Chromatography-isotope Dilution Tandem Mass Spectrometry Research Articles

Per- and polyfluoroalkyl substances (PFAS), perceived stress, and depressive symptoms in a prospective cohort study of black women

BackgroundPer- and polyfluoroalkyl substances (PFAS) are endocrine-disrupting chemicals with neurotoxic properties. PFAS have been associated with depressive symptoms among women in some studies, but little research has evaluated the effects of PFAS mixtures. Further, no study has investigated interactions of PFAS-depression associations by perceived stress, which has been shown to modify the effects of PFAS on other health outcomes. ObjectiveIn a prospective cohort study of reproductive-aged Black women, we investigated associations between PFAS and depressive symptoms and the extent to which perceived stress modified these associations. MethodsWe analyzed data from 1499 participants (23-35 years) in the Study of Environment, Lifestyle, and Fibroids. We quantified concentrations of nine PFAS in baseline plasma samples using online solid-phase extraction-liquid chromatography-isotope dilution tandem mass spectrometry. Participants reported perceived stress via the Perceived Stress Scale (PSS-4; range = 0-16) at baseline and depressive symptoms via the Center for Epidemiologic Studies Depression Scale (CESD; range = 0-44) at the 20-month follow-up visit. We used Bayesian Kernel Machine Regression to estimate associations between PFAS concentrations, individually and as a mixture, and depressive symptoms, and to assess effect modification by PSS-4 scores, adjusting for confounders. ResultsBaseline perfluorodecanoic acid concentrations were associated with greater depressive symptoms at the 20-month follow-up, but associations for other PFAS were null. The PFAS were not associated with depressive symptoms when evaluated as a mixture. The association between the 90th percentile (vs. 50th percentile) of the PFAS mixture with CES-D scores was null at the 10th (β = 0.03; 95 % CrI = 0.20, 0.25), 50th (β = 0.02; 95 % CrI = -0.16, 0.19), and 90th (β = 0.01; 95 % CrI = 0.18, 0.20) percentiles of PSS-4 scores, suggesting perceived stress did not modify the PFAS mixture. ConclusionIn this prospective cohort study, PFAS concentrations—assessed individually or as a mixture—were not appreciably associated with depressive symptoms, and there was no evidence of effect modification by perceived stress.

Urinary biomonitoring of glyphosate exposure among male farmers and nonfarmers in the Biomarkers of Exposure and Effect in Agriculture (BEEA) study

Glyphosate is the most widely applied herbicide worldwide. Glyphosate biomonitoring data are limited for agricultural settings. We measured urinary glyphosate concentrations and assessed exposure determinants in the Biomarkers of Exposure and Effect in Agriculture (BEEA) study. We selected four groups of BEEA participants based on self-reported pesticide exposure: recently exposed farmers with occupational glyphosate use in the last 7 days (n = 98), farmers with high lifetime glyphosate use (>80th percentile) but no use in the last 7 days (n = 70), farming controls with minimal lifetime use (n = 100), and nonfarming controls with no occupational pesticide exposures and no recent home/garden glyphosate use (n = 100). Glyphosate was quantified in first morning void urine using ion chromatography isotope-dilution tandem mass spectrometry. We estimated associations between urinary glyphosate concentrations and potential determinants using multivariable linear regression. Glyphosate was detected (≥0.2 µg/L) in urine of most farmers with recent (91 %) and high lifetime (93 %) use, as well as farming (88 %) and nonfarming (81 %) controls; geometric mean concentrations were 0.89, 0.59, 0.46, and 0.39 µg/L (0.79, 0.51, 0.42, and 0.37 µg/g creatinine), respectively. Compared with both control groups, urinary glyphosate concentrations were significantly elevated among recently exposed farmers (P < 0.0001), particularly those who used glyphosate in the previous day [vs. nonfarming controls; geometric mean ratio (GMR) = 5.46; 95 % confidence interval (CI): 3.75, 7.93]. Concentrations among high lifetime exposed farmers were also elevated (P < 0.01 vs. nonfarming controls). Among recently exposed farmers, glyphosate concentrations were higher among those not wearing gloves when applying glyphosate (GMR = 1.91; 95 % CI: 1.17, 3.11), not wearing long-sleeved shirts when mixing/loading glyphosate (GMR = 2.00; 95 % CI: 1.04, 3.86), applying glyphosate exclusively using broadcast/boom sprayers (vs. hand sprayer only; GMR = 1.70; 95 % CI: 1.00, 2.92), and applying glyphosate to crops (vs. non-crop; GMR = 1.72; 95 % CI: 1.04, 2.84). Both farmers and nonfarmers are exposed to glyphosate, with recency of occupational glyphosate use being the strongest determinant of urinary glyphosate concentrations. Continued biomonitoring of glyphosate in various settings is warranted.

Urinary glyphosate levels and association with mortality in the 2013-16 National Health and Nutrition Examination Survey.

Glyphosate is the most commonly used herbicide in the USA; however, its safety is still under debate. We assessed glyphosate levels and their association with overall mortality in a representative sample of the US adult population from the 2013 to 2016 National Health and Nutrition Examination Survey. We extracted data on urinary glyphosate (N = 2910) measured by ion chromatography isotope-dilution tandem mass spectrometry. Associations between glyphosate concentrations and demographic, lifestyle and other exposures were analyzed. Data were linked to public-use Mortality Files for 2019. The mean (STD) glyphosate level was 0.53 (0.59) ng/ml, with 25.7% of the subjects having glyphosate levels at or below the detection limit. At multivariate analysis, age and creatinine were associated with glyphosate urinary levels (both P < 0.0001). There was a borderline association between glyphosate levels and mortality (HRadj 1.33; 95% CI 0.99-1.77 P = 0.06). When 3,5,6-trichloropyridinol was excluded from the Cox model, glyphosate exhibits a significant association with mortality (HRadj 1.33; 95% CI 1.00-1.77; P = 0.0532). These nationally representative data suggest that recent exposure to glyphosate could be associated with increased mortality. More studies are necessary to understand population-level risk associated with the product, given its widespread use in agriculture.

Fast and Simple Liquid Chromatography-Isotope Dilution Tandem Mass Spectrometry Method for Therapeutic Drug Monitoring of Dalbavancin in Long-Term Treatment of Subacute and/or Chronic Infections

Dalbavancin (DBV) is a long-acting antistaphylococcal lypoglycopeptide that is being increasingly used for long-term treatment of a wide range of subacute and/or chronic infections, mainly osteo-articular infections (OAI). Population pharmacokinetic studies showed that two 1500 mg doses 1 week apart can ensure effective treatment for several weeks. In this scenario, therapeutic drug monitoring (TDM) can be a helpful tool for providing clinicians with real-time feedback on the duration of optimal treatment by measuring drug concentrations over time in each single patient. The aim of this study was to develop and validate a fast and simple analytical method based on the Liquid Chromatography-Isotope Dilution Tandem Mass Spectrometry (ITD LC-MS/MS) technique for measuring DBV concentrations in human plasma microsamples. It will allow an innovative, very convenient and minimally invasive way of sampling. Analysis was performed by simple single-step sample preparation and very short instrumental run time (4 min). Analytical performance met all criteria in terms of specificity, sensitivity, linearity, precision, accuracy, matrix effect, extraction recovery, limit of quantification, dilution integrity and stability under different conditions set by the European Medicines Agency (EMA) for drug quantification by means of bioanalytical methods. The method was successfully applied for measuring DBV concentrations (range = 2.0-77.0 mg/L) in a cohort of patients receiving long-term DBV treatment of subacute and/or chronic infections.

Fast and Sensitive Analysis of Cefiderocol in Human Plasma Microsamples by Liquid Chromatography-Isotope Dilution Tandem Mass Spectrometry for Therapeutic Drug Monitoring

Cefiderocol (C) is a parenteral siderophore cephalosporin with relevant inter-individual pharmacokinetic variability among critically ill patients, which may potentially affect effective drug exposure. Therapeutic drug monitoring (TDM) may concur in improving the real-time management of C therapy in clinics. In this study, we developed and validated a fast and sensitive Liquid Chromatography-Isotope Dilution Tandem Mass Spectrometry (LC-ITD-MS/MS) method for measuring C in human plasma microsamples, as small as 3 microliters. Analysis was preceded by a user-friendly pre-analytical single-step and was performed by means of a very fast chromatographic run of 4 min, followed by positive electrospray ionization and detection on a high sensitivity triple quadrupole tandem mass spectrometer operated in multiple reaction monitoring mode. The straightforward analytical procedure was successfully validated, based on the European Medicines Agency (EMA) guidelines, in terms of specificity, sensitivity, linearity, precision, accuracy, matrix effect, extraction recovery, limit of quantification, and stability. The novel method was successfully applied to TDM of C in more than 50 cases of critically carbapenem-resistant Gram-negative bacterial infections and enabled us to optimize antibiotic therapy.

Relationship between serum thyroid hormones and their associated metabolites, and gene expression bioindicators in the back skin of Rana [Lithobates] catesbeiana tadpoles and frogs during metamorphosis.

Anuran metamorphosis is characterized by profound morphological changes including remodeling of tissues and organs. This transition is initiated by thyroid hormones (THs). However, the current knowledge of changing levels of THs during metamorphosis relies on pooled samples using methods known for high variability with sparse reporting of measured variation. Moreover, establishing a clear linkage between key gene expression bioindicators and TH levels throughout the metamorphic process is needed. Using state-of-the-art ultra-high performance liquid chromatography isotope-dilution tandem mass spectrometry, we targeted 12 THs and metabolites in the serum of Rana [Lithobates] catesbeiana (n=5-10) across seven distinct postembryonic stages beginning with premetamorphic tadpoles (Gosner stage 31-33) and continuing through metamorphosis to a juvenile frog (Gosner stage 46). TH levels were related to TH-relevant gene transcripts (thra, thrb, and thibz) in back skin of the same individual animals. Significant increases from basal levels were observed for thyroxine (T4) and 3,3',5-triiodothyronine (T3) at Gosner stage 41, reaching maximal levels at Gosner stage 44 (28 ± 10 and 2.3 ± 0.5 ng/mL, respectively), and decreasing to basal levels in juvenile frogs. In contrast, 3,5-diiodothyronine (T2) increased significantly at Gosner stage 40 and was maintained elevated until stage 44. While thra transcript levels remained constant and then decreased at the end of metamorphic climax, thrb and thibz were induced to maximal levels at Gosner stage 41, followed by a decrease to basal levels in the froglet. This exemplifies the exquisite timing of events during metamorphosis as classic early response genes are transcribed in anticipation of peak TH concentrations. The distinct T2 concentration profile suggests a biological role of this biomolecule in anuran postembryonic development and an additional aspect that may be a target of anthropogenic chemicals that can disrupt anuran metamorphosis and TH signalling. Hence, as a second aim of the study, we set out to find additional bioindicators of metamorphosis, which can aid future investigations of developmental disruption. Using a sensitive nanoLC-Orbitrap system an untargeted analysis workflow was applied. Among 6,062 endogenous metabolites, 421 showed metamorphosis-dependent concentration dynamics. These potential bioindicators included several carnitines, prostaglandins and some steroid hormones.

Concentrations of Per- and Polyfluoroalkyl Substances in Paired Maternal Plasma and Human Milk in the New Hampshire Birth Cohort.

Per- and polyfluoroalkyl substances (PFAS) are environmentally persistent endocrine-disrupting chemicals associated with long-term health outcomes. PFAS are transferred from maternal blood to human milk, an important exposure source for infants, and understanding of this transfer is evolving. We characterized concentrations of 10 PFAS in human milk (n = 426) and compared milk-to-plasma concentrations of 9 PFAS among a subset of women with paired samples (n = 294) from the New Hampshire Birth Cohort Study using liquid chromatography-isotope dilution tandem mass spectrometry. We examined the relationship between perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) in plasma versus milk and fit linear regression models to assess relationships between milk PFOA and PFOS and participant characteristics. The median plasma PFOA concentration was 0.94 ng/mL (interquartile range, IQR, 0.59-1.34) and that of PFOS was 2.60 ng/mL (IQR 1.80-3.90); the median milk PFOA concentration was 0.017 ng/mL (IQR 0.012-0.027) and that of PFOS was 0.024 ng/mL (IQR 0.016-0.036). PFOA and PFOS plasma and milk concentrations showed correlations of ρ = 0.83 and 0.77, respectively (p < 0.001). Parity, previous lactation, week of milk collection, and body mass index were inversely associated with milk PFAS. We estimate that even among our general population cohort, some infants (∼6.5%) are exposed to amounts of PFAS via milk that may have long-term health impacts.

Exposure to glyphosate in the United States: Data from the 2013–2014 National Health and Nutrition Examination Survey

BackgroundExposure to glyphosate, the most used herbicide in the United States, is not well characterized. We assessed glyphosate exposure in a representative sample of the U.S. population ≥ 6 years from the 2013–2014 National Health and Nutrition Examination Survey. MethodsWe quantified glyphosate in urine (N = 2,310) by ion chromatography isotope-dilution tandem mass spectrometry. We conducted univariate analysis using log-transformed creatinine-corrected glyphosate concentrations with demographic and lifestyle covariates we hypothesized could affect glyphosate exposure based on published data including race/ethnicity, sex, age group, family income to poverty ratio, fasting time, sample collection season, consumption of food categories (including cereal consumption) and having used weed killer products. We used multiple logistic regression to examine the likelihood of glyphosate concentrations being above the 95th percentile and age-stratified multiple linear regression to evaluate associations between glyphosate concentrations and statistically significant covariates from the univariate analysis: race/ethnicity, sex, age group, fasting time, cereal consumption, soft drink consumption, sample collection season, and urinary creatinine. ResultsGlyphosate weighted detection frequency was 81.2 % (median (interquartile range): 0.392 (0.263–0.656) μg/L; 0.450 (0.266–0.753) μg/g creatinine). Glyphosate concentration decreased from age 6–11 until age 20–59 and increased at 60+ years in univariate analyses. Children/adolescents and adults who fasted > 8 h had significantly lower model-adjusted geometric means (0.43 (0.37–0.51) μg/L and 0.37 (0.33–0.39) μg/L) than those fasting ≤ 8 h (0.51 (0.46–0.56) μg/L and 0.44 (0.41–0.48) μg/L), respectively. The likelihood (odds ratio (95 % CI)) of glyphosate concentrations being > 95th percentile was 1.94 (1.06–3.54) times higher in people who fasted ≤ 8 h than people fasting > 8 h (P = 0.0318). ConclusionsThese first nationally representative data suggest that over four-fifths of the U.S. general population ≥ 6 years experienced recent exposure to glyphosate. Variation in glyphosate concentration by food consumption habits may reflect diet or lifestyle differences.

Urinary biomonitoring of glyphosate exposure among male farmers and non-farmers in the Biomarkers of Exposure and Effect in Agriculture (BEEA) study

BACKGROUND AND AIM: Glyphosate is the most widely applied herbicide worldwide. Despite potential health effects of glyphosate, biomonitoring data of glyphosate exposure in agriculture and other settings are limited. We measured urinary glyphosate concentrations and assessed their determinants among male farmers and non-farmers from Iowa and North Carolina in the BEEA study. METHODS: Based on questionnaire-assessed pesticide exposure histories, we selected four groups of BEEA participants: recently exposed farmers with occupational glyphosate use in the last 7 days (n=98), farmers with high cumulative lifetime days of glyphosate use (&amp;#x3e;80th percentile) but no use in the last 7 days (n=70), farmers with minimal lifetime glyphosate use (n=100), and non-farmers with no occupational pesticide exposure (n=100). We quantified glyphosate in first-morning void urine samples using ion chromatography isotope-dilution tandem mass spectrometry. We estimated geometric mean urinary glyphosate concentrations across groups and evaluated associations with potential determinants using linear regression. RESULTS: Glyphosate was detected in urine of most recently (91%), high-lifetime (93%), and low-lifetime (88%) exposed farmers, as well as non-farmers (81%); geometric mean concentrations were 0.86, 0.58, 0.44, and 0.37 µg/L, respectively. Compared to non-farmers, urinary glyphosate concentrations were significantly elevated among recently exposed farmers (P&amp;#x3c;0.0001), particularly those who used glyphosate within 1 day of urine collection [age- and creatinine-adjusted geometric mean ratio (GMR)=6.4, 95% confidence interval (CI)=4.3-9.3] and those not wearing gloves during glyphosate application (GMR=2.6, 95% CI=2.0-3.4). CONCLUSIONS: Preliminary results suggest that a high proportion of both farming and non-farming populations may be exposed to glyphosate. Substantial exposure contrast between those with and without recent occupational glyphosate use was detectable in urine. Given the short elimination half-life of glyphosate, the exposure differences between groups may be even greater than those reflected by measured urine concentrations. Continued biomonitoring of glyphosate in various settings is warranted. KEYWORDS: Glyphosate, exposure assessment, pesticide biomonitoring

Urinary concentrations of non-persistent endocrine disrupting chemicals and fecundability in a preconception cohort study

Background and aim: Non-persistent endocrine-disrupting chemicals (EDCs) are found in consumer products including personal care products, plastics, and cleaning supplies. EDCs can affect hormonal pathways involved in reproduction. We examined prospectively the association between urinary concentrations of select non-persistent EDCs and fecundability, the per cycle probability of conception. Methods: We used data from PRESTO and Snart Foraeldre.dk, web-based preconception cohort studies that recruited female participants who were aged 21-45 years, residents of North America or Denmark, and trying to conceive without fertility treatment (2013-2019). Participants completed a baseline questionnaire and follow-up questionnaires every 8 weeks for up to 12 months. A subset of 207 participants residing in Boston, Massachusetts (n=119), Detroit, Michigan (n=18), or Aalborg, Denmark (n=70) provided urine samples during in-person clinic visits. We measured concentrations of 7 phenols, 4 parabens, triclocarban, 15 phthalate metabolites and 2 phthalate alternative metabolites using on-line solid-phase extraction-high-performance liquid chromatography-isotope dilution-tandem mass spectrometry. We used proportional probabilities models to estimate fecundability ratios (FR) and 95% confidence intervals (CI), adjusting for potential confounders. Results: Concentrations of some non-persistent EDCs were associated with reduced fecundability. The adjusted FR for the highest vs. lowest quartile of benzophenone-3 was 0.53 (95% CI: 0.28-0.99), with evidence of a monotonic association. Bisphenol S and 2,5’-dichlorophenol, and ethyl paraben concentrations were also associated with reduced fecundability. Among phthalate metabolites, mono-ethyl phthalate (highest vs. lowest quartile: FR=0.71, 95% CI: 0.45-1.12), monocarboxyoctyl phthalate (highest vs. lowest quartile: FR=0.71, 95% CI: 0.44-1.14), and the non-phthalate plasticizer cyclohexane-1,2-dicarboxylic acid monohydroxy isononyl ester (&amp;#x2265;0.6 µg/g creatinine vs. &amp;#x3c;limit of detection: FR=0.59, 95% CI: 0.37-0.95) were associated with reduced fecundability. Conclusions: Biomarkers of some non-persistent EDCs were associated with reduced fecundability. Future analysis of additional urine specimens in these cohorts will enable examination of chemical mixtures on fecundability. Key words: endocrine-disrupting chemicals, fecundability, fertility, phenols, phthalates

Abstract 25: Per- and polyfluoroalkyl substances and obesity in Florida firefighters

Abstract Background/Objective: Per- and polyfluoroalkyl substances (PFASs) are hazardous synthetic chemicals that have been linked to adverse human health effects such as cancer and endocrine disruption. Firefighters have been shown to be occupationally exposed to PFAS through aqueous film-forming foam (AFFF) used during difficult-to-suppress fires, and in the textile liners of their safety turnout gear. PFASs have both hydrophobic and hydrophilic chemical structures, giving them strong thermal stability and making them resistant to environmental and physiological degradation. Studies of human exposures to PFAS have observed associations between some PFAS and increased risk of obesity or elevated body mass index (BMI). Given the unique occupational exposures of firefighters to PFAS, we examine the association between obesity and PFAS in a sample of Florida firefighters. Methods: A cross-sectional study design was used to collect a health survey and a blood sample from a non-probabilistic sample of career Florida fighters between June and October 2021. The health surveys, administered on REDCap using tablet devices, assessed information on firefighter socio-demographic and work characteristics. We quantified 7 distinct PFASs using a solid-phase extraction-high-performance liquid chromatography-isotope dilution-tandem mass spectrometry approach; the limit of detection was between 0.5 and 0.05 ng/mL, depending on the analyte. All 7 PFASs, including Perfluorobutanesulfonic Acid (PFBS), Perfluoroheptanoic Acid (PFHpA), Perfluorohexanesulfonic Acid (PFHxS), Perfluorooctanoic Acid (PFNA), Perfluorononanoic Acid (PFNA), Perfluorooctanesulfonic Acid (PFOS), and Perfluoroctanesulfonamide (PFOSA), were detected in the blood samples; concentrations below the limit of detection were replaced by the limit of detection/√2.35. Results: Among the 208 firefighters who completed the survey and provided a blood sample, 92.8% were male, 16.2% Hispanic/Latinx, 81.7% White, 89.8% used AFFF at their fire department, with a group mean age 40.2±10.3 standard deviation. Approximately 15.8% of firefighters were of healthy weight, 51.5% overweight, and 32.7% obese. Firefighter body mass index was positively correlated with serum concentrations of PFHxS (rs=.17;p=.020) and PFBS (rs=.60;p=.26). Group geometric mean of each PFAS congener (in ng/mL): PFBS (0.09), PFHpA (0.08), PFHxS (2.17), PFOA (1.38), PFNA (0.42), PFOS (2.69), and PFOSA (0.10). Total serum PFAS concentrations was highest among obese firefighters (7.62 ng/mL) and lowest in healthy weight firefighters (6.55 ng/mL). Conclusions: Firefighters who were overweight and obese, based on body mass index, had higher total serum PFAS concentrations than those firefighters of healthy weight. Both long- and short-chain PFASs, PFHxS and PFBS respectively, were positively correlated with firefighter body mass index. Citation Format: Alberto J. Caban-Martinez, Paola Louzado Feliciano, Simi Oduwole, Natasha Schaefer Solle, Catalina Gonzalez-Umana, Thomas Stone, Erin N. Kobetz. Per- and polyfluoroalkyl substances and obesity in Florida firefighters [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 25.

Prenatal alcohol exposure can be determined from baby teeth: Proof of concept.

Prenatal alcohol exposure (PAE), leading to fetal alcohol spectrum disorders (FASD), is a serious public health issue in the United States and globally. Diagnosis of FASD is crucial in obtaining appropriate care, but it is not always possible when PAE cannot be documented. Deciduous teeth from a child with known PAE and a child with known absence of PAE were analyzed using liquid chromatography-isotope dilution tandem mass spectrometry (LC-IDMS/MS) in a multiple-reaction monitoring mode for direct markers and LC-high resolution MS in positive and negative mode with hydrophilic interaction liquid chromatography and reverse-phase chromatography, respectively, for indirect markers. Direct markers of PAE (ethyl glucuronide and ethyl sulfate) were detected in prenatal and postnatal dentine from a case tooth but not from a control tooth. Indirect biomarker analysis indicated a dysregulation of amino acids and an increase in cholesterol sulfate in the case compared to the control tooth. This proof-of-concept study demonstrates for the first time that direct biomarkers of PAE are detectable and measurable in deciduous teeth which begin forming in utero and are typically naturally shed between 5 and 12 years of age. Further examination of these novel biomarkers may allow diagnosis of FASD where documentation of PAE is otherwise unavailable. Furthermore, because teeth grow incrementally, defined growth zones can be sampled allowing for identification of gestational timing of PAE to help better understand mechanisms underlying alcohol's disruption of perinatal development.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) and PFAS Mixtures with Incident Hypertension: the Study of Women’s Health Across the Nation 1999-2017

BACKGROUND AND AIM: Perfluoroalkyl and polyfluoroalkyl substances (PFAS) exposure may cause a variety of hypertension-inducing pathophysiological responses. However, the one epidemiologic study that has examined PFAS and hypertension incidence in adults reported no significant associations. This study aimed to examine the associations between PFAS and incident hypertension. METHODS: This study included 1,058 midlife women free of hypertension from the multi-racial/ethnic Study of Women’s Health Across the Nation (SWAN) Multi-Pollutant Study with approximately annual follow-up visits between 1999 and 2017. Baseline serum PFAS concentrations were quantified by high-performance liquid chromatography-isotope dilution-tandem mass spectrometry. Hypertension was defined as blood pressure ≥140 mmHg systolic or ≥90 mmHg diastolic or receiving anti-hypertensive treatment. Cox proportional hazards (PH) model were utilized to calculate hazards ratios (HR) and 95% confidence intervals (CI) with adjustment for race/ethnicity, study site, educational attainment, financial strain, smoking status, passive smoking, alcohol consumption, total calorie intake, menopausal status, and body mass index. Elastic net-penalized Cox PH regression was implemented to model PFAS mixtures and construct an integrative index, environmental risk score (ERS), to evaluate the joint effect of PFAS mixtures. RESULTS:During 11,843 person-years of follow-up, 470 participants developed incident hypertension. Compared with the lowest tertile, women in the highest tertile of baseline serum concentrations had adjusted HRs of 1.36 (95% CI: 1.08-1.73) for total perfluorooctane sulfonate (PFOS) (P-trend=0.01), 1.31 (95% CI: 1.03-1.67) for linear perfluorooctanoate (n-PFOA) (P-trend=0.01), and 1.37 (95% CI: 1.07-1.75) for 2-(N-ethyl-perfluorooctane sulfonamido) acetate (EtFOSAA) (P-trend=0.01). No significant associations were observed for perfluorononanoate (PFNA) and perfluorohexane sulfonate (PFHxS). In the mixture analysis, women in the highest tertile of ERS had an HR of 1.53 (95% CI: 1.20-1.96) (P-trend=0.0008), compared with those in the lowest tertile. CONCLUSIONS:Our findings suggest an association between PFAS and incident hypertension. PFAS may be an underappreciated contributing factor to women’s cardiovascular disease risk. KEYWORDS: PFAS, Mixtures, Mixture analysis, Cardiovascular diseases

Simple and accurate quantitative analysis of cefiderocol and ceftobiprole in human plasma using liquid chromatography-isotope dilution tandem mass spectrometry: interest for their therapeutic drug monitoring and pharmacokinetic studies.

Cefiderocol and ceftobiprole are new generation cephalosporin antibiotics that exhibit high inter-individual plasma concentration variability that potentially impact their efficacy or toxicity. The aim of this study was to develop and validate a selective, simple, and fastUPLC-MS/MS method for simultaneous quantification of cefiderocol and ceftobiprole in human plasma to enabletheir therapeutic drug monitoring (TDM) and support PK and PK/PD studies, in particular in critically ill patients. After a simple and fast single-step protein precipitation, cefiderocol and ceftobiprole were separated on a Waters Acquity UPLC BEH C18 column by linear gradient elution; with subsequent detection by Shimadzu MS 8060 triple quadrupole tandem mass spectrometer in a positive ionization mode. Analysis time was 5min per run. The analytical performance of the method in terms of specificity, sensitivity, linearity, precision, accuracy, matrix effect (ME), extraction recovery (ER), limit of quantification, dilution integrity, and stability of analytes under different conditions metall criteria for a bioanalytical method for the quantification of drugs. The calibration curves were linear over the range of 1-200mg/L for cefiderocol and 0.5-100mg/L for ceftobiprole with a linear regression coefficient above 0.995 for both. A simple, fast, and selective liquid chroma-tography-tandem mass spectrometry method was developed and validated for the simultaneous quantification of cefiderocol and ceftobiprole. This new method was successfully applied to the measurement of plasma concentration of cefiderocol and ceftobiprole in critically ill patients and showed good performance for their therapeutic monitoring and optimizing antibiotic therapy.

Per- and Polyfluoroalkyl Substances (PFAS) and Hormone Levels during the Menopausal Transition: Study of Women’s Health Across the Nation (SWAN)

Background: PFAS are endocrine disrupting chemicals that have been associated with an earlier age at menopause. However, information on their association with serum hormone concentrations is limited and inconsistent. We examined longitudinal associations between serum PFAS concentrations at baseline and serial serum concentrations of follicle stimulating hormone (FSH), estradiol (E2), testosterone (T) and sex hormone-binding globulin (SHBG) in the Study of Women’s Health Across the Nation (SWAN), a multi-racial/ethnic, community-based cohort of women transitioning through menopause. Methods: We assayed serum concentrations of perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), 2-(N-ethyl-perfluorooctane sulfonamide) acetate (EtFOSAA), 2-(N-methyl-perfluorooctane sulfonamide) acetate (MeFOSAA), perfluorohexane sulfonate (PFHxS), and perfluorononanoate (PFNA) in 1,398 women eligible for the SWAN Multi-Pollutant Study in 1999-2000 who were followed approximately annually to 2016. Serum PFAS concentrations were quantified by online solid phase extraction-high performance liquid chromatography-isotope dilution-tandem mass spectrometry. Hormone and PFAS concentrations were log-transformed. Linear mixed regression with random intercepts was used to analyze longitudinal associations, adjusting for menopausal status, smoking, parity, race/ethnicity, site and body mass index (BMI). Results: At baseline, women had a mean age of 49.5 years, a mean BMI of 28.0 and included white (50.5%), black (22.0%), Chinese (12.7%) and Japanese (14.8%) women. PFAS were not associated with E2. In adjusted models including BMI, FSH was positively associated with total PFOS (β=0.041, 95% CI=0.000, 0.0092), branched-PFOS, (β=0.044, 95% CI=0.006, 0.0083), and n-PFOA (β=0.055, 95% CI=0.008, 0.0103) but not with EtFOSAA, MeFOSAA, PFHxS, or PFNA. T and SHBG were negatively associated with PFOS, n-PFOA and EtFOSAA, but these associations were greatly attenuated and not significant after adjustment for BMI. Conclusions: The results of this prospective study suggest that PFAS, especially PFOS and its precursors (MeFOSAA and EtFOSAA), and PFOA are associated with higher FSH concentrations in women during the menopausal transition, consistent with findings that PFAS affects reproductive aging.

Per- and Polyfluoroalkyl Substances (PFAS) and Incident Diabetes in Midlife Women: Study of Women’s Health Across the Nation (SWAN)

Background: Diabetogenic effects of per- and polyfluoroalkyl substances (PFAS) have been suggested. However, evidence based on population-based prospective cohort studies is limited. We examined the association between serum PFAS concentrations and incident diabetes in the Study of Women’s Health Across the Nation (SWAN), a community-based population study of midlife women.Methods: We included 1,226 diabetes-free women aged 45-56 years at the baseline of the SWAN Multi-Pollutant Study in 1999-2000 who were followed up to 2016. Serum PFAS concentrations were quantified by online solid phase extraction-high performance liquid chromatography-isotope dilution-tandem mass spectrometry. We used k-means clustering and identified three overall PFAS concentration patterns as mixtures (low, medium, high). Cox proportional hazards models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs).Results: We identified 137 incident diabetes cases (median follow-up=16 years, incident rate=8.15 per 1000 person-years). After adjustment for age, race/ethnicity, site, education, income, body mass index, smoking status, alcohol, physical activity, menopausal status and hormone use, the HRs comparing the lowest with the highest tertiles were 1.56 (95% CI: 1.15-2.11) for n-perfluorooctanoate (n-PFOA) (p-for-trend=0.004); 1.56 (95% CI: 1.19-2.14) for perfluorohexane sulfonate (PFHxS) (p-for-trend=0.001); 1.43 (95% CI: 1.05-1.95) for branched-perfluorooctane sulfonate (branched-PFOS) (p-for-trend=0.02); and 1.61 (95% CI: 1.16-2.24) for 2-(N-methyl-perfluorooctane sulfonamide) acetate (MeFOSAA) (p-for-trend=0.003). The high overall PFAS concentration mixture pattern had a significantly higher HR of 1.44 (95% CI: 1.01-2.05) compared with the low mixture pattern.Conclusions: This prospective cohort study with up to 17 years of follow-up suggests that PFAS, especially PFOA, PFHxS, and PFOS and its precursor (MeFOSAA), individually or as mixtures, may increase diabetes risk in midlife women. Reduced exposure to PFAS may be an important preventative approach to lowering population-wide diabetes risk.

Associations ofPerfluoroalkyl Substances withIncident Natural Menopause: the Study of Women’s Health Across the Nation

Context: Previous epidemiologic studies of per- and polyfluoroalkyl substances (PFAS) and menopausal timing conducted in cross-sectional settings were limited by reverse causation because PFAS serum concentrations increase after menopause.Objectives: To investigate associations between PFAS serum concentrations and incident natural menopause.Design and Setting: A prospective cohort of midlife women, the Study of Women’s Health Across the Nation, from 1999 to 2017.Participants: 1120 multi-racial/ethnic premenopausal women (White, Black, Chinese and Japanese) aged 45-56 years in 1999-2000.Methods: Serum PFAS concentrations were measured using an online solid phase extraction-high performance liquid chromatography-isotope dilution-tandem mass spectrometry. The final menstrual period was determined during the annual follow-up visits. Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs).Results: Participants contributed 5466 person-years of follow-up, and 578 had incident natural menopause. Compared to the lowest tertile, women at the highest tertile of baseline serum concentrations had adjusted HR for natural menopause of 1.26 (95%CI: 1.02-1.57) for n-perfluorooctane sulfonic acid (n-PFOS) (Ptrend=0.03), 1.27 (95%CI: 1.01-1.59) for branched-PFOS (Ptrend=0.03), and 1.31 (95%CI: 1.04-1.65) for n-perfluorooctanoic acid (Ptrend=0.01). Women were classified into four clusters based on their overall PFAS concentrations as mixtures: low, low-medium, medium-high, and high. Compared to the low cluster, the high cluster had a HR of 1.63 (95% CI: 1.44-1.84), which is interpreted as 2.0 years earlier experience of natural menopause.Conclusion: This study suggests that select PFAS serum concentrations are associated with earlier natural menopause, a risk factor for adverse health outcomes in later life.

Measurement of urine albumin by liquid chromatography-isotope dilution tandem mass spectrometry and its application to value assignment of external quality assessment samples and certification of reference materials.

Urine albumin is measured in clinical laboratories by immunoturbidimetry. However, large biases are observed among the different routine methods. To standardize the measurement of urine albumin, a reference measurement procedure (RMP) and urine albumin certified reference materials (CRMs) are needed. A candidate RMP for urine albumin based on liquid chromatography-isotope dilution tandem mass spectrometry (LC-IDMS/MS) using human serum albumin as calibration standard was developed. Isotope-labeled human albumin was used as internal standard. Urine samples were digested using trypsin and eight resulting "signature" peptides of albumin were quantified by LC-IDMS/MS. The candidate RMP was employed in value assignment of external quality assessment (EQA) samples and certification of urine albumin reference materials. The commutability of the developed CRMs was assessed against patient samples. The candidate RMP (recovery 101.5-103.2% and CV 1.2-3.3% at about 7-40mg/L) met optimal performance goal. The lower limit of quantification was 0.03mg/L as determined by signal-to-noise method. The EQA results from clinical laboratories using different immunoturbidimetric methods were generally comparable with assigned target values determined by the candidate RMP, with albumin concentrations ranging from 5 to 226mg/L. Urine albumin reference materials (two levels) certified using thecandidate RMP showed good commutability in a preliminary study. With optimal method precision and trueness, as well as comparability with routine methods, the developed RMP may be used for value assignment of EQA samples or certification of reference materials, which are important pillars in urine albumin method standardization.

Determination of purity values of amino acid reference materials by mass balance method: an approach to the quantification of related structure impurities.

A systematic procedure for the determination of purity values of amino acid reference materials was developed by use of mass balance method where four categories of impurities (related structure impurities (RSIs), water, organic solvent residue (OSR), and non-volatile residue (NVR)) were quantified separately. The amount of RSIs was determined using a combination of three quantification methods. To ensure metrological traceability in the determination of RSIs, at least one such impurity in each candidate amino acid reference material was quantified using liquid chromatography-isotope dilution tandem mass spectrometry (LC-IDMS/MS). Other RSIs were determined using external calibration liquid chromatography-tandem mass spectrometry (LC-MS/MS) or o-phthaldialdehyde (OPA) derivatization, followed by liquid chromatography-ultraviolet (LC-UV) measurement. As the UV absorption of most RSIs came basically from the same chromophore after OPA derivatization, a relative peak area approach was used in the LC-UV method to quantify the amount of RSIs by comparing their peak areas with that of a reference RSI. The reference RSI was pre-selected and the amount determined by LC-IDMS/MS separately. The absence of D-amino acids was confirmed using Marfey's reagent derivatization, followed by LC-UV analysis. The amounts of water, OSR, and NVR were measured using Karl Fischer coulometry, gas chromatography-mass spectrometry (GC-MS) and thermogravimetry, respectively. By using this procedure, four amino acid (L-valine, L-leucine, L-isoleucine, and L-phenylalanine) certified reference materials (CRMs) were developed from the candidate materials. The homogeneity and stability of the CRMs were demonstrated by use of LC-IDMS/MS or OPA-LC-UV method, following the principles in ISO 17034 and ISO Guide 35.Graphical abstract.

Association Between Bisphenol A Exposure and Risk of All-Cause and Cause-Specific Mortality in US Adults

Bisphenol A (BPA) is a major public health concern because of its high-volume industrial production, ubiquitous exposure to humans, and potential toxic effects on multiple organs and systems in humans. However, prospective studies regarding the association of BPA exposure with long-term health outcomes are sparse. To examine the association of BPA exposure with all-cause mortality and cause-specific mortality among adults in the United States. This nationally representative cohort study included 3883 adults aged 20 years or older who participated in the US National Health and Nutrition Examination Survey 2003-2008 and provided urine samples for BPA level measurements. Participants were linked to mortality data from survey date through December 31, 2015. Data analyses were conducted in July 2019. Urinary BPA levels were quantified using online solid-phase extraction coupled to high-performance liquid chromatography-isotope dilution tandem mass spectrometry. Mortality from all causes, cardiovascular disease, and cancer. This cohort study included 3883 adults aged 20 years or older (weighted mean [SE] age, 43.6 [0.3] years; 2032 women [weighted, 51.4%]). During 36 514 person-years of follow-up (median, 9.6 years; maximum, 13.1 years), 344 deaths occurred, including 71 deaths from cardiovascular disease and 75 deaths from cancer. Participants with higher urinary BPA levels were at higher risk for death. After adjustment for age, sex, race/ethnicity, socioeconomic status, dietary and lifestyle factors, body mass index, and urinary creatinine levels, the hazard ratio comparing the highest vs lowest tertile of urinary BPA levels was 1.49 (95% CI, 1.01-2.19) for all-cause mortality, 1.46 (95% CI, 0.67-3.15) for cardiovascular disease mortality, and 0.98 (95% CI, 0.40-2.39) for cancer mortality. In this nationally representative cohort of US adults, higher BPA exposure was significantly associated with an increased risk of all-cause mortality. Further studies are needed to replicate these findings in other populations and determine the underlying mechanisms.