Metabolic changes associated with PFAS exposure in firefighters: A pilot study.

This pilot study investigated the association between occupational exposure to per- and polyfluoroalkyl substances (PFASs) and metabolic profiles among two groups of aviation firefighters (n = 37), with an average of 6 and 31 years of working experience (here referred as junior and senior firefighters) at airports across Australia, with samples collected in 2013. PFAS levels in serum were determined in a previous study to be >17 times higher in the senior firefighter group, reflecting the difference in their occupational exposure to fluorosurfactants among the groups. The aim was to examine metabolic patterns across a broad range of PFAS exposure by comparing metabolic differences and their associations with PFAS levels. In this cross-sectional study, the length of firefighting experience and PFAS levels in serum were both further associated with changes in several classes of metabolites, including free fatty acids, bile acids, amino acids, lipids and metabolites related to gut microbial metabolism. The metabolites associated with the length of firefighting experience showed similarities with the metabolites associated with PFAS levels. A non-monotonic response to PFAS concentrations, particularly in saturated fatty acids, was also observed. In the junior firefighter group, the PFAS concentrations were positively associated with saturated fatty acids, i.e., the saturated fatty acid levels increased with increased PFAS levels. In the senior firefighter group, the trend was opposite, with saturated fatty acids decreasing with increasing levels of PFAS. Accounting for potential confounding factors such as BMI and age could not explain the results. While the study population was small, our results plausibly indicate that PFAS exposure can lead to a metabolic compensation strategy that is disrupted at high, long-term exposures. Our study also suggests that serum metabolites serve as better effect-based markers of the impact of exposure than the traditional clinical measurements alone, such as total triglycerides or total cholesterol.

Temporal trends of per- and polyfluoroalkyl substances concentrations: Insights from Australian human biomonitoring 2002-2021 and the U.S. NHANES programs 2003-2018.

Perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorononanoic acid (PFNA) are persistent contaminants detected in human blood worldwide, raising significant health concerns. In response, countries such as the United States and Australia have implemented regulatory measures to limit their use. This study analysed temporal trends in serum concentrations of these four PFAS and how these trends align with regulatory measures, using data from NHANES (2003-2004 to 2017-2018) and the Australian Human Biomonitoring Program (2002-2003 to 2020-2021). Multiple regression analyses adjusted for age and gender were performed to estimate mean concentration changes over time, and differences within each dataset were assessed. Results indicated significant reductions (p < 0.001) in PFOS, PFOA, and PFHxS concentrations post-2002-2003, while PFNA concentrations increased until 2009-2010 before declining in both Australia and the U.S. Age-related trends in the U.S. during the last monitoring period showed higher PFAS concentrations in the oldest age groups, while in Australia, this trend was evident for PFOS and PFHxS. In Australia, the age group of 0-5 years had PFOA and PFNA concentrations similar to those of adults over 46 years, indicating ongoing exposure. Gender differences were consistent in both programs, with females aged 6-15, 31-45, and 46-60 years exhibiting lower serum concentrations, particularly in the 31-45 years age group. These findings support Australian and U.S. efforts to reduce PFAS exposure through regulatory actions, highlight the need to address ongoing exposure in young children, and consider gender-specific factors affecting PFAS concentrations.

Sex-dimorphism in human serum endocannabinoid and n-acyl ethanolamine concentrations across the lifespan.

The endocannabinoid (ECB) system has recently been considered a potential treatment target for various clinical disorders. However, research around age- and sex-related changes within the ECB system is relatively limited. To improve our understanding of these changes, the current study measured arachidonoyl ethanolamide (AEA), 2-arachidonoyl glycerol (2-AG), oleoylethanolamine (OEA), palmitoylethanolamine (PEA), arachidonic acid (AA), cortisol, and progesterone in pooled serum samples stratified by sex (male and female) and age groups (5-15; 15-30; 30-45; 45-60; 60-75; 85+), using liquid-chromatography tandem mass spectrometry. Serum progesterone levels significantly increased in females of the 15-30 and 30-45 age groups, before declining. Significantly higher cortisol, AEA, 2-AG, OEA, and PEA were found in males and in older age, while significantly higher AA was found in females. Our results indicate that ECBs and related hormones exhibit sexual dimorphism in the age ranges that correspond with female pregnancy, menopause, and post menopause. Male testosterone levels most likely influences male ECB changes throughout the lifespan. Future research could capitalise on these findings by performing repeated measurements in individuals in a longitudinal style, to further refine the temporal profile of age-specific changes to the ECB system identified here.

Improving Wastewater-Based Tobacco Use Estimates Using Anabasine.

In wastewater-based epidemiology (WBE), nicotine metabolites have been used as biomarkers for monitoring tobacco use. Recently, the minor tobacco alkaloids anabasine and anatabine have been suggested as more specific biomarkers for tobacco use since nicotine use can be from both tobacco and non-tobacco sources. This study aimed to provide an in-depth evaluation of the suitability of anabasine and anatabine as WBE biomarkers of tobacco and subsequently estimate their excretion factors for WBE applications. Pooled urine (n = 64) and wastewater samples (n = 277), collected between 2009 and 2019 in Queensland, Australia, were analyzed for nicotine and its metabolites (cotinine and hydroxycotinine), as well as anabasine and anatabine. Anabasine performed as the better biomarker, showing a similar per capita load in pooled urine (2.2 ± 0.3 µg/day/person) and wastewater samples (2.3 ± 0.3 µg/day/person), while the per capita load of anatabine in wastewater was 50% higher than its load in urine. It is estimated that 0.9 µg of anabasine was excreted per cigarette smoked. Triangulation of tobacco sales data and tobacco use estimated from either anabasine or cotinine showed that anabasine-based estimates were 5% higher than sales data, while cotinine-based estimates were between 2 and 28% higher. Our results provided concrete evidence to confirm the suitability of anabasine as a specific biomarker for monitoring tobacco use by WBE.

An Exploratory Analysis of Firefighter Reproduction through Survey Data and Biomonitoring.

Firefighters are occupationally exposed to chemicals that may affect fertility. To investigate this effect, firefighters were recruited to contribute blood, urine, breast milk or semen samples to (1) evaluate chemical concentrations and semen parameters against fertility standards and the general population; (2) assess correlations between chemical concentrations and demographics, fire exposure and reproductive history; and (3) consider how occupational exposures may affect reproduction. A total of 774 firefighters completed the online survey, and 97 firefighters produced 125 urine samples, 113 plasma samples, 46 breast milk samples and 23 semen samples. Blood, urine and breast milk samples were analysed for chemical concentrations (semivolatile organic compounds, volatile organic compounds, metals). Semen samples were analysed for quality (volume, count, motility, morphology). Firefighter semen parameters were below WHO reference values across multiple parameters. Self-reported rates of miscarriage were higher than the general population (22% vs. 12-15%) and in line with prior firefighter studies. Estimated daily intake for infants was above reference values for multiple chemicals in breast milk. More frequent fire incident exposure (more than once per fortnight), longer duration of employment (≥15 years) or not always using a breathing apparatus demonstrated significantly higher concentrations across a range of investigated chemicals. Findings of this study warrant further research surrounding the risk occupational exposure has on reproduction.

First indication of perfluoroalkyl substances in human serum from Papua New Guinea.

Human biomonitoring programs of per- and polyfluoroalkyl substances (PFAS) have been conducted around the world to assess human exposure and health risk. Inquiry into population PFAS levels in a socioeconomically and geographically unique region such as the Pacific Island Papua New Guinea, may provide new insights into PFAS exposure pathways and sources. This study presented the first indication of PFAS exposure in the Papua New Guinea population. De-identified serum samples were pooled from surplus pathology serum samples collected between 2019 and 2020. A total of 11 PFAS were detected in the serum pools including 10 perfluoroalkyl acids (PFAA) and 9Cl-F53B (a perfluorooctane sulfonic acid - PFOS alternative). The observed PFAA profile was somewhat similar to that observed for general population data of other countries such as Australia, Malaysia, and Canada suggesting similar exposure sources and/or pathways. However, PFAS concentrations were consistently lower than concentrations in the serum measured in pools obtained from Australia. The detection of 9Cl-F53B in all pools was a new finding which might be related to exposure from locally industrial sources.

Longitudinal measurements of per- and poly-fluoroalkyl substances (PFAS) in archived human serum samples between 1975 and 1995 in Australia.

Per- and poly-fluoroalkyl substances (PFAS) are a group of manmade compounds produced since the 1950 s and used in a range of industrial processes and consumer products. In Australia, PFAS serum concentrations have been measured in the general population since 2002. However, few studies have retrospectively measured PFAS concentrations in serum samples representative of a general population prior to 2000, none of which have been conducted in Australia. To understand the general population's exposure to PFAS prior to 2002, longitudinal PFAS serum concentration measurements are required. In the current study, we accessed 'The Busselton Health Study Data Bank' to analyse archived serum samples for PFAS. Repeat serum samples collected in 1975, 1981 and 1995 were obtained from 17 participants. Of the 35 PFAS analysed, 13 PFAS were detected in the serum samples collected in 1975. Both the detection frequency and ∑PFAS serum concentrations increased between 1975 and 1995. Median ∑PFAS serum concentration increased over 7-fold; from 3.3 ng/mL in 1975-26 ng/mL in 1995. The increase in serum concentrations reflects the global production history of these PFAS during this period in time.

Associations between serum perfluoroalkyl acid (PFAA) concentrations and health related biomarkers in firefighters.

OBJECTIVES: Firefighters who used aqueous film forming foam in the past have experienced elevated exposures to perfluoroalkyl acids (PFAAs). The objective of this study was to examine the associations between clinical chemistry endpoints and serum concentrations of perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS), perfluoroheptane sulfonate (PFHpS) and perfluorooctane sulfonate (PFOS) in firefighters. Multiple linear regression was used to assess relationships between PFAA serum concentrations and biochemical markers for cardiovascular disease, kidney-, liver- and thyroid function, in a cross-sectional survey of 783 firefighters with elevated levels of PFHxS, PFHpS and PFOS in relation to the most recently reported levels in the general Australian population. Linear logistic regression was used to assess the odds ratios for selected self-reported health outcomes. Repeated measures linear mixed models were further used to assess relationships between PFAAs and biomarkers for cardiovascular disease and kidney function longitudinally in a subset of the firefighters (n = 130) where serum measurements were available from two timepoints, five years apart. In the cross-sectional analysis, higher levels of all PFAAs were significantly associated with higher levels of biomarkers for cardiovascular disease (total-cholesterol, and LDL-cholesterol). For example, doubling in PFOS serum concentration were associated with increases in total cholesterol (ß:0.111, 95% confidence interval (95%CI): 0.026, 0.195 mmol/L) and LDL-cholesterol (ß: 0.104, 95%CI:0.03, 0.178 mmol/L). Doubling in PFOA concentration, despite not being elevated in the study population, were additionally positively associated with kidney function marker urate (e.g., ß: 0.010, 95%CI; 0.004, 0.016 mmol/L) and thyroid function marker TSH (e.g., ß: 0.087, 95%CI: 0.014, 0.161 mIU/L). PFAAs were not associated with any assessed self-reported health conditions. No significant relationships were observed in the longitudinal analysis. Findings support previous studies, particularly on the association between PFAAs and serum lipids.