Jochen F. Mueller

Introduction: Intermittent fasting (IF) is becoming increasingly popular as a method of weight management, but it is unknown whether it affects plasticiser intake with resultant changes in glycaemic control in diabetes and vitamin D (VitD) levels; therefore, this study was undertaken in a cohort of control and type-2 diabetic (T2D) subjects during Ramadan time-restricted feeding (TRF). Methods: In T2D subjects (n = 19) and controls (n = 31) undertaking TRF, 24 h urinary levels of phthalate metabolites, bisphenols and serum VitD were determined pre- and post-TRF by liquid chromatography–tandem mass spectrometry (LC-MS/MS). Anthropometric data and glycosylated haemoglobin (HbA1c) were measured. Results: T2D subjects were older (52 versus 36.73 years, p < 0.001), and had higher BMI (36.54 versus 27.67 kg/m², p < 0.001), body weight (101.77 versus 80.36 kg, p < 0.001), and HbA1c (8.38 versus 5.46%, p < 0.001) compared to controls, while VitD levels did not differ (60.43 versus 63.95 nmol/L, p > 0.05). Post-TRF, HbA1c was unchanged in T2D subjects and there was no difference in weight, BMI or VitD. Increased mono-iso-butyl phthalate (MiBP) in T2D subjects (10 versus 6.1 ng/mL, p = 0.001) and mono-n-butyl phthalate (MnBP) in T2D subjects (37 versus 13 ng/mL, p = 0.018) and controls (8.3 versus 5.4 ng/mL, p = 0.007) were observed post-TRF; however, significance was lost after adjusting for baseline differences in age, BMI, and HbA1c using a general linear model (GLM) repeated-measures ANOVA. Despite having no median differences in DEHP (di-2-ethylhexyl phthalate) metabolites pre- and post-TRF, analyses revealed a significant time × HbA1c interaction for [mono(2-ethyl-5-carboxypentyl) phthalate, MECPP: F(1,42) = 4.79, p = 0.03, mono(2-ethyl-5-hydroxyhexyl) phthalate, MEHHP: F(1,42) = 8.56, p = 0.006, mono(2-ethylhexyl) phthalate, MEHP: F(1,42) = 4.64, p = 0.03 and mono(2-ethyl-5-oxohexyl) phthalate, MEOHP: F(1,42) = 8.19, p = 0.007] and time × group interactions [MEHHP: F(1,42) = 14.27, p < 0.001, MEHP: F(1,42) = 6.35, p = 0.01 and MEOHP: F(1,42) = 10.30, p = 0.003]. Estimated marginal means (adjusted for age, BMI, HbA1c, and VitD) further confirmed higher concentrations of DEHP metabolites [MECPP, MEHHP, MEHP, and MEOHP] in T2D participants over time compared with controls. Additionally, monomethyl phthalate (MMP) trajectories were significantly influenced by the time × group interaction (F(1,42) = 4.28, p = 0.04), with post-TRF elevations observed in T2D subjects. Vitamin D status was observed to modify mono(3-carboxypropyl) phthalate (MCPP) and MEP trajectories over time. Conclusion: Ramadan TRF is associated with changes in plasticiser metabolite levels, with estimated increased levels in T2D subjects versus healthy controls. Metabolite levels were influenced by HbA1c and vitamin D, though BMI was not observed to be a contributing factor.

The everyday use of plastic products exposes us to plastic-associated chemicals (PACs), which have been associated with risks to human health. We present the results of the Plastic Exposure Reduction Transforms Health Trial, with an observational cohort of 211 Australian participants and a 7-day pilot randomized controlled trial in 60 participants. Intervention groups received combinations of plastic-free kitchenware, low-plastic personal-care products and food sourced from more than 100 producers that minimized all plastic touchpoints from paddock to plate, while the control group received no intervention. The primary trial outcome was a reduction in urinary plastics-associated chemicals levels. In the cohort study, highly processed, plastic-packaged and canned foods were important modifiable factors for urinary PAC metabolite levels. Additionally, we observed negative associations between cardiometabolic biomarkers and higher urinary di(2-ethylhexyl) phthalate metabolites. Our randomized controlled dietary intervention maintained participants’ daily energy intake while decreasing plastic exposure (P < 0.001) and urinary levels of mono-n-butyl phthalate, monobenzyl phthalate and bisphenol A by 37.5% (95% confidence interval (CI): −55.6, −12.0; P = 0.007), 53.5% (95% CI: −72.7, −20.6; P = 0.005) and 59.7% (95% CI: −82.5, −6.87; P = 0.033), respectively. Intervention groups provided with foods that had minimal to no contact with plastic had the broadest effect on PAC excretion, and replacing low-plastic personal-care products alone led to an independent decrease in urinary mono-n-butyl phthalate, compared to no intervention. Despite constant plastic exposures, limiting food plastics touchpoints decreases select PACs in 7 days. Australian and New Zealand Clinical Trials Registry: ACTRN12622001252707.

Background: Plasticisers with endocrine-disrupting potential are ubiquitous and associate with obesity and type-2 diabetes (T2D), with higher levels reported in the Middle East. However, no data exist on plasticiser exposure in Bahrain where T2D affects 15% of the national population. Methods: An observational exploratory study in T2D (n = 60) and controls (n = 96), analysed for 24 h urinary plasticiser levels (liquid chromatography tandem mass spectrometry (LC-MS/MS)). Correlation and generalised linear model (GLM) analyses were employed to examine associations. Results: T2D were older (p < 0.001), had higher body mass index (BMI) (p < 0.001), body weight (p < 0.001) and glycosylated haemoglobin A1c (HbA1c) (p < 0.001). Correlation analysis revealed differences in inter-plasticiser, and plasticiser and biomarker relationships, with loss or reversal in T2D compared to controls. Mono-n-butyl phthalate (MnBP) levels were higher in T2D (p = 0.04); however, regression analysis revealed significant association with age. The GLM analyses demonstrated marked differences in the levels of mono(3-carboxypropyl) phthalate (MCPP), mono(2-ethyl-5-carboxypentyl) phthalate (MECPP), monoethyl phthalate (MEP) and bisphenol S (BPS), with lower levels in T2D versus controls (B = −3.41, p = 0.01; B = −5.28, p < 0.001; B = −8.94, p < 0.001; B = −6.09, p = 0.006, respectively); however, these contrasts appeared to be substantially confounded by BMI and/or age. Positive influence of age and negative influence of BMI when observed across the full dataset were generally reversed in T2D. Levels were complementary to those previously reported for the Middle East. Conclusions: The study indicates the phthalate levels in Bahrain are elevated though complementary to studies of phthalates in the Middle East; within those levels, the study indicates differential exposure–response relationships with plasticisers, influenced by age and BMI, in those with T2D compared to healthy controls.

Passive air samplers are well-suited for monitoring persistent organic pollutants (POPs) in ambient air. While the presence of POPs had been documented in Australian air, no data existed on structurally similar, halogenated natural products (HNPs), although these were frequently found in marine biota samples from Australia at levels exceeding those of anthropogenic POPs. This study reports quantitative data of the HNP 2,4,6-tribromoanisole (2,4,6-TBA) along with three POPs (polychlorinated biphenyls (PCBs) 153 and 138 as well as hexachlorobenzene (HCB)) in six selected passive air samples from different Australian regions (islands, coastal cities, and inland). For the most abundant HNP, 2,4,6-TBA, time-averaged concentrations for one year were determined at up to 420 pg/m ³ (One Tree Island), indicating its predominant natural production in the Great Barrier Reef (GBR). High concentrations of 2,4,6-TBA (17 pg/m ³ ), even in the remote inland sample (~ 800 km from the sea), led to the conclusion that the marine-derived 2,4,6-TBA was transported over long distances in air and can be found ubiquitously in Australian air. Even in the coastal cities of Brisbane and Darwin, 2,4,6-TBA levels were comparable to those of the PCBs. The HNP 2,3,3',4,4',5,5'-heptachloro-1'-methyl-1,2'-bipyrrole (Q1) was also detected in air from two islands. Its presence in air from One Tree Island was in line with expectations, given the high levels in marine mammal samples from the GBR. In direct comparison, the ~15 times higher ratio of Q1/2,4,6-TBA in air from Phillip Island indicated Q1 could be even more abundant in this marine region than in the GBR.

Humans may be exposed to thousands of per- and polyfluoroalkyl substances (PFAS), yet only a small fraction of these are regularly monitored, potentially underestimating the associated risks. This study used high-resolution mass spectrometry (HRMS)-based non-target analysis to examine for previously unreported PFAS in pooled serum from Australians. Samples collected between 2002 and 2021 from men aged 30 years in the general population (GP, n = 27) and firefighters (FF, n = 18), categorized into three age groups (31–45, 46–60, and ≥60), were analyzed. Fourteen PFAS were identified or structurally annotated, including six known (level 1a-1b) and seven suspects (level 2b-3a). Additionally, six suspects with CHF₂ or CF₃ functionalities were tentatively annotated. Two previously unreported PFAS in human serum, hydrogen-substituted 2:1 perfluoroether sulfonic acid (2:1 H-PFESA) and hexafluoro-1,2-propanediol (HFPrD), were detected in 42% and 56% of samples, respectively. Further analysis of these two compounds in broader GP serum pools, including six age groups and both sexes, revealed their presence even in children under five, with relatively high intensities. No clear temporal, age, sex, or occupation-related trends were observed, suggesting widespread ongoing population exposure. These findings underscore the need for expanded HRMS-based monitoring to better assess human PFAS exposure.

The rate of biodegradation in aquatic environments is a large source of uncertainty in chemical exposure assessments. Currently, there are insufficient biodegradation data and limited understanding of spatial variation in biodegradation, particularly across diverse aquatic environments. This study investigated the spatial variation in chemical biodegradation rate constants (k) across seven distinct aquatic environments in Australia including marine, mangrove, estuarine, and freshwater ecosystems, using a modified OECD 309 test. Significant spatial variation in k was found for 36 of 38 chemicals (ANOVA, p < 0.05). In addition, the average log k for the chemicals was strongly correlated with the average log k of the same chemicals in 18 European rivers measured using the same method (Pearson r = 0.94, p < 0.001), illustrating inter-continental consistency in the relative biodegradation behaviour of the chemicals. However, the standard deviation in log k was larger across the Australian sites than across the European sites for many chemicals. These findings provide two key insights: first, that diverse aquatic environments demonstrate greater spatial variability in k than rivers; and second, that despite this spatial variability, the modified OECD 309 method can reliably rank chemicals according to their biodegradability and thus be useful in persistence assessments.

Despite Australia's high antimicrobial use, their residues in wastewater and their impacts on receiving waters remain largely unknown. This study assessed the occurrence, removal, and risk for antimicrobial resistance (AMR) of 102 antimicrobial substances and selected transformation products (TPs) in wastewater effluent from 47 wastewater treatment plants (WWTPs) across Australia. Thirty-two antimicrobials and 13 TPs were detected, with 14 analytes occurring at >80% frequencies. Ampicillin, penicillin V, penicilloic V acid, fluconazole, and tazobactam M1 were observed with high median concentrations of >0.2 μg/L. Collectively, the WWTPs released 5.4 kg/day or 0.54 g/day/1000 inhabitants of antimicrobials/TPs into natural waters, with β-lactams, quinolones, nitroimidazoles/azoles, and sulfonamides comprising high volumes, which was correlated with the population's socioeconomic statuses. Thirty-seven analytes were removed at rates >80% post-treatment, whereas quinolones, nitroimidazoles/azoles, lincosamides, and macrolide TPs were observed with poor removal efficiencies, which were affected by treatment processes and regional climate. Comparing measured concentrations with the predicted no-effect concentrations for AMR selection (PNEC_AMR), 7 antimicrobials exerted selection risk for resistant bacteria. Concerningly, ciprofloxacin posed medium/high risk in most of the assessed WWTPs. The accumulative effects of antimicrobial classes and certain TPs might further aggravate adverse impacts on AMR development. Our study provides insights into the presence and AMR implications of antimicrobials in treated wastewater, aiming to safeguard public health and ecosystems.