Concentrations Of Diethyl Phthalate Research Articles

Urinary Phthalate Metabolite Concentrations among Workers in Selected Industries: A Pilot Biomonitoring Study

Phthalates are used as plasticizers and solvents in industrial, medical and consumer products; however, occupational exposure information is limited. We sought to obtain preliminary information on occupational exposures to diethyl phthalate (DEP), di-n-butyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) by analyzing for their metabolites in urine samples collected from workers in a cross-section of industries. We also obtained data on metabolites of dimethyl phthalate (DMP), benzylbutyl phthalate (BzBP), di-isobutyl phthalate and di-isononyl phthalate. We recruited 156 workers in 2003-2005 from eight industry sectors. We assessed occupational contribution by comparing end-shift metabolite concentrations to the US general population. Evidence of occupational exposure to DEHP was strongest in polyvinyl chloride (PVC) film manufacturing, PVC compounding and rubber boot manufacturing where geometric mean (GM) end-shift concentrations of DEHP metabolites exceeded general population levels by 8-, 6- and 3-fold, respectively. Occupational exposure to DBP was most evident in rubber gasket, phthalate (raw material) and rubber hose manufacturing, with DBP metabolite concentrations exceeding general population levels by 26-, 25- and 10-fold, respectively, whereas DBP exposure in nail-only salons (manicurists) was only 2-fold higher than in the general population. Concentrations of DEP and DMP metabolites in phthalate manufacturing exceeded general population levels by 4- and >1000-fold, respectively. We also found instances where GM end-shift concentrations of some metabolites exceeded general population concentrations even when no workplace use was reported, e.g. BzBP in rubber hose and rubber boot manufacturing. In summary, using urinary metabolites, we successfully identified workplaces with likely occupational phthalate exposure. Additional work is needed to distinguish occupational from non-occupational sources in low-exposure workplaces.

Advanced H2O2 oxidation for diethyl phthalate degradation in treated effluents: effect of nitrate on oxidation and a pilot-scale AOP operation

One of the objectives of this study was to delineate the effect of nitrate on diethyl phthalate (DEP) oxidation by conducting a bench-scale ultraviolet (UV)/H2O2 and O3/H2O2 operations as suggested in a previous study. We also aim to investigate DEP oxidation at various UV doses and H2O2 concentrations by performing a pilot-scale advanced oxidation processes (AOP) system, into which a portion of the effluent from a pilot-scale membrane bioreactor (MBR) plant was pumped. In the bench-scale AOP operation, the O3 oxidation alone as well as the UV irradiation without H2O2 addition could be among the desirable alternatives for the efficient removal of DEP dissolved in aqueous solutions at a low DEP concentration range of 85+/-15 microg/L. The adverse effect in the UV/H2O2 process was significantly greater than that in the UV oxidation alone, and its oxidation was almost halved by the nitrate. However, the nitrate clearly enhanced the DEP oxidation in the O3 oxidation and O3/H2O2 process. Especially, the addition of nitrate almost doubled the DEP oxidation efficiency in the O3/H2O2 process. The series of pilot-scale AOP operations confirmed that about 30-50% of DEP dissolved in the treated MBR effluent streams was, at least, oxidized by the O3 oxidation alone as well as the UV irradiation without H2O2 addition. The UV photolysis of H2O2 was most effective for DEP degradation with an H2O2 concentration of 40 mg/L at a UV dose of 500 mJ/cm2.

Physisorption and Desorption of Diethyl Phthalate and Isopropanol on a Silicon Surface

Physisorption and desorption of organic compounds on a silicon surface in a two-component system consisting of isopropanol (IPA) and diethyl phthalate (DEP) were measured in situ by means of a quartz crystal microbalance and were analyzed based on the rate theory. The surface concentration in a steady state changed corresponding to the gas-phase concentrations of IPA and DEP. The measured surface concentration in a steady state was reproduced by calculation taking into account the larger limit of surface concentration which depended on the rate parameters of the organic compounds. The area occupied by the organic molecules, estimated in this study, indicated that the interaction between DEP molecules and IPA molecules on silicon surface was quite small in a two-component IPA-DEP system.

Diethyl phthalate in compost: Ecotoxicological effects and response of the microbial community

There is a great need to understand the environmental impacts of organic pollutants on soil health. Phthalates are widely used in consumables and can be found extensively. We studied the toxicity of diethyl phthalate (DEP), spiked in a compost plant growth substrate, by means of the acute toxicity Flash test and on the basis of the germination and plant growth of radish seedlings. The response of the microbial community to DEP in the growth substrate was studied by PCR-DGGE (denaturing gradient gel electrophoresis). In the acute toxicity test, DEP was found to be less toxic as a pure compound than when mixed with the compost mixture. This suggests the synergistic effect of unknown toxic compounds or the release of compounds due to DEP addition. The same DEP concentration level in compost substrate induced toxic response in both plant test and microbial community analysis. The diversity of the major microbial community was reduced from a broad community to only 10 major species at toxic concentrations of DEP. Several of the identified microbial species are known to be able to degrade phthalates, which means that the suppression of other microbial species might be due to the substrate availability and toxicity. The major species identified included Sphingomonas sp., Pseudomonas sp., Actinomycetes sp.

Dibutyl phthalate biodegradation by the white rot fungus, Polyporus brumalis

In this study, white rot fungus, Polyporus brumalis, was applied to degrade dibutyl phthalate (DBP), a major environmental pollutant. The degradation potential and resulting products were evaluated with HPLC and GC/MS. As DBP concentration increased to 250, 750, and 1,250 microM, the mycelial growth of P. brumalis was inhibited. However, growth was still observed in the 1,250 microM concentration. DBP was nearly eliminated from culture medium of P. brumalis within 12 days, with 50% of DBP adsorbed by the mycelium. Diethyl phthalate (DEP) and monobutyl phthalate (MBP) were detected as intermediate degradation products of DBP. In culture medium, the concentration of DEP was higher than that of MBP during the incubation period. After 12-15 days, the concentrations of both decreased rapidly in the culture medium. The primary final degradation product of DBP in culture medium was phthalic acid anhydride, as well as trace amounts of aromatic compounds, such as alpha-hydroxyphenylacetic acid, benzyl alcohol, and O-hydroxyphenylacetic acid. According to these results, the degradation of DBP in culture medium by the white rot fungus, P. brumalis, may be completed through two pathways-transesterification and de-esterification-which successively combine into an intracellular degradation pathway.

Adsorptive removal of phthalate ester (Di-ethyl phthalate) from aqueous phase by activated carbon: A kinetic study

Adsorptive studies were carried out on Di-ethyl phthalate (DEP) removal from aqueous phase onto activated carbon. Batch sorption studies were performed and the results revealed that activated carbon demonstrated ability to adsorb DEP. Influence of varying experimental conditions such as DEP concentration, pH of aqueous solution, and dosage of adsorbent were investigated on the adsorption process. Sorption interaction of DEP onto activated carbon obeyed the pseudo second order rate equation. Experimental data showed good fit with both the Langmuir and Freundlich adsorption isotherm models. DEP sorption was found to be dependent on the aqueous phase pH and the uptake was observed to be greater at acidic pH.

Photochemical degradation of diethyl phthalate with UV/H 2O 2

The decomposition of diethyl phthalate (DEP) in water using UV–H 2O 2 process was investigated in this paper. DEP cannot be effectively removed by UV radiation and H 2O 2 oxidation alone, while UV–H 2O 2 combination process proved to be effective and could degrade this compound completely. With initial concentration about 1.0 mg/L, more than 98.6% of DEP can be removed at time of 60 min under intensity of UV radiation of 133.9 μW/cm 2 and H 2O 2 dosage of 20 mg/L. The effects of applied H 2O 2 dose, UV radiation intensity, water temperature and initial concentration of DEP on the degradation of DEP have been examined in this study. Degradation mechanisms of DEP with hydroxyl radicals oxidation also have been discussed. Removal rate of DEP was sensitive to the operational parameters. A simple kinetic model is proposed which confirms to pseudo-first order reaction. There is a linear relationship between rate constant k and UV intensity and H 2O 2 concentration.

Chronic toxicity of diethyl phthalate in male Wistar rats—A dose–response study

Diethyl phthalate (DEP) is widely used in personal care products, plastics and medical devices at various concentrations, but its information is limited on its toxicity associated with exposure at high as well as low doses for a prolonged period. Therefore, a study was undertaken to understand the dose–response toxic effect of DEP in male Wistar rats. Control rats were fed on normal diet and water ad libitum. Rats were given DEP dissolved individually in corn oil mixed with the diet at 10, 25 and 50 mg/kg of the diet/day, which is equal to 0.57, 1.425 and 2.85 mg/kg body wt/day. After 5 months of treatment animals were sacrificed, enzymes and other biochemical parameters in the serum and liver were assessed. Liver weight to body weight ratio showed a significant increase only in 10 ppm DEP treated rats. A significant increase was observed in the serum ACP, LDH, ALT enzyme levels of 10 mg/kg treated rats as compared to control, 25 and 50 mg/kg treated rats. Other biochemical parameters like glycogen, total cholesterol, total triglycerides and lipid peroxidation were also increased in the liver of all the three treated groups. In the 10 and 50 mg/kg diet/day treated rats, there was a significant decrease in liver total GSH as compared to controls and 25 mg/kg treated rats. Histology of liver showed severe vacuolations, fatty degeneration and loss of hepatic architecture in the 10 mg/kg treated rats, whereas in the 25 and 50 mg/kg treated rats only loss of hepatic architecture and granular deposits in the hepatocytes was predominant. Histology of liver by electron micrographs showed a significant dose-dependent proliferation of mitochondria in the hepatocytes, while the 10 mg/kg treated rats showed increased number of peroxisomes in the hepatocytes. It is evident from this study that treatment with higher concentrations of DEP results in mitochondrial proliferation as well as accumulation of glycogen, cholesterol and triglycerides within the liver, but exposure to lower concentrations for longer periods results in increase in peroxisome numbers leading to severe hepatocellular changes which can be confirmed by significantly increased liver weights, elevated enzyme levels in the serum and liver and impaired metabolism of glycogen, cholesterol and triglyceride as well as altered liver histology.

Influence of Gas Velocity and Humidity on Diethyl Phthalate Adsorption and Desorption on Silicon Surface

The real-time adsorption and desorption of water and diethyl phthalate on silicon surface were studied using a quartz crystal microbalance in ambient nitrogen, having various values of humidity, gas velocity and diethyl phthalate concentration. In a steady state, the adsorbed amount of water and diethyl phthalate is considered to depend only on each concentration in the ambient nitrogen. However, in a non-steady state state, the gas velocity at the quartz crystal microbalance enhances both the adsorption rate and the desorption rate. Therefore, the gas velocity at the measurement point is concluded to be one of the key parameters that influence the organic contamination measurement.

The occurrence and removal of phthalates in a trickle filter STW

This study investigated the fate of phthalates in a trickle filter sewage treatment works. A wide variety of phthalates were researched of which only two were present in significant amounts. Mean concentrations of di-(2-ethylhexyl) phthalate (DEHP) and diethyl phthalate (DEP) measured throughout the system were 23.6 and 25.0 μg/l in raw sewage, 22.0 and 24.8 μg/l in primary, 14.6 and 0.60 μg/l in trickle filter, 18.6 and 0.10 μg/l in humus tank and 18.5 and 0.40 μg/l in reedbed effluents, respectively. Removal by the trickle filter was constantly high for DEP (94–99%) whereas DEHP was variable (<1–44%). Mean concentrations of DEHP and DEP in raw sludge were 30.2 and 1.60 μg/g dry wt, respectively. A mass balance for DEHP was calculated using data from field studies and estimates of sludge production at the works. The mass balance approach helped to provide information that could be used to improve the design and operation of sewage treatment works.

Surface Deposition of Diethyl Phthalate on SiO2 and Si3N4 Wafers in Simulated Cleanroom Environment

The surface deposition kinetics of airborne diethyl phthalate (DEP), a representative compound for high-boiling-point organic contaminants in cleanroom environments, were investigated in this study. Between the two types of wafer surfaces evaluated, wafer surfaces with oxide (SiO2) and wafer surfaces with nitride (Si3N4), DEP exhibited a stronger propensity to absorb on the SiO2 wafers, presumably due to the greater dipole moment between DEP and SiO2 surfaces. Under well-controlled exposure conditions, the rate parameters of a theoretical surface kinetic model were determined by employing a heuristic algorithm for numerical optimization to match the experimental profile. Subsequently, a series of time-dependent surface DEP concentrations were simulated and validated with the experimental data under various ambient concentrations. Estimation of the allowable wafer exposure durations and the maximum ambient concentrations were exemplified based on the guideline recommended by the International Technology Roadmap for Semiconductors (ITRS).1

Sorption of diethyl phthalate by nitrocellulose fibers

AbstractThe manner in which diethyl phthalate (DEP) is absorbed into nitrocellulose (NC) fibers has been observed microscopically. The movement of pure DEP into dry fibers proceeds by capillary motion up the central canal (lumen) and through microcracks between fibrils. Attack, measured by a large change in birefringence, spreads from these foci, and within the time scale of the experiment there is little interaction with the primary (outer) wall of the fiber. If, however, the lumen and other capillary passages are blocked by water or other liquid, then attack proceeds evenly from the outer wall and a sharp boundary between swollen and unswollen material moves at a uniform speed towards the center of the fiber and appears to be unaffected by the fibrillar structure (Case II swelling). If the supply of DEP to the surface is interrupted, this boundary becomes immobile, and the concentration of DEP in the swollen layer is that which is just sufficient to saturate residual un‐nitrated hydroxyl groups on the NC. Reducing the activity of the DEP by admixture with benzene results in similar sharp boundaries, presumably because capillaries become blocked with spent diluent. Apart from capillary action, movement is always perpendicular to the fiber axis.

Studies of micro high-performance liquid chromatography : III. Development of a “micro-pre-column method” for pre-treatment of samples

A sample pre-treatment method is described in which components are adsorbed on a micro pre-column, and an investigation of the method (with phthalic acid esters in water as sample components) is reported. The esters could be concentrated in the pre-column simply and rapidly, and were separated in a micro separation column. Concentrations of diethyl phthalate in the ppb-range were rapidly determined by pre-treatment of 10 ml or less of the aqueous solution. The method was suitable for use in micro-performance liquid chromatography.

Structure of polysiloxanes: Influence of solvent on size and polymer‐solvent interaction of linear polydimethylsiloxanes

AbstractMolecular weight, sizes, and second virial corfficients of a linear polydimethylsiloxane polymer (MW = 4.57 × 105) in mixtures of toluene‐diethylphthalate have been determined by light scattering. Intrinsic viscosities have also been measured in the same mixed solvents. As expected, as the diethylphthalate concentration was increased the molecules contracted and the second virial coefficients became more negative. The data were used to attempt to decide between two current theories relating these quantities. No choice could be made. It was found that the calculated values of Flory's universal constant, φ, were much smaller than those usually obtained. It is proposed that this is due to an abnormally broad molecular weight distribution in the polysiloxane.