Tarragona County Research Articles

Air concentrations of trace elements in a municipality under the influence of Tarragona petrochemical complex: Human health risks

One of the largest petrochemical complexes of southern Europe is located in Tarragona County (Catalonia, Spain). Despite environmental monitoring is routinely conducted in the area, the long-term occurrence of airborne trace elements has been poorly investigated. In the present study, the concentrations of arsenic (As), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb) and vanadium (V) were analysed in air samples collected in El Morell, a town potentially impacted by the petrochemical. Air samples were simultaneously collected in the town of Cambrils, as a background site. Meteorological data and retro trajectories analysis were used to evaluate the impact of the petrochemical industry on the levels of trace elements in air. Subsequently, human health risks due to inhalation exposure to the trace elements were also assessed. Except for V, air concentrations were significantly higher near the oil refinery than the background levels. Human health risks were also estimated to be higher in the vicinity of the petrochemical complex. In turn, air inhalation of Pb and V was higher than their dietary intakes. The present data should be considered only as preliminary, since the sampling was taken during only three weeks, which is an insufficient period to extract reliable conclusions. Further long-term studies should be focused on assessing the influence of temporary variables, such as meteorological conditions and fugitive or sporadic emissions.

Temporal trend of the dietary exposure to metals/metalloids: A case study in Tarragona County, Spain

In 2018, samples of various food groups were randomly purchased in different establishments of Tarragona County (Catalonia, Spain). The levels of As, Be, Cd, Cr, Hg, Mn, Ni, Pb, Sn, Tl and V were determined in the analyzed foodstuffs and their dietary intakes were estimated. Manganese was the element showing the highest concentration, while Be, Cr and Tl were not detected in any of the samples. Fish and shellfish was the only food group with detectable traces of all the remaining elements. The current levels were compared with the results of two previous surveys conducted in 1998 and 2013 in the same area. Although the levels of the analyzed elements in foodstuffs increased during the period 2013–2018, their intakes decreased by an average of 60%, due to consumption patterns changes by the population. Children and adolescents exceeded the maximum recommended intake of Ni set by the EFSA, while the dietary exposure to Pb for children was also above safety values. Compared with the concentrations found in 2013, Ni was the only element showing an increase, as well as an increase of human dietary intake. Meat, vegetables and milk were identified as the main contributors to Ni exposure. This trend was also correlated with changes in the biological burden of the same elements previously reported for the population of the area, for whom an increase of Ni in lungs was reported. Based on these results, Ni should be included as a target metal by food safety authorities, being suggested its inclusion in future Total Diet Studies.

Trace Elements in Blood of the Population Living near a Hazardous Waste Incinerator in Catalonia, Spain.

In 2012, the concentrations of trace elements (As, Be, Cd, Cr, Hg, Mn, Ni, Pb, Sn, Tl, and V) were measured in blood samples of the population living in the vicinity of a hazardous waste incinerator (HWI) located in Tarragona County (Catalonia, Spain). This study is part of a wide surveillance program aimed at assessing the impact of the facility on the public health conducted since 1998, before the HWI started operating. Lead was the metal occurring with the highest concentration (21.7μgkg-1), followed by Mn (19.7μgkg-1) and Hg (4.62μgkg-1). Arsenic (6.99μgkg-1) showed a low detection rate (49%), while the rest of the analyzed trace elements were not detected. In 2017, a new sampling campaign was conducted, and three new trace elements (Co, Cu, and Sb) were added. In the most recent survey, Cu reached a mean concentration of 931μgkg-1, up to 60-fold higher than that corresponding to the remaining trace elements. Relatively high levels were also found for Sb (16.0μgkg-1), Mn (13.9μgkg-1), and Pb (13.0μgkg-1). In comparison with the baseline study (1998), Hg, Mn, and Pb significantly decreased over time. Some trace elements showed significant differences according to sex, age, and area of residence. In general, the concentrations of trace elements in blood were similar to, or even lower than, those reported in the scientific literature. Hence, the exposure to trace elements does not mean any additional health risk for the population living near the HWI. This conclusion is in agreement with other studies carried out in the framework of this surveillance program, in which trace elements have been measured in different biological matrices, such as hair and autopsy tissues (brain, bone, kidney, liver, and lungs).

Air quality, health impacts and burden of disease due to air pollution (PM10, PM2.5, NO2 and O3): Application of AirQ+ model to the Camp de Tarragona County (Catalonia, Spain)

The purpose of this study was to assess the impact to human health of air pollutants, through the integration of different technics: data statistics (spatial and temporal trends), population attributable fraction using AIRQ+ model developed by the WHO, and burden of disease using Disability-Adjusted Life Years (DALYs). The levels of SO2, NO, NO2, O3, H2S, benzene, PM10, PM2.5, CO, benzo(a)pyrene and metals, obtained between 2005 and 2017 from the air quality monitoring network across Camp de Tarragona County, were temporally and spatially determined. Health impacts were evaluated using the AIRQ+ model. Finally, the burden of disease was assessed through the calculation of Years of Lost life (YLL) and Years Lost due to Disability (YLD). In general terms, air quality was good according to European quality standards, but it did not fulfil the WHO guidelines, especially for O3, PM10 and PM2.5. Several decreasing (NO, NO2, SO2, PM10 and benzene) and an increasing (O3) temporal trend were found. Correlation between unemployment rate and air pollutant levels was found, pointing that the economic crisis (2008–2014) was a factor influencing the air pollutant levels. Reduction of air pollutant levels (PM2.5) to WHO guidelines in the Camp de Tarragona County would decrease the adult mortality between 23 and 297 cases per year, which means between 0.5 and 7% of all mortality in the area. In this County, for lung cancer, ischemic heart disease, stroke, and chronic obstructive pulmonary disease due to levels of PM2.5 above the WHO threshold limits, DAYLs were 240 years. This means around 80 DALYs for 100,000 persons every year -between 2005 and 2017. Population attributable fraction (PAF) and burden of disease (DALYs) methodologies are suitable tools for regional and national policymakers, who must take decisions to prevent and to control air pollution and to analyse the cost-effectiveness of interventions.

Metals in biological tissues of the population living near a hazardous waste incinerator in Catalonia, Spain: Two decades of follow-up

During the period 1996–1998, a hazardous waste incinerator (HWI) was built in Constantí (Tarragona County, Catalonia, Spain). Because of the potential adverse effects of toxic emissions, mainly metals and dioxins and furans, waste incinerators in general have been an important cause of concern for the public opinion. For that reason, to assess its environmental impact on the surroundings, as well as the potential human health risks of the HWI, environmental and biological monitoring studies have been carried out since 1996–1998, when the baseline concentrations were established. This article summarizes all the results corresponding to metals in biological tissues of the population living near the HWI, two decades after the construction of the facility. In 1996–1998, the baseline concentrations of a number of elements (As, Be, Cd, Cr, Hg, Mn, Ni, Pb, Sn, Tl and V) were determined in samples of hair, blood and autopsy tissues (bone, brain, liver, lung and kidney) of subjects living in the area. In successive 5-year periods, new surveys were conducted to periodically measure the levels of metals in the same biological tissues. The daily dietary intake of these metals was also estimated for the population of the area. The results of this surveillance program do no suggest additional adverse health risks of metals for the population living near the HWI. However, special attention should be paid to Cr, due not only to the increases of this element observed in most analyzed biological tissues, but also in its dietary intake.

Prenatal exposure to PFOS and PFOA in a pregnant women cohort of Catalonia, Spain

This study was aimed at assessing the prenatal exposure to perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in a cohort of pregnant women living in Reus (Tarragona County, Catalonia, Spain). These chemicals were biomonitored in maternal plasma during the first trimester of pregnancy, at delivery, and in cord blood. The dietary exposure of PFOS and PFOA was estimated by using questionnaires of food frequency and water intake, as well as data on food levels previously reported in the same area. In addition, the exposure through air inhalation and indoor dust ingestion was also calculated. Finally, a physiologically-based pharmacokinetic (PBPK) model was applied in order to establish the prenatal exposure of the fetus/child and to adjust exposure assessment vs. biomonitoring results. Probabilistic calculations of fetal exposure were performed by forward internal dosimetry and Monte-Carlo simulation. Mean plasma levels of PFOA were 0.45, 0.13 and 0.12 ng/mL at the first trimester, at delivery and in cord plasma, while those of PFOS were 2.93, 2.21, and 1.17 ng/mL, respectively. Traces of PFOS were found in all samples in the trimester and at delivery, and almost in all cord blood samples. Transplacental transfers of PFOS and PFOA were estimated to be around 70% and 60%, respectively. A temporal decrease trend in plasma levels of PFOS and PFOA was noticed, when comparing current values with data obtained 10 years ago in the same area. In agreement with many other studies, dietary intake was the main route of exposure to PFOS and PFOA in our cohort of pregnant women. It is an important issue to establish the exposure in critical windows periods such as fetal development to perfluoroalkylated substances, but also to other endocrine disrupting chemicals.

Seasonal characterization and dosimetry-assisted risk assessment of indoor particulate matter (PM10-2.5, PM2.5-0.25, and PM0.25) collected in different schools

Inhalation of particulate matter (PM) has been linked to serious adverse health effects, such as asthma, cardiovascular diseases and lung cancer. In the present study, coarse (PM10-2.5), accumulation mode (PM2.5-0.25), and quasi-ultrafine (PM0.25) particulates were collected inside twelve educative centers of Tarragona County (Catalonia, Spain) during two seasons (cold and warm). Chemical characterization of PM, as well as risk assessment were subsequently conducted in order to evaluate respiratory and digestive risks during school time for children. Levels and chemical composition of PM were very different among the 12 centers. Average PM levels were higher during the cold season, as well as the concentrations of most toxic metals. In most schools, PM levels were below the daily PM10 threshold established in the regulation (50 μg/m3), with the exception of school number 1 during the cold season. On average, and regardless of season, coarse PM was highly influenced by mineral matter, while organic matter and elemental carbon were prevalent in quasi-ultrafine PM. The concentrations of the toxic elements considered by the legislation (As, Cd, Pb, and Ni) were below their correspondent regulatory annual limits. Calculated risks were below the safety thresholds, being fine fractions (PM2.5-0.25 and PM0.25) the main contributors to both digestive and respiratory risks.

Monitoring dioxins and furans in plasma of individuals living near a hazardous waste incinerator: Temporal trend after 20 years

The concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed in 40 plasma samples of individuals living in zones under potential influence of the emissions of a hazardous waste incinerator (HWI) (Tarragona County, Catalonia, Spain). Samples corresponded to subjects of different gender, age and specific areas of residence. The levels of PCDD/Fs were compared to those obtained in a baseline study (1998), as well as in previous surveys (2002, 2007 and 2012). The current mean concentration of PCDD/Fs in plasma was 6.79 pg I-TEQ/g lipid, which was significantly lower than the baseline concentration (27.0 pg I-TEQ/g lipid). A significant decrease was also observed in comparison to the results obtained in 2002 and 2007 (15.7 and 9.4 pg I-TEQ/g, respectively), while the current PCDD/F levels were similar to those obtained in 2012 (6.18 pg I-TEQ/g lipid). This important reduction in plasma PCDD/F levels is in accordance with the decreasing trend in the daily dietary intake of PCDD/Fs, which diminished from 210.1 pg I-TEQ (baseline) to 8.54 pg WHO-TEQ (current). OCDD was the predominant congener in plasma, while 2,3,7,8-TeCDD and 1,2,3,4,7,8,9-HpCDF showed the lowest levels. Based on the above results, as well as other recent data on the levels of PCDD/Fs in human milk, we conclude that the presence of the HWI does not mean additional and significant risks –as regards to PCDD/F exposure-for the population living in the neighborhood of the facility.

Concentrations of dioxins and furans in breast milk of women living near a hazardous waste incinerator in Catalonia, Spain

Since 1999, a hazardous waste incinerator (HWI) is operating in Constantí (Tarragona County, Catalonia, Spain). In 1996–1998, when the facility was being built, we started a monitoring program aimed at evaluating the impact of the emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) by the HWI on the environment and the human health. This study aimed at determining the current concentrations of PCDD/Fs in breast milk samples of women living nearby the HWI and at comparing these levels and profiles with those obtained in the baseline (1996–1998) and previous surveys (2002, 2007 and 2012). Furthermore, the association between the dietary intake of PCDD/Fs and the congener profiles in breast milk was also explored. Twenty milk samples were collected from women living in Tarragona downtown and near the industrial area where the HWI is placed. The content of PCDD/Fs was analyzed by following a procedure derived from the US EPA methods 1613 and 8290A. The mean concentration of PCDD/Fs was 2.26 pg WHO-TEQ/g fat. No significant differences were found between women living in industrial and urban areas (1.67 pg vs. 2.48 pg WHO-TEQ/g fat). Interestingly, a notable significant reduction (81%) was observed with respect to the concentrations found in the baseline study. The profiles of PCDD/Fs in breast milk were similar independently on the area and period of collection, being mainly influenced by the intake of fish, meat, oils and fats. The decreasing trend of PCDD/Fs in human milk agrees with the reduction observed in the dietary intake of these pollutants. It was also concluded that the current levels of PCDD/Fs in human milk levels are not influenced by the HWI stack emissions.

Combining monitoring and modelling approaches for BaP characterization over a petrochemical area

In this study, air concentrations of BaP in two different seasons (winter 2015 and summer 2016) and BaP levels in ground vegetation from Tarragona County were used as control simulations performed with the WRF-CHIMERE air quality modelling system, in order to reproduce the incidence of that hazardous chemical in air and soils. The CTM was validated for the present climatology, showing a good ability to represent air and soil concentrations of BaP over the target domain (petrochemical, chemical, urban and background sites), particularly in the winter. Then, the variation of the BaP concentrations in air and soils were simulated for the time series 1996–2015 and for the climate change scenario RCP8.5 (2031–2050). While an increase is projected for the levels in air, particularly in chemical and remote sites where the variation can go up to 10%, in terms of soil deposition the findings are the opposite, with an evident decrease in soil BaP concentrations, particularly for background sites. Finally, a potential health effect of BaP for the local population (lung cancer) was assessed. Although according to the projections the EU threshold for BaP atmospheric incidence (1 ng m−3) will not be reached by 2050, there will be an increase in the life-time risk of lung cancer, particularly in the most populated areas within the simulation domain.

Dietary intake of PCDD/Fs by the population of Tarragona County, Catalonia, Spain. Temporal trends (1998-2018)

Dietary intake of PCDD/Fs by the population of Tarragona County, Catalonia, Spain. Temporal trends (1998-2018)

Levels of PCDD/Fs in foodstuffs in Tarragona County (Catalonia, Spain): Spectacular decrease in the dietary intake of PCDD/Fs in the last 20 years

In this study, we determined the levels polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in 45 “composite” samples of food items belonging to 12 food groups. Foodstuffs were purchased in various locations of Tarragona County, Catalonia, Spain. The daily dietary intake of PCDD/Fs was subsequently estimated for the population living in that County. The highest toxic equivalent (WHO-TEQ) value corresponded to fish (0.103 ng/kg ww), followed by seafood (0.071 ng/kg ww) and eggs (0.070 ng/kg ww). In contrast, the lowest PCDD/F concentrations corresponded to vegetables, tubers, pulses, and fruits (each, 0.003 ng/kg ww). The current dietary intake of PCDD/Fs by the adult population was estimated in 8.54 pg WHO-TEQ/day, being fish and seafood the food groups with the greatest contribution to the dietary exposure of PCDD/Fs, followed by eggs, as well as by meat, oils and fats. The current study shows a continued decrease in the exposure to PCDD/Fs by the general population of Tarragona County since the first survey in the area conducted in 1998. The reduction observed in the last 20 years (from 210 pg I-TEQ/day to 8.54 pg WHO-TEQ/day) is certainly spectacular. The current daily intake (0.122 pg WHO-TEQ/kg bw) is also lower than most intakes recently reported in a number of regions and countries.

Multi-component determination of atmospheric semi-volatile organic compounds in soils and vegetation from Tarragona County, Catalonia, Spain

Tarragona County (Spain) is home to the most important chemical/petrochemical industrial complex in Southern Europe, which raises concerns about the presence and effects of the numerous environmental contaminants. In order to assess the levels and patterns of five classes of semi-volatile organic compounds (SVOCs) - polycyclic aromatic hydrocarbons (PAHs), synthetic musks (SMs), polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs) and one organochlorine pesticide, hexachlorobenzene (HCB), 27 samples of soil and vegetation (Piptatherum L.) from different areas (petrochemical, chemical, urban/residential, and background) of Tarragona County were analysed. The results show that PAHs levels in soils ranged from 45.12 to 158.00ng/g and the urban areas presented the highest concentrations, mainly associated with the presence of a nearby highway and several roads with heavy traffic. PAHs levels in vegetation samples ranged from 42.13 to 80.08ng/g, where the greatest influence came from the urban and petrochemical areas. In the case of SMs, levels in soils and vegetation samples ranged from 5.42 to 10.04ng/g and from 4.08 to 17.94ng/g, respectively, and in both cases, background areas (at least 30km away from the main SVOCs emission sources) showed the highest levels, suggesting an influence of the personal care products derived from beach-related tourism in the coast. PCBs (from 6.62 to 14.07ng/g in soils; from 0.52 to 4.41ng/g in vegetation) prevailed in the chemical area in both matrices, probably associated with the presence of two sub-electrical stations located in the vicinities. In general terms, BFRs and HCB values recorded in soil and vegetation samples were quite similar between matrices and sampling areas.

Prenatal exposure estimation of BPA and DEHP using integrated external and internal dosimetry: A case study

Prenatal exposure to Endocrine disruptors (EDs), such as Bisphenol A (BPA) and di (2-ethylhexyl) phthalate (DEHP), has been associated with obesity and diabetes diseases in childhood, as well as reproductive, behavioral and neurodevelopment problems. The aim of this study was to estimate the prenatal exposure to BPA and DEHP through food consumption for pregnant women living in Tarragona County (Spain). Probabilistic calculations of prenatal exposure were estimated by integrated external and internal dosimetry modelling, physiologically based pharmacokinetic (PBPK) model, using a Monte-Carlo simulation. Physical characteristic data from the cohort, along with food intake information from the questionnaires (concentrations of BPA and DEHP in different food categories and the range of the different food ratios), were used to estimate the value of the total dietary intake for the Tarragona pregnancy cohort. The major contributors to the total dietary intake of BPA were canned fruits and vegetables, followed by canned meat and meat products. In turn, milk and dairy products, followed by ready to eat food (including canned dinners), were the most important contributors to the total dietary intake of DEHP. Despite the dietary variations among the participants, the intakes of both chemicals were considerably lower than their respective current tolerable daily intake (TDI) values established by the European Food Safety Authority (EFSA). Internal dosimetry estimates suggest that the plasma concentrations of free BPA and the most important DEHP metabolite, mono (2-ethylhexyl) phthalate (MEHP), in pregnant women were characterized by transient peaks (associated with meals) and short half-lives (< 2 h). In contrast, fetal exposure was characterized by a low and sustained basal BPA and MEHP concentration due to a lack of metabolic activity in the fetus. Therefore, EDs may have a greater effect on developing organs in young children or in the unborn child.

Human exposure to brominated flame retardants through the consumption of fish and shellfish in Tarragona County (Catalonia, Spain)

The concentrations of 19 brominated flame retardants (BFRs) (8 polybrominated diphenyl ethers (PBDEs), 8 methoxylated PBDEs (MeO-PBDEs) and 3 emerging flame retardants) were determined in 10 species of fish and shellfish widely consumed in Tarragona County (Catalonia, Spain), by pressurized liquid extraction followed by gas chromatography coupled to tandem mass spectrometry. A higher occurrence of PBDEs was found in all the analyzed samples, while MeO-PBDEs were only detected in a few ones and the levels of emerging pollutants were relatively low. In contrast, hexabromobenzene was found in almost all samples at concentrations ranging between non detected and 0.2 ng g−1 wet weight (w.w.). Salmon, sole, hake, cod and tuna showed the highest concentrations of ΣPBDEs (>0.8 ng g−1 w.w.), while mussel was the species with the highest level of MeO-PBDEs (1.5 ng g−1 w.w.). The dietary exposure of BFRs through consumption of these 10 species of fish and shellfish by the population of Tarragona County was estimated for different subpopulations, classified according to age and gender. Furthermore, calculations were performed in upper-, middle- and lower-bound risk scenarios. According to our data, the current concentrations of BFRs in fish and shellfish suggest no significant health risks for the consumers.

Application of the Multimedia Urban Model to estimate the emissions and environmental fate of PAHs in Tarragona County, Catalonia, Spain

The Multimedia Urban Model (MUM-Fate) was used to estimate the emissions, fate and transport of polycyclic aromatic hydrocarbons (PAHs) in Tarragona County, Catalonia, Spain, where the largest chemical/petrochemical industrial complex of Southern Europe is located. MUM-Fate is a Level III steady-state fugacity model consisting of seven bulk media compartments (lower and upper air, surface water, sediment, soil, vegetation, and an organic film that coats impervious surfaces). The model was parameterized according to environmental conditions in Tarragona County, and used to back-calculate emissions from measured air concentrations of naphthalene, anthracene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene. Modelled results in soils were within the range reported for measured concentrations. Estimated emissions of ∑6PAH were 42ty−1, with phenanthrene having the greatest value (16ty−1). The fate and transport of ∑6PAH were subsequently estimated by running the model an illustrative emission rate of 1molh−1. Organic film on impervious surfaces was the compartment that achieved the highest concentrations of PAHs, being up to 2·108ngm−3. However, as the film conveys chemicals to surface waters, the persistence in this compartment was <1day. Soils and sediments were the greatest sinks for PAHs, with a persistence of 100–1000days. The greatest loss of PAHs was due to advection from air, followed by photodegradation from air. These results provide a first approximation of the current emissions and fate of PAHs in Tarragona County.

Influence of the uncertainty in the validation of PBPK models: A case-study for PFOS and PFOA

Physiologically-based pharmacokinetic (PBPK) models are mathematical representations of the human body aimed at describing the time course distribution of chemicals in human tissues. Since parameterization of PBPK models is based on empirical estimation and experimental data, simulation results may have high degree of uncertainty. As a consequence, the reliability of model validation is highly affected. In this study, the parametric uncertainty associated with PBPK models developed for perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were analyzed and the different validation approaches were discussed for a case-study in Tarragona County (NE of Spain). Physicochemical parameters and dietary intake of PFOS and PFOA were estimated from previous investigations performed in Tarragona County. A sensitivity analysis (SA) was performed to understand the degree of influence of input parameters on the final outcomes. The uncertainty of the PBPK models' outcome was assessed by propagating the parametric uncertainty using the Latin Hypercube Sampling (LHS) technique. The elimination constants (Tm and Kt) as well as the Free fraction and the Intake, were the most influential parameters according to the SA results, being up to 83% for PFOS and 99.9% for PFOA. The validation of the PBPK model, which was performed using different approaches, showed clear discrepancies in the visual validation when compared with the statistical analysis.

Monitoring PAHs in the petrochemical area of Tarragona County, Spain: comparing passive air samplers with lichen transplants.

The levels of 16 polycyclic aromatic hydrocarbons (PAHs) were determined in 8 passive air samples (PAS) and 6 lichen transplants (Ramalina fastigiata) deployed for a period of 2months in different zones of Tarragona County (Catalonia, Spain), an area with an important number of chemical and petrochemical industries. The accumulated amount of the sum of the 16 PAHs ranged between 1363 to 7866ng/sample in air samples. The highest concentration was found in the neighborhood of Puigdelfí (village of Perafort), in the vicinity of a big oil refinery and well under the potential influence of the petrochemical emissions. In lichen samples, the sum of the 16 PAHs ranged between 247 and 841ng/g (dry weight), being the greatest value also observed in Puigdelfí. Data on the levels and profiles of PAHs in both passive monitoring methods were compared. A significant positive linear correlation was found between the concentrations of low molecular weight PAHs in lichens and the amounts accumulated in passive air samples (R = 0.827, P < 0.05), being especially significant the correlation of 4-ring PAHs (R = 0.941, P < 0.05). These results strongly suggest that lichens can be used to monitor gas-phase PAHs, providing data that can be quantitatively translated into equivalents for air.

Physiologically based pharmacokinetic modeling of perfluoroalkyl substances in the human body

Currently, there are limited data on the levels of perfluoroalkyl substances other than perfluorooctane sulfonic acid and perfluorooctanoic acid in the human body. Most of this information has been extracted from biological monitoring of plasma while the occurrence of perfluoroalkyl substances in other human tissues is rarely studied. The objective of the present study was to develop a physiologically based pharmacokinetic model to assess the concentration of perfluoroalkyl substances in human tissues, based on an existing model previously validated for perfluorooctane sulfonic acid and perfluorooctanoic acid. Experimental data on concentrations of perfluoroalkyl substances in human tissues from individuals in Tarragona County (Catalonia, Spain) were used to estimate the values of some distribution and elimination parameters needed for the simulation. No significant correlations were found between these parameters and the chain lengths. The model was finally validated for five perfluoroalkyl substances.

PBPK modeling for PFOS and PFOA: Validation with human experimental data

In recent years, because of the potential human toxicity, concern on perfluoroalkyl substances (PFASs) has increased notably with special attention to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Unfortunately, there is currently an important knowledge gap on the burdens of these chemicals in most human tissues, as the reported studies have been mainly focused on plasma. In order to overcome these limitations, the use of physiologically-based pharmacokinetic (PBPK) models has been extended. The present study was aimed at testing an existing PBPK model for their predictability of PFOS and PFOA in a new case-study, and also to adapt it to estimate the PFAS content in human tissue compartments. Model validation was conducted by means of PFOA and PFOS concentrations in food and human drinking water from Tarragona County (Catalonia, Spain), and being the predicted results compared with those experimentally found in human tissues (blood, liver, kidney, liver and brain) of subjects from the same area of study. The use of human-derived partition coefficient (Pk) data was proven as more suitable for application to this PBPK model than rat-based Pk values. However, the uncertainty and variability of the data are still too high to get conclusive results. Consequently, further efforts should be carried out to reduce parametric uncertainty of PBPK models. More specifically, a deeper knowledge on the distribution of PFOA and PFOS within the human body should be obtained by enlarging the number of biological monitoring studies on PFASs.