Serum concentration trends and apparent half-lives of per- and polyfluoroalkyl substances (PFAS) in Australian firefighters.

BACKGROUND: Per- and polyfluoroalkyl substances (PFASs) are persistent manmade compounds used in aqueous film forming foam (AFFF). The extensive use of AFFF has led to widespread environmental PFAS contamination and exposures of firefighters. OBJECTIVES: To determine PFAS blood serum concentration trends and apparent serum half-lives in firefighters after the replacement of AFFF. METHODS: Current and former employees of an Australian corporation providing firefighting services, where AFFF formulations had been used since the 1980s up until 2010, were recruited in 2018-2019 to participate in this study. Special focus was put on re-recruiting participants who had provided blood samples five years prior (2013-2014). Participants were asked to provide a blood sample and fill in a questionnaire. Serum samples were analysed for 40 different PFASs using HP LC-MS/MS. RESULTS: A total of 799 participants provided blood samples in 2018-2019. Of these, 130 previously provided blood serum in 2013-2014. In 2018-2019, mean (arithmetic) serum concentrations of perfluorooctane sulfonate (PFOS, 27 ng/mL), perfluoroheptane sulfonate (PFHpS, 1.7 ng/mL) and perfluorohexane sulfonate (PFHxS, 14 ng/mL) were higher than the levels in the general Australian population. Serum concentrations were associated with the use of PFOS/PFHxS based AFFF. Participants who commenced service after the replacement of this foam had serum concentrations similar to those in the general population. Mean (arithmetic) individual apparent half-lives were estimated to be 5.0 years (perfluorooctanoic acid (PFOA)), 7.8 years (PFHxS), 7.4 years (PFHpS) and 6.5 years (PFOS). CONCLUSION: This study shows how workplace interventions such as replacement of AFFF can benefit employees at risk of occupational exposure.

Temporal trends of perfluoroalkyl substances in an Australian wastewater treatment plant: A ten-year retrospective investigation.

Per- and poly-fluoroalkyl substances (PFAS) are a problematic group of chemicals used in various industrial and household products. They have been extensively detected in wastewater as a result of day-to-day product usage. Due to concerns about their safety, voluntary and regulatory action to limit the manufacture and use of some individual PFAS has occurred since the year 2000. The impact that this intervention has had on the use and potential exposure of Australians has not been measured. Wastewater serves as a powerful tool to assess the chemical use or consumption patterns of a population over time. We accessed a ten-year wastewater archiving program to conduct a temporal analysis of PFAS trends in an urban Australian population between the years 2010 and 2020. Results showed a decline in the concentrations for most PFAS, and a change in the PFAS profile from perfluorosulfonic acids and long-chain perfluorocarboxylic acids, to the short-chain perfluorocarboxylic acids and PFOS-replacement degradation products such as 5:3 FTCA. Intermittent pulses of PFAS that were significantly higher than 'background' levels (i.e., representing the PFAS input from primarily households) were observed, suggesting continuing industrial PFAS input within the wastewater catchment. This study highlights the long-term consequences of the diffuse use of persistent chemicals in products, and their ability to continue to enter the wastewater stream for decades.

Do food and stress biomarkers work for wastewater-based epidemiology? A critical evaluation.

Dietary characteristics and oxidative stress are closely linked to the wellbeing of individuals. In recent years, various urinary biomarkers of food and oxidative stress have been proposed for use in wastewater-based epidemiology (WBE), in efforts to objectively monitor the food consumed and the oxidative stress experienced by individuals in a wastewater catchment. However, it is not clear whether such biomarkers are suitable for wastewater-based epidemiology. This study presents a suite of 30 urinary food and oxidative stress biomarkers and evaluates their applicability for WBE studies. This includes 22 biomarkers which were not previously considered for WBE studies. Daily per capita loads of biomarkers were measured from 57 wastewater influent samples from nine Australian catchments. Stability of biomarkers were assessed using laboratory scale sewer reactors. Biomarkers of consumption of vitamin B2, vitamin B3 and fibre, as well as a component of citrus had per capita loads in line with reported literature values despite susceptibility of degradation in sewer reactors. Consumption biomarkers of red meat, fish, fruit, other vitamins and biomarkers of stress had per capita values inconsistent with literature findings, and/or degraded rapidly in sewer reactors, indicating that they are unsuitable for use as WBE biomarkers in the traditional quantitative sense. This study serves to communicate the suitability of food and oxidative stress biomarkers for future WBE research.

Harmonizing analytical chemistry and clinical epidemiology for human biomonitoring studies. A case-study of plastic product chemicals in urine.

There is an interdisciplinary interface between analytical chemistry and epidemiology studies with respect to the design, execution, and analysis of environmental epidemiology cohorts and studies. Extracting meaningful results linking chemical exposure to human health outcomes begins at study design and spans the entire workflow. Here we discuss analytical experimental design from an exposure science perspective, and propose a reporting checklist for the design of human biomonitoring studies. We explain key analytical chemistry concepts of blanks and limits of reporting and present a case series of plastic product chemical exposure in prenatal urine specimens from the Barwon Infant Study.

Per- and polyfluoroalkyl substances (PFAS) in Australia: Current levels and estimated population reference values for selected compounds.

BACKGROUND: Increased public awareness of PFAS contamination in Australia has resulted in serum biomonitoring efforts in individuals in potentially affected communities. However, population-based reference values for assessing whether individual results exceed the typical range in the Australian general population are not currently available. OBJECTIVE: Estimate population upper bound reference values based on updated serum PFAS concentrations in pooled samples from southeast Queensland, Australia and population variation observed in the US National Health and Nutrition Examination Survey (NHANES) datasets. METHODS: We calculated ratios of 95th percentile to arithmetic mean (P95:AM ratios) using data from the NHANES 2013-14 and 2015-16 cycle samples for frequently detected PFASs: PFOA, linear and branched PFOS, perfluorononanoate (PFNA), perfluorodecanoate (PFDA), and perfluorohexanesulfonate (PFHxS). We estimated Australian age-specific means for PFAS using pooled serum samples collected in 2014-15 and 2016-17. We used the P95:AM ratios to estimate 95th percentile concentrations in the Australian population based on the results of the 2016-17 pooled samples. RESULTS AND CONCLUSIONS: P95:AM ratios for each PFAS were similar across NHANES cycle and age group, so overall compound-specific ratios were estimated for PFOA (2.1), PFNA (2.4), PFDA (2.7), PFHxS (2.7), and linear (2.4) and summed PFOS (2.3). Australian mean PFAS concentrations continued previously reported declining trends. The estimated P95 values can be used as preliminary substitutes for more rigorous population reference values to identify samples with clearly elevated serum PFAS concentrations in Australian biomonitoring efforts. Given uncertainties and variability inherent in this evaluation, the estimated P95 values should be interpreted with caution. Mean and estimated P95 serum PFAS concentrations in Australia should continue to be monitored to document declining trends in population serum concentrations.

Integrated chemical exposure assessment of coastal green turtle foraging grounds on the Great Barrier Reef.

The Great Barrier Reef receives run-off from 424,000 km2 catchment area across coastal Queensland, incorporating diffuse agricultural run-off, and run-off point sources of land-based chemical pollutants from urban and industrial development. Marine biota, such as green turtles (Chelonia mydas), are exposed to these diverse chemical mixtures in their natural environments, and the long term effects on turtle and ecosystem health remain unknown. This study was part of a larger multi-disciplinary project characterising anthropogenic chemical exposures from the marine environment and turtle health. The aim of this study was to screen for a wide range of anthropogenic chemical pollutants present in the external and internal environment of green turtles, using a combination of traditional targeted chemical analyses, non-target suspect screening, and effect-based bioassay methods, while employing a case-control study design. A combination of passive (water) and grab (water, sediment) samples were investigated. Three known green turtle foraging sites were selected for sampling: two coastal 'case' sites influenced primarily by urban/industrial and agricultural activities, respectively; and a remote, offshore 'control' site. Water and sediment samples from each of the three sampling locations showed differences in chemical pollutant profiles that reflected the dominant land uses in the adjacent catchment. Targeted mass spectrometric analysis for a range of pesticides, industrial chemicals, pharmaceuticals and personal care products found the greatest detection frequency and highest concentrations in coastal samples, compared to the control. Non-target screening analysis of water showed clear differentiation in chemical profile of the urban/industrial site. In-vitro assays of sediment samples from the control site had lowest induction, compared to coastal locations, as expected. Here we present evidence that turtles foraging in coastal areas are exposed to a range of anthropogenic pollutants derived from the adjacent coastal catchment areas.

A mass estimate of perfluoroalkyl substance (PFAS) release from Australian wastewater treatment plants.

Perfluoroalkyl substances (PFASs) have been used in large quantities for a variety of applications in Australian industry and household products. Through the course of their everyday use, PFASs enter the wastewater stream however current treatment processes provide only partial removal of these chemicals from wastewater. The release of treated effluent and re-use of biosolids represents an important point source of PFASs into the Australian environment yet the scale of PFAS release from Australian WWTPs is unknown. For the first time, influent, effluent and biosolids samples from 14 WWTPs across Australia were assessed for 9 PFASs and the national loads of these PFASs released from WWTPs estimated. Ʃ9PFASs ranged from 0.98 to 440 ng/L (influent), 21-560 ng/L (effluent) and 5.2-150 ng/g (biosolids). National loads of PFOA and PFOS in effluent were estimated at 65 kg and 26 kg per annum respectively. In biosolids, annual loads were estimated at 2 kg and 8 kg respectively. The continued detection of PFOS over a decade after its phase out, the increasing use of PFOS alternatives together with their resistance to degradation processes suggests that PFASs will be a priority for regulators and waste management to prevent further contamination of Australia's water resources.

Perfluorinated alkyl acids in the serum and follicular fluid of UK women with and without polycystic ovarian syndrome undergoing fertility treatment and associations with hormonal and metabolic parameters.

Women with polycystic ovarian syndrome (PCOS) undergoing treatment for infertility could be a sensitive subpopulation for endocrine effects of exposure to perfluorinated alkyl acids (PFAAs), persistent organic pollutants with potential endocrine activity. Women with, PCOS (n = 30) and age- and BMI-matched controls (n = 29) were recruited from a UK fertility clinic in 2015. Paired serum and follicular fluid samples were collected and analysed for 13 PFAAs. Sex steroid and thyroid hormones, and metabolic markers were measured and assessed for associations with serum PFAAs. Four PFAAs were detected in all serum and follicular fluid samples and concentrations in the two matrices were highly correlated (R2 > 0.95): perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonate (PFHxS), and perfluorononanoic acid (PFNA). Serum PFOS was positively associated with age (1 ng/mL per yr, p < 0.05) and was higher in PCOS cases than controls (geometric mean [GM] 3.9 vs. 3.1 ng/mL, p < 0.05) and in women with irregular vs. regular menstrual cycles (GM 3.9 vs. 3.0 ng/mL, p = 0.01). After adjustment for confounders, serum testosterone was significantly associated with PFOA, PFHxS, PFNA, and the molar sum of the four frequently detected serum PFAAs (approximately 50 percent increase per ln-unit) among controls but not PCOS cases. HbA1c in PCOS cases was inversely associated with serum PFOA, PFHxs, and sum of PFAAs (2-3 mmol/mol per ln-unit). In controls, fasting glucose was positively associated with serum PFOA and sum of PFAAs (0.25 nmol/L per ln-unit increase in PFAAs). Few other associations were observed. The analyses and findings here should be considered exploratory in light of the relatively small sample sizes and large number of statistical comparisons conducted. However, the data do not suggest increased sensitivity to potential endocrine effects of PFAAs in PCOS patients.

Australia-wide assessment of perfluoroalkyl substances (PFASs) in landfill leachates.

Leachate from 27 landfills was analysed for nine perfluoroalkyl substances (PFASs). Five PFASs were detected ubiquitously, with perfluorohexanoate (PFHxA) the predominant PFAS (mean 1700ng/L; range 73-25,000ng/L). Despite the complexity of landfill-specific factors, some general trends in PFAS concentrations were observed. Mean concentrations of eight PFASs were higher in operating landfills (or landfill cells) accepting primarily municipal waste, compared to closed municipal landfills. Landfills accepting primarily construction and demolition wastes produced leachate that had higher mean PFAS concentrations than municipal landfills. Younger landfills appeared to have a higher burden of waste containing PFASs (or their precursors), as significant relationships (p<0.05) were observed between selected PFAS concentrations and landfill age. Increasing pH and total organic carbon (TOC) in leachate were associated with increased concentrations of several PFASs. Eight landfills discharged leachate to wastewater treatment plants (WWTPs). Estimated masses of PFASs discharged reached a maximum of 62g annually (PFHxA), with a national estimate reaching 31kg (PFHxA) annually. The practise of treating leachate at WWTPs allows redistribution of PFASs between the solid and liquid waste streams, although the contribution of leachate to the total load of PFASs entering WWTPs is minor compared to domestic waste water sources.

Cross-sectional biomonitoring study of pesticide exposures in Queensland, Australia, using pooled urine samples.

A range of pesticides are available in Australia for use in agricultural and domestic settings to control pests, including organophosphate and pyrethroid insecticides, herbicides, and insect repellents, such as N,N-diethyl-meta-toluamide (DEET). The aim of this study was to provide a cost-effective preliminary assessment of background exposure to a range of pesticides among a convenience sample of Australian residents. De-identified urine specimens stratified by age and sex were obtained from a community-based pathology laboratory and pooled (n = 24 pools of 100 specimens). Concentrations of urinary pesticide biomarkers were quantified using solid-phase extraction coupled with isotope dilution high-performance liquid chromatography-tandem mass spectrometry. Geometric mean biomarker concentrations ranged from <0.1 to 36.8 ng/mL for organophosphate insecticides, <0.1 to 5.5 ng/mL for pyrethroid insecticides, and <0.1 to 8.51 ng/mL for all other biomarkers with the exception of the DEET metabolite 3-diethylcarbamoyl benzoic acid (4.23 to 850 ng/mL). We observed no association between age and concentration for most biomarkers measured but noted a "U-shaped" trend for five organophosphate metabolites, with the highest concentrations observed in the youngest and oldest age strata, perhaps related to age-specific differences in behavior or physiology. The fact that concentrations of specific and non-specific metabolites of the organophosphate insecticide chlorpyrifos were higher than reported in USA and Canada may relate to differences in registered applications among countries. Additional biomonitoring programs of the general population and focusing on vulnerable populations would improve the exposure assessment and the monitoring of temporal exposure trends as usage patterns of pesticide products in Australia change over time.

Maternal exposure to perfluoroalkyl acids measured in whole blood and birth outcomes in offspring.

Perfluoralkyl and polyfluoralkyl substances have been measured in plasma and serum of pregnant women as a measure of prenatal exposure. Increased concentrations of individual perfluoroalkyl acids (PFAAs), (typically perfluorooctanoic acid (PFOA) and perfluoroctane sulfonate (PFOS) have been reported to be associated with reductions in birth weight and other birth outcomes. We undertook a study of 14 PFAAs in whole blood (including PFOS, PFHxS, PFHpA, PFOA, PFNA, PFDA and PFUnDA) from 98 pregnant women in Western Australia from 2008 to 2011. Median concentrations (in µg/L) were: PFOS 1.99; PFHxS 0.33; PFOA 0.86; PFNA 0.30; PFDA 0.12 and PFUnDA 0.08. Infants born to women with the highest tertile of PFHxS exposure had an increased odds of being <95% of their optimal birth weight (OR 3.5, 95% CI 1.1-11.5). Conversely, maternal blood concentrations of PFUnDA were associated with non-significant increases in average birth weight (+102g, 95% CI -41, 245) and significant increases in proportion of optimal birth weight (+4.7%, 95% CI 0.7, 8.8) per ln-unit change. This study has reported a range of PFAAs in the whole blood of pregnant women and suggests that PFHxS and PFUnDA may influence foetal growth and warrant further attention. Additional studies are required to identify the sources of PFAA exposure with a view to prevention, in addition to further studies investigating the long term health effects of these ubiquitous chemicals.

Occurrence and distribution of brominated flame retardants and perfluoroalkyl substances in Australian landfill leachate and biosolids.

The levels of perfluroalkyl substances (PFASs), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDDs) were studied in Australian landfill leachate and biosolids. Leachate was collected from 13 landfill sites and biosolids were collected from 16 wastewater treatment plants (WWTPs), across Australia. Perfluorohexanoate (PFHxA) (12-5700ng/L) was the most abundant investigated persistent, bioaccumulative and toxic (PBT) chemical in leachate. With one exception, mean concentrations of PFASs were higher in leachate of operating landfills compared to closed landfills. Polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane isomers (HBCDDs) were detected typically at operating landfills in comparatively lower concentrations than the PFASs. Decabromodiphenyl ether (BDE-209) (<0.4-2300ng/g) and perfluoroctanesulfonate (PFOS) (

Rapid, automated online SPE-LC-QTRAP-MS/MS method for the simultaneous analysis of 14 phthalate metabolites and 5 bisphenol analogues in human urine.

Phthalates and bisphenol A (BPA) have received special attention in recent years due to their frequent use in consumer products and potential for adverse effects on human health. BPA is being replaced with a number of alternatives, including bisphenol S, bisphenol B, bisphenol F and bisphenol AF. These bisphenol analogues have similar potential for adverse health effects, but studies on human exposure are limited. Accurate measurement of multiple contaminants is important for estimating exposure. This paper describes a sensitive and automated method for the simultaneous determination of 14 phthalate metabolites, BPA and four bisphenol analogues in urine using online solid phase extraction coupled with high-performance liquid chromatography/tandem mass spectrometry using a hybrid triple-quadrupole linear ion trap mass spectrometer (LC-QTRAP-MS/MS), requiring very little sample volume (50µL). Quantification was performed under selected reaction monitoring (SRM) mode with negative electrospray ionization. The use of SRM combined with an enhanced product ion scan within the same analysis was examined. Unequivocal identification was provided by the acquisition of three SRM transitions per compound and isotope dilution. The analytical performance of the method was evaluated in synthetic and human urine. Linearity of response over three orders of magnitude was demonstrated for all of the compounds (R(2)>0.99), with method detection limits of 0.01-0.5ng/mL and limits of reporting of 0.07-3.1ng/mL. Accuracy ranged from 93% to 113% and inter- and intra-day precision were <22%. Finally, the validated method has been successfully applied to a cohort of pregnant women to measure biomarker concentrations of phthalates and bisphenols, with median concentrations ranging from 0.3ng/mL (bisphenol S) to 18.5ng/mL (monoethyl phthalate).

Concentrations of phthalates and DINCH metabolites in pooled urine from Queensland, Australia.

Dialkyl phthalate esters (phthalates) are ubiquitous chemicals used extensively as plasticizers, solvents and adhesives in a range of industrial and consumer products. 1,2-Cyclohexane dicarboxylic acid, diisononyl ester (DINCH) is a phthalate alternative introduced due to a more favourable toxicological profile, but exposure is largely uncharacterised. The aim of this study was to provide the first assessment of exposure to phthalates and DINCH in the general Australian population. De-identified urine specimens stratified by age and sex were obtained from a community-based pathology laboratory and pooled (n=24 pools of 100). Concentrations of free and total species were measured using online solid phase extraction isotope dilution high performance liquid chromatography tandem mass spectrometry. Concentrations ranged from 2.4 to 71.9ng/mL for metabolites of di(2-ethylhexyl)phthalate, and from <0.5 to 775ng/mL for all other metabolites. Our data suggest that phthalate metabolites concentrations in Australia were at least two times higher than in the United States and Germany; and may be related to legislative differences among countries. DINCH metabolite concentrations were comparatively low and consistent with the limited data available. Ongoing biomonitoring among the general Australian population may help assess temporal trends in exposure and assess the effectiveness of actions aimed at reducing exposures.

Use of pooled samples to assess human exposure to parabens, benzophenone-3 and triclosan in Queensland, Australia.

Parabens, benzophenone-3 and triclosan are common ingredients used as preservatives, ultraviolet radiation filters and antimicrobial agents, respectively. Human exposure occurs through consumption of processed food and use of cosmetics and consumer products. The aim of this study was to provide a preliminary characterisation of exposure to selected personal care product chemicals in the general Australian population. De-identified urine specimens stratified by age and sex were obtained from a community-based pathology laboratory and pooled (n=24 pools of 100). Concentrations of free and total (sum of free plus conjugated) species of methyl, ethyl, propyl and butyl paraben, benzophenone-3 and triclosan were quantified using isotope dilution tandem mass spectrometry; with geometric means 232, 33.5, 60.6, 4.32, 61.5 and 87.7ng/mL, respectively. Age was inversely associated with paraben concentration, and females had concentrations approximately two times higher than males. Total paraben and benzophenone-3 concentrations are significantly higher than reported worldwide, and the average triclosan concentration was more than one order of magnitude higher than in many other populations. This study provides the first data on exposure of the general Australian population to a range of common personal care product chemical ingredients, which appears to be prevalent and warrants further investigation.

Emerging contaminants (pharmaceuticals, personal care products, a food additive and pesticides) in waters of Sydney estuary, Australia.

The current investigation of marine water from 30 sites adjacent to stormwater outlets across the entire Sydney estuary is the first such research in Australia. The number of analytes detected were: 8/59 pharmaceutical compounds (codeine, paracetamol, tramadol, venlafaxine, propranolol, fluoxetine, iopromide and carbamazepine), 7/38 of the pesticides (2,4-dichlorophenoxyacetic acid (2,4-D), 3,4-dichloroaniline, carbaryl, diuron, 2-methyl-4-chlorophenoxyacetic acid (MCPA), mecoprop and simazine) and 0/3 of the personal care products (PCPs) analysed. An artificial sweetener (acesulfame) was detected, however none of the nine antibiotics analysed were identified. Sewage water is not discharged to this estuary, except infrequently as overflow during high-precipitation events. The presence of acesulfame (a recognised marker of domestic wastewater) and pharmaceuticals in water from all parts of the estuary after a dry period, suggests sewage water is leaking into the stormwater system in this catchment. The pesticides are applied to the environment and were discharged via stormwater to the estuary.

Combined thermal and herbicide stress in functionally diverse coral symbionts.

Most reef building corals rely on symbiotic microalgae (genus Symbiodinium) to supply a substantial proportion of their energy requirements. Functional diversity of different Symbiodinium genotypes, endorsing the host with physiological advantages, has been widely reported. Yet, the influence of genotypic specificity on the symbiont's susceptibility to contaminants or cumulative stressors is unknown. Cultured Symbiodinium of presumed thermal-tolerant clade D tested especially vulnerable to the widespread herbicide diuron, suggesting important free-living populations may be at risk in areas subjected to terrestrial runoff. Co-exposure experiments where cultured Symbiodinium were exposed to diuron over a thermal stress gradient demonstrated how fast-growing clade C1 better maintained photosynthetic capability than clade D. The mixture toxicity model of Independent Action, considering combined thermal stress and herbicide contamination, revealed response additivity for inhibition of photosynthetic yield in both tested cultures, emphasizing the need to account for cumulative stressor impacts in ecological risk assessment and resource management.

Historical trends of PBDEs and HBCDs in sediment cores from Sydney estuary, Australia.

This paper presents the first historical data on the occurrence of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDs) in estuarine sediment from Australia. Sediment cores and surficial sediment samples were collected from four locations within Sydney estuary, Australia. Large increases in concentrations were observed for all compounds between 1980 and 2014, especially for BDE-209 (representative usage of Deca-BDE commercial mixture), which was found in surficial sediment at an average concentration of 42 ng/g dry wt (21-65 ng/g dry wt). PBDE congeners representative of both the Penta- and Octa-BDE commercial mixtures (∑6PBDEs) were also found in their highest concentrations in surficial sediments (average: 1.3 ng/g dry wt; range: 0.65-2.5 ng/g dry wt). PBDE concentrations in surficial sediments were relatively high when compared with those presented in the available literature. This suggests that their input into the Sydney estuary has not decreased since their bans almost a decade earlier. After a sharp increase in the 1990s, HBCD concentrations peaked at an average of 3.5 ng/g dry wt (1.8-5.3 ng/g dry wt) in surficial samples. With global legislation on HBCDs allowing its usage for the next 10 years, it is expected that its input into the estuary is likely to continue.

Evaluation of polybrominated diphenyl ethers (PBDEs) in matched cat sera and house dust samples: investigation of a potential link between PBDEs and spontaneous feline hyperthyroidism.

The cause of feline hyperthyroidism (FH), a common endocrinopathy of domestic cats, is unknown. A potential association between exposure to environmental contaminants polybrominated diphenyl ethers (PBDEs) and FH was investigated. The median serum level for the sum of congeners BDE-47, BDE-99, BDE-153, BDE-154 and BDE-183 (Σ5) in hyperthyroid and euthyroid cats was 82 and 174 ng g(-1)lw respectively with no significant difference in PBDE levels or profiles between groups. Overall, the median (min to max) concentration of PBDEs in cat serum (n=65) was 118 ng g(-1)lw (5-5260 ng g(-1)lw), which is approximately 10 times higher than that observed in the Australian human population. Furthermore, congener composition in feline serum samples was dominated by congener BDE-99, followed by BDE-47 then BDE-153 which differs from results of human biomonitoring. There was no correlation between PBDE levels in feline serum samples and matched house dust samples (n=25). However the similarity of BDE-47/99 ratio in each matrix suggests dust is likely the dominant exposure. Calculation of the daily exposure dose via dust ingestion for cats equated to a mean of 33 ng kg(-1) bw d(-1) (0.2-150 ng kg(-1) bw d(-1)). Differences in exposure estimates for Australian and US cats, based on dust ingestion alone, are consistent with the observed differences in body burdens. Our results do not support a role for PBDE exposure in the aetiopathogenesis of FH.

The effect of ongoing blood loss on human serum concentrations of perfluorinated acids.

Perfluorinated alkyl acids (PFAAs) have been detected in serum at low concentrations in background populations. Higher concentrations haven been observed in adult males compared to females, with a possible explanation that menstruation offers females an additional elimination route. In this study, we examined the significance of blood loss as an elimination route of PFAAs. Pooled serum samples were collected from individuals undergoing a medical procedure involving ongoing blood withdrawal called venesection. Concentrations from male venesection patients were approximately 40% lower than males in the general population for perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). A simple pharmacokinetic model was used to test the hypothesis that blood loss could explain why adult males have higher concentrations of PFAAs than females, and why males undergoing venesections had lower concentrations compared to males in the general population. The model application generally supported these hypotheses showing that venesection might reduce blood serum concentrations by 37% (PFOA) and 53% (PFOS) compared to the observed difference of 44% and 37%. Menstruation was modeled to show a 22% reduction in PFOA serum concentrations compared to a 24% difference in concentrations between males and females in the background population. Uncertainties in the modeling and the data are identified and discussed.