Human exposure to Bisphenol A (BPA) is omnipresent. Both the extent of the exposure and its toxicological relevance are controversially discussed. We aim to reliably determine and evaluate the extent ...of BPA body burden in the German population from 1995 to 2009 based on 600 24 h urine samples and corresponding plasma samples from the Environmental Specimen Bank. We determined total and unconjugated BPA in urine and plasma using on-line solid-phase extraction high-performance liquid chromatography coupled to isotope dilution tandem mass spectrometry with a limit of quantification (LOQ) of 0.1 μg/l. In the stored urines, total BPA was quantifiable in >96% (median: 1.49 μg/l; 95th percentile: 7.37 μg/l), whereas unconjugated BPA was quantifiable only in <15% of the samples. Total BPA concentrations decreased over time, but 24 h urine volumes increased. Therefore, daily intakes calculated from the 24 h urines remained rather constant at a median of 0.037 and a 95th percentile of 0.171 μg BPA/kg body weight/day. In 60 corresponding plasma samples, total BPA levels were generally below the LOQ of 0.1 μg/l and, if quantifiable, most BPA was unconjugated, thus hinting to external contamination. We see total BPA in urine as the most appropriate and robust marker for BPA exposure assessment (if controlled for BPA contamination). Unconjugated BPA in urine and unconjugated or total BPA in plasma where contamination or breakdown of the glucuronide cannot be ruled out are of no value for human exposure assessment.
Objective: 40,000 residents in Arnsberg, Germany, had been exposed to drinking water contaminated with perfluorinated compounds (PFCs). Internal exposure of the residents of Arnsberg to six PFCs was ...assessed in comparison with reference areas. Design and participants: One hundred seventy children (5-6 years of age), 317 mothers (23-49 years), and 204 men (18-69 years) took part in the cross-sectional study. Measurements: Individual consumption of drinking water and personal characteristics were assessed by questionnaire and interview. Perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS), perfluorohexanoate, perfluorohexanesulfonate (PFHxS), perfluoropentanoate, and perfluorobutanesulfonate (PFBS) in blood plasma and PFOA/PFOS in drinking water samples were measured by solid-phase extraction, high-performance liquid chromatrography, and tandem mass spectrometry detection. Results: Of the various PFCs, PFOA was the main compound found in drinking water (500-640 ng/L). PFOA levels in blood plasma of residents living in Arnsberg were 4.5-8.3 times higher than those for the reference population (arithmetic means Arnsberg/controls: children 24.6/5.2 μg/L, mothers 26.7/3.2 μg/L, men 28.5/6.4 μg/L). Consumption of tap water at home was a significant predictor of PFOA blood concentrations in Arnsberg. PFHxS concentrations were significantly increased in Arnsberg compared with controls (p < 0.05). PFBS was detected in 33% of the children, 4% of the women, and 13% of the men in Arnsberg compared with 5%, 0.7%, and 3%, respectively, in the reference areas (p < 0.05). Regression analysis showed that age and male sex were significant predictors of PFOS, PFOA, and PFHxS; associations of other regressors (diet, body mass index) varied among PFCs. Conclusions: PFC concentrations in blood plasma of children and adults exposed to PFC-contaminated drinking water were increased 4- to 8-fold compared with controls.
•1,2- and 1,4-Naphthoquinone have a key role in the naphthalene metabolism regarding the possibly carcinogenic properties of naphthalene.•Mercapturic acids of 1,2- and 1,4-naphthoquinone are proposed ...as new biomarkers in human urine.•This paper presents a very sensitive LC–MS/MS-method for their quantification.
Naphthalene shows carcinogenic properties in animal experiments. As the substance is ubiquitary present in the environment and has a possibly high exposure at industrial workplaces, the determination of naphthalene metabolites in humans is of environmental–medical as well as occupational–medical importance. Here, biomarkers of 1,2- and 1,4-naphthoquinone, as possibly carcinogenic metabolites in the naphthalene metabolism, are of outstanding significance.
We developed and validated a liquid chromatography–tandem mass-spectrometric (LC–MS/MS) method for the simultaneous determination of the naphthoquinone mercapturic acids of 1,2- and 1,4-naphthoquinone in human urine samples as a sum of naphthoquinone- and dihydroxynaphthalene-mercapturic acid. Except for enzymatic hydrolysis and acidification, no further sample preparation is necessary. For sample clean-up, a column switching procedure is applied. The mercapturic acids are extracted from the urinary matrix on a restricted access material (RAM RP 18) and separated on a reversed phase column (Synergi Polar RP C18). The metabolites were quantified by tandem mass spectrometry using labelled D5-1,4-NQMA as internal standard. The limits of detection are 3μg/l for 1,2-NQMA and 1μg/l for 1,4-NQMA. Intraday- and interday precision for pooled urine (spiked with 10μg/l and 30μg/l of the analytes) ranges from 5.9 to 15.1% for 1,2-NQMA and from 2.0 to 10.8% for 1,4-NQMA. The developed method is suited for the sensitive and specific determination of the mercapturic acids of naphthoquinones in human urine. A good precision and low limits of detection were achieved. Application of those new biomarkers in biomonitoring studies may give deeper insights into the mechanisms of the human naphthalene metabolism.
In human metabolism studies we found that after oral application of di(2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DiNP) and di(2-propylheptyl) phthalate (DPHP), at least 74, 44 and 34%, ...respectively, are excreted via urine. In contrast to the short chain phthalates, their oxidized products, not the simple monoesters, were found to be the main metabolites. Based on urinary phthalate metabolite concentrations we estimated in 102 German subjects between 6 and 80 years of age median daily intakes (μg/kg/day) of 2.7 for DEHP, 2.1 for di-n-butyl phthalate, 1.5 for diisobutyl phthalate, 0.6 for DiNP, and 0.3 for butylbenzyl phthalate. In general, children have higher exposures compared to adults and seem to have a more effective oxidative metabolism of phthalates. For individual phthalates tolerable daily intake (TDI) values have been deduced. However, in rats some phthalates have been shown to act as endocrine disrupters via a common mechanism of action in a dose-additive manner. Therefore, the concept of a cumulative TDI value may be more appropriate for the consideration of the overall exposure and the potential human health risks resulting from everyday and simultaneous exposure to several phthalates.
A simple pharmacokinetic model to predict concentrations of metabolites of di-2-ethylhexyl phthalate, DEHP, in humans starting from intakes of DEHP was developed and applied. This model predicts ...serum and urine concentrations of five DEHP metabolites: MEHP, 5oxo-MEHP, 5OH-MEHP, 5cx-MEPP, and 2cx-MMHP. The model was calibrated using data from an individual who dosed himself with 48.5 mg DEHP, and then took blood and urine samples over a 44-h period. The calibrated model was then used in two applications: one on a second set of individuals whose exposure to DEHP was through PVC medical devices in a blood platelet donation procedure, and one on background exposures in the United States (US). Based on 2001/02 NHANES data, median US background urine concentrations of MEHP, 5OH-MEHP, and 5oxo-MEHP are 4.1, 20.1, and 14.0 microg/l, respectively. Creatine and urine volume-correction approaches were used to backcalculate an average daily dose of DEHP in the range of 0.6-2.2 microg/kg per day. A "background cohort" including 8 individuals and 57 complete days of urination were assumed to be exposed to1.5 microg/kg per day, spread out in equal doses of 0.3 microg/kg per day at 0900, 1200, 1500, 1800, and 2100 h. The average predicted urine concentrations were 4.6, 15.9, and 9.4 microg/l for MEHP, 5OH-MEHP, and 5oxo-MEHP. These are similar, but the two secondary metabolites are slightly lower than medians found in NHANES. This slight difference between the NHANES results and the background simulations could have been due to differences in metabolism between the individual who provided the calibration data (61-year-old Caucasian male) and the general US population. Another explanation evaluated was that urine concentrations further from the time of exposure may have larger disparities between MEHP and the two secondary metabolites as compared with concentrations measured closer to the time of exposure.
We determined the internal exposure of 111 German primary school starters by analyzing urinary metabolites of six phthalates: butyl benzyl phthalate (BBzP), di-iso-butyl phthalate (DiBP), di-n-butyl ...phthalate (DnBP), di (2-ethylhexyl) phthalate (DEHP), di-iso-nonyl phthalate (DiNP) and di-iso-decylphthalate (DiDP). From the urinary metabolite levels, we calculated daily intakes and related these values to Tolerable Daily Intake (TDI) values. By introducing the concept of a relative cumulative Tolerable Daily Intake (TDI
cum) value, we tried to account for the cumulative exposure to several of the above-mentioned phthalates. The TDI
cum was derived as follows: the daily intake (DI) calculated from the metabolite level was divided by the TDI for each phthalate; this ratio was multiplied by 100% indicating the TDI percentage for which the DI accounted. Finally the % TDIs of the different phthalates were totalled to get the TDI
cum. A TDI
cum above 100% is a potential cause for concern. We confirmed the ubiquitous exposure of the children to all phthalates investigated. Exposures were within range of levels previously reported for GerES, albeit slightly lower. Regarding daily intakes, two children exceeded the TDI for DnBP, whereas one child closely approached the TDI for DEHP. 24% of the children exceeded the TDI
cum for the three most critical phthalates: DEHP, DnBP and DiBP. Furthermore, 54% of the children had total exposures that used up more than 50% the TDI
cum. Therefore, the overall exposure to a number of phthalates, and the knowledge that these phthalates (and other anti-androgens) act in a dose-additive manner, urgently warrants a cumulative risk assessment approach.
For Europe as a whole, data on internal exposure to environmental chemicals do not yet exist. Characterization of the internal individual chemical environment is expected to enhance understanding of ...the environmental threats to health.
We developed and applied a harmonized protocol to collect comparable human biomonitoring data all over Europe.
In 17 European countries, we measured mercury in hair and cotinine, phthalate metabolites, and cadmium in urine of 1,844 children (5-11 years of age) and their mothers. Specimens were collected over a 5-month period in 2011-2012. We obtained information on personal characteristics, environment, and lifestyle. We used the resulting database to compare concentrations of exposure biomarkers within Europe, to identify determinants of exposure, and to compare exposure biomarkers with health-based guidelines.
Biomarker concentrations showed a wide variability in the European population. However, levels in children and mothers were highly correlated. Most biomarker concentrations were below the health-based guidance values.
We have taken the first steps to assess personal chemical exposures in Europe as a whole. Key success factors were the harmonized protocol development, intensive training and capacity building for field work, chemical analysis and communication, as well as stringent quality control programs for chemical and data analysis. Our project demonstrates the feasibility of a Europe-wide human biomonitoring framework to support the decision-making process of environmental measures to protect public health.
High amounts of acrylamide in some foods result in an estimated daily mean intake of 50 microg for a western style diet. Animal studies have shown the carcinogenicity of acrylamide upon oral ...exposure. However, only sparse human toxicokinetic data is available for acrylamide, which is needed for the extrapolation of human cancer risk from animal data. We evaluated the toxicokinetics of acrylamide in six young healthy volunteers after the consumption of a meal containing 0.94 mg of acrylamide. Urine was collected up to 72 hours thereafter. Unchanged acrylamide, its mercapturic acid metabolite N-acetyl-S-(2-carbamoylethyl)cysteine (AAMA), its epoxy derivative glycidamide, and the respective metabolite of glycidamide, N-acetyl-S-(2-hydroxy-2-carbamoylethyl)cysteine (GAMA), were quantified in the urine by liquid chromatography-mass spectrometry. Toxicokinetic variables were obtained by noncompartmental methods. Overall, 60.3 +/- 11.2% of the dose was recovered in the urine. Although no glycidamide was found, unchanged acrylamide, AAMA, and GAMA accounted for urinary excretion of (mean +/- SD) 4.4 +/- 1.5%, 50.0 +/- 9.4%, and 5.9 +/- 1.2% of the dose, respectively. Apparent terminal elimination half-lives for the substances were 2.4 +/- 0.4, 17.4 +/- 3.9, and 25.1 +/- 6.4 hours. The ratio of GAMA/AAMA amounts excreted was 0.12 +/- 0.02. In conclusion, most of the acrylamide ingested with food is absorbed in humans. Conjugation with glutathione exceeds the formation of the reactive metabolite glycidamide. The data suggests an at least 2-fold and 4-fold lower relative internal exposure for glycidamide from dietary acrylamide in humans compared with rats or mice, respectively. This should be considered for quantitative cancer risk assessment.
In a retrospective human biomonitoring study we analyzed 24
h urine samples taken from the German Environmental Specimen Bank for Human Tissues (ESBHum), which were collected from 634 subjects ...(predominantly students, age range 20–29 years, 326 females, 308 males) in 9 years between 1988 and 2003 (each
n⩾60), for the concentrations of primary and/or secondary metabolites of di-
n-butyl phthalate (DnBP), di-iso-butyl phthalate (DiBP), butylbenzyl phthalate (BBzP), di(2-ethylhexyl) phthalate (DEHP) and di-iso-nonyl phthalate (DiNP). Based on the urinary metabolite excretion we estimated daily intakes of the parent phthalates and investigated the chronological course of the phthalate exposure. In over 98% of the urine samples metabolites of all five phthalates were detectable indicating a ubiquitous exposure of the German population to all five phthalates throughout the last 20 years. The median daily intakes in the subsets between 1988 and 1993 were quite constant for DnBP (approx. 7
μg/kg
bw/d) and DEHP (approx. 4
μg/kg
bw/d). However, from 1996 the median levels of both phthalates decreased continuously until 2003 (DnBP 1.9
μg/kg
bw/d; DEHP 2.4
μg/kg
bw/d). By contrast, the daily intake values for DiBP were slightly increasing over the whole time frame investigated (median 1988: 1.1
μg/kg
bw/d; median 2003: 1.4
μg/kg
bw/d), approximating the levels for DnBP and DEHP. For BBzP we observed slightly decreasing values, even though the medians as of 1998 levelled off at around 0.2
μg/kg
bw/d. Regarding daily DiNP exposure we found continuously increasing values, with the lowest median being 0.20
μg/kg
bw/d for the subset of 1988 and the highest median for 2003 being twice as high. The trends observed in phthalate exposure may be associated with a change in production and usage pattern. Female subjects exhibited significantly higher daily intakes for the dibutyl phthalates (DnBP
p=0.013; DiBP
p=0.004). Compared to data from US National Health and Nutrition Examination Surveys (NHANES) exposure levels of the dibutyl phthalates were generally higher in our German study population, while levels of BBzP were somewhat lower. Overall, for a considerable 14% of the subjects we observed daily DnBP intakes above the tolerable daily intake (TDI) value deduced by the European Food Safety Authority (EFSA) (10
μg/kg
bw/d). However, the frequency of exceedance decreased during the years and was beneath 2% in the 2003 subset. Even though transgressions of the exposure limit values of the EFSA and the US Environmental Protection Agency (US EPA) occurred only in a relatively small share of the subjects, one has to take into account the cumulative exposure to all phthalates investigated and possible dose-additive endocrine effects of these phthalates.
Phthalates like di-(2-ethylhexyl) phthalate (DEHP) are commonly used as plasticizers and their metabolites are suspect of especially reproductive toxicity.
The aim of our study was to assess ...phthalate exposure in adults by measuring urinary phthalate metabolite levels and to explore individual temporal variability. Urine samples were collected by 27 women and 23 men aged 14–60 years during 8 consecutive days. We quantified four monoesters, four oxidative DEHP metabolites, and two secondary metabolites of di-isononyl phthalate (DiNP) by a LC/LC–MS/MS method.
If we analyzed all 399 available samples independent of classification, the highest median values of primary metabolites in this study were found for mono-
n-butyl phthalate (MnBP: 49.6
μg/l), followed by mono-isobutyl phthalate (MiBP: 44.9
μg/l), mono-benzyl phthalate (MBzP: 7.2
μg/l), and mono-2-ethylhexyl phthalate (MEHP: 4.9
μg/l). The median concentrations of the oxidized metabolites of DEHP were 8.3
μg/l for mono-(2-carboxymethylhexyl) phthalate (2cx-MMHP), 19.2
μg/l for mono-(2-ethyl-5-hydroxyhexyl) phthalate (5OH-MEHP), 14.7
μg/l for mono-(2-ethyl-5-oxohexyl) phthalate (5oxo-MEHP), and 26.2
μg/l for mono-(2-ethyl-5-carboxypentyl) phthalate (5cx-MEPP). The concentrations of the two DiNP secondary metabolites mono (oxoisononyl) phthalate (oxo-MiNP) and mono(hydroxyisononyl) phthalate (OH–MiNP) ranged from <LOD to 304
μg/l (median: 3.0
μg/l, 2.9
μg/g creatinine) and <LOD to 698
μg/l (median: 5.5
μg/l, 5.2
μg/g creatinine), respectively. Phthalate metabolite levels did not consistently differ by sex or age. There was substantial day-to-day variation of urinary levels with considerable within-subject variability. Intraclass correlation coefficients adjusted for sex and age ranged between 0.21 and 0.48 for unadjusted metabolite levels and between 0.20 and 0.57 for creatinine-adjusted levels.
The secondary metabolites of DiNP were detectable in nearly all samples and were therefore sensitive biomarkers of DiNP exposure. Our results of within-subject variability suggest that exposure assessment should not be based on a single urine measurement.
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