Endocrine disruptors in dialysis therapies: A literature review

Endocrine disrupting chemicals (EDCs) were defined as "an exogenous substance or mixture that alters function(s) of the endocrine system and consequently causes adverse health effects". These compounds are mainly eliminated by the renal route. However, patients with end-stage kidney disease treated by dialysis (ESKDD) can no longer eliminate these EDCs efficiently. Furthermore, EDCs exposure could occur via leaching from medical devices used in dialysis therapy. As a result, ESKDD patients are overexposed to EDCs. The aims of this study were to summarize EDCs exposure of ESKDD patients and to evaluate the factors at the origin of this exposure. To handle these objectives, we performed a literature review. An electronic search on PubMed, Embase and Web of science databases was performed. Twenty-six studies were finally included. The EDCs reported in these studies were Bisphenol A (BPA), Bisphenol S (BPS), Bisphenol B (BPB), Nonylphenol, Di(2-ethylhexyl) phthalate (DEHP), Di-n-butyl phthalate (DBP), and Butylbenzyl phthalate (BBP). Regarding the environment of dialysis patients, BPA, BPB, BPS, DEHP, DBP and nonylphenol have been found. Environmental exposure affects EDCs blood levels in ESKDD patients who are overexposed to BPA, BPS, BPB and DEHP. For ESKDD patients, dialyzers with housing in polycarbonate and fibers in polysulfone seem to overexpose them to BPA. Regarding dialysis therapy, peritoneal dialysis seems to decrease patient exposure vs hemodialysis therapy, and hemodiafiltration therapy seems to reduce this exposure vs hemodialysis therapy. Regarding DEHP, levels tend to increase during dialysis and when DEHP plasticizer is used in PVC devices. Finally, in the European Union a regulation on medical devices was adopted on 5 April 2017 and has been applied recently. This regulation will regulate EDCs in medical devices and thereby contribute to reconsideration of their conceptions and, finally, to reduction of ESKDD patients' exposure.

Leaching of plasticizers from polyvinylchloride perfusion lines by different lipid emulsions for premature infants under clinical conditions

Plasticizers migrate from polyvinylchloride (PVC) infusion systems into lipid emulsions. The aim of this study was to investigate the leaching of different plasticizers from PVC perfusion lines by a selection of lipid emulsions under clinical conditions. Seven PVC perfusion lines with an equal length of 150cm and three internal diameters were perfused with three lipid emulsions: Intralipid^® 20%, ClinOleic^® 20% and SMOFlipid^® 20%, mimicking clinical conditions. The concentrations of the plasticizers were measured directly in the emulsions by gas chromatography - mass spectrometry. Of the four plasticizers examined in this study, di (2-ethylhexyl) phthalate (DEHP) leached the most and was found, on average, at 46.5μg/ml in the emulsions - around one order of magnitude higher than the other plasticizers. This study demonstrates that the leaching of DEHP by lipid emulsions in conditions of total parenteral nutrition is many times higher than should be accepted and higher when compared to the other plasticizers. There was no significant difference in leaching of plasticizers in relation to the type of lipid emulsion. The influence of tube diameter on the leaching rate of plasticizers should be taken into account especially in particular exposed patients.

A review of alternatives to di (2-ethylhexyl) phthalate-containing medical devices in the neonatal intensive care unit

OBJECTIVE

To conduct an extensive literature and toxicological database review on substitute compounds and available alternative medical products to replace polyvinyl chloride (PVC) and/or di(2-ethylhexyl) phthalate (DEHP), and conduct a DEHP-medical inventory analysis at a large metropolitan neonatal intensive care unit (NICU).

STUDY DESIGN

A systematic search for DEHP-free alternative products was performed using online databases. An informal audit of a large metropolitan NICU was undertaken in 2005 and 2006; 21 products were identified that could potentially contain DEHP. Availability of DEHP-free alternatives was determined through company websites and phone interviews.

RESULT

Two alternative approaches are available for replacing DEHP in NICU medical products: (1) replacement by DEHP-free plasticizers; and (2) replacement of PVC entirely through the use of other polymers. Both approaches seem to provide less harmful substitutes to DEHP, but support PVC-free polymers as the preferred alternative. However, significant data gaps exist, particularly for the alternative polymers. In all, 10 out of 21 (48%) products in the NICU audit were DEHP-free; six consisted of alternative polymers and four of alternative plasticizers. Of the remaining 11 products, only three were available without DEHP at the time of the audit.

CONCLUSION

Because of significant data gaps, systematic toxicological testing of DEHP-free alternatives is imperative. Continued development of alternative products is also needed.

[Manufacturing waste of hemodialyzers decreases oxidative phosphorylation of mitochondria isolated from rats]

INTRODUCTION

The persistence of manufacturing waste in hemodialysers is a neglected aspect of lack of hemodialysis biocompatibility. The effect of waste was tested on mitochondria isolated from rat liver.

MATERIAL AND METHODS

After throwing the first two liters of the rinse solution of hemodialysers, the third liter is lyophilized. The waste is placed in the presence of mitochondria. The parameter V3 is the synthesis of ATP, the respiratory control (RC) is the ability to activate phosphorylation in the presence of ADP, ADP/O is the ratio of ADP used on oxygen consumption. The study was conducted on two hemodialyzers sterilized with gamma rays (Tricea and APS) and one hemodialyzer sterilized with flowing steam (FX60).

RESULTS

The respiratory parameters in the presence of waste are expressed as percentage of values obtained in the presence of control (sterile water). The respective values with Tricea, APS and the FX are for V3: 67±14, 79±10, and 81±8% (T vs A p=0.02; T vs F p=0.01; A vs F p=0.68) ; for CR : 44±6, 63±7, and 74±9% (T vs A p<0.001; T vs X p<0.001; A vs F p=0.004) ; for ADP/O : 75±11, 90±19, 91±11% (T vs A p=0.16; T vs F p=0.01; A vs F p=0.68). The dose-response curves confirm the differences concerning V3 and RC but not concerning ADP/O.

CONCLUSION

The hemodialyzers contain waste which has toxic effects on isolated mitochondria. This waste impairs the oxidative phosphorylation. The fact that this waste is still present in the dialyzers despite rinsing with two liters should alert users about the importance of extensive rinsing and manufacturers about the importance of effective procedures in order to eliminate manufacturing waste.

Evaluation of the direct toxicity of trioctyltrimellitate (TOTM), di(2-ethylhexyl) phthalate (DEHP) and their hydrolysis products on isolated rat hepatocytes

Plasticizers are added to polyvinyl chloride (PVC) to confer flexibility to the polymer. Di(2-ethylhexyl) phthalate (DEHP) is the most commonly used of them. However, due to its non covalent bond to the PVC, DEHP tends to vaporize easily. A significant exposure has been recorded in dialyzed patients since medical tubings. Most animal species metabolize DEHP rapidly into monoethylhexyl phthalate (MEHP) and 2-ethylhexanol (2-EH). Because of the suspected toxicity of DEHP, an alternative plasticizer, trioctyltrimellitate (TOTM) has aroused increasing interest. The aim of this study was to determine on isolated rat hepatocytes in vitro, the direct hepatotoxic potential of both DEHP and TOTM and their hydrolytic products. To evaluate the possible toxic liver risk resulting from exposure to DEHP and TOTM, isolated rat hepatocytes were incubated with either DEHP, TOTM, MEHP or their common metabolite (2-EH) for 3 hours. Cell viability was periodically estimated thanks to trypan blue tests (15 - 180 min). The activity of lactate dehydrogenase (LDH) was also monitored (1h, 2h, 3h). The results obtained with trypan blue test and with direct LDH activity measurements, were satisfactorily correlated. Hepatocytes treated with both plasticizers and metabolites on the one hand, and the controls (untreated suspension) on the other hand, showed important differences as for cell viability. The acute toxicity on hepatocytes is mainly due to MEHP. Among DEHP, TOTM, MEHP, 2-EH and after intraperitoneal injection of those compounds, only DEHP and MEHP were able to induce a significant hydrogen peroxide (H2O2) production by the rat hepatocytes. These observations enable us to confirm the hypothesis according to which DEHP and MEHP cause an imbalance between the synthesis and the degradation of H2O2. Our results suggest a short-term in vitro cytotoxicity of MEHP. Even if trypan blue and LDH tests offered good results and were easily branded, further assays as well as MTT-tests should performed in order to confirm the cytotoxicity of the compounds tested.

Induction of propranolol metabolism in isolated rats hepatocytes treated by di(2-ethylhexyl) phthalate (DEHP) and mono(2-ethylhexyl) phthalate (MEHP)

Blood lines of polyvinyl chloride (PVC) for hemodialysis usually contain di(2-ethylhexyl) phthalate (DEHP) as a plasticizer. Previous studies show that 1 mg/kg of this plasticizer can leach into the blood during one dialysis session. It is rapidly metabolized in the liver. Mono(2-ehtylhexyl) phthalate (MEHP), its main metabolite can be detected as well. After oral administration to rodents, both compounds caused a variety of adverse biological effects such as testicular atrophy, peroxisome proliferation and hepatic peroxisomal enzyme induction. Male wistar rats were treated intraperitoneally by DEHP and MEHP using twice the dose of that involved in human exposure during a dialysis session. Propranolol metabolism by hepatocytes was investigated after fresh isolation from treated and untreated rats by means of reverse phase HPLC. The choice of propranolol as a substrate was made because of its rather quick liver metabolisation. Phenobarbital was chosen in the study as a reference of enzymatic inducer to evaluate the inducing effect of DEHP and MEHP. Propranolol was metabolized by the hepatocytes of both treated and untreated rats. Hepatocytes isolated from rats treated by phenobarbital, MEHP and DEHP were shown to have a higher speed constant of metabolism indicating a rapid metabolism of propranolol. Under these conditions, in fact, propranolol metabolisation was found to be respectively 6, 2.7, 2 times faster than the propranolol metabolisation of untreated rats. The hypothesis that DEHP and MEHP are enzymatic inducers, particularly cytochrome P450 (CYP) inducers of the xenobiotics metabolism on the intact liver after IP administration has become been found to be valid. The results obtained in this study confirm the value of isolated hepatocytes as an in vivo drug metabolism predictive model.

Evaluation of childhood exposure to di(2-ethylhexyl) phthalate from perfusion kits during long-term parenteral nutrition

Leachability of the plasticizer di(2-ethylhexyl) phthalate (DEHP) from administration sets into intravenous parenteral emulsions containing fat was investigated. DEHP is added to polyvinyl chloride (PVC) to impart flexibility. However, DEHP is a lipid-soluble suspected carcinogen that is hepatotoxic and teratogenic in rodents, and has been shown to leach from PVC products containing lipophilic mixtures. Consequently, total parenteral nutrition (TPN) mixtures containing fat emulsions should be stored in ethylvinyl acetate (EVA) bags rather than PVC packs. However, while TPN bags are made of EVA, they contain PVC-DEHP residues and the lines used between TPN bags and venous catheters are made of PVC-DEHP. The present study quantified the amount of DEHP leached from bags and tubing that could potentially contaminate patients during home TPN. Four types of emulsions containing fat were studied. Levels of DEHP in the bag and at the outlet tubing were measured by high-performance liquid chromatography (HPLC). This was measured during simulated TPN at different times after starting perfusion, 1 day after reconstitution of solutions in the bags, and 1 week later after storage at 4 degrees C. Detectable and stable amounts of DEHP were found to leach from bags (0.2 +/- 0.008 mg to 0.7 +/- 0.02 mg) and DEHP content increased in the outlet tubing (0.8 +/- 0.09 mg to 2 +/- 0.07 mg) during simulated infusions. The same phenomenon was observed after 1 week of storage at 4 degrees C. DEHP extraction by TPN depends on the lipid content of each TPN preparation and the flow rate. These results suggest that children treated with prolonged TPN are regularly exposed to significant amounts of DEHP.

Comparative study of the leachability of di(2-ethylhexyl) phthalate and tri(2-ethylhexyl) trimellitate from haemodialysis tubing

The leachability of both Di(2-ethylhexyl) phthalate (DEHP) and Tri(2-ethylhexyl) trimellitate (TEHTM) or Trioctyl trimellitate (TOTM) from haemodialysis tubing was investigated in 20 patients with chronic renal failure undergoing maintenance haemodialysis. The blood tubing made of common polyvinyl chloride (PVC) plasticized with DEHP (group 1 patients) were replaced with tubing plasticized with TOTM-DEHP (group 2 patients). The patient blood obtained from the inlet and the outlet of the dialyzer was analyzed during a 4 h-dialysis session. Thus, the circulating concentrations of both DEHP and TOTM resulting from the release from dialyzer tubes were estimated using High-performance Liquid chromatograph (HPLC). With the common PVC-DEHP blood tubing, a DEHP quantity of 122.95+/-33.94 mg was extracted from tubing during a single dialysis session (ranging from 55 to 166.21 mg). During the same period, the total amounts of DEHP retained by the patients were 27.30+/-9.22 mg (ranging from 12.50 to 42.72 mg). As for blood tubing plasticized with TOTM-DEHP, 41.80+/-4.47 mg of DEHP and 75.11+/-25.72 mg of TOTM were extracted. During the same period, the amounts of DEHP and TOTM retained by the patients were 3.42+/-1.37 mg and 4.87+/-2.60 mg, respectively. The extraction rate both plasticizers was correlated with serum lipid content (cholesterol+triglyceride) (r(2)=0.75 for DEHP and r(2)=0.64 for TOTM). In the present investigation, less TOTM and DEHP were apparently released from haemodialysis tubing plasticized with TOTM-DEHP than DEHP released from haemodialysis tubing plasticized with DEHP only. TOTM seems to be a superior alternative to DEHP for use in medical devices because of its potential lower leachability. To recommend it as an alternative plasticizer, its possible toxicity towards human body should be investigated before it can be used routinely. However, patients undergoing haemodialysis using tubing plasticized with DEHP only are regularly exposed to non negligible amounts of DEHP. In view of several biological effects previously reported, it is time to reconsider the use of DEHP only as a plasticizer.

Blood tubing and cytokine production: effect of sterilization

Blood tubings commonly represent an integral component of hemodialysis circuits. Different factors may influence their biocompatibility, such as the type of material, the sterilization mode and the geometry. In vivo the final biocompatibility may be further complicated by the individual host response, the flow parameters, and the impact of mechanical trauma on blood's cellular components (i.e. erythrocytes). In this in vitro study we evaluated some commercially available blood tubings sterilized by different methods as to their interaction with normal leukocyte population and tested the response of these cells in terms of cytokines (IL-1beta, IL-1Ra, TNF-alpha). As a positive control, leukocytes were incubated with 0.5 ng/mL of bacterial lipopolysaccharide (LPS) or with Cuprophan of comparable surface. The results showed that cytokine production was markedly reduced, particularly in the case of gamma-ray-sterilized tubings. Of interest, it was not always related to the adherence. However in some cases, particularly of gamma-ray sterilization, adherence was none, despite the cytokine production.

Exposure of hemodialysis patients to di-2-ethylhexyl phthalate

The migration of di-2-ethylhexyl phthalate (DEHP) from dialyzers was studied in 21 patients with chronic renal failure undergoing maintenance hemodialysis. The circulating concentrations of DEHP were measured by high performance liquid chromatography in blood of patients obtained from the inlet and the outlet of the dialyzer during a 4-h dialysis session. During treatment of renal failure using plasticized tubing, the plasma level of DEHP increased. On average, an estimated 75.2 mg of DEHP was extracted from the dialyzer during a single dialysis session, with a range of 44.3-197. 1 mg. On the other hand, the total amount of DEHP retained by the patient during the dialysis session was evaluated by the difference between the AUCout and the AUCin and ranged from 3.6 to 59.6 mg. The rate of extraction of DEHP from the dialyzer was correlated (r=0.705, P<0.05) with serum lipid content (cholesterol and triglyceride).So, we confirmed that patients on hemodialysis are always regularly exposed to considerable amounts of DEHP. However, several metabolic effects have been reported in various animal species following treatment with DEHP, such as changes in lipid metabolism and in hepatic microsomal drug-metabolizing enzyme activities. DEHP is now a well-known hepatic peroxisomal proliferator in rodents and an inducer of many peroxisomal and non-peroxisomal enzymes. So, lipid metabolism modifications and hepatic changes observed in hemodialysis patients could be explained from chronic exposition to DEHP. In the coming years, it seems necessary to reconsider the use of DEHP as a plasticizer in medical devices. Highly unacceptable amounts of DEHP leached during the dialysis session could be easily avoided by careful selection of hemodialysis tubing.

Hepatocarcinogenic potential of di(2-ethylhexyl)phthalate in rodents and its implications on human risk

The plasticizer di(2-ethylhexyl) phthalate (DEHP), to which humans are extensively exposed, was found to be hepatocarcinogenic in rats and mice. DEHP is potentially set free from objects made of synthetic materials (e.g., those used in medicine). Chronically, the greatest amounts are transferred to persons undergoing hemodialysis (up to 3.1 mg/kg b.w. per day) who would thus be considered the individuals most endangered by tumorigenesis. Although toxicokinetics seem to play a certain unclear role in the course of DEHP-related toxicity, toxicodynamic factors appear more decisive. DEHP is a representative of "peroxisome proliferators" (PP), a distinct group of substances that, in rodents, do not only induce peroxisomes but also specific enzymes in other organelles, organ growth, and DNA synthesis. The cluster of the characteristic effects of PP is generally, although perhaps not quite appropriately summarized as "peroxisome proliferation," and is strongest in the liver. The lowest observed effect level (LOEL) and the no observed effect level (NOEL) of peroxisome proliferation in the rat, as determined by the induction of specific enzymes (peroxisomal beta-oxidation, carnitine-acetyl-transferase, cytochrome P-452), DNA synthesis, and hepatomegaly, may be assumed as 50 and 25 mg/kg b.w. per day, respectively. DEHP and other carcinogenic PP are neither genotoxic nor tumor initiators, but they appear to be tumor promoters, also implicating a threshold level for the carcinogenic effect. Although a causal relationship between a particular effect of peroxisome proliferation and hepatocarcinogenesis is as yet unknown, peroxisome proliferation as a whole phenomenon appears to be associated with the potential of tumor induction, as shown by comparison of the relative strength of individual PP and by comparison of species and organ specificities. Likewise, LOEL and NOEL of rodent carcinogenesis, that is, 300 and 50 to 100 mg/kg b.w. per day, respectively, are above but not too far from the corresponding values for the investigated parameters of peroxisome proliferation. Thus, with respect to dose alone, worst-case exposure in hemodialysis patients is at least 16-fold below the LOEL of any characterized PP-specific effect of DEHP and approximately 100-fold below that of DEHP-related tumorigenesis. Also, primates are less responsive to PP than rats with respect to the investigated biochemical and morphological parameters. If this lower primate responsiveness is extrapolated to estimate carcinogenicity in humans, we might thus arrive at an even larger safety margin than when based on exposure alone. Doses of PP hypolipidemics that had clearly induced several indicators of peroxisome proliferation in rats did not cause any clear-cut enhancements in the peroxisomes of patients, even though most of these hypolipidemics were considerably stronger PP than DEHP. Thus, an actual threat to humans by DEHP seems rather unlikely. Accordingly, hepatocarcinogenesis was neither enhanced in workers exposed to DEHP nor in patients treated with hypolipidemics.

Human sperm motility is affected by plasticizers and diesel particle extracts

In order to test various drugs and possibly hazardous compounds on living cells in vitro a system with human spermatozoa was employed. A population of human spermatozoa was transferred into a defined medium by a swim-up procedure or by separation on a Percoll gradient. Such a population is rather homogenous with respect to motility characteristics and was found to be useful for this purpose. Different modes of response were recorded, indicating various effect mechanisms. Effects of various phthalates used as plastic softeners in the production of medical equipment, and extracts from diesel particulate material were recorded. All these compounds interfered with sperm motility in a dose-response fashion. Immediate effects of phthalates were modest, but upon prolonged exposure effects became more evident. Sperm motility was more affected by diethyl-hexyl and dibutyl phthalates. Significant effects were noted for the different phthalates with regard both to percent motility and to some of the various qualities of motility, such as velocity, linearity and amplitude of the track. Thus, the pattern of response considering the motion variables was not the same with the different phthalates. With regard to the effects on sperm motion di-n-octyl phthalate seemed to be the least toxic, followed by dibutyl phthalate. The initial effects of diesel particulate extracts were moderate and mainly restricted to percent motile sperm but upon exposure for 18 hr the effects became more pronounced for all the movement variables.