Urinary Mandelic Acid Research Articles

Assessment of the Workers' Exposure to Styrene in a Polymer Manufacturing Industry: Correlation Between Air and Biological Monitoring Methods

Background and Objective: Styrene is widely used in the production of many products, such as paints, glues, and plastics. There is a high potential for exposure to this toxic solvent in workplaces. The present study aimed to assess the levels of exposure to styrene via air and biological monitoring methods and determine the correlation between them in styrene-exposed workers. Materials and Methods: A total of 44 workers from a polymer manufacturing industry were studied, and the workers’ inhalational exposure to styrene was measured. In addition, the levels of urinary mandelic acid were determined. Data was analyzed using the SPSS (version 22.0) software. Results: The time-weighted average (TWA) exposure to styrene was equal to 18.35±11.02 ppm. The mean urinary mandelic acid was 150 mg/g creatinine. Moreover, a significant correlation was observed between the styrene concentration and the urinary mandelic acid (r=0.841). The correlation was stronger in workers with no skin exposure than in those with this type of exposure. Furthermore, a significant correlation was observed based on working hours per day (less than or more than 8 hours per day) so that the correlation was better for workers with shorter exposures (r= 0.922 vs. 0.713). Conclusion: The findings of the present study indicated a relatively strong correlation between inhalational exposure to styrene and the levels of mandelic acid in urine. In addition, smoking and working conditions, such as skin exposure and working hours per day, can affect the levels of urinary mandelic acid. Therefore, these factors should be considered in the exposure assessment of workers exposed to styrene.

Styrene and ethylbenzene exposure and type 2 diabetes mellitus: A longitudinal gene–environment interaction study

Styrene and ethylbenzene (S/EB) are identified as hazardous air contaminants that raise significant concerns. The association between S/EB exposure and the incidence of type 2 diabetes mellitus (T2DM), and the interaction between genes and environment, remains poorly understood. Our study consisted of 2219 Chinese adults who were part of the Wuhan-Zhuhai cohort. A follow-up assessment was conducted after six years. Exposure to S/EB was quantified by determining the concentrations of urinary biomarkers of exposure to S/EB (UBE-S/EB; urinary phenylglyoxylic acid level plus urinary mandelic acid level). Logistic regression models were constructed to investigate the relations of UBE-S/EB and genetic risk score (GRS) with T2DM prevalence and incidence. The interaction effects of UBE-S/EB and GRS on T2DM were investigated on multiplicative and additive scales. UBE-S/EB was dose-dependently and positively related to T2DM prevalence and incidence. Participants with high levels of UBE-S/EB [relative risk (RR) = 1.930, 95% confidence interval (CI): 1.157–3.309] or GRS (1.943, 1.110–3.462) demonstrated the highest risk of incident T2DM, in comparison to those with low levels of UBE-S/EB or GRS. Significant additive interaction between UBE-S/EB and GRS on T2DM incidence was discovered with relative excess risk due to interaction (95% CI) of 0.178 (0.065–0.292). The RR (95% CI) of T2DM incidence was 2.602 (1.238–6.140) for individuals with high UBE-S/EB and high GRS, compared to those with low UBE-S/EB and low GRS. This study presented the initial evidence that S/EB exposure was significantly related to increased risk of T2DM incidence, and the relationship was interactively aggravated by genetic predisposition.

Determination of phenylglyoxylic acid and mandelic acid in urine by ultra high performance liquid chromatography tandem mass spectrometry

Objective: To develop a method for the analysis of phenylglyoxylic acid (PGA) and mandelic acid (MA) in urine by ultra-high performance liquid chromatography tandem mass spectrometry. Methods: The study was conducted in April 2022. Urine samples were directly diluted with the initial mobile phase, separated by Waters HSS T3 column after passing through the membrane, and analyzed under negative ionization mode (ESI(-)) and multiple reaction monitoring (MRM) conditions, the contents of PGA and MA in human urine were quantitatively determined by external standard method. Results: The determination of PGA and MA showed a good linear relationship within the range of 10-1000 ng/ml, with a correlation coefficient of 0.9999. The linear regression equation of PGA was y=1141.4x+2157.3, the detection limit and lower limit of quantification of the method were 0.081 ng/ml and 0.269 ng/ml, and the recovery rate was 90.47%-99.83%. The linear regression equation of MA was y=62.8x+140.3, the detection limit and lower limit of quantification of the method were 0.551 ng/ml and 1.836 ng/ml, and the recovery rate was 92.75%-101.09%. The intra and inter batch precision of PGA and MA were both<5%. Conclusion: An ultra-high performance liquid chromatography tandem mass spectrometry method for the analysis of PGA and MA in urine was established.The sample pretreatment operation is simple, and the accuracy and precision of the method meet the standard requirements. It can be used for monitoring and evaluating PGA and MA in urine of the general population and occupational contact population.

Urinary metabolites as exposure biomarkers of benzene, toluene, ethylbenzene, and xylene in footwear workers and assessment of pulmonary function

Aim: This pilot cross-sectional study focused on biological monitoring of the benzene, toluene, ethylbenzene, and xylene (BTEX) urinary metabolites trans, trans-muconic acid (tt-MA), s-phenyl mercapturic acid (SPMA), hippuric acid (HA), mandelic acid (MA), and methylhippuric acid (MHA) and measured the effects of workplace BTEX exposure on pulmonary function of workers engaged in footwear manufacturing. Materials and Methods: Urinary metabolites tt-MA, SPMA, HA, MA, and MHA concentration in urine samples of study participants (N = 35) were analyzed by reverse-phase high-pressure liquid chromatography. Pulmonary function parameters were measured by spirometer and peak flow meter. Demographic information and work exposure information of study participants were collected by questionnaire interview. Results: In exposed workers, concentration of urinary SPMA, tt-MA, and HA was significantly higher (P < 0.01, in all) than the control group. Reduction in both force expiratory volume in 1 s (Forced expiratory volume in one second) and peak expiratory flow rate (PEFR) were inversely associated (P < 0.01) with growing years of age among all workers. Inverse association was measured between urinary tt-MA and decline in forced vital capacity and PEFR (P < 0.05, for each) in workers. Based on the questionnaire interview, workers were not found to be aware of workplace exposure hazards. Conclusions: Exposure biomarkers of benzene (tt-MA and SPMA) and toluene (HA) were significantly higher in workers than the control group. Study results evident the presence of occupational exposure to benzene and toluene in footwear workers. Deterioration in FEV1 and PEFR were also measured among all workers with growing years of age. The sample size was small in the present study, so further research required to confirm our results.

Facile and sensitive determination of urinary mandelic acid by combination of metal organic frameworks with microextraction by packed sorbents

In this study, two hybrid metal organic frameworks including MOF-5@ Fe3O4-NH2 and MOF-5@ SBA-15 for the first time were synthetized and combined with microextraction by packed sorbent (MEPS) to extract of mandelic acid (MA) from urine samples. The synthetized sorbents were characterized using FE-SEM, XRD and FT-IR techniques. The important parameters in MEPS procedure including sample volume, extraction draw_discard cycles, elution solvent volume and desorption draw-eject cycles were optimized using response surface methodology (RSM) with central composite design (CCD). The results indicated that the volume of elution solvent was the most important parameter in the recovery of MA by MOF-MEPS procedure. The optimized MOF-MEPS method offered an acceptable efficiency for the recovery of MA from urine samples (MOF-5@Fe3O4-NH2 and MOF-5@SBA-15: 94.5% and 90.3%, respectively, RSD < 3.54%). The limit of detection (LOD) of MA calculated by MOF-MEPS procedure combined with high performance liquid chromatography for MOF-5@ Fe3O4-NH2 and MOF-5@ SBA-15 were calculated to be 0.10 and 0.13 μg mL−1, respectively. The linearity dynamic ranges (LDRs) determination of urinary MA by MOF-5@ Fe3O4-NH2 and MOF-5@ SBA-15 were 0.2–100 and 0.2–90 μg mL−1, respectively. The results of the present study implied that the proposed technique is a fast and sensitive procedure for extraction and determination of MA from urine samples.

Ethylbenzene and styrene exposure in the United States based on urinary mandelic acid and phenylglyoxylic acid: NHANES 2005–2006 and 2011–2012

Ethylbenzene and styrene are air toxicants with widespread nonoccupational exposure sources, including tobacco smoke and diet. Ethylbenzene and styrene (EB/S) exposure was quantified from their common metabolites measured in spot urine samples obtained from participants (≥6 years old) in the 2005–2006 and 2011–2012 cycles of the National Health and Nutrition Examination Survey (NHANES; N = 4690). EB/S metabolites mandelic acid (MA) and phenylglyoxylic acid (PGA) were measured using ultra-high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). MA and PGA were detected in 98.9% and 90.6% of tested urine specimens, respectively. Exclusive smokers had 2-fold and 1.6-fold higher median urinary MA and PGA, respectively, compared with non-users. Sampleweighted regression analysis among exclusive smokers showed that smoking 0.5 pack cigarettes per day significantly increased MA (+97.9 μg/L) and PGA (+69.3 μg/L), controlling for potential confounders. In comparison, exposure from the median daily dietary intake of grain products increased MA by 1.95 μg/L and was not associated with statistically significant changes in urinary PGA levels. Conversely, consuming vegetables and fruit was associated with decreased MA and PGA. These results confirm tobacco smoke as a major source of ethylbenzene and styrene exposure for the general U.S. population.

Evaluation of the Suitability of Establishing Biological Exposure Indices of Styrene.

BackgroundThis study was designed to provide logical backgrounds for the revision of biological exposure indices (BEIs) for styrene exposure in Korea. In order to investigate the correlation between airborne styrene and biological exposure indices, we measured urinary mandelic acid (MA) and phenylglyoxylic acid (PGA) in workers exposed to styrene occupationally, as well as airborne styrene at workplaces.MethodsSurveys were conducted for 56 subjects. The concentrations of airborne styrene and urinary metabolites of styrene were measured in 36 workers who were occupationally exposed to styrene, and in 20 controls. Air samples were collected using personal air samplers and analyzed by gas chromatography. Urine samples were collected at the end of the shift and analyzed by high performance liquid chromatography.ResultsThe geometric mean concentration of airborne styrene was 9.6 ppm. The concentrations of urinary MA, PGA, and MA+PGA in the exposure group were 267.7, 143.3, and 416.8 mg/g creatinine, respectively. The correlation coefficients for correlation between airborne styrene and MA, PGA, and MA+PGA were 0.714, 0.604, and 0.769, respectively. The sum of urinary MA and PGA corresponding to an exposure of 20 ppm styrene was 603 mg/g creatinine.ConclusionThe correlation of the sum of urinary MA and PGA with airborne styrene was better than the correlation of each individual urinary determinant. It is considered appropriate to amend the concentration of urinary MA+PGA to 600 mg/g creatinine as a BEI, which corresponds to an airborne styrene concentration of 20 ppm in Korea.

Correction to: Selective determination of mandelic acid in urine using molecularly imprinted polymer in microextraction by packed sorbent.

In the original publication of the article, there is an error in Fig.2c. The authors would like to correct this error and the corrected version of Fig.2c is as follow.

Management of Pheochromocytoma in Dakar: Diagnostic and Therapeutic Advances throughout 16 Cases

Introduction: Management of pheochromocytoma faces different challenges leading to misdiagnosis and therapeutic delay in developing countries. The aim of our study was to evaluate the diagnostic and therapeutic features as well as the evolution of our management strategies in hospital setting in recent years in Dakar. Patients and Method: We carried out a retrospective study over 12 years (January 2005 to June 2017), in 4 hospitals in Dakar. We only included patients with established diagnosis of pheochromocytoma upon clinical, biological, radiological and histological arguments. Results: During this period, 16 observations have been collected and were all about female patients. The mean age at the time of diagnosis was 36.81 years. The clinical signs were dominated by hypertension found for 14 patients. At biological examination, hypersecretion catecholamine was found in 13 patients, high urinary metanephrines in 7 patients, high plasmatic metanephrines in 2 patients and raised urinary Vanyl Mandelic Acid (VMA) in 4 patients. Dosage of chromogranin A showed high level for one patient. Abdominal CT scan allowed making the adrenal origin of tumors precise. One patient presented bilateral pheochromocytoma. Before being treated surgically, all patients had had medical preparation. The surgical treatment by median laparotomy consisted of an enucleation of the tumor in 2 patients, and adrenal resection in 11patients.The evolution after surgery was favorable in 12 patients out of 13. One patient died 2 days after surgery by hemodynamic instability. In 2 patients who presented metastases, multidrug therapy with cyclophosphamide, vincristine and dacarbazine was decided after a multidisciplinary meeting, but they died before treatment. Conclusion: Management of pheochromocytomas in developing countries is obviously improving, but the mortality rate remains high. Early diagnosis and perioperative care are to be targeted for better outcome and prognosis of this rare tumor in our areas.

Determination of phenylglyoxylic acid and mandelic acid in urine by high performance liquid chromatography method

Objective: To revise the standard method for the determination of phenylglyoxylic acid(PGA)and mandelic acid(MA) in urine by ultra-performance liquid chromatography. Methods: The original standard method was evaluated by experiment, and the chromatographic column, the detection limit,quantitation limit and stabilityof the method were studied. Results: The samples were separated by BEH Phenyl(50mm×2.1mm×1.7μm)column and the internal standard working curve method was used. The regression equations were y=3.660 7x+0.066 3 and y=5.161 2x-0.007 3 for MA and PGA respectively. Linear correlation coefficients were 0.999 3 and 0.999 1. Linearity ranges were 0.10-1.00 mg/ml,0.04-0.40 mg/ml. The recoveries of PGA and MA were 91.6%-97.1% and 84.3%-99.0%,the precision were 0.9%-4.6% and 0.5%-1.9%. The detection limit and quantitation limit of the method were 1.1 mg/L and 3.7 mg/L for PGA, 5.4 mg/L and 17.9 mg/L for MA. Conclusion: The method uses the phenyh modified chromatographic column, determines the detection limit. The method can improve quantitation limit, the detection accuracy and meet the detection of occupational population samples.

Selective determination of mandelic acid in urine using molecularly imprinted polymer in microextraction by packed sorbent.

Mandelic acid (MA) is a major metabolite of ethylbenzene and styrene. For the first time, a selective, fast, and easy-to-use procedure was developed for the determination of MA in urine samples. The new procedure is based on MIMEPS, the combination of a molecularly imprinted polymer (MIP) and microextraction by packed sorbent (MEPS). High-performance liquid chromatography with ultraviolet detection (HPLC-UV) was used for the separation and determination of MA. The bulk polymerization method was used to synthesize the MIP, and the MIP and non-imprinted polymer (NIP) were characterized by Fourier transform infrared spectroscopy. The selectivity of the MIP was investigated in the presence of interferents. In addition, we investigated the various parameters that affect the performance of the MEPS, including the pH of the sample, the number of extraction cycles, sample volume, and the types and volumes of the washing and elution solvents. A six-point calibration curve was obtained in the range of 0.2-20µg/mL (R 2=0.9994). The extraction recovery was more than 88.8%. The limit of detection and the limit of quantitation were 0.06 and 0.2µg/mL, respectively. The intra- and inter-day precisions were in the range of 3.6-4.7% and 3.8-5.1%, respectively. The accuracy was -8.4 to -11.1%. The optimized procedure was selective, sensitive, and rapid, and it was both user friendly and environmentally friendly. The sample preparation process took only about 5min, so the MIMEPS-HPLC-UV procedure is recommended as an alternative for the biomonitoring of workers exposed to ethylbenzene and/or styrene.

Development of a fast method for simultaneous determination of hippuric acid, mandelic acid, and creatinine in urine by capillary zone electrophoresis using polymer multilayer-coated capillary.

This paper reports the development of a fast separation method employing capillary zone electrophoresis for the simultaneous determination of hippuric acid, mandelic acid, and creatinine in samples of urine using a coated capillary. The background electrolyte was composed of 10mmolL-1 tris(hydroxymethyl)aminomethane and 30mmolL-1 2-hydroxy-isobutyric acid at pH3.6. The internal standard was 3,5-dihydroxybenzoic acid. Separations were performed in a fused silica capillary (32cm total length, 8.5cm effective length, and 50μm internal diameter) coated with crosslinked hydroxypropyltrimethyl ammonium chloride chitosan and κ-carrageenan. Direct UV detection was performed at a wavelength of 200nm. Samples and standards were injected hydrodynamically (-50mbar, 3s) using the short-end injection procedure. The electrophoretic system was operated under constant voltage of 30kV with positive polarity on the injection side. The separation time for hippuric acid, mandelic acid, and creatinine was less than 70s. The evaluation of some analytical parameters of the method for the three analytes showed good linearity (R 2 > 0.99), limit of detections of 0.21 to 0.63mgL-1, inter-day precision better than 3.0% (peak area), and recovery in the range of 98 to 106%. The method developed was applied in the analysis of the three analytes in urine samples. Graphical Abstract New method using capillary zone electrophoresis for analysis of creatinine, hippuric acid and mandelic acid in urine.

Low Serum Testosterone Levels Are Associated with Elevated Urinary Mandelic Acid, and Strontium Levels in Adult Men According to the US 2011-2012 National Health and Nutrition Examination Survey.

BackgroundLittle is known regarding the effects of environmental exposure of chemicals on androgenic system in the general population. We studied 5,107 subjects included in the National Health and Nutrition Examination Survey (2011–2012).MethodsUrinary, serum, and blood levels of 15 subclasses comprising 110 individual chemicals were analyzed for their association with serum testosterone levels. The subjects were divided into high and low testosterone groups according to the median testosterone concentration (374.51 ng/dL). Odds ratios (ORs) of individual chemicals in association with testosterone were estimated using logistic regression after adjusting for age, ethnicity, cotinine, body mass index, creatinine, alcohol, and the poverty income ratio.ResultsAdjusted ORs for the highest versus lowest quartiles of exposure were 2.12 (95% CI: 1.07, 4.21; Ptrend = 0.044), 1.84 (95% CI: 1.02, 3.34; Ptrend = 0.018) for the association between urinary mandelic acid, and strontium quartiles with low testosterone concentrations in adult men, respectively. However, no association was observed for the remaining chemicals with testosterone.ConclusionsThe National Health and Nutrition Examination Survey data suggest that elevations in urinary mandelic acid, and strontium levels are negatively related to low serum testosterone levels in adult men.

Health hazards among workers in plastic industry

Styrene is a basic building block for manufacturing thousands of products throughout the world. The present study aimed to (1) detect the presence of styrene and/or its metabolites in the workers in one of the Egyptian plastic factories; (2) demonstrate some common health effects of styrene exposure among the same group by some laboratory investigations and compare them with the unexposed healthy individuals; and (3) correlate the duration of styrene exposure and its level in the blood with the severity of the demonstrated health effects. This study was conducted in one of Egyptian plastic factories. The exposed group was 40 male workers, ranging in age from 18 to 33 years (23.20 ± 4.09), working 12 h/day with 1 day off, and working without any protective equipment. A control group of 50 unexposed healthy males matched with the exposed group for age (21-35 yrs (23.40 ± 4.05)), sex, socioeconomic status, and smoking habit is selected. Written individual consent is obtained from all participants followed by (a) a full medical and occupational history and full clinical examination; (b) ventilatory function tests: forced vital capacity (FVC), slow vital capacity, forced expiratory volume in the 1st second (FEV₁)%, FEV₁/FVC%, peak expiratory flow, and mid-expiratory flow 25-75%; (c) analyses of β₂ microglobulin; blood styrene level; and urinary mandelic acid; and (d) cytogenetic study. The study results showed a statistically significant difference between the exposed and the control groups as regard the blood styrene level, urinary mandelic acid level, β₂ microgloblin in urine, and chromosomal study. The study also showed a statistically significant correlation between the duration of styrene exposure and ventilatory function parameters, also between the duration of styrene exposure and some detectable chromosomal aberrations. Our study recommends the implementation of preemployment and periodic medical examinations and health education programs using personal protective equipments and following the recommended allowable concentrations of styrene exposure.

Exposure to Styrene in Fiberglass-Reinforced Plastic Manufacture

The aim of the work is to define occupational exposure to styrene in fiberglass manufacture; the phase of stretching styrene resins needs some manual handling and leads workers to be exposed to styrene. We surveyed 20 workers in two companies manufacturing fiberglass, checking environmental levels and urinary concentrations of mandelic acid (MA), and phenylglioxylic acid (PGA). Workers completed a questionnaire collecting their medical history. Environmental monitoring showed some styrene concentrations higher than the threshold limit value-time-weighted average. Biological monitoring confirmed these findings and four workers had levels of urinary PGA and MA concentrations higher than the Biological Exposure Indices of the American Conference of Governmental Industrial Hygienists. This picture confirms that, even though the risk is known and the manufacturing cycle is well-defined, workers nevertheless risk exposure. More research is needed to optimize the work processes and the protection systems to lower this risk.

Urinary 8-Hydroxydeoxyguanosine as a Biomarker of Oxidative DNA Damage in Workers Exposed to Ethylbenzene

This study assessed the relationships between ethylbenzene exposure and levels of 8-hydroxydeoxyguanosine (8-OHdG) among spray painters. Sixty-four male workers employed at a large shipyard were recruited for this investigation. Fifteen spray painters exposed to paint, together with two non-exposed groups, namely 19 sandblasting workers and 30 office staffs were selected as the subjects. Personal exposure to xylene and ethylbenzene in air were collected using diffusive samplers. Urine samples of the spray painters were collected after a month-long holiday leave and during the pre- and post-workshifts. Urine samples of sandblasting workers and office staffs were gathered after their shift. Urinary mandelic acid and methyl hippuric acid were used as biological indices of dose of ethylbenzene and xylene, respectively. Urinary 8-OHdG was used as biomarker of oxidative DNA damage. The post-workshift concentration of urinary 8-OHdG for 10 spray painters (30.3 ± 9.28 μg g(-1) creatinine) significantly exceeded that of holiday leave (7.20 ± 1.08 μg g(-1) creatinine; P = 0.001). The post-workshift concentration of urinary 8-OHdG was higher among 15 spray painters (29.0 ± 6.52 μg g(-1) creatinine) than sandblasting workers (9.14 ± 2.05 μg g(-1) creatinine; P = 0.01) and office staffs (8.35 ± 0.84 μg g(-1) creatinine; P = 0.007). A stepwise regression model revealed an 8.11 μg g(-1) creatinine increase per 1 p.p.m. increase in ethylbenzene [95% confidence interval (CI) 4.13-12.1]. A stepwise regression model revealed an increase of 6.04 μg g(-1) creatinine (95% CI 2.23-9.84) per 1 p.p.m. in ethylbenzene after adjustment of age (95% CI 2.23-9.84). This pilot study suggests that occupational exposure to paint increases oxidative DNA injury. Moreover, urinary 8-OHdG levels displayed greater DNA damage in spray painters compared to other unexposed groups and their holiday leave samples. A significant correlation was found between urinary 8-OHdG and the exposure to ethylbenzene. The ethylbenzene exposure could not explain all urinary 8-OHdG measured. Other components of paint deserve further investigation.

A Field Evaluation of Mandelic Acid in Urine as a Compliance Monitor for Styrene Exposure

Abstract The Special Studies Unit of Cal/OSHA monitored mandelic acid in urine and styrene exposure in a survey of 324 workers in the fiberglass-reinforced plastics industry. The urine was sampled at the end of the shift, and the mandelic acid was analyzed by high-performance liquid chromatography. A stepwise regression analysis shows that the mandelic acid (MA) concentration is affected by the styrene concentration, the urine's specific gravity, effective respirator usage, work rate, and sampling on Friday; it is unaffected by skin exposure to styrene or exposure to other solvents. The regression model supports the Biological Exposure Index (BEI) of 1 g/L if the MA concentration is standardized for specific gravity. In a comparison of styrene and MA compliance decision, 7 percent of the subjects were false positives, i.e., violating the BEI while in compliance with the styrene threshold limit value. Since one of the false positives was using an organic vapor respirator, the MA monitoring did demonstrate ...

Melanotic neuroectodermal tumor of infancy in thigh of an infant—a rare case report with diagnostic implications

Melanotic neuroectodermal tumor of infancy (MNTI) is an uncommon tumor of neural crest origin, almost invariably identified in the head and neck region. It is a relatively benign tumor but can recur and rarely metastasize. Herein, a rare case of MNTI in the thigh of an infant is documented. Radiographic imaging showed a sclerotic and lytic lesion in the metadiaphyseal region of the right femur with a soft tissue component. The clinicoradiological impression was of a malignant round cell tumor and osteomyelitis. The patient's urinary vanil mandelic acid (VMA) level was elevated. FNAC smears revealed a tumor with round to polygonal cells, focally containing black melanin pigment. Biopsy and tumor excision revealed a tumor with cells in cords and nests embedded in a fibrocollagenous stroma and showed bone and soft tissue infiltration. On immunohistochemistry, tumor cells displayed immunoreactivity to vimentin, cytokeratin (CK), CK7, CK19, and MIC2, and focal reactivity for synaptophysin and HMB45. Diagnosis of an MNTI was made. The patient underwent induction chemotherapy with extracorporeal radiotherapy, followed by a soft tissue excision that revealed residual tumor. Surgically, free marrow margins were accomplished, and the patient is currently being followed-up. To the best of our knowledge this case is the fifth documented case in the English literature of MNTI in the thigh. The diagnostic and therapeutic implications are discussed.

Effect of Physical Exertion on the Biological Monitoring of Exposure to Various Solvents Following Exposure by Inhalation in Human Volunteers: III. Styrene

This study evaluated the impact of different work load intensities on biological indicators of styrene exposure. Four adult Caucasian men, aged 20 to 44 years, were recruited. Groups of 2–4 volunteers were exposed to 20 ppm of styrene in an exposure chamber according to scenarios involving either aerobic, muscular, or both types of physical exercise for 3 or 7 hr. The target intensities for each 30-min exercise period—interspaced with 15 min at rest—were the following: REST, 38 watts AERO (time-weighted average intensity), 34 watts AERO/MUSC, 49 watts AERO/MUSC, and 54 watts AERO for 7 hr and 22 watts MUSC for 3 hr. End-exhaled air samples were collected at 15 time points during and after 7-hr exposures for the determination of styrene concentrations. Urine samples were collected before the start of exposure, after the first 3 hr of exposure, and at the end of exposure for the determination of mandelic acid (MA) and phenylglyoxilic acid (PGA) concentrations. Compared with exposure at rest, styrene in alveolar air increased by a factor up to 1.7, while the sum of urinary MA and PGA increased by a factor ranging from 1.2 to 3.5, depending on the exposure scenario. Concentrations of biological indicators of styrene fluctuated with physical exertion and were correlated with the magnitude of the physical activity and pulmonary ventilation. Despite the physical exertion effect, urinary concentrations of styrene metabolites after a single-day exposure remain below the current biological exposure index value recommended by ACGIH®; therefore, no additional health risk is expected. However, results shows that work load intensities must be considered in the interpretation of biological monitoring data and in the evaluation of the health risk associated with styrene exposure.

Assessing variability and comparing short-term biomarkers of styrene exposure using a repeated measurements approach

The aim of this work is to compare several short-term biomarkers of styrene exposure, namely urinary styrene (StyU), mercapturic acids (M1 + M2), mandelic acid (MA), phenylglyoxylic acid (PGA), phenylglycine (PHG), and 4-vinylphenol conjugates (VP), for use as biomarkers of exposure in epidemiologic studies. A repeated measurements protocol (typically 4 measurements per worker over 6 weeks) was applied to measure airborne styrene (StyA) and urinary biomarkers in 10 varnish and 8 fiberglass reinforced plastic workers. Estimated geometric mean personal exposures to StyA were 2.96 mg/m 3 in varnish workers and 15.7 mg/m 3 in plastic workers. The corresponding levels of StyU, M1 + M2, MA, PGA, MA + PGA, PHG and VP were 5.13 μg/L, 0.111, 38.2, 22.7, 62.6, 0.978, and 3.97 mg/g creatinine in varnish workers and 8.38 μg/L, 0.303, 146, 83.4, 232, 2.85 and 3.97 mg/g creatinine in plastic workers. Within-worker ( σ wY 2 ) and between-worker ( σ bY 2 ) variance components were estimated from the log-transformed data as were the corresponding fold ranges containing 95% of the respective lognormal distributions of daily levels ( w R 0.95) and subject-specific mean levels ( b R 0.95). Estimates of w R 0.95 (range: 4–26) were generally smaller than those of b R 0.95 (range: 5–790) for both environmental and biological markers; this indicates that exposures varied much more between workers than within workers in these groups. Since attenuation bias in an estimated exposure–response relationship increases with the variance ratio λ = σ wY 2 / σ bY 2 , we estimated values of λ for all exposure measures in our study. Values of λ were typically much less than one (median = 0.220) and ranged from 0.089 for M1 + M2 in plastic workers to 1.38 for PHG in varnish workers. Since values of λ were 0.147 and 0.271 for StyA in varnish workers and plastic workers, respectively, compared to 0.178 and 0.210 for MA in the same groups, our results suggest that either air measurements or conventional biomarker measurements (urinary MA) would be comparable surrogates for individual exposures in epidemiologic studies.