Di(2-ethylhexyl)phthalate (DEHP) exposure of voluntary plasma and platelet donors

Neonatal di-(2-ethylhexyl)phthalate exposure induces permanent alterations in secretory CRH neuron characteristics in the hypothalamus paraventricular region of adult male rats

Corticotrophin-releasing hormone (CRH) neurons in the hypothalamic paraventricular nucleus (PVN) play a critical role in the modulation of the hypothalamic-pituitary-adrenal (HPA) axis. Early-life exposure to di-(2-ethylhexyl) phthalate (DEHP) has been associated with an increased risk of developing psychiatric disorders in adulthood. The present work was designed to explore the impact of neonatal exposure to DEHP on adult PVN CRH neuronal activity. DEHP or vehicle was given to male rat pups from PND16 to PND22. Then, anxiety-like behaviors, serum corticosterone and testosterone, immunohistochemistry, western blotting, fluorescence in situ hybridization and acute ex vivo slice electrophysiological recordings were used to evaluate the influence of DEHP on adult PVN secretory CRH neurons. Neonatal DEHP-exposed rats exhibited enhanced anxiety-like behaviors in adults, with an increase in CORT. Secretory CRH neurons showed higher spontaneous firing activity but could be inhibited by GABAAR blockers. CRH neurons displayed fewer firing spikes, prolonged first-spike latency, depolarizing shifts in GABA reversal potential and strengthened GABAergic inputs, as indicated by increases in the frequency and amplitude of sIPSCs. Enhancement of GABAergic transmission was accompanied by upregulated expression of GAD67 and downregulated expression of GABABR1, KCC2 and GAT1. These findings suggest that neonatal exposure to DEHP permanently altered the characteristics of secretory CRH neurons in the PVN, which may contribute to the development of psychiatric disorders later in life.

Environmentally relevant DEHP exposure during gestational and lactational period inhibits filamin a testicular expression

Toxicological studies have revealed that DEHP exposure during pregnancy may induce developmental disorders, especially in male offspring, leading to morphological and functional alterations in the reproductive system by mechanisms that should be investigated. Thus, the aim of this work was to analyze the testicular toxicity induced by an environmentally relevant DEHP dose during development and its impact on FLNA, a protein that participates in the blood-testis barrier assembly. We used male Wistar rats exposed to DEHP during pregnancy and lactation. The results showed that DEHP exposure during development and lactation increased body weight, decreased gonadal weight and shortened anogenital distance. This phthalate induced morphological changes in the testis, suggestive of hypospermatogenesis. DEHP exposure decreased the number of FLNA positive cells and the expression of FLNA and claudin-1 in prepubertal testes. Furthermore, DEHP inhibited FLNA and claudin-1 protein expression in adult male rats. These results indicated that exposure to DEHP during gestation and lactation perturbed testis development and suggested that FLNA is a target protein of DEHP, possibly contributing to the phthalate-induced damage on BTB.

An insight into sex-specific neurotoxicity and molecular mechanisms of DEHP: A critical review

Di-2-Ethylhexyl Phthalate (DEHP) is often used as an additive in polyvinyl chloride (PVC) to give plastics flexibility, which makes DEHP widely used in food packaging, daily necessities, medical equipment, and other products. However, due to the unstable combination of DEHP and polymer, it will migrate to the environment in the materials and eventually contact the human body. It has been recorded that low-dose DEHP will increase neurotoxicity in the nervous system, and the human health effects of DEHP have been paid attention to because of the extensive exposure to DEHP and its high absorption during brain development. In this study, we review the evidence that DEHP exposure is associated with neurodevelopmental abnormalities and neurological diseases based on human epidemiological and animal behavioral studies. Besides, we also summarized the oxidative damage, apoptosis, and signal transduction disorder related to neurobehavioral abnormalities and nerve injury, and described the potential mechanisms of neurotoxicity caused by DEHP. Overall, we found exposure to DEHP during the critical developmental period will increase the risk of neurobehavioral abnormalities, depression, and autism spectrum disorders. This effect is sex-specific and will continue to adulthood and even have an intergenerational effect. However, the research results on the sex-dependence of DEHP neurotoxicity are inconsistent, and there is a lack of systematic mechanisms research as theoretical support. Future investigations need to be carried out in a large-scale population and model organisms to produce more consistent and convincing results. And we emphasize the importance of mechanism research, which can enhance the understanding of the environmental and human health risks of DEHP exposure.

Exposure to DEHP induces testis toxicity and injury through the ROS/mTOR/NLRP3 signaling pathway in immature rats

As the most abundantly used phthalate derivative, di-(2-ethylhexyl) phthalate (DEHP) leads to reproductive disorders, especially in males. Testicular injury can be triggered when the testis is exposed to DEHP during the immature stage. However, the potential mechanism is largely unclear. In the present study, Sprague-Dawley rats were exposed to 0, 250 and 500 mg/kg/day DEHP from postnatal day (PND) 20 to PND 30. The spermatogonia cell line GC-1 and spermatocyte cell line GC-2 were exposed to different doses of monoethylhexyl phthalate (MEHP), a metabolite of DEHP. Testicular injury was observed. Oxidative stress was evaluated both in vivo and in vitro. Our results showed that after DEHP exposure, the testicular structure was damaged and spermatogenesis was disturbed. We also found that oxidative stress was increased, as indicated by the upregulation of the important factors in the antioxidant pathway. Furthermore, the expression of autophagy-related proteins was significantly downregulated. Autophagy inhibition led to activation of the pyroptosis pathway. Nucleotide-binding and oligomerisation (NOD) domain-like receptor (NLR) family pyrin domain (PYD)-containing 3 (NLRP3), Caspase-1 and cytokine interleukin-1β (IL-1β) were significantly upregulated. Additionally, an imbalance in self-renewal and differentiation was observed in germ cells after DEHP exposure, causing the cessation of germ cell development. In summary, these data suggest that DEHP exposure enhances oxidative stress, downregulates autophagy, induces NLRP3 inflammasome activation and subsequently triggers pyroptosis in vivo and in vitro, which provides novel insight into DEHP-related injury in immature testes in the context of pyroptosis.

Prenatal exposure to phthalate esters and its impact on child development

Endocrine disruptive chemicals (EDCs) cause adverse health effects through interaction with endocrine systems. They are classified by chemical structure, effects on specific endocrine systems, their bioaccumulation and/or persistence in the environment, and/or clinically observable effects. In industrial nations, people are exposed to complex mixtures of many different substances all of which may have multiple and deleterious effects upon the individual. The clinical importance of epigenetic changes caused by the action of EDCs during vulnerable phases of development is currently unclear but of particular relevance. Epidemiological studies are criticized because reproducibility is not always guaranteed. Nevertheless, they remain the method of choice for the development and analysis of suitable model systems. Positive associations, despite of sometimes conflicting results, are the key in the selection of factors that can then be analyzed in model systems in an unbiased way. This article reports EDC-caused effects in the fields of growth and metabolism, neurocognitive development and sexual development and reproduction focusing mainly on phthalates and their metabolites. However, research will have to focus on the interactions of different EDCs and their consequences of prenatal and early life exposure.

Effects of intravenous and oral di(2-ethylhexyl) phthalate (DEHP) and 20% Intralipid vehicle on neonatal rat testis, lung, liver, and kidney

The highest human exposures to the plasticizer di(2-ethylhexyl) phthalate (DEHP) occur through intravenous (iv) exposure from medical procedures. Rodent toxicity studies, mainly using oral exposures, have identified male reproductive toxicity after developmental exposure to DEHP as the primary concern. Other organs are also affected by DEHP and route may influence the degree of target organ involvement. Cammack et al. (2003) reported a critical study focused on testicular toxicity using oral and iv exposures of neonatal Sprague-Dawley rats to 60, 300, or 600 mg/kg body weight/day DEHP in Intralipid vehicle. The present study followed the same dosing paradigm and included assessment of additional organs to evaluate the potential utility of this design for DEHP alternatives. Reduction of testis weight was observed in all DEHP treatment groups and germ cell and Sertoli cell toxicity was observed at the two highest doses with both routes. Lung granulomas occurred in all iv DEHP groups, possibly related to increased fat particle size in DEHP lipid emulsions. Lung alveolar development was inhibited after both oral and iv high dose DEHP. Toxicity of oral Intralipid vehicle was observed in germ and Sertoli cells. The lack of such effects after iv vehicle exposure suggested that this may be a gut-mediated effect.

Risk assessment of endocrine disrupting phthalates and hormonal alterations in children and adolescents

Risk assessment and hormone evaluation were carried out for di(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP), endocrine disrupting chemicals (EDCs), in 302 Korean children (n = 223) and adolescents (n = 79) (< age 19). Urinary and serum concentrations of DEHP, MEHP (mono(2-ethylhexyl) phthalate), DBP, MBP (monobutyl phthalate), and PA (phthalic acid, a common final metabolite of phthalates) were detected in children and adolescents. Daily exposure levels were estimated to be 16.45 ± 36.50 μg/kg b.w./day for DEHP, which is one-third of the tolerable daily intake (TDI) value (50 μg/kg b.w./day), but 14 out of 302 participants had a hazard index (HI = intake/TDI) value >1. The mean daily exposure level of DBP was 1.23 ± 1.45 μg/kg b.w./day, which is one-eighth of the TDI value (10 μg/kg b.w./day), but 1 out of 302 participants had a HI value > 1. Positive correlations were observed between serum DBP or MEHP, and serum estradiol (E2) and/or luteinizing hormone (LH) in prepubescent children. In addition, serum MBP levels were found to be negatively correlated with serum triiodothyronine (T3) or thyroxine (T4) in male participants, and serum DEHP levels with serum thyroid stimulating hormone (TSH) in female adolescents. Low-density lipoprotein (LDL) levels were positively correlated with serum PA levels in children and adolescents. DEHP, DBP or its metabolites may be associated with altered hormone levels in children and adolescents. Data suggest that exposure levels of DEHP and DBP in Korean children need to be reduced to levels below TDI to protect them from EDC-mediated toxicities. Abbreviations: DBP: dibutyl phthalate; DEHP: di(2-ethylhexyl) phthalate; E2: estradiol; EDC: endocrine disrupting chemical; EFSA: European Food Safety Authority; FSH: follicle stimulating hormone; HDL: high density lipoprotein; HI: hazard index; LDL: low density lipoprotein; LH: luteinizing hormone; MEHP: mono(2-ethylhexyl) phthalate; MBP: monobutyl phthalate; PA: phthalic acid; PPAR: peroxisome proliferator-activated receptor gamma; PVC: polyvinyl chloride; T3: triiodothyronine; T4: thyroxine; TDI: tolerable daily intake; TG: triglyceride; TSH: thyroid stimulating hormone; UPLC/MS/MS: Ultra Performance Liquid Chromatography/Tandem Mass Spectrometry; WWF: World Wildlife Fund.

Exposure to the plasticizer di(2-ethylhexyl) terephthalate (DEHTP) in Portuguese children - Urinary metabolite levels and estimated daily intakes

Classical ortho-phthalate plasticizers are, due to their endocrine disrupting potency and reproductive toxicity, increasingly replaced by alternative plasticizers. Di(2-ethylhexyl) terephthalate (DEHTP) is one of these substitutes. In this study, we investigated DEHTP exposure in 107 Portuguese children (4-17years old) by analyzing specific DEHTP metabolites in their urine using a newly developed LC-MS/MS method. We could detect the major, specific DEHTP metabolite mono(2-ethyl-5-carboxypentyl) terephthalate (5cx-MEPTP) in 100% of the samples with levels above the limit of quantification in 96% of the samples (median concentration 4.19μg/L; 95th percentile 26.4μg/L; maximum 3400μg/L). Other minor DEHTP metabolites (5OH-MEHTP, 5oxo-MEHTP and 2cx-MMHTP) were detected at lower rates and levels. Daily DEHTP intakes calculated from urinary 5cx-MEPTP levels were generally far below the tolerable daily intake (TDI) of 1000μg/kgbw/d (median 0.67μg/kgbw/d; 95th percentile 6.25μg/kgbw/d; maximum 690μg/kgbw/d). However, for one child the biomarker-derived health-based guidance value (HBM-I value) for 5cx-MEPTP of 1800μg/L was exceeded by about a factor of two. Levels of 5cx-MEPTP and calculated daily DEHTP intakes were higher in normal/under-weight children who nourished on their usual diet compared to overweight/obese children who received nutritional guidance with fresh and unprocessed food (p=0.043 and p<0.001 respectively). This indicates to processed and fatty foodstuff as a major source of DEHTP exposure. Additionally, we found children of lower age having higher DEHTP intakes (p=0.045). Again, foodstuff as a major DEHTP source, together with other child specific DEHTP sources such as mouthing of toys or ingestion of dust might be contributing factors. With the present study, we provide a first data set on the omnipresent DEHTP exposure in children. So far, general levels of DEHTP exposure seem no cause for concern. However, due to the increasing use of DEHTP as an ortho-phthalate substitute, possible increasing exposures in the future should be followed closely.

Metabolism and urinary excretion kinetics of di(2-ethylhexyl) terephthalate (DEHTP) in three male volunteers after oral dosage

Di(2-ethylhexyl) terephthalate (DEHTP) is used as a substitute for di(2-ethylhexyl) phthalate (DEHP), an ortho-phthalate-based plasticizer that is classified and labeled due to its toxicity to reproduction. In this study the metabolism and urinary excretion kinetics of DEHTP were investigated by single oral dosage of 50 mg DEHTP to three male volunteers (resulting in individual dosages between 0.55 and 0.59 mg/kg body weight). Separate urine samples were consecutively collected for 48 h. In analogy to DEHP, we quantified specific side-chain-oxidized monoester metabolites of DEHTP (5OH-MEHTP, 5oxo-MEHTP, 5cx-MEPTP and 2cx-MMHTP) by HPLC-MS/MS with online sample clean-up and isotope dilution. All postulated metabolites were detectable in all samples after dosage. The predominant, specific urinary metabolite was 5cx-MEPTP representing about 13.0 % of the applied dose as mean of the three volunteers (range 7.0-20.4 %) in urine, followed by 5OH-MEHTP (mean: 1.8 %; range 1.3-2.4 %) and 5oxo MEHTP (mean: 1.0 %; range 0.6-1.6 %). 2cx-MMHTP was a minor metabolite representing only 0.3 % (range 0.2-0.4 %). In total, about 16.1 % of the dose was recovered in urine as the above investigated specific metabolites within 48 h with the major share (95 %) being excreted within the first 24 h. Investigation of the glucuronidation patterns revealed that the carboxy-metabolites are excreted almost completely in their free form (>90 %), whereas for 5OH-MEHTP and 5oxo-MEHTP, glucuronidation is preferred (>70 %). With this study we provide reliable urinary excretion factors to calculate DEHTP intakes based on metabolite concentrations in environmental and occupational studies.

Considerable exposure to the endocrine disrupting chemicals phthalates and bisphenol-A in intensive care unit (ICU) patients

Critical care medicine has largely benefited from plastic-containing medical devices. However, bisphenol-A (BPA) and phthalates present in the plastics can leach from such devices. We hypothesized that intensive care unit (ICU) patients are exposed to BPA and phthalates through (plastic) medical devices. Serum (n = 118) and urine (n= 102) samples of adult ICU patients (n = 35) were analyzed for total BPA and phthalate metabolites (PMs). Our results showed that adult ICU patients are continuously exposed to phthalates, such as di(2-ethylhexyl)phthalate (DEHP), as well as to BPA, albeit to a lesser extent. This exposure resulted in detectable high serum and urinary levels in almost every patient and at every studied time point. Moreover, these levels were significantly higher than in controls or compared to referenced literature. The chronology of exposure was demonstrated: pre-operative urinary and serum levels of the DEHP metabolites were often below the detection limit. Plastic-containing medical devices were the main source of DEHP exposure: post-operative patients on hemofiltration, extracorporeal membrane oxygenation or both showed serum levels 100-or 1000-fold higher than the levels in the general population reported in the literature. The serum and some of the urinary levels of the DEHP metabolites are the highest ever reported in humans; some at biologically highly relevant concentrations of ≥ 10-50 μM. Despite the continuously tightening regulations, BPA and DEHP appear to be still present in (some) medical devices. Because patient safety is a concern in the ICU, further research into the (possibly toxic and clinical) effects of these chemicals released from medical devices is imperiously necessary.

The adverse cardiac effects of Di(2-ethylhexyl)phthalate and Bisphenol A

The ubiquitous nature of plastics has raised concerns pertaining to continuous exposure to plastic polymers and human health risks. Of particular concern is the use of endocrine-disrupting chemicals in plastic production, including di(2-ethylhexyl)phthalate (DEHP) and bisphenol A (BPA). Widespread and continuous exposure to DEHP and BPA occurs through dietary intake, inhalation, dermal and intravenous exposure via consumer products and medical devices. This article reviews the literature examining the relationship between DEHP and BPA exposure and cardiac toxicity. In vitro and in vivo experimental reports are outlined, as well as epidemiological studies which examine the association between these chemicals and cardiovascular outcomes. Gaps in our current knowledge are also discussed, along with future investigative endeavors that may help resolve whether DEHP and/or BPA exposure has a negative impact on cardiovascular physiology.

Health hazard assessment of occupationally di-(2-ethylhexyl)-phthalate-exposed workers in China

Di-(2-ethylhexyl)-phthalate (DEHP) is a potential hazard to human health. The effects of occupational high level DEHP exposure on human health were evaluated by measuring the plasma cholinesterase, residues, renal and hepatic biochemical markers. The study was conducted in three representative polyvinyl chloride manufacturing facilities from large size (S1), medium side (S2) to small size (S3). Total 456 adult males including 352 exposed workers (occupational) and 104 control workers (background) were selected. The average DEHP concentrations in respirable particulate matter were 233, 291, and 707 μg m(-3) for S1-S3, respectively, compared with 0.26 μg m(-3) in the background atmosphere (labeled by S4). The results showed significant decreases in post exposure plasma cholinesterase (PChE) levels (<30%) from the exposed workers as compared to baseline. These exposed workers had been evaluated for plasma DEHP residues. Regression analyses explored that PChE decreased significantly with increasing plasma DEHP residues. Serum aspartate aminotransferase, alanine aminotransferase, creatinine, urea, gamma glutamyltransferase, malondialdehyde, total antioxidant and C-reactive protein were significantly raised as compared to the controls. Of the 352 exposed workers, 116 (33.0%) had a daily DEHP intake 22.7 μg kg bw(-1)d(-1) , which is more than 20 μg kg bw(-1)d(-1) specified by the US Environmental Protection Agency. The study demonstrated that occupational phthalate exposure produces health hazards.

Effects of di-n-butyl phthalate on the physiology and ultrastructure of cucumber seedling roots

Agricultural pollution caused by the use of plastic sheetings has been documented to be a widespread problem in most of the major crop-planting regions of the world. In order to better understand the phytotoxic mechanisms induced by phthalic acid esters involved with this problem, Cucumber sativus L. cv Jinyan No. 4 were sown in pots to the three-leaf-stage in the presence of di-n-butyl phthalate (DBP; 0, 30, 50, 100, and 200 mg L(-1)) for 1, 3, 5, or 7 days. Physiology, biochemistry, and ultrastructure of seedling roots were examined. The results indicated that activities of three antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD)) were stimulated at low-DBP treatments and decreased under higher levels (>100 mg L(-1)) compared to the controls. On the other hand, SOD and POD provided a better defense against DBP-induced oxidative damage in the roots of cucumber seeding, compared to CAT. The productions of both malondialdehyde (MDA) and proline (Pro) were promoted under DBP stress. Visible impact on the cytoderm, mitochondrion, and vacuole was detected, possibly as a consequence of free radical generation. These results suggested that activation of the antioxidant system by DBP led to the formation of reactive oxygen species that resulted in cellular damage.

Evaluation of the Di(2-ethylhexyl)phthalate released from polyvinyl chloride medical devices that contact blood

Extraction methods that simulate those used in the clinic are recommended for obtaining extraction solutions. For polyvinyl chloride (PVC) medical devices that have contact with human blood, an alternative medium (ethanol/water mixture) is suggested as an extraction screening vehicle to evaluate the di(2-ethylhexyl)phthalate (DEHP) released. A test comparing the extraction ability between the alternative medium and whole blood from three healthy volunteers has been conducted. An experimental method is provided outlining the chemical analysis of the DEHP released from medical devices made with polyvinyl chloride (PVC). Gas chromatography-mass spectrometry (GC-MS) in the selective ion monitoring (SIM) mode was used to analyze and quantify the extracted DEHP. The linear range of the SIM method was 0.1-200 μg/mL, and the recoveries were 89.6-101.5% and 91.0-98.9% when using the ethanol/water mixture and whole blood as the extraction media, respectively. The validated method demonstrates that it is suitable for the determination of the DEHP released from PVC medical devices that have contact with blood. The results from the determination of the DEHP released will be compared with the limits derived from toxicological data for the parenteral exposure route and certain population groups, and the results will be used in the risk assessment of medical devices.

Effects of diethylphthalate and di-(2-ethyl)hexylphthalate on the physiology and ultrastructure of cucumber seedlings

Phthalic acid esters (PAEs) are one kind of persistent organic pollutants. This study was conducted to investigate the effects of diethylphthalate (DEP) and di(2-ethyl)hexylphthalate (DEHP) with different concentrations (0, 30, 50, 100, and 200 mg L(-1)) on early seedling growth of Cucumis sativus L. Physiological, biochemical, and ultrastructure of seedling leaves were examined for 7-day exposure. The three antioxidant enzymes' activities was stimulated at low-DEP treatments and decreased under higher levels (>200 mg L(-1)) compared to the controls. Furthermore, MDA and H2O2 gradually enhanced with the elevation of DEP and DEHP concentration. Significant impact on the chloroplast and mitochondrion was visible, possibly as a consequence of free radical generation. DEP induced bigger and more starch grains in chloroplasts than DEHP. This study concluded that the effects of DEP and DEHP on cucumber seedlings represented the adverse impacts of DEP and DEHP on the ecosystem and agricultural production. The environmental harm caused by DEP was severer than DEHP.

Exposure to the endocrine disruptor di(2-ethylhexyl)phthalate affects female reproductive features by altering pulsatile LH secretion

The patterns of growth of preovulatory follicles and corpora lutea, as well as plasma concentrations of estradiol, progesterone and LH were evaluated in sheep exposed to DEHP. There were not found effects on the preovulatory follicular dynamics nor on the ovulatory efficiency between DEHP-exposed and control sheep. However, plasma estradiol concentration was significantly higher in the ewes exposed to DEHP than in the control females (P<0.001). Afterwards, DEHP-exposed ewes had significantly higher plasma progesterone concentration from Day 2 of the luteal phase (P<0.05), although there were no differences between groups in the macro- and microscopic features of the corpora lutea. Analysis of mean basal concentrations of LH showed lower values in DEHP-exposed than in control sheep (0.3 ± 01 ng/mL vs. 0.7 ± 0.1; P<0.05). Moreover, the frequency of LH pulses was 0.3 pulses/4 h, with amplitude of 0.6 ng/mL, in the control group; on the other hand, the pulsatile secretion of LH in the DEHP-exposed group was undetectable during the period of sampling.

Commercially available blood storage containers

Plastic blood bags improve the safety and effectiveness of blood component separation and storage. Progress towards optimal storage systems is driven by medical, scientific, business and environmental concerns and is limited by available materials, consumer acceptance and manufacturing and regulatory concerns. Blood bag manufacturers were invited to submit lists of the bags they manufacture. The lists were combined and sorted by planned use. The lists were analysed by experts to assess the degree to which the products attend to scientific problems. Specific issues addressed included the use of di-ethylhexyl phthalate (DEHP) as plasticizer for polyvinyl chloride (PVC) blood bags, the size, material and thickness of platelet bags, and the fracture resistance of plasma bags. Alternatives to DEHP for red blood cell (RBC) storage exist, but are mostly in a developmental stage. Plastic bags (DEHP-free, PVC-free) for platelet storage with better gas diffusion capabilities are widely available. Alternatives for plasma storage with better fracture resistance at low temperatures exist. Most RBC products are stored in DEHP-plasticized PVC as no fully satisfactory alternative exists that ensures adequate storage with low haemolysis. A variety of alternative platelet storage systems are available, but their significance - other than improved oxygen transport - is poorly understood. The necessity to remove DEHP from blood bags still needs to be determined.

Assessment of adult human exposure to phthalate esters in the urban centre of Paris (France)

Human exposure to phthalates was assessed through digestive and respiratory intakes. Six phthalates (DMP, DEP, DnBP, BBP, DEHP, DnOP) were investigated in drinking water, in current foodstuff and in ambient air. Digestive intake was prevailing (92 %) with a major contribution of food (95.5 %). Phthalate intake from water was mainly due to bottled water (60 %) in spite of the minor volume absorbed daily. From the respiratory tract, it was dominated by DEP: 30.3 ng kg(-1) bw day(-1) and the part played by indoor air prevailed. Total intake were as ng kg(-1) bw day(-1), for DEHP: 1458, DnBP: 191.8, BBP: 164.3, DEP: 107.7, DMP: 79.1.

Exposure to di(2-ethylhexyl) phthalate in premature neonates in a neonatal intensive care unit in Taiwan

OBJECTIVE

Neonates are exposed to high levels of di(2ethylhexyl) phthalate through numerous medical procedures in the neonatal intensive care unit. Our aim was to assess the contribution of specific medical devices to the di(2-ethylhexyl) phthalate exposure of neonates.

DESIGN

Prospective.

SETTING

University hospital.

PATIENTS

We recruited 32 premature neonates, 20 with very low birth weight (<1500 g) and 12 with low birth weight (<2500 g), and 31 controls at a neonatal intensive care unit from a medical center in central Taiwan.

INTERVENTIONS

Interventions were based on a clinical need and used standard materials and devices, including endotracheal tubes, continuous positive airway pressure, oxygen hood, intravenous injection, intralipid injection, blood transfusion, orogastric tubes, nasogastric tubes, umbilical venous catheterization, umbilical arterial catheterization, chest tube, and isolate.

MEASUREMENTS AND MAIN RESULTS

We recorded the medical procedures of each subject, collected their urine samples, and determined the urinary concentration of three metabolites of di(2-ethylhexyl) phthalate using reversed-phase high-performance liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry. Median levels of di(2-ethylhexyl) phthalate metabolites in premature neonates treated with an endotracheal tube and orogastric tube or nasogastric tube were significantly higher than those not treated with an endotracheal tube, orogastric tube, or nasogastric tube. Median levels of di(2-ethylhexyl) phthalate metabolites in premature neonates treated with intravenous injection were ≥ 2-fold higher than those of healthy controls who received intravenous injections (p = .01). Median levels of three di(2-ethylhexyl) phthalate metabolites were similar in very-low-birth-weight and low-birth-weight neonates.

CONCLUSIONS

These data suggest that polyvinyl chloride-containing devices are the major defining factor in di(2-ethylhexyl) phthalate exposure levels in neonates in the neonatal intensive care unit. We urge the use of polyvinyl chloride-free or alternative materials in medical devices, especially for endotracheal tubes, orogastric tubes, nasogastric tubes, and intravenous tubing in the neonatal intensive care unit. The health effects of high di(2-ethylhexyl) phthalate exposure on premature neonates in the neonatal intensive care unit is worthy of further investigation.

A critical evaluation of the creatinine correction approach: can it underestimate intakes of phthalates? A case study with di-2-ethylhexyl phthalate

The creatinine correction approach has been used to estimate daily intake for contaminants whose primary route of elimination is through urine. This method is challenged using the phthalate di-2-ethylhexyl phthalate (DEHP) as an example. An alternate prediction approach based on human experimental metabolism and urinary excretion data on DEHP was developed. This alternate model was developed from urine measurements of four metabolites of DEHP from two individuals partaking in different experiments, for up to 44 h after known exposures. Particular attention was paid to the changing ratios of the metabolites over time: they took a certain form when exposure was in the "near" (the past few hours) versus the "distant" (24 h or more) past. The creatinine correction approach was applied to measurements of the same four metabolites from 18 individuals in the National Health And Nutrition Evaluation Survey (NHANES) 2003/2004. The alternate model was also applied to these individuals, and the results were compared. Predictions using the two methods were similar or the creatinine correction predicted higher concentrations when the ratio suggested that the DEHP exposure was "near" in time, but the alternate approach predicted intakes that were an order of magnitude higher when the ratios suggested that the intake was "distant". As much as 25% of all NHANES measurements contain metabolites whose key ratio suggest that exposure was "distant". Uncertainties notwithstanding, the analysis in this article suggests that the creatinine correction approach should be used cautiously for DEHP and possibly other contaminants with similar exposure characteristics: rapid metabolism with metabolite urine elimination half-lives on the order of hours, and exposure patterns that may not be continuous and ongoing.

Adverse events and safety issues in blood donation--a comprehensive review

Although blood donation is generally safe, a variety of risks and complications exist, the most common being iron deficiency, vasovagal reactions and citrate-related events. In the last decades, extensive efforts have significantly improved recipient and product safety, but there is still great potential to optimise donor care. Many therapies in modern medicine depend on the prompt availability of blood products, therefore it is crucial to maintain a motivated and healthy donor pool in view of a limited number of healthy volunteers willing and able to give blood or blood components. We present a comprehensive review on adverse events addressing all types of blood donation including whole blood, plasma, platelet, peripheral blood stem cell, leucocyte and bone marrow donation. In addition, we outline strategies for the prevention and treatment of these events and give a blueprint for future research in this field.

Assessing exposure to phthalates - the human biomonitoring approach

Some phthalates are developmental and reproductive toxicants in animals. Exposure to phthalates is considered to be potentially harmful to human health as well. Based on a comprehensive literature research, we present an overview of the sources of human phthalate exposure and results of exposure assessments with special focus on human biomonitoring data. Among the general population, there is widespread exposure to a number of phthalates. Foodstuff is the major source of phthalate exposure, particularly for the long-chain phthalates such as di(2-ethylhexyl) phthalate. For short-chain phthalates such as di-n-butyl-phthalate, additional pathways are of relevance. In general, children are exposed to higher phthalate doses than adults. Especially, high exposures can occur through some medications or medical devices. By comparing exposure data with existing limit values, one can also assess the risks associated with exposure to phthalates. Within the general population, some individuals exceed tolerable daily intake values for one or more phthalates. In high exposure groups, (intensive medical care, medications) tolerable daily intake transgressions can be substantial. Recent findings from animal studies suggest that a cumulative risk assessment for phthalates is warranted, and a cumulative exposure assessment to phthalates via human biomonitoring is a major step into this direction.

Estimated daily intake of phthalates in occupationally exposed groups

Improved analytical methods for measuring urinary phthalate metabolites have resulted in biomarker-based estimates of phthalate daily intake for the general population, but not for occupationally exposed groups. In 2003-2005, we recruited 156 workers from eight industries where materials containing diethyl phthalate (DEP), dibutyl phthalate (DBP), and/or di(2-ethylhexyl) phthalate (DEHP) were used as part of the worker's regular job duties. Phthalate metabolite concentrations measured in the workers' end-shift urine samples were used in a simple pharmacokinetic model to estimate phthalate daily intake. DEHP intake estimates based on three DEHP metabolites combined were 0.6-850 μg/kg/day, with the two highest geometric mean (GM) intakes in polyvinyl chloride (PVC) film manufacturing (17 μg/kg/day) and PVC compounding (12 μg/kg/day). All industries, except phthalate manufacturing, had some workers whose DEHP exposure exceeded the U.S. reference dose (RfD) of 20 μg/kg/day. A few workers also exceeded the DEHP European tolerable daily intake (TDI) of 50 μg/kg/day. DEP intake estimates were 0.5-170 μg/kg/day, with the highest GM in phthalate manufacturing (27 μg/kg/day). DBP intake estimates were 0.1-76 μg/kg/day, with the highest GMs in rubber gasket and in phthalate manufacturing (17 μg/kg/day, each). No DEP or DBP intake estimates exceeded their respective RfDs. The DBP TDI (10 μg/kg/day) was exceeded in three rubber industries and in phthalate manufacturing. These intake estimates are subject to several uncertainties; however, an occupational contribution to phthalate daily intake is clearly indicated in some industries.

Inflammatory effects of phthalates in neonatal neutrophils

Hospitalized infants are exposed to numerous devices containing the plasticizer di-(2-ethylhexyl) phthalate. Urinary levels of the phthalate metabolite, mono-(2-ethylhexyl) phthalate (MEHP), are markedly elevated in premature infants. Phthalates inactivate peroxisome proliferator-activated receptor-gamma (PPAR-gamma), a nuclear transcription factor that mediates the resolution of inflammation, a process impaired in neonates. We speculate that this increases their susceptibility to MEHP, and this was analyzed. MEHP inhibited neutrophil apoptosis; neonatal cells were more sensitive than adult cells. In neonatal, but not in adult neutrophils, MEHP also inhibited chemotaxis, stimulated oxidative metabolism, and up-regulated expression of NADPH oxidase-1. In both adult and neonatal neutrophils, MEHP stimulated IL-1beta and VEGF production, whereas IL-8 production was stimulated only in adult cells. In contrast, MEHP-inhibited production of MIP-1beta by adult cells, and Regulated on Activation Normal T Cell Expressed and Secreted (RANTES) by neonatal neutrophils. The effects of MEHP on apoptosis and oxidative metabolism in neonatal cells were reversed by the PPAR-gamma agonist, troglitazone. Whereas troglitazone had no effect on MEHP-induced alterations in inflammatory protein or chemokine production, constitutive IL-8 and MIP-1beta production was reduced in adult neutrophils, and RANTES and MIP-1beta in neonatal cells. These findings suggest that neonatal neutrophils are more sensitive to phthalate-mediated inhibition of PPAR-gamma, which may be related to decreased anti-inflammatory signaling.

Apheresis affects bone and mineral metabolism

BACKGROUND

Apheresis is a procedure to selectively obtain blood components. For the collection process citrate is routinely used. It inhibits coagulation by binding to ionized calcium and leads to metabolic alkalosis.

OBJECTIVE

Whether regular apheresis affects bone and mineral metabolism is unknown. The intention of this study was to investigate 1) the acute effects of apheresis on acid-base balance, bone and mineral metabolism and 2) to compare bone mineral density (BMD) at the lumbar spine and hip of donors to matched control subjects.

DESIGN

In this open, observational, single-center, cross-sectional study we enrolled 102 regular plasma and thrombocyte donors to pursue objective 1) and compared those to 102 matched controls (CTR) for objective 2).

RESULTS

Platelet donation led to significant decreases in serum ionized calcium (-17%) and phosphate (-18%), to marked increases in base excess (57%) and PTH levels (192%) during apheresis. Baseline biochemical comparisons between donors and CTR revealed significantly lower values for donors for serum calcium, albumin, and 25-hydroxyvitamin D levels. Mean Z-score at the lumbar spine adjusted for BMI, average physical activity and daily calcium intake was lower for donors (-0.28+/-0.11) when compared to CTR subjects (0.06+/-0.11, P<0.05). Total and neck femoral BMD was also lower in the donor group, however, this difference was not significant.

CONCLUSIONS

Exposure to citrate during the apheresis procedure acutely affects mineral and bone metabolism. Regular donations of blood components compromised BMD at the lumbar spine. If confirmed, strategies to prevent long-term effects on bone need to be formulated.

A simple pharmacokinetic model to characterize exposure of Americans to di-2-ethylhexyl phthalate

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.

What additional factors beyond state-of-the-art analytical methods are needed for optimal generation and interpretation of biomonitoring data?

BACKGROUND

The routine use of biomonitoring (i.e., measurement of environmental chemicals, their metabolites, or specific reaction products in human biological specimens) to assess internal exposure (i.e., body burden) has gained importance in exposure assessment.

OBJECTIVES

Selection and validation of biomarkers of exposure are critical factors in interpreting biomonitoring data. Moreover, the strong relation between quality of the analytical methods used for biomonitoring and quality of the resulting data is well understood. However, the relevance of collecting, storing, processing, and transporting the samples to the laboratory to the overall biomonitoring process has received limited attention, especially for organic chemicals.

DISCUSSION

We present examples to illustrate potential sources of unintended contamination of the biological specimen during collection or processing procedures. The examples also highlight the importance of ensuring that the biological specimen analyzed both represents the sample collected for biomonitoring purposes and reflects the exposure of interest.

CONCLUSIONS

Besides using high-quality analytical methods and good laboratory practices for biomonitoring, evaluation of the collection and handling of biological samples should be emphasized, because these procedures can affect the samples integrity and representativeness. Biomonitoring programs would be strengthened with the inclusion of field blanks.

Human body burdens of chemicals used in plastic manufacture

In the last decades, the availability of sophisticated analytical chemistry techniques has facilitated measuring trace levels of multiple environmental chemicals in human biological matrices (i.e. biomonitoring) with a high degree of accuracy and precision. As biomonitoring data have become readily available, interest in their interpretation has increased. We present an overview on the use of biomonitoring in exposure and risk assessment using phthalates and bisphenol A as examples of chemicals used in the manufacture of plastic goods. We present and review the most relevant research on biomarkers of exposure for phthalates and bisphenol A, including novel and most comprehensive biomonitoring data from Germany and the United States. We discuss several factors relevant for interpreting and understanding biomonitoring data, including selection of both biomarkers of exposure and human matrices, and toxicokinetic information.

Reproductive and developmental toxicity of phthalates

The purposes of this review are to (1) evaluate human and experimental evidence for adverse effects on reproduction and development in humans, produced by exposure to phthalates, and (2) identify knowledge gaps as for future studies. The widespread use of phthalates in consumer products leads to ubiquitous and constant exposure of humans to these chemicals. Phthalates were postulated to produce endocrine-disrupting effects in rodents, where fetal exposure to these compounds was found to induce developmental and reproductive toxicity. The adverse effects observed in rodent models raised concerns as to whether exposure to phthalates represents a potential health risk to humans. At present, di(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP), and butyl benzyl phthalate (BBP) have been demonstrated to produce reproductive and developmental toxicity; thus, this review focuses on these chemicals. For the general population, DEHP exposure is predominantly via food. The average concentrations of phthalates are highest in children and decrease with age. At present, DEHP exposures in the general population appear to be close to the tolerable daily intake (TDI), suggesting that at least some individuals exceed the TDI. In addition, specific high-risk groups exist with internal levels that are several orders of magnitude above average. Urinary metabolites used as biomarkers for the internal levels provide additional means to determine more specifically phthalate exposure levels in both general and high-risk populations. However, exposure data are not consistent and there are indications that secondary metabolites may be more accurate indicators of the internal exposure compared to primary metabolites. The present human toxicity data are not sufficient for evaluating the occurrence of reproductive effects following phthalate exposure in humans, based on existing relevant animal data. This is especially the case for data on female reproductive toxicity, which are scarce. Therefore, future research needs to focus on developmental and reproductive endpoints in humans. It should be noted that phthalates occur in mixtures but most toxicological information is based on single compounds. Thus, it is concluded that it is important to improve the knowledge of toxic interactions among the different chemicals and to develop measures for combined exposure to various groups of phthalates.

Phthalate removal throughout wastewater treatment plant: case study of Marne Aval station (France)

The fate of six phthalates: dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DnBP), butyl benzyl phthalate (BBP), bis (2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP) was investigated throughout wastewater treatment processes in the wastewater treatment plant (WWTP) of Marne Aval (France). That plant treats wastewater from a highly populated area and was used as a pilot station for development of nitrification processes. In wastewater, at each step of treatment, DEHP was always the major compound (9 to 44 microg L(-1)), followed by DEP (1.6 to 25 microg L(-1)). Other phthalates averaged 1 microg L(-1) and DnOP remained close to the detection limit in nearly all cases. In sludge, the prevailing compound was also DEHP (72 microg g(-1)) which is consistent with its tendency to get sorbed upon suspended matter (SM). DnOP came in third, in relation with its resistance to biodegradation. For the studied period, the removal efficiency of DEHP from wastewater was about 78%. That removal seemed to proceed rather from particle settling than from biodegradation. A highly significant correlation (p<0.001) was found between DEHP and SM concentrations throughout treatment processes. The other compounds: DMP, DEP, DnBP and BBP, displayed satisfactory efficiencies ranging from 68 to over 96% for the lighter ones obviously more easily degraded. Under rainy periods, the plant discharge impact upon Marne River quality in terms of phthalate fluxes, appeared to be minor as compared to the amount brought by the storm overflows in the same area. Downstream of the WWTP discharge, DEHP concentration remained under the European norm for surface water (NQE: 1.3 microg L(-1)). Our study documents the behaviour of phthalate esters throughout a WWTP which treatment device is used by 55% of the WWTP in the river Seine basin.

Cross validation and ruggedness testing of analytical methods used for the quantification of urinary phthalate metabolites

Since the publication of our first analytical method in 2000 to detect and quantify phthalate metabolites in human urine, we have modified the method several times to improve performance, reduce the volume of matrix and solvents used, and to increase the number of analytes in one analytical run. We performed cross method validation and ruggedness testing after each modification to ensure that the analytical method adopted is robust and produces accurate and reproducible data when compared to the previously used method. Here, we present the results from the evaluation of the ruggedness of our analytical approach under variable experimental conditions, using the current analytical method. Minor deviations of the standard experimental conditions, i.e., pH, incubation time, amount of deconjugation enzyme, and incubation temperature, had no effect on final analyte concentrations. Furthermore, we validated the method to ensure accuracy at concentrations beyond the highest calibration standard. The concentrations obtained by using a lower volume of urine agreed well with original levels, suggesting broad linear calibration range as well as complete hydrolysis of the glucuronide conjugates with the standard amount of beta-glucuronidase used for deglucuronidation; also, the time of incubation (90 min) was adequate regardless of the amount of glucuronide present. We also summarize the precision of concentration data acquired by the five different analytical approaches we have used since 2000. The correlation plots of concentration data for each analyte obtained from split sample analysis, using three of these approaches, produced linear curves (R(2)>0.98) with slopes and intercepts that were not statistically different (p>0.05) from 1 and 0, respectively. These results suggest that the data are reproducible and accurate, regardless of the analytical method used. Furthermore, analysis of quality control urine samples made over the years confirmed the stability of the phthalate metabolites in urine at -70 degrees C for several years and the consistency of the analytical measurements obtained by using various methodological approaches over time.

Phthalates: Toxicology and exposure

Phthalates are used as plasticizers in PVC plastics. As the phthalate plasticizers are not chemically bound to PVC, they can leach, migrate or evaporate into indoor air and atmosphere, foodstuff, other materials, etc. Consumer products containing phthalates can result in human exposure through direct contact and use, indirectly through leaching into other products, or general environmental contamination. Humans are exposed through ingestion, inhalation, and dermal exposure during their whole lifetime, including intrauterine development. This paper presents an overview on current risk assessments done by expert panels as well as on exposure assessment data, based on ambient and on current human biomonitoring results. Some phthalates are reproductive and developmental toxicants in animals and suspected endocrine disruptors in humans. Exposure assessment via modelling ambient data give hints that the exposure of children to phthalates exceeds that in adults. Current human biomonitoring data prove that the tolerable intake of children is exceeded to a considerable degree, in some instances up to 20-fold. Very high exposures to phthalates can occur via medical treatment, i.e. via use of medical devices containing DEHP or medicaments containing DBP phthalate in their coating. Because of their chemical properties exposure to phthalates does not result in bioaccumulation. However, health concern is raised regarding the developmental and/or reproductive toxicity of phthalates, even in environmental concentrations.

Human biomonitoring: State of the art

Human biomonitoring (HBM) of dose and biochemical effect nowadays has tremendous utility providing an efficient and cost effective means of measuring human exposure to chemical substances. HBM considers all routes of uptake and all sources which are relevant making it an ideal instrument for risk assessment and risk management. HBM can identify new chemical exposures, trends and changes in exposure, establish distribution of exposure among the general population, identify vulnerable groups and populations with higher exposures and identify environmental risks at specific contaminated sites with relatively low expenditure. The sensitivity of HBM methods moreover enables the elucidation of human metabolism and toxic mechanisms of the pollutants. So, HBM is a tool for scientists as well as for policy makers. Blood and urine are by far the most approved matrices. HBM can be done for most chemical substances which are in the focus of the worldwide discussion of environmental medicine. This especially applies for metals, PAH, phthalates, dioxins, pesticides, as well as for aromatic amines, perfluorinated chemicals, environmental tobacco smoke and volatile organic compounds. Protein adducts, especially Hb-adducts, as surrogates of DNA adducts measuring exposure as well as biochemical effect very specifically and sensitively are a still better means to estimate cancer risk than measuring genotoxic substances and their metabolites in human body fluids. Using very sophisticated but nevertheless routinely applicable analytical procedures Hb-adducts of alkylating agents, aromatic amines and nitro aromatic compounds are determined routinely today. To extend the spectrum of biochemical effect monitoring further methods should be elaborated which put up with cleavage and separation of the adducted protein molecules as a measure of sample preparation. This way all sites of adduction as well as further proteins, like serum albumin could be used for HBM. DNA-adducts indicate the mutagenicity of a chemical substance as well as an elevated cancer risk. DNA-adducts therefore would be ideal parameters for HBM. Though there are very sensitive techniques for DNA adduct monitoring like P32-postlabelling and immunological methods they lack specificity. For elucidating the mechanism of carcinogenesis and for a broad applicability and comparability in epidemiological studies analytical methods must be elaborated which are strictly specific for the chemical structure of the DNA-adduct. Current analytical possibilities however meet their borders. In HBM studies with exposure to genotoxic chemicals especially the measurement of DNA strand breaks in lymphocytes and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in white blood cells has become very popular. However, there is still a lack of well-established dose-response relations between occupational or environmental exposures and the induction of 8-OHdG or formation of strand breaks which limits the applicability of these markers. Most of the biomarkers used in population studies are covered by standard operating procedures (SOPs) as well as by internal and external quality assessment schemes. Therefore, HBM results from the leading laboratories worldwide are analytically reliable and comparable. Newly upcoming substances of environmental relevance like perfluorinated compounds can rapidly be assessed in body fluids because there are very powerful laboratories which are able to elaborate the analytical prerequisites in due time. On the other hand, it is getting more and more difficult for the laboratories to keep up with a progress in instrumental analyses. In spite of this it will pay to reach the ultimate summit of HBM because it is the only way to identify and quantify human exposure and risk, elucidate the mechanism of toxic effects and to ultimately decide if measures have to be taken to reduce exposure. Risk assessment and risk management without HBM lead to wrong risk estimates and cause inadequate measures. In some countries like in USA and in Germany, thousands of inhabitants are regularly investigated with respect to their internal exposure to a broad range of environmentally occurring substances. For the evaluation of HBM results the German HBM Commission elaborates reference- and HBM-values.

Determination of secondary, oxidised di-iso-nonylphthalate (DINP) metabolites in human urine representative for the exposure to commercial DINP plasticizers

Di-iso-nonylphthalate (DINP) is the major plasticizer for polyvinylchloride (PVC) polymers. Two DINP products are currently produced: DINP 1 and DINP 2. We analyzed the isononyl alcohol mixtures (INA) used for the synthesis of these two DINP plasticizer products and thus identified 4-methyloctanol-1 as one of the major constituents of the alkyl side chains of DINP 1 (8.7%) and DINP 2 (20.7%). Based on this isomer, we postulated the major DINP metabolites renally excreted by humans: mono-(4-methyl-7-hydroxy-octyl)phthalate (7OH-MMeOP), mono-(4-methyl-7-oxo-octyl)phthalate (7oxo-MMeOP) and mono-(4-methyl-7-carboxy-heptyl)phthalate (7carboxy-MMeHP). We present a fast and reliable on-line clean-up HPLC method for the simultaneous determination of these three DINP metabolites in human urine. We used ESI-tandem mass spectrometry for detection and isotope dilution for quantification (limit of quantification 0.5microg/l). Via these three oxidised DINP isomer standards, we quantified the excretion of all oxidised DINP isomers with hydroxy (OH-MINP), oxo (oxo-MINP) and carboxy (carboxy-MINP) functional groups. With this approach, we can for the first time reliably quantify the internal burden of the general population to DINP. Mean urinary metabolite concentrations in random samples from the general German population (n=25) were 14.9microg/l OH-MINP, 8.9microg/l oxo-MINP and 16.4microg/l carboxy-MINP. Metabolites strongly correlated with each other over all samples analyzed (R>0.99, p<0.0001).