued, open-access status, abstract and press release readability, timing of publication and press release distribution, journal impact factor, study type and sample size, statistical significance of finding(s), number of scholarly citations, and the Altmetric Attention Score (a measure of media attention).

DISCUSSION

Of papers reporting a statistically significant association with health harm, those with a press release received 20 times more media attention (as assessed by Altmetric scores) than those that did not. However, only 6.2% of all papers and 7.8% of significant papers issued one. Among papers with a press release, media attention was positively correlated with better abstract and press release readability and speed in issuing the press release. Scholarly citations were positively correlated with media attention, presence of a press release, and open-access status.

CONCLUSION

Most papers with significant findings on PFAS are published without a press release and receive little or no media attention. This reduces the likelihood that important research is reaching the public and decisionmakers who can translate science into action. Issuing a press release and receiving media attention also appear to increase scholarly citations. We provide recommendations for authors to increase the reach and impact of future papers.

Polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, pesticides, and diabetes in the Anniston Community Health Survey follow-up (ACHS II): single exposure and mixture analysis approaches

Dioxins and dioxin-like compounds measurements were added to polychlorinated biphenyls (PCBs) and organochlorine pesticides to expand the exposure profile in a follow-up to the Anniston Community Health Survey (ACHS II, 2014) and to study diabetes associations. Participants of ACHS I (2005-2007) still living within the study area were eligible to participate in ACHS II. Diabetes status (type-2) was determined by a doctor's diagnosis, fasting glucose ≥125 mg/dL, or being on any glycemic control medication. Incident diabetes cases were identified in ACHS II among those who did not have diabetes in ACHS I, using the same criteria. Thirty-five ortho-substituted PCBs, 6 pesticides, 7 polychlorinated dibenzo-p-dioxins (PCDD), 10 furans (PCDF), and 3 non-ortho PCBs were measured in 338 ACHS II participants. Dioxin toxic equivalents (TEQs) were calculated for all dioxin-like compounds. Main analyses used logistic regression models to calculate odds ratios (OR) and 95 % confidence intervals (CI). In models adjusted for age, race, sex, BMI, total lipids, family history of diabetes, and taking lipid lowering medication, the highest ORs for diabetes were observed for PCDD TEQ: 3.61 (95 % CI: 1.04, 12.46), dichloro-diphenyl dichloroethylene (p,p'-DDE): 2.07 (95 % CI 1.08, 3.97), and trans-Nonachlor: 2.55 (95 % CI 0.93, 7.02). The OR for sum 35 PCBs was 1.22 (95 % CI: 0.58-2.57). To complement the main analyses, we used BKMR and g-computation models to evaluate 12 mixture components including 4 TEQs, 2 PCB subsets and 6 pesticides; suggestive positive associations for the joint effect of the mixture analyses resulted in ORs of 1.40 (95% CI: -1.13, 3.93) for BKMR and 1.32 (95% CI: -1.12, 3.76) for g-computation. The mixture analyses provide further support to previously observed associations of trans-Nonachlor, p,p'- DDE, PCDD TEQ and some PCB groups with diabetes.

Fluoride exposure and cognitive neurodevelopment: Systematic review and dose-response meta-analysis

Many uncertainties still surround the possible harmful effect of fluoride exposure on cognitive neurodevelopment in children. The aim of this systematic review and meta-analysis was to characterize this relation through a dose-response approach, by comparing the intelligence quotient (IQ) scores in the highest versus the lowest fluoride exposure category with a random-effects model, within a one-stage dose-response meta-analysis based on a cubic spline random-effects model. Out of 1996 potentially relevant literature records, 33 studies were eligible for this review, 30 of which were also suitable for meta-analysis. The summary mean difference of IQ score, comparing highest versus lowest fluoride categories and considering all types of exposure, was -4.68 (95% confidence interval-CI -6.45; -2.92), with a value of -5.60 (95% CI -7.76; -3.44) for drinking water fluoride and -3.84 (95% CI -7.93; 0.24) for urinary fluoride. Dose-response analysis showed a substantially linear IQ decrease for increasing water fluoride above 1 mg/L, with -3.05 (95% CI -4.06; -2.04) IQ points per 1 mg/L up to 2 mg/L, becoming steeper above such level. A weaker and substantially linear decrease of -2.15 (95% CI -4.48; 0.18) IQ points with increasing urinary fluoride emerged above 0.28 mg/L (approximately reflecting a water fluoride content of 0.7 mg/L). The inverse association between fluoride exposure and IQ was particularly strong in the studies at high risk of bias, while no adverse effect emerged in the only study judged at low risk of bias. Overall, most studies suggested an adverse effect of fluoride exposure on children's IQ, starting at low levels of exposure. However, a major role of residual confounding could not be ruled out, thus indicating the need of additional prospective studies at low risk of bias to conclusively assess the relation between fluoride exposure and cognitive neurodevelopment.

A new consensus on reconciling fire safety with environmental & health impacts of chemical flame retardants

Flame retardants are chemical substances that are intended to mitigate fire safety risks posed by a range of goods including furniture, electronics, and building insulation. There are growing concerns about their effectiveness in ensuring fire safety and the potential harms they pose to human health and the environment. In response to these concerns, on 13 June 2022, a roundtable of experts was convened by the UKRI Six Clean Air Strategic Priorities Fund programme 7. The meeting produced a Consensus Statement that summarises the issues around the use of flame retardants, laying out a series of policy recommendations that should lead to more effective fire safety measures and reduce the human and environmental health risks posed by these potentially toxic chemicals.

Advancing the science on chemical classes

BACKGROUND

Hazard identification, risk assessment, regulatory, and policy activity are usually conducted on a chemical-by-chemical basis. Grouping chemicals into categories or classes is an underutilized approach that could make risk assessment and management of chemicals more efficient for regulators.

OBJECTIVE AND METHODS

While there are some available methods and regulatory frameworks that include the grouping of chemicals (e.g.,same molecular mechanism or similar chemical structure) there has not been a comprehensive evaluation of these different approaches nor a recommended course of action to better consider chemical classes in decision-making. This manuscript: 1) reviews current national and international approaches to grouping; 2) describes how groups could be defined based on the decision context (e.g., hazard/risk assessment, restrictions, prioritization, product development) and scientific considerations (e.g., intrinsic physical-chemical properties); 3) discusses advantages of developing a decision tree approach for grouping; 4) uses ortho-phthalates as a case study to identify and organize frameworks that could be used across agencies; and 5) discusses opportunities to advance the class concept within various regulatory decision-making scenarios.

RESULTS

Structural similarity was the most common grouping approach for risk assessment among regulatory agencies (national and state level) and non-regulatory organizations, albeit with some variations in its definition. Toxicity to the same target organ or to the same biological function was also used in a few cases. The phthalates case study showed that a decision tree approach for grouping should include questions about uses regulated by other agencies to encourage more efficient, coherent, and protective chemical risk management.

DISCUSSION AND CONCLUSION

Our evaluation of how classes of chemicals are defined and used identified commonalities and differences based on regulatory frameworks, risk assessments, and business strategies. We also identified that using a class-based approach could result in a more efficient process to reduce exposures to multiple hazardous chemicals and, ultimately, reduce health risks. We concluded that, in the absence of a prescribed method, a decision tree approach could facilitate the selection of chemicals belonging to a pre-defined class (e.g., chemicals with endocrine-disrupting activity; organohalogen flame retardants [OFR]) based on the decision-making context (e.g., regulatory risk management).

A science-based agenda for health-protective chemical assessments and decisions: overview and consensus statement

The manufacture and production of industrial chemicals continues to increase, with hundreds of thousands of chemicals and chemical mixtures used worldwide, leading to widespread population exposures and resultant health impacts. Low-wealth communities and communities of color often bear disproportionate burdens of exposure and impact; all compounded by regulatory delays to the detriment of public health. Multiple authoritative bodies and scientific consensus groups have called for actions to prevent harmful exposures via improved policy approaches. We worked across multiple disciplines to develop consensus recommendations for health-protective, scientific approaches to reduce harmful chemical exposures, which can be applied to current US policies governing industrial chemicals and environmental pollutants. This consensus identifies five principles and scientific recommendations for improving how agencies like the US Environmental Protection Agency (EPA) approach and conduct hazard and risk assessment and risk management analyses: (1) the financial burden of data generation for any given chemical on (or to be introduced to) the market should be on the chemical producers that benefit from their production and use; (2) lack of data does not equate to lack of hazard, exposure, or risk; (3) populations at greater risk, including those that are more susceptible or more highly exposed, must be better identified and protected to account for their real-world risks; (4) hazard and risk assessments should not assume existence of a "safe" or "no-risk" level of chemical exposure in the diverse general population; and (5) hazard and risk assessments must evaluate and account for financial conflicts of interest in the body of evidence. While many of these recommendations focus specifically on the EPA, they are general principles for environmental health that could be adopted by any agency or entity engaged in exposure, hazard, and risk assessment. We also detail recommendations for four priority areas in companion papers (exposure assessment methods, human variability assessment, methods for quantifying non-cancer health outcomes, and a framework for defining chemical classes). These recommendations constitute key steps for improved evidence-based environmental health decision-making and public health protection.

Chemical Effects on Breast Development, Function, and Cancer Risk: Existing Knowledge and New Opportunities

Population studies show worrisome trends towards earlier breast development, difficulty in breastfeeding, and increasing rates of breast cancer in young women. Multiple epidemiological studies have linked these outcomes with chemical exposures, and experimental studies have shown that many of these chemicals generate similar effects in rodents, often by disrupting hormonal regulation. These endocrine-disrupting chemicals (EDCs) can alter the progression of mammary gland (MG) development, impair the ability to nourish offspring via lactation, increase mammary tissue density, and increase the propensity to develop cancer. However, current toxicological approaches to measuring the effects of chemical exposures on the MG are often inadequate to detect these effects, impairing our ability to identify exposures harmful to the breast and limiting opportunities for prevention. This paper describes key adverse outcomes for the MG, including impaired lactation, altered pubertal development, altered morphology (such as increased mammographic density), and cancer. It also summarizes evidence from humans and rodent models for exposures associated with these effects. We also review current toxicological practices for evaluating MG effects, highlight limitations of current methods, summarize debates related to how effects are interpreted in risk assessment, and make recommendations to strengthen assessment approaches. Increasing the rigor of MG assessment would improve our ability to identify chemicals of concern, regulate those chemicals based on their effects, and prevent exposures and associated adverse health effects.

Presumptive Contamination: A New Approach to PFAS Contamination Based on Likely Sources

While research and regulatory attention to per- and polyfluoroalkyl substances (PFAS) has increased exponentially in recent years, data are uneven and incomplete about the scale, scope, and severity of PFAS releases and resulting contamination in the United States. This paper argues that in the absence of high-quality testing data, PFAS contamination can be presumed around three types of facilities: (1) fluorinated aqueous film-forming foam (AFFF) discharge sites, (2) certain industrial facilities, and (3) sites related to PFAS-containing waste. While data are incomplete on all three types of presumptive PFAS contamination sites, we integrate available geocoded, nationwide data sets into a single map of presumptive contamination sites in the United States, identifying 57,412 sites of presumptive PFAS contamination: 49,145 industrial facilities, 4,255 wastewater treatment plants, 3,493 current or former military sites, and 519 major airports. This conceptual approach allows governments, industries, and communities to rapidly and systematically identify potential exposure sources.

Biomonitoring of Polybrominated Dioxins & Furans, Polychlorinated Dioxins & Furans, and Dioxin Like Polychlorinated Biphenyls in Vietnamese Female Electronic Waste Recyclers

OBJECTIVE

E-waste is rising globally. This is a follow up to our study reporting metals/polybrominated diphenyl ethers (PBDE's)/polychlorinated biphenyls (PCBs) in female e-waste recyclers. Here we report polybrominated, polychlorinated dioxins/furans, and dioxin-like polychlorinated biphenyls in these same workers.

METHODS

Female Vietnamese recyclers and non-recyclers recruited; blood samples collected. Polybrominated, polychlorinated dioxins/furans, and dioxin-like polychlorinated biphenyls levels compared in recyclers, non-recyclers, and National Health and Nutrition Examination Surveys (NHANES).

RESULTS

Recyclers >non-recyclers: 12378-PBDD, 2378-TBDF, 12378-PCDF, 123478-HxCDF, 123678-HxCDF, 1234678-HpCDF, PCB-126. Non-recyclers >NHANES: 123478-HxCDF, 123678-HxCDF, 234678- HxCDF, PCB-126, PCB-169. NHANES >non-recyclers: 12378-PCDD, 123478-HxCDD, 123678-HxCDD, 123789-HxCDD, 1234678-HpCDD, 123789-HxCDF, 1234678-HpCDF, 1234789-HpCDF, OCDF, PCB-81, PCB-114, PCB-156, PCB-157, PCB-167, PCB-189. Recyclers >NHANES: S: 2378-TeCDF, 12378-PCDF, 23478-PCDF, 123478-HxCDF, 123678- HxCDF, 234678-HxCDF, PCB-126. NHANES >recyclers: 12378-PCDD, 123478-HxCDD, 123678-HxCDD, 123789-HxCDD, 1234678-HpCDD, OCDD, 123789-HxCDF, 1234678-HpCDF, 1234789-HpCDF, OCDF, PCB- 81, PCB-114, PCB-156, PCB-157, PCB-189.

CONCLUSION

12378 PCDD, 2378-TCDD, PCB 126 makeup most total dioxin equivalences (TEQs) in AQ5 these workers, indicating increased exposure; remediation indicated.

Expanded assessment of xenobiotic associations with antinuclear antibodies in the United States, 1988-2012

BACKGROUND

The prevalence of autoimmunity in the U.S. has increased recently for undetermined reasons. Little is known about associations between autoimmunity and environmental causes.

OBJECTIVES

In a large representative sample of the U.S. population, we expanded our prior exploratory study of how exposures to selected xenobiotics and dioxin-like (DL) mixtures relate to antinuclear antibodies (ANA), the most common biomarker of autoimmunity.

METHODS

We analyzed cross-sectional data on 12,058 participants aged ≥ 12 years from three time periods of the National Health and Nutrition Examination Survey between 1988 and 2012, of whom 14% were ANA-positive. We used lognormal regression models and censored-data methods to estimate ANA associations with xenobiotic concentrations overall and in sex, age, and race/ethnicity subgroups. Our analyses adjusted for potential confounders and appropriately handled concentrations below detection limits.

RESULTS

Observed ANA associations were positive for most DL compounds and nonDL polychlorinated biphenyls (PCBs), negative for most phthalates, and mixed for other xenobiotic classes. After correcting for multiple comparisons, some associations remained statistically significant. In subgroup analyses, the most significant finding was a positive ANA association with N-acetyl-S-(2-hydroxy-3-butenyl)-L-cysteine (MHB2) in males, followed by positive associations with 2,2',3,5'-tetrachlorobiphenyl (PCB 44), 2,2',4,5'-tetrachlorobiphenyl (PCB 49), and 2,2',3,4',5',6-hexachlorobiphenyl (PCB 149) in 12-19 year-olds, and with 3,4,4',5-tetrachlorobiphenyl (PCB 81), 2,2',3,3',4,4',5,5',6-nonachlorobiphenyl (PCB 206), and N-acetyl-S-(phenyl)-L-cysteine (PMA) in Mexican Americans. Negative associations were found with mono-benzyl phthalate (MBzP) in 20-49 year-olds and mono-n-butyl phthalate (MnBP) in 12-19 year-olds. In overall analyses, combining stratum-specific results across race/ethnicity strata revealed a positive ANA association with PCB 81 and a negative ANA association with N-acetyl-S-(2-hydroxyethyl)-L-cysteine (HEMA).

DISCUSSION

This study identified potential associations between ANA and various xenobiotics. Further investigation to confirm these observations and elucidate effects of certain xenobiotics on immune regulation could have important mechanistic, preventive, and treatment implications for a variety of immune-mediated disorders.

Circulating MicroRNAs, Polychlorinated Biphenyls, and Environmental Liver Disease in the Anniston Community Health Survey

BACKGROUND

Polychlorinated biphenyl (PCB) exposures have been associated with liver injury in human cohorts, and steatohepatitis with liver necrosis in model systems. MicroRNAs (miRs) maintain cellular homeostasis and may regulate the response to environmental stress.

OBJECTIVES

We tested the hypothesis that specific miRs are associated with liver disease and PCB exposures in a residential cohort.

METHODS

Sixty-eight targeted hepatotoxicity miRs were measured in archived serum from 734 PCB-exposed participants in the cross-sectional Anniston Community Health Survey. Necrotic and other liver disease categories were defined by serum keratin 18 (K18) biomarkers. Associations were determined between exposure biomarkers (35 ortho-substituted PCB congeners) and disease biomarkers (highly expressed miRs or previously measured cytokines), and Ingenuity Pathway Analysis was performed.

RESULTS

The necrotic liver disease category was associated with four up-regulated miRs (miR-99a-5p, miR-122-5p, miR-192-5p, and miR-320a) and five down-regulated miRs (let-7d-5p, miR-17-5p, miR-24-3p, miR-197-3p, and miR-221-3p). Twenty-two miRs were associated with the other liver disease category or with K18 measurements. Eleven miRs were associated with 24 PCBs, most commonly congeners with anti-estrogenic activities. Most of the exposure-associated miRs were associated with at least one serum hepatocyte death, pro-inflammatory cytokine or insulin resistance bioarker, or with both. Within each biomarker category, associations were strongest for the liver-specific miR-122-5p. Pathways of liver toxicity that were identified included inflammation/hepatitis, hyperplasia/hyperproliferation, cirrhosis, and hepatocellular carcinoma. Tumor protein p53 and tumor necrosis factor α were well integrated within the top identified networks.

DISCUSSION

These results support the human hepatotoxicity of environmental PCB exposures while elucidating potential modes of PCB action. The MiR-derived liquid liver biopsy represents a promising new technique for environmental hepatology cohort studies. https://doi.org/10.1289/EHP9467.

Serum concentrations of legacy and emerging per- and polyfluoroalkyl substances in the Anniston Community Health Surveys (ACHS I and ACHS II)

BACKGROUND

Residents of Anniston Alabama were highly exposed to polychlorinated biphenyls (PCBs) due to longstanding manufacturing in the area. The Anniston Community Health Surveys (ACHS I-2005-2007 and II, 2014) have linked these exposures with a variety of deletereous health outcomes. In addition to PCBs, these individuals were likely simultaneously exposed to other persistent organic pollutants including per and polyfluoroalkyl substances (PFAS), which are an emerging class of ubiquitous industrial chemicals that are measurable in the blood of most individuals and have themselves been linked increased risk of some non communicable diseases.

METHODS

To characterize PFAS exposures in ACHS I and ACHS II, we measured eight environmentally significant PFAS in serum by UPLC coupled electrospray ionization tandem mass spectrometry. Perfluorooctane sulfonate (PFOS), Perfluorooctanoic acid (PFOA), Perfluorononanoate (PFNA), Perfluorohexane sulfonate (PFHxS), Perfluoroheptanoic acid (PFHpA), Perfluorobutanesulfonic acid (PFBS), Hexafluoropropylene oxide dimer acid (HFPO-DA), and 4:2 Fluorotelomer sulfonic acid (4.2 FTS) were extracted from matched serum samples of individuals who participated in the original ACHS I (2005-2007; n = 297) and the follow up ACHS II (2014; n = 336). Data were collected in negative multiple reaction monitoring (MRM) mode with monitoring of quantitation and qualifier ions for all target PFAS analytes, surrogates and internal standards. VARCLUS procedure was used to create hierarchical clusters between PFAS and other legacy persistent organic pollutants which may share similar exposure routes.

RESULTS

Overall, circulating PFAS levels decreased approximately 50% from ACHS I (2005-2007) to ACHS II (2014), but these changes varied by compound. Mean levels of PFOS were >3 times higher in ACHS I subjects than in conpemporaneous NHANES subjects (2005-2006; ACHS I mean: 71.1 ng/ml; NHANES mean: 20.2 ng/mL), and this relationship persisted in ACHS II subjects (2014: ACHS II mean: 34.7 ng/ml; NHANES mean: 5.92 ng/mL). PFNA was also higher in both ACHS I and ACHS II subjects in comparision to NHANES whereas levels of PFOA and PFHxS were lower than in NHANES. Finally, cluster analysis revealed that in ACHS II, most PFAS tracked with polybrominated diphenyl ethers, except PFNA and PFHpA which clustered with industrial PCBs. In ACHS I, PFAS analytes correlated more closely with industrial PCBs and chlorinated pesticides.

CONCLUSIONS

Participants in the Anniston Community Health Surveys have higher levels of PFOS and PFNA than the general population with average PFOS levels >3 times contemporaneous NHANES levels. Since PFAS were not known to be manufactured in the area, more work needs to be completed to determine if population demographics, proximity to a military base, or regional manufacturing can explain the elevated levels.