Synthesis of DEHP metabolites as biomarkers for GC-MS evaluation of phthalates as endocrine disrupters

Phthalates are used primarily as plasticizers to make polyvinyl chloride (PVC) soft and flexible. In recent years the phthalate esters have attracted increasing attention as environmental and biomedical pollutants and, because of their toxicological characteristics. In particular, they are more and more recognized as endocrine disrupters. In this context, we describe herein an efficient synthetic pathway leading to a series of metabolites of di(2-ethylhexyl) phthalate (DEHP). Mono(2-ethylhexenyl) phthalate was used as starting material to obtain these products in good yield, large scale and GC-MS purity. The metabolites of DEHP were synthesized, for the first time, as biomarkers to verify their quantitative determination in human urine and serum by GC-MS analysis for studying the exposure to phthalates and establishing reference values.     

Release of diethyl-2-hexyl phthalate from stored blood on contact with polyvinyl chloride

Softness and flexibility of PVC are due to the addition of plasticizers in high concentration; the most used of them for blood storage bags is DEHP. In this work, a method for labelling DEHP with 14C from 14C phtalic anhydrid is given. A piece of PVC from a commercial blood bag is labelled, in our laboratory, with 14C DEHP and used to follow the kinetics of DEHP leaching in blood during storage. It is also used to study the influence of some parameters such as lipids amount of blood, shaking, and plastic sterilisation on this leaching. DEHP leaching is a three steps phenomenon and the level is not correlated to lipids content of blood. Thermal treatment of PVC and shaking have an influence on leaching. DEHP is not metabolised during blood storage at 4 degrees C and can not be detected as free molecule; it is absorbed on plasmatic proteins.     

Phthalates Are Metabolised by Primary Thyroid Cell Cultures but Have Limited Influence on Selected Thyroid Cell Functions In Vitro

Phthalates are plasticisers added to a wide variety of products, resulting in measurable exposure of humans. They are suspected to disrupt the thyroid axis as epidemiological studies suggest an influence on the peripheral thyroid hormone concentration. The mechanism is still unknown as only few in vitro studies within this area exist. The aim of the present study was to investigate the influence of three phthalate diesters (di-ethyl phthalate, di-n-butyl phthalate (DnBP), di-(2-ethylhexyl) phthalate (DEHP)) and two monoesters (mono-n-butyl phthalate and mono-(2-ethylhexyl) phthalate (MEHP)) on the differentiated function of primary human thyroid cell cultures. Also, the kinetics of phthalate metabolism were investigated. DEHP and its monoester, MEHP, both had an inhibitory influence on 3''-5''-cyclic adenosine monophosphate secretion from the cells, and MEHP also on thyroglobulin (Tg) secretion from the cells. Results of the lactate dehydrogenase-measurements indicated that the MEHP-mediated influence was caused by cell death. No influence on gene expression of thyroid specific genes (Tg, thyroid peroxidase, sodium iodine symporter and thyroid stimulating hormone receptor) by any of the investigated diesters could be demonstrated. All phthalate diesters were metabolised to the respective monoester, however with a fall in efficiency for high concentrations of the larger diesters DnBP and DEHP. In conclusion, human thyroid cells were able to metabolise phthalates but this phthalate-exposure did not appear to substantially influence selected functions of these cells.     

Children’s Phthalate Intakes and Resultant Cumulative Exposures Estimated from Urine Compared with Estimates from Dust Ingestion,Inhalation and Dermal Absorption in Their Homes and Daycare Centers

Total daily intakes of diethyl phthalate (DEP), di(n-butyl) phthalate (DnBP), di(isobutyl) phthalate (DiBP), butyl benzyl phthalate (BBzP) and di(2-ethylhexyl) phthalate (DEHP) were calculated from phthalate metabolite levels measured in the urine of 431 Danish children between 3 and 6 years of age. For each child the intake attributable to exposures in the indoor environment via dust ingestion, inhalation and dermal absorption were estimated from the phthalate levels in the dust collected from the child’s home and daycare center. Based on the urine samples, DEHP had the highest total daily intake (median: 4.42 µg/d/kg-bw) and BBzP the lowest (median: 0.49 µg/d/kg-bw). For DEP, DnBP and DiBP, exposures to air and dust in the indoor environment accounted for approximately 100%, 15% and 50% of the total intake, respectively, with dermal absorption from the gas-phase being the major exposure pathway. More than 90% of the total intake of BBzP and DEHP came from sources other than indoor air and dust. Daily intake of DnBP and DiBP from all exposure pathways, based on levels of metabolites in urine samples, exceeded the Tolerable Daily Intake (TDI) for 22 and 23 children, respectively. Indoor exposures resulted in an average daily DiBP intake that exceeded the TDI for 14 children. Using the concept of relative cumulative Tolerable Daily Intake (TDI_cum), which is applicable for phthalates that have established TDIs based on the same health endpoint, we examined the cumulative total exposure to DnBP, DiBP and DEHP from all pathways; it exceeded the tolerable levels for 30% of the children. From the three indoor pathways alone, several children had a cumulative intake that exceeded TDI_cum. Exposures to phthalates present in the air and dust indoors meaningfully contribute to a child’s total intake of certain phthalates. Such exposures, by themselves, may lead to intakes exceeding current limit values.     

On-line clean-up by multidimensional liquid chromatography-electrospray ionization tandem mass spectrometry for high throughput quantification of primary and secondary phthalate metabolites in human urine

We developed a new and fast multidimensional on-line HPLC-method for the quantitative determination of the secondary, chain oxidized monoester metabolites of diethylhexylphthalate (DEHP), 5-hydroxy-mono-(2-ethylhexyl)-phthalate (5OH-MEHP) and 5-oxo-mono-(2-ethylhexyl)-phthalate (5oxo-MEHP) in urine samples from the general population. Also included in the method were the simple monoester metabolites of DEHP, dioctylphthalate (DOP), dibutylphthalate (DBP), butylbenzylphthalate (BBzP) and diethylphthalate (DEP). Except for enzymatic hydrolysis for deconjugation of the metabolites no further sample pre-treatment step is necessary. The phthalate metabolites are stripped from urinary matrix by on-line extraction on a restricted access material (LiChrospher((R)) ADS-8) precolumn, transferred in backflush-mode and chromatographically resolved by reversed-phase HPLC. Eluting metabolites are detected by ESI-tandem mass spectrometry in negative ionization mode and quantified by isotope dilution. Within a total run time of 25 min we can selectively and sensitively quantify seven urinary metabolites of six commonly occurring phthalate diesters including the controversial di(2-ethylhexyl)phthalate (DEHP). The detection limits for all analytes are in the low ppb range (0.5-2.0 microgram/l urine). First results on a small non-exposed group (n=8) ranged for 5OH-MEHP from 0.59 to 124 microgram/l, for 5oxo-MEHP from 相似文献   

Differential effects of phthalates on the testis and the liver

Phthalates have been shown to elicit contrasting effects on the testis and the liver, causing testicular degeneration and promoting abnormal hepatocyte proliferation and carcinogenesis. In the present study, we compared the effects of phthalates on testicular and liver cells to better understand the mechanisms by which phthalates cause testicular degeneration. In vivo treatment of rats with di-(2-ethylhexyl) phthalate (DEHP) caused a threefold increase of germ cell apoptosis in the testis, whereas apoptosis was not changed significantly in livers from the same animals. Western blot analyses revealed that peroxisome proliferator-activated receptor (PPAR) alpha is equally abundant in the liver and the testis, whereas PPAR gamma and retinoic acid receptor (RAR) alpha are expressed more in the testis. To determine whether the principal metabolite of DEHP, mono-(2-ethylhexyl) phthalate (MEHP), or a strong peroxisome proliferator, 4-chloro-6(2,3-xylindino)-2-pyrimidinylthioacetic acid (Wy-14,643), have a differential effect in Sertoli and liver cells by altering the function of RAR alpha and PPARs, their nuclear trafficking patterns were compared in Sertoli and liver cells after treatment. Both MEHP and Wy-14,643 increased the nuclear localization of PPAR alpha and PPAR gamma in Sertoli cells, but they decreased the nuclear localization of RAR alpha, as previously shown. Both PPAR alpha and PPAR gamma were in the nucleus and cytoplasm of liver cells, but RAR alpha was predominant in the cytoplasm, regardless of the treatment. At the molecular level, MEHP and Wy-14,643 reduced the amount of phosphorylated mitogen-activated protein kinase (activated MAPK) in Sertoli cells. In comparison, both MEHP and Wy-14,643 increased phosphorylated MAPK in liver cells. These results suggest that phthalates may cause contrasting effects on the testis and the liver by differential activation of the MAPK pathway, RAR alpha, PPAR alpha, and PPAR gamma in these organs.     

Phthalates Biomarker Identification and Exposure Estimates in a Population of Pregnant Women

Phthalates are known reproductive and developmental toxicants in experimental animals. However, in humans, there are few data on the exposure of pregnant women that can be used to assess the potential developmental exposure experienced by the fetus. We measured several phthalate metabolites in maternal urine, maternal serum, and cord serum samples collected at the time of delivery from 150 pregnant women from central New Jersey. The urinary concentrations of most metabolites were comparable to or less than among the U.S. general population, except for mono(2-ethylhexyl) phthalate (MEHP), mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), three metabolites of di(2-ethylhexyl) phthalate (DEHP). The median urinary concentrations of MEHHP (109 μ g/l) and MEOHP (95.1 μ g/l) were more than 5 times their population-based concentrations, whereas the median urinary concentration of MEHP was more than 20 times higher. High concentration of MEHP may indicate a recent exposure to the parent chemical DEHP in the hospital shortly before the collection of the samples. Calculation of daily intakes using the urinary biomarker data reveals that none of the pregnant women tested had integrated exposures to DEHP greater than the Agency for Toxic Substances and Disease Registry's minimal risk levels (MRLs chronic 60, intermediate 100 μ g/kg/day). No abnormal birth outcomes (e.g., birth weight, Apgar Score, and gestational age) were noted in those newborns whose mothers had relatively greater exposure to DEHP during the perinatal period than others in this study. Significantly greater concentrations and detection frequencies in maternal urine than in maternal serum and cord serum suggest that the urinary concentrations of the phthalate metabolites may be more reliable biomarkers of exposure than their concentrations in other biological specimens.     

Degradation of bis(2-ethylhexyl) phthalate constituents under methanogenic conditions

The degradation of bis(2-ethylhexyl) phthalate (DEHP) and its intermediary hydrolysis products 2-ethylhexanol (2-EH) and mono(2-ethylhexyl) phthalate (MEHP) was investigated in a methanogenic phthalic acid ester-degrading enrichment culture at 37°C. 2-Ethylhexanoic acid (2-EHA), a plausible degradation product of 2-EH, was also studied. The culture readily degraded 2-EH via 2-EHA to methane which was formed in stoichiometric amounts assuming complete degradation of 2-EH to methane and carbon dioxide. MEHP was degraded to stoichiometric amounts of methane with phthalic acid as a transient intermediate. DEHP remained unaffected throughout the experimental period (330 days).Abbreviations 2-EH 2-ethylhexyl alcohol - 2-EHA 2-ethylhexanoic acid - BBP butylbenzyl phthalate - Be-CoA benzoyl Coenzyme A - CoA Coenzyme A - DEHP bis(2-ethylhexyl) phthalate - MEHP mono(2-ethylhexyl) phthalate - MSW municipal solid waste - PA phthalic acid - PAE phthalic acid ester - TMS trimethylsilyl derivative     

Thrombocyte storage in plasma. Preparation and storage of thrombocyte concentrates in polyvinyl chloride PL 146 standard bags

Platelet concentrates (PC) were prepared from CPD-blood using PL-146 triple bag system (Fenwal). They were stored in 60 ml plasma at room temperature for 72 h with gentle agitation by side-over-side rotation with 2 rpm. PC contained on average more than 0.55.10(11) platelets form 450 ml blood. There were significant correlations between pH-values and platelet number as well as percentage of disc-shaped platelets. pH-values, number of platelets and morphology were well maintained in all PC, but 4 of 18 had pH-values below 6.0 after 72 h. This means that 95% of the stored PC had sufficient quality after 48 h and only 78% had it after 72 h.     

Determination of di(2-ethylhexyl)phthalate and mono(2-ethylhexyl)phthalate in human serum using liquid chromatography-tandem mass spectrometry

Concentrations of mono(2-ethylhexyl)phthalate (MEHP), and di(2-ethylhexyl)phthalate (DEHP), in serum of healthy volunteers were determined by high performance liquid chromatography (HPLC) with tandem mass spectrometry (LC/MS/MS). The serum was extracted with acetone, followed by hexane extraction under acidic conditions, and then applied to the LC/MS/MS. Recoveries of 20 ng/ml of MEHP and DEHP were 101+/-5.7 (n=6) and 102+/-6.5% (n=6), respectively. The limits of quantification (LOQ) of MEHP and DEHP in the method were 5.0 and 14.0 ng/ml, respectively. The concentration of MEHP in the serum was at or less than the LOQ. The concentration of DEHP in the serum was less than the LOQ. Contaminations of MEHP and DEHP from experimental reagents, apparatus and air during the procedure were less than the LOQ and were estimated to be <1.0 and 2.2+/-0.6 ng/ml, respectively. After subtraction of the contamination, the net concentrations of MEHP and DEHP in the serum were estimated at or <5 and <2 ng/ml, respectively. To decrease contamination by DEHP, the cleanup steps and the apparatus and solvent usage were minimized in the sample preparation procedures. The high selectivity of LC/MS/MS is the key for obtaining reliable experimental data from in the matrix-rich analytical samples and for maintaining a low level contamination of MEHP and DEHP in this experimental system. This method would be a useful tool for the detection of MEHP and DEHP in serum.     

Biodegradation of an endocrine-disrupting chemical, di-2-ethylhexyl phthalate, by Bacillus subtilis No. 66

A bacterial strain capable of rapidly degrading di-2-ethylhexyl phthalate (DEHP) was isolated from soil and identified as Bacillus subtilis. The organism also utilized di-butyl phthalate, di-ethyl phthalate, di-pentyl phthalate, di-propyl phthalate, and phthalic acid as sole carbon sources; and their biodegradation ratio was over 99%, when the incubation was performed for 5 days at 30°C. The microorganism degraded di-2-ethylhexyl phthalate and di-butyl phthalate through the intermediate formation of mono-2-ethylhexyl phthalate and mono-butyl phthalate, which were then metabolized to phthalic acid and further by a protocatechuate pathway, as evidenced by oxygen uptake studies and GC-MS analysis. The decontamination of soil polluted with di-2-ethylhexyl phthalate by B. subtilis was investigated. Experimental results showed that the strain could degrade about 80% of 5 mM DEHP simply by adding 8% culture medium to soil, indicating that the degradation can occur even when other organisms are present.     

Serum Phthalate Levels and Time to Pregnancy in Couples from Greenland,Poland and Ukraine

Phthalates are ubiquitous industrial chemicals that have been associated with altered reproductive function in rodents. Several human studies have reported an inverse association between male testosterone and phthalate levels. Our aim was to investigate time to pregnancy (TTP) according to serum levels of diethylhexyl phthalate (DEHP) and diisononyl phthalate (DiNP) metabolites in both partners. In 2002-2004 we enrolled 938 pregnant women and 401 male spouses from Greenland, Poland and Ukraine. Six oxidized metabolites of DEHP and DiNP were summarized for each of the two parent compounds to provide proxies of the internal exposure. We used Cox discrete-time models to estimate fecundability ratios (FR) and 95% confidence intervals (95% CIs) for men and women according to their proxy-DEHP or -DiNP serum levels adjusted for a fixed set of covariates.The FR was slightly elevated among women with high levels of DEHP (FR=1.14, 95% CI 1.00;1.30) suggesting a shorter TTP in these women. The FR was unrelated to DiNP in women, whereas the results for men were inconsistent pointing in opposite directions. First-time pregnant women from Greenland with high serum DiNP levels had a longer TTP. This study spanning large contrast in environmental exposure does not indicate adverse effects of phthalates on couple fecundity. The shorter TTP in women with high levels of DEHP metabolites is unexplained and needs further investigation.     

Structure-dependent inhibition of human and rat 11β-hydroxysteroid dehydrogenase 2 activities by phthalates

Phthalates are diesters of phthalic acid and an alcohol moiety. Phthalates have been classified as endocrine disruptors and have a broad range of effects with unknown mechanisms. Some of the effects of phthalate are consistent with disruptions of normal glucocorticoid homeostasis, and in particular, with defective function of 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2). In the present study, we tested 12 phthalate diesters and four monoesters for the inhibition of human and rat kidney 11β-HSD2. We examined the modes of inhibition and looked for a relationship between the potency for inhibition and the chemical structures. Of the phthalate diesters we tested, dipropyl phthalate (DPrP) and di-n-butyl phthalate (DBP) significantly inhibited both human and rat 11β-HSD2 activities. The IC₅₀s were 85.59 μM for DPrP and 13.69 μM for DBP when calculated for rat 11β-HSD2. As diesters, 8 of the phthalates did not affect 11β-HSD2 enzyme activity. Compared to the diesters that were inhibitory, the 8 non-inhibitory phthalates, had either fewer carbons, that is 1 or 2 carbons in the alcohol moiety, or more carbons, 5–10, as a branched or unbranched chain in the alcohol moeity. However, phthalates could be inhibitors with six carbons in the alcohol moiety if the carbons were cyclized, as in dicyclohexyl phthalate (DCHP), which inhibited rat 11β-HSD2 with an IC₅₀ of 32.64 μM. Thus, whether a phthalate is an inhibitor may reflect the size and shape of the compound. Although the diesters are the compounds used in manufacturing and present as environmental contaminants, it is the monoester metabolites that are detected in human serum and urine. We showed that mono (2-ethylhexyl) phthalate (MEHP) significantly inhibited human (IC₅₀ = 110.8 ± 10.9) and rat (121.8 ± 8.5 μM) 11β-HSD2 activity even though its parent compound, di(2-ethylhexyl) phthalate (DEHP) did not. MEHP was a competitive inhibitor of 11β-HSD2 enzymatic activity. We conclude that phthalates of a certain size act as competitive inhibitors.     

Effects of early pubertal exposure to di-(2-ethylhexyl) phthalate on social behavior of mice

Di-(2-ethylhexyl) phthalate (DEHP), a main member of phthalates used as plasticizer in PVC plastics, is an environmental endocrine disrupter. The present study investigated the effect of DEHP on social behavior of mice following pubertal exposure (1, 10, 50, and 200 mg/kg/d) from postnatal day 28 through postnatal day 42. The results showed that, in pubertal females, DEHP reduced the time spent in social play and social investigation and inhibited sociability, but a contrary effect was found in pubertal males, suggesting that the effect of DEHP on pubertal social behavior displays sex differences. In adults, DEHP reduced sociability in females and inhibited social play and social investigation in males, suggesting that early pubertal exposure to DEHP not only plays a significant role in puberty but also alters social behavior in adults. In addition, the present study showed that the higher dose of DEHP (50, 200 mg/kg/d) reduced the relative weight of bilateral testis and anogenital distance of pubertal or adult males, suggesting an anti-androgenic activity of DEHP. These results suggest that early pubertal exposure to DEHP sex- and age- specifically affected the social behaviors of pubertal and even adult mice.     

Docking study: PPARs interaction with the selected alternative plasticizers to di(2-ethylhexyl) phthalate

Phthalates, used in medical devices (MDs), have been identified as reproductive and developmental toxicants. Their toxicity varies somewhat depending on the specific phthalate and is in part linked to the activation of Peroxisome Proliferating-Activated Receptors (PPARs). So, the use of MDs containing targeted phthalates such as di(2-ethylhexyl) phthalate (DEHP) has been challenged by European directive 2007/47/EC. Therefore, MDs manufacturers were forced to quickly find replacement plasticizers. However, very little toxicological and epidemiological studies are available on human health. So, we proceeded to dock these chemicals in order to identify compounds that are likely to interact with PPARs binding sites. The results obtained are generally very mixed on the harmlessness of these alternatives. Moreover, no data exist on the biological effects of their possible metabolites. As DEHP toxicity resulted mainly from its major metabolites, generalizing the use of these plasticizers without conducting extensive studies on the possible effects on human health of their metabolites seems inconceivable.     

Toxicogenomic Screening of Replacements for Di(2-Ethylhexyl) Phthalate (DEHP) Using the Immortalized TM4 Sertoli Cell Line

Phthalate plasticizers such as di(2-ethylhexyl) phthalate (DEHP) are being phased out of many consumer products because of their endocrine disrupting properties and their ubiquitous presence in the environment. The concerns raised from the use of phthalates have prompted consumers, government, and industry to find alternative plasticizers that are safe, biodegradable, and have the versatility for multiple commercial applications. We examined the toxicogenomic profile of mono(2-ethylhexyl) phthalate (MEHP, the active metabolite of DEHP), the commercial plasticizer diisononyl cyclohexane-1,2-dicarboxylate (DINCH), and three recently proposed plasticizers: 1,4-butanediol dibenzoate (BDB), dioctyl succinate (DOS), and dioctyl maleate (DOM), using the immortalized TM4 Sertoli cell line. Results of gene expression studies revealed that DOS and BDB clustered with control samples while MEHP, DINCH and DOM were distributed far away from the control-DOS-BDB cluster, as determined by principle component analysis. While no significant changes in gene expression were found after treatment with BDB and DOS, treatment with MEHP, DINCH and DOM resulted in many differentially expressed genes. MEHP upregulated genes downstream of PPAR and targeted pathways of cholesterol biosynthesis without modulating the expression of PPAR’s themselves. DOM upregulated genes involved in glutathione stress response, DNA repair, and cholesterol biosynthesis. Treatment with DINCH resulted in altered expression of a large number of genes involved in major signal transduction pathways including ERK/MAPK and Rho signalling. These data suggest DOS and BDB may be safer alternatives to DEHP/MEHP than DOM or the commercial alternative DINCH.     

Sex Steroid Hormone Levels and Reproductive Development of Eight-Year-Old Children following In Utero and Environmental Exposure to Phthalates

In utero exposure to phthalates may adversely affect reproductive development in children due to the anti-androgenic properties of the pthalates. Accordingly, we aimed to determine the effects of in utero and environmental phthalate exposure on the reproductive development of eight-year-old children. We recruited 180 children in central Taiwan during November 2001 and followed them until August 2009 when all children became eight years old. Birth outcomes were collected. Bone age, hormone concentrations, and reproductive developmental stages were determined. Phthalate metabolite levels, including mono-2-ethylhexyl phthalate [MEHP], mono-n-butyl phthalate [MnBP], and mono-benzyl phthalate [MBzP], were assessed. No significant gender differences were found in in utero phthalate exposure. Maternal urinary levels of phthalate metabolites did not correlate significantly with birth outcomes, physical characteristics, and reproductive hormones of the eight-year-old children. Regarding the urinary phthalate metabolite levels of the eight-year-old children, MEHP correlated significantly with serum progesterone levels. MEHP levels in girls correlated significantly with serum progesterone levels. MnBP correlated significantly with serum FSH in all children. In girls, MnBP correlated with serum FSH, and MBzP correlated with serum progesterone and FSH levels. Urinary phthalate metabolite levels did not correlate with female developmental stages or the development of female reproductive organs. Phthalate metabolites did not correlate with the physical characteristics and reproductive hormones in boys. Therefore, environmental exposure to phthalates, as determined by urinary phthalate metabolite levels of eight-year-old children, may affect reproductive hormone levels in children, indicating that further studies on the environmental health effects of phthalates are warranted.     

Anaerobic degradation of phthalic acid esters during digestion of municipal solid waste under landfilling conditions

Anaerobic microorganisms in municipal solid waste samples from laboratory-scale landfill reactors and a pilot-plant biogas digestor were investigated with the aim of assessing their ability to transform four commercially used phthalic acid esters (PAEs) and phthalic acid (PA). The PAEs studied were diethyl phthalate (DEP), butylbenzyl phthalate (BBP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). No biological transformation of DEHP could be detected in any of the experiments. Together with waste samples from the simulated landfilling conditions, the PAEs (except DEHP) were hydrolytically transformed to their corresponding monoesters. These accumulated as end products, and in most cases they were not further degraded. During incubation with waste from the biogas digestor, the PAEs (except DEHP) were completely degraded to methane and carbon dioxide. The influence of the landfill development phase on the transformations was investigated utilizing PA and DEP as model substances. We found that during both the intense and stable methanogenic (but not the acidogenic) phases, the microoganisms in the samples had the potential to transform PA. A shorter lag phase was observed for the PA transformation in the samples from the stable methanogenic phase as compared with earlier phases. This indicates an increased capacity to degrade PA during the aging phases of the municipal solid waste in landfills. No enhancement of the DEP transformation could be observed as conditions in the methanogenic landfill model changed over a year's time. The results indicate that microorganisms developing in a methanogenic landfill environment have a substantially lower potential to degrade PAEs compared with those developing in a biogas reactor.Abbreviations BBP butylbenzyl phthalate - DEHP bis(2-ethylhexyl) phthalate - CoA coenzyme A - DBP dibutyl phthalate - DEP diethyl phthalate - DS dry solids - MBeP monobenzyl phthalate - MBuP monobutyl phthalate - MEP monoethyl phthalate - MSW municipal solid waste - PA phthalic acid - PAE(s) phthalic acid ester(s) - VFA volatile fatty acids     

Genotoxicity studies of di(2-ethylhexyl)phthalate and its metabolites in CHO cells

The widely used plasticizer di(2-ethylhexyl)phthalate (DEHP), its hydrolysis products mono(2-ethylhexyl)phthalate (MEHP) and 2-ethylhexanol, and also phthalic acid have been tested for clastogenic activity in cultured Chinese hamster ovary (CHO) cells. Only MEHP was found to cause chromosome damage. MEHP was without effect in the SCE and HGPRT mutation test in CHO cells. The clastogenicity of MEHP suggests a role for this compound in the observed carcinogenicity of DEHP and its positive effect in the dominant lethal assay.     

Morphological transformation and catalase activity of syrian hamster embryo cells treated with hepatic peroxisome proliferators,TPA and nickel sulphate

The abilities of the hepatic peroxisome proliferators (HPPs) clofibrate, di(2-ethylhexyl)phthalate (DEHP), mono(2-ethylhexyl)- phthalate (MEHP), 2,4-dichlorophenoxy acetic acid (2,4-D), 2,4,5-trichlorophenoxy acetic acid (2,4,5-T) and tiadenol to induce morphological transformation and to increase the catalase activity of Syrian hamster embryo (SHE) cells were studied. DEHP, MEHP, clofibrate and tiadenol induced morphological transformation of SHE cells and increased the catalase activity. DEHP was more potent than clofibrate and tiadenol in both inducing catalase and morphological transformation, while MEHP seemed more potent than DEHP in inducing catalase, but not morphological transformation, 2,4,5-T and 2,4-D did not induce morphological transformation, but 2,4,5-T was more potent than clofibrate in increasing the catalase activity. These results show that several HPPs induce morphological transformation of SHE cells and an increase in the catalase activity. There is, however, no direct connection between these two parameters, as seen from the results of 2,4,5-T. The tumor promoter TPA, and the metal salt nickel sulphate, induced morphological transformation of SHE cells without any appreciable increase in the catalase activity. These results further corroborate the dissociation between induction of morphological transformation and the increase in catalase activity.Abbreviations Clofibrate ethyl-2-(p-chlorophenox) isobutyrate - 2,4-D 2,4-dichlorophenoxy acetic acid - DEHP di(2-ethylhexyl)phthalate - HPP hepatic peroxisome proliferator - MEHP mono(2-ethylhexyl)phthalate - SHE Syrian hamster embryo - 2,4,5-T 2,4,5-trichlorophenoxy acetic acid - tiadenol di(hydroxyethylthio)-1,10-decane