Determination of 2,5-hexandione by high-performance liquid chromatography after derivatization with dansylhydrazine

A sensitive method for the determination of free and total urinary 2,5-hexandione (2,5-HD) using high-performance liquid chromatography with fluorescence detection was developed. After purification of urine with a disposable C18 cartridge, 2,5-HD was derivatized with dansylhydrazine; 1,3-diacetyl benzene (1,3-DAB) was added to the samples, as internal standard, prior to extraction. The resulting fluorescent adducts were separated on a reversed-phase column with a gradient mobile phase of 25 mM phosphate buffer (pH 6.4) and acetonitrile. The retention times of the 2,5-HD and 1,3-DAB derivatives were 9.4 and 13.7 min, respectively. The derivatives were detected by a fluorescence detector (excitation 340 nm, emission 525 nm). The mean recoveries of 2,5-HD and 1,3-DAB were 92.0 and 94.0%, respectively; the detection limit of 2,5-HD (signal-to-noise ratio of 3) was 5 micrograms/l in urine without hydrolysis and ca. 12 micrograms/l in hydrolyzed samples. The method was applied to 39 urine samples from workers exposed to n-hexane; the mean values were 2.597 mg/l (S.D. = +/- 0.758) for total 2,5-HD and 0.179 mg/l (S.D. = +/- 0.086) for free 2,5-HD. Urine samples of 22 non-exposed subjects showed a mean concentration of 0.437 mg/l (S.D. = +/- 0.109) and 0.022 mg/l (S.D. = +/- 0.011) for total and free 2,5-HD, respectively.

Biological monitoring of occupational exposure to enflurane (ethrane) in operating room personnel

Biological monitoring of occupational exposure to enflurane (ethrane) can be achieved by measuring concentrations of inorganic fluorides in the blood and urine and of enflurane in alveolar air and venous blood. Measurement of these concentrations, however, has limitations. Another method for monitoring exposure to enflurane is to measure its concentration in urine throughout the period of exposure. In this study, we measured the environmental and urinary concentrations of enflurane. Enflurane in the ambient atmosphere was determined in 18 operating theaters of eight hospitals in Italy. Ambient air concentrations exceeded the National Institute for Occupational Safety and Health-recommended time-weighted average exposure level of 1 ppm (median: 1.31 ppm). Enflurane was detected in urine of 159 exposed subjects (anesthetists, surgeons, and nurses). A significant correlation was found between enflurane concentration in urine produced during the shift and environmental concentration (r = 0.77, p = .0001). The results showed that urinary enflurane concentration can be used as an appropriate biological exposure index. The biological values proposed are 153 micrograms/l, corresponding to 75 ppm of environmental exposure; 22 micrograms/l, corresponding to 10 ppm of environmental exposure; and 3.5 micrograms/l, corresponding to 1 ppm of environmental exposure. The proposed values can be regarded as time-weighted average samples, reflecting exposure for a 4-h period.

Drinking habits and occupational exposure to inhalation anesthetics at low doses

The aim of this study was to evaluate certain indicators which are an expression of hepatic (serum aminotransferases activities) and hematologic (erythrocyte mean corpuscular volume) changes among health care personnel exposed to inhalation anaesthetics (nitrous oxide and isoflurane). A total of 172 subjects employed in a single hospital were divided into four groups according to exposure and drinking habits: group (i) non drinkers and unexposed subjects, group (ii) drinkers and unexposed subjects, group (iii) non drinkers and exposed subjects, group (iv) drinkers and exposed subjects. No change in aminotransferases activity or in mean erythrocyte size was detected, which could be regarded as the result of anesthetics exposure. Increased aspartate aminotransferase values among unexposed drinkers were related to alcohol intake. This observation was confirmed by the relationship between AST behaviour and quantitative alcohol intake. Hence, when studying any effect involving functions related to the biotransformation of xenobiotics, in which the liver plays a primary role, the importance of establishing the exact daily amount of ethanol intake is stressed.

Respiratory measurements of occupational exposure to industrial solvents

The authors report the parameters which rule the absorption and elimination of polluting solvent vapours in exposed subjects (ventilation, pulmonary capillary flow, solubility coefficients, environmental concentration, exposure times). These parameters are included in the equations showing the absorption and elimination indexes and lung clearances. The absorption and elimination indexes implied are discussed stressing their practical usefulness in the field of biological monitoring, industrial hygiene and in preventive medicine.

Urinary styrene in the biological monitoring of styrene exposure

The urinary excretion of styrene represents a promising indicator of exposure to this solvent. Nevertheless extensive research under field conditions is scant. In this investigation 214 styrene-exposed workers from 10 fiberglass-reinforced plastics factories were studied. Environmental monitoring was performed by personal passive sampling. Blood styrene and the urinary excretion of styrene and its main metabolites, mandelic acid (MA) and phenylglyoxylic acid (PGA), were measured. The correlation coefficient between the time-weighted average of environmental styrene and the mean urinary excretion of styrene was 0.88 (0.91 after logarithmic transformation), compared with the 0.82 and 0.78 of the end-of-shift MA and PGA values, respectively. A high correlation (0.86) was also found between styrene in the blood and urine. The results, obtained under field conditions with a large group of exposed workers, confirm the usefulness of the urinary excretion of styrene as an exposure index for the biological monitoring of styrene exposure.

Urinary excretion of unmetabolized benzene as an indicator of benzene exposure

Benzene concentrations in urine samples (Cu, ng/L) from 110 workers exposed to benzene in chemical plants and gasoline pumps were determined by injecting urine supernate into a gas chromatograph. The urine was saturated with anhydrous N2SO4 to facilitate the passage of benzene in the air over the urine. The solvent was stripped from the urine surface and concentrated on an adsorbent substrate (Carbotrap tube) by means of a suction pump (flow rate 150 ml/m). Wash-up of the head space was achieved by simultaneous intake of filtered air through charcoal. Benzene was thermically desorbed and injected in a column (thermal tube disorder, Supelco; 370 degrees C thermal flash; borosilicate capillary glass column SPB-1, 60 m length, 0.75 mm ID, 1 microns film thickness; GC Dani 8580-FID). Benzene concentrations in the urine from 40 non-exposed subjects (20 smokers > 20 cigarette/d and 20 nonsmokers) were also determined [median value of 790 ng/L (10.17 nmol/L) and 131 ng/L (1.70 nmol/L), respectively]. The 8-h time-weighted exposure intensity (Cl, micrograms/m3) of individual workers was monitored by means of charcoal tubes. The median value for exposure to benzene was 736 micrograms/m3 (9.42 mumol/m3) [geometric standard deviation (GSD) = 2.99; range 64 micrograms/m3 (0.82 mumol/m3) to 13,387 micrograms/m3) (171.30 mumol/m3)]. The following linear correlation was found between benzene concentrations in urine (Cu, ng/L) and benzene concentrations in the breathing zone (Cl, micrograms/m3): log(Cu) = 0.645 x log(Cl) + 1.399 r = .559, n = 110, p < .0001 With exclusion of workers who smoked from the study, the correlation between air benzene concentration and benzene measured in urine was: log(Cu) = 0.872 x log(Cl) + 0.6 r = .763, n = 63, p < .0001 The study results indicate that the urinary level of benzene is an indicator of occupational exposure to benzene.

Methylene chloride exposure in industrial workers

Methods of environmental and biological monitoring were applied in order to evaluate exposure to methylene chloride in workers operating in a factory where this substance was used as a solvent. For the measurement of methylene chloride in environmental concentration, the ambient air was sampled by using personal passive dosimeters. The activated charcoal was desorbed with CS2 and injected into a gas chromatograph connected with a mass spectrometer. The biological monitoring of exposed workers was performed by determining the concentration of CO in alveolar air (CA, ppm) and methylene chloride in urine (Cu, mu/L). Immediately after the end of the exposure, a urine sample was collected avoiding solvent loss and using gas-tight samplers. Excretion level in urine was determined by using headspace gas chromatography linked to a mass spectrometer. The CO was determined at the end of the shift by using a portable instrument. A group of 20 workers (12 smokers and 8 nonsmokers) in the manufacturing plant were monitored. No significant correlation was observed among the CO of all subjects and the concentration of methylene chloride in ambient air. When those workers who smoked were removed from the analysis, a correlation between the methylene chloride concentration in air and the CO concentration in alveolar air was found. Significant linear correlation was found between the environmental concentration of methylene chloride in the breathing zone and methylene chloride concentration in urine.

[The measurement of a benzene metabolite, urinary S-phenylmercapturic acid (S-PMA), in man by HPLC]

Benzene is a widely used solvent, currently present in the industrial environment at concentrations in the order of ppm. A valid method of biological monitoring that is easy to perform is needed for assessing occupational exposures. Benzene is metabolized in the body by microsomal cytochrome P-450 mono-oxygenase system into benzene epoxide. Benzene epoxide is metabolized along three different pathways which end in the excretion of trans, trans muconic acid, S-phenyl-mercapturic (S-PMA) and different phenols. A new method has been developed to evaluate urinary S-PMA of subjects exposed to benzene. Human urine is acidified with HCl to PH 1 and passed through a Sep-Pak C18 cartridge. The cartridges are washed with diluted HCl and a mixture of water/methanol/acetic acid and then eluted with acidified chloroform. The eluate is dried and reconstituted with a buffer phosphate, then passed through an anionic exchange cartridge (SAX) which is washed with diluted buffer and diluted HCl. S-PMA is recovered by eluting with concentrated buffer and is transformed into S-phenyl-cysteine. Finally, S-phenyl-cysteine is detected by HPLC connected with a fluorescence detector (wavelengths: excitation 330 nm, emission 440 nm) after derivatization with o-phthalaldehyde (OPA) and 2-mercapto-ethanol (MCE). The detection limit of the method is about 0.5 micrograms/l, the recovery of S-PMA is 90.0% and the variation coefficient is 3.8%. The method was checked on urine samples of 8 male non-smokers and 10 smokers: median values of 1.3 and 9.2 micrograms/g creatinine respectively of S-PMA were obtained. A further analysis on urine samples of 66 occupationally exposed workers (smokers and non-smokers) revealed a median value of S-PMA of 46.6 micrograms/g creatinine, compared with a median environmental benzene exposure of 1.99 mg/m3. These results suggest that S-PMA can be regarded in the future as a useful indicator for monitoring individual and collective low-level benzene exposure.

On the need of a sampling strategy in biological monitoring: the example of hexane exposure

Ambient and biological monitoring of hexane exposure were repeatedly carried out in 14 female shoe makers. Airborne hexane (Ci-H) was measured in 4-h samples collected by a diffusive method. Urinary spot samples were collected before, during (at noon), and at the end of a work shift. 2,5-Hexanedione (2,5HD) in urine collected at noon was poorly related to morning Ci-H. End-of-shift 2,5HD were also poorly related to afternoon air samples. The correlation was still relatively low when end-of-shift 2,5HD was related to 8-h TWA Ci-H (r = 0.44; P < 0.01 on a linear scale, and r = 0.58, P < 0.01 on a log-log scale). End-of-shift 2,5HD levels estimated on the basis of pre-shift values using a mathematical model were much higher (2.3 times on average) than those experimentally measured during the study period. Owing to its relatively long half-time, 2,5HD seems to be influenced not only by current exposure, but also by hexane absorbed during the day(s) preceding sampling. The lack of a sampling strategy may account not only for inconsistencies between environmental and biological data, but also for a possible misuse of biological monitoring when utilized for risk assessment. Despite sometimes poor correlations with Ci-H, 2,5HD may still be preferred to other indicators as a marker of effective internal dose. A sampling strategy should ensure that measured values are representative of the individual risk for adverse effects.

[Evaluation of several neuropsychological parameters in subjects occupationally exposed to anesthetics]

51 workers, occupationally exposed to anaesthetic gases and vapours (nitrous oxide, halothane, and isoflurane), were studied monitoring their environmental and biological exposure. Moreover, they were tested for visual reaction times and neurobehavioural batteries. There was no evidence of important neurotoxic effects nor of neurobehavioural problems with low concentrations of anaesthetics.

[Measurements and environmental and biological monitoring of occupational exposure to inhalation anesthetics]

This paper reports the data of nitrous oxide (N2O) environmental pollution in 269 operating rooms of 47 hospitals in Italy in 1989-91. In 40% of the operating rooms the N2O concentrations are lower than 50 ppm, limit value proposed by Health Council for new operating rooms. In 65.4% of the operating room studied, N2O mean environmental concentrations are lower than 100 ppm, value proposed by the above-mentioned Health Council as limit value for the already existing operating rooms. Concerning the biological monitoring, the authors report several N2O data in urine (2193), whose levels confirm the data obtained with environmental monitoring. The authors believe that they presently have reliable methods to perform biological and environmental monitoring: the two techniques are complementary in the assessment of the exposure. The method of measuring N2O concentrations as exposure index, both for the environmental and biological monitoring, is considered very useful to simplify the performance of the analyses. In order to assess exposure more precisely, it is however necessary also to determine the environmental and/or biological measure of the other different anaesthetics used.

Acquired dyschromatopsia among styrene-exposed workers

We investigated the occurrence of color vision loss in 75 styrene-exposed workers and in 60 referents. Color vision was evaluated by adopting the Lanthony D 15 desaturated panel, a test specifically suited to detect mild acquired dyschromatopsia. The results of the test were expressed as Color Confusion Index. Styrene exposure was evaluated with both environmental and biological monitoring. Airborne levels of the solvent were 3.2 to 549.5 mg/m3. In styrene-exposed workers color vision was significantly impaired when compared with referents matched for age. A significative correlation was found between environmental and urinary levels of styrene and Color Confusion Index excluding the influence of age in multiple regression analysis, indicating the possibility of a dose-effect relationship. The findings suggest that styrene can induce an early appearance of a dose-dependent color vision loss.

Biological monitoring of the occupational exposure to halothane (fluothane) in operating room personnel

The concentration of halothane (fluothane) in the ambient atmosphere was determined in five operating theaters of two hospitals in Italy. The concentrations of halothane in the ambient air exceeded the NIOSH recommended time-weighted average exposure levels (median value: 10.38 mg/m3). Halothane was detected in the urine of 58 exposed subjects (anesthetists, surgeons, and nurses). A significant correlation was found between the halothane concentration in urine produced during the shift (Cu, micrograms/L) and halothane environmental concentration (CI, mg/m3) (Cu = 0.242 x CI + 3.51) (N = 58; r = 0.92; p less than 0.0001). The results show that the urinary halothane concentration can be used as an appropriate biological exposure index. The biological values proposed are: 92 micrograms/L, corresponding to a 50 ppm of environmental exposure; 6.5 micrograms/L, corresponding to 2 ppm of environmental exposure and 3.9 micrograms/L, corresponding to a 0.5 ppm of environmental exposure.

1,2-Dichloropropane hepatotoxicity in rats after inhalation exposure

The hepatic effects of 1,2-dichloropropane (DCP) were investigated in male Wistar rats exposed to 15, 50, 100, 250, 450, 1000, 1300, 1800 or 4900 mg DCP m-3. At the end of a 4-h period of exposure, average blood DCP levels were 0.025 and 5.38 micrograms ml-1 in animals treated with 15 and 1300 mg m-3, respectively. Blood DCP concentrations were correlated with the air DCP concentrations in the inhalation chamber. At DCP concentrations of 100 mg m-3 or higher, the liver non-protein thiol (NPT) content was significantly reduced. Assays performed 20 h after 4-h DCP exposure showed that exposure to 100-1000 mg DCP m-3 had no effect on hepatic NPT levels. The NPT content increased only in the liver of rats exposed to higher (1300-4900 mg m-3) DCP concentrations. Treatment with DCP did not cause hepatic lipid peroxidation and did not modify total protein content. The observed changes in liver cell thiol homeostasis are likely to reflect the action of reactive intermediates formed during DCP metabolism. These changes can occur in rats following exposure to considerably low levels of DCP vapour.

[A method for measuring urinary concentrations of benzene. Its use in monitoring of subjects exposed to low levels]

Benzene is a widely diffuse solvent (atmosphere, cigarette smoke, some foods); in the industrial environment benzene is currently present at concentrations of ppm. A valid method of biological monitoring that is easy to perform is needed for assessing occupational and non-occupational exposures. A new method has been developed to evaluate low concentrations of benzene in urine samples by means of a "dynamic" headspace (50 ml of urine in a 120 ml vial). The urine is saturated with anhydrous Na2SO4 in order to support the entrance of benzene in the air over the urine. The solvent is stripped from the urine surface and concentrated on an adsorbent substrate (Carbotrap 100 tube) by means of a suction pump (150 ml/min). A simultaneous intake of filtered air through a charcoal tube allows wash-up of the headspace. Benzene is thermically desorbed and injected in a column (Thermal tube desorber-Supelco; 370 degrees C thermal flash; borosilicate capillary glass column SPB-1 60 m length, 0.75 mm I.D., 1 micron film thickness; G.C. Dani 8580-FID). The detection limit of the method is about 50 ng/l and the variation coefficient is 4.7%. The method was checked on urine samples of 5 non-smokers and 5 smokers: mean values of 135 and 944 ng/l respectively were obtained. A further analysis on urine samples of 60 smokers revealed a significant relationship (p less than 0.001) between urinary benzene concentrations and C0 alveolar concentrations (r = 0.626). A close relationship between benzene exposure levels and urinary concentrations was found in a group of workers exposed to low environmental benzene concentrations (mean value 1200 micrograms/m3) (r = 0.763).

Methyl ethyl ketone (MEK) in urine as biological index of exposure

Fifteen human volunteers were exposed to methyl ethyl ketone (MEK) vapor at 11.9-621.8 mg/m3 for a period of 2 to 4 hours at rest (ten cases) and during light physical exercise (five cases). Subsequently 78 workers occupationally exposed to MEK in a manufacture of leather suitcases (median value: 75.5 mg/m3; geometrical standard deviation: 3.12 mg/m3; range: 6-790) were studied. The analyses were performed by means of a Gas Chromatograph (GC) Hewlett-Packard 5880 A connected with a Mass Selective Detector (MSD). The relative uptake (R) of MEK was about 0.54 (standard deviation: 0.05) and it keeps practically constant either at rest or during light effort (V < 30 L/min). A linear relationship existed in the experimentally exposed subjects between urinary concentration (Cu) and amount of MEK absorbed (U) (Cu = 3.05 x U-162.1; r = 0.95; n = 15) (Cu = micrograms/L; U = mg). Both in the experimentally exposed subjects and in the occupationally exposed workers, the urinary concentration of MEK shoved a linear relationship to the corresponding environmental time-weighted average concentration (CI). The correlation coefficients (r) were 0.93 in occupationally exposed subjects (regression equation: Cu = 0.004 x CI + 0.118; n = 78); Cu = mg/L; CI = mg/m3) and more than 0.93 in experimentally exposed groups. The findings indicate that the urinary concentration of MEK can be used as an appropriate biological exposure indicator.(ABSTRACT TRUNCATED AT 250 WORDS)

[Biological limits of exposure: evolution of interpretative and methodologic criteria]

Biological monitoring is an extremely efficient investigation tool in evaluation of exposure to exogenous substances, in both occupational and environmental settings. However, although biological tests have been widely acclaimed as the ideal approach to or as a completion of environmental measurements, they have had difficulty in becoming firmly established due to a number of limitations of various nature. Besides the numerous uncertainties in the set-up phase, which depend on the choice of indicators or criteria for their use, difficulties are still incurred in making a univocal interpretation of the results. These difficulties are due to the limited pharmaco-kinetic information available on the various substances and to the wide variability in individual biological response. The possibility of extrapolating Biological Exposure Limits (BELs) from the corresponding TLV-TWA, by means of calculations based on the experimental regressions observed between internal and external dose indices, has up to now been considered a dubious operation from a formal point of view and merely indicative for practical purposes. This paper examines the possibility of establishing BELs that are fixed taking account of the influence of the various biological variables, thus permitting a more correct, objective and generalised use of biological indicators in current practice. From the regression function and relative tolerance limits, intended as a range of values within which regression values can be expected to be found with a probability that can be fixed a priori, it is possible to calculate 3 BEL values for each environmental TLV-TWA concentration. The question of which of these different values should be selected as a BEL for practical purposes must be solved on the basis of a series of observations related to the type of investigation being performed and the context in which the results are to be used. It should be emphasized that each BEL value has its own particular sensitivity and specificity, i.e., the possibility of correctly classifying the exposure conditions in relation to the environmental values. If sensitivity and specificity values are known, it is possible to calculate the predictive value of the biological measurements compared to the environmental measurements; if numerical data on these parameters are available, account can be taken of the variability of the results in a rigourously scientific manner.(ABSTRACT TRUNCATED AT 400 WORDS)

[Biological monitoring of occupational exposure to airborne pollutants]

Biological monitoring of inert substances requires knowledge of the mechanisms regulating respiratory absorption. The authors examine the influence of parameters such as work load, exposure duration and biotransformation on the respiratory absorption of inert airborne pollutants in the workplace. Attention is also given to the possibility of using biological thresholds or Biological Equivalent Limits (BELs).

Evaluation of exposure to isoflurane (Forane): environmental and biological measurements in operating room personnel

The concentration of isoflurane (Forane) in the ambient atmosphere was determined in 11 operating theaters of 5 hospitals in Italy. The concentration of isoflurane in the ambient air exceeds the recommended time-weighted average exposure levels (median value: 113 mumol/m3). Isoflurane was detected in the urine of 45 exposed subjects (anesthetists, surgeons, and nurses). A significant correlation was found between the isoflurane concentration in urine produced during the shift (Cu' nmol/l) and isoflurane environmental concentration (Cl' mumol/m3) (Cu = 0.243 X Cl + 3.712) (r = .90). The results show that the urinary isoflurane concentration can be used as an appropriate biological exposure index. The authors suggest a biological exposure index of 18 nmol/l (3.4 micrograms/l). This is the biological value obtained after 4 h of an average environmental exposure to 81 mumol/m3 (2 ppm).

Urinary concentration, environmental concentration, and respiratory uptake of some solvents: effect of the work load

The physical demands of the workplace differ depending on specific jobs. This implies that workers exposed to the same environmental level of an airborne contaminant can absorb different amounts of it depending on their pulmonary ventilation. Starting from the relationship between the uptake (U) and the urinary concentration of six solvents (Cu) (acetone, styrene, toluene, xylenes, methylchloroform, tetrachloroethylene) and from the equation expressing their lung uptake (U = K.V.CI.R.T) the expected values of a biological index after a given time of exposure can be derived. Such values are a function not only of the environmental level of exposure (CI) but also of the pulmonary ventilation (V - dependent solvent) and of the retention index (R) (V - R dependent solvent).

Urinary excretion of tetrachloroethylene (perchloroethylene) in experimental and occupational exposure

Fifteen human volunteers were exposed to tetrachloroethylene (perchloroethylene, tetrachloroethene) vapor at 3.6-316 mg/m3 for 2-4 hr at rest (10 cases) and during light physical exercise (5 cases). Subsequently, 55 workers who were occupationally exposed to tetrachloroethylene in eight commercial dry cleaning facilities were studied (median value, 66 mg/m3; geometric standard deviation, 3.15 mg/m3). In both the experimentally exposed subjects and occupationally exposed workers the urinary concentration of tetrachloroethylene showed a linear relationship to the corresponding environmental time-weighted average concentration. The findings indicate that the urinary concentration of tetrachloroethylene can be used as an appropriate biological exposure indicator. In occupationally exposed subjects performing moderate work, the urinary tetrachloroethylene concentration corresponding to the time-weighted average of the threshold limit value proved to be 120 mcg/L and its 95% lower confidence limit (biological threshold) 100 mcg/L. The effects of workload on the tetrachloroethylene urinary elimination are also accounted for.

[Personal diffusive samplers: evaluation of the optimal sampling time]

A simple programme in basic language is formulated, which can be used with a personal computer, to evaluate the minimum and maximum sampling time of personal passive samplers at given concentrations of solvents. It is possible to evaluate also the sampler's response time to the peak concentration of the solvent and, once an arbitrary sampling time has been chosen, it is possible to know the concentration range to get exact determinations.

[HPLC determination of low concentrations of benzene]

A laboratory study, using generated atmosphere containing 0.14/23.3 mg/m3 of Benzene, was conducted to adapt an existing industrial hygiene monitoring method for measuring low concentrations of Benzene. This method was developed to determine concentrations of Benzene in the ambient air and around refinery/petrochemical plant. The air sample is collected on a diffusive personal sampler (Zambelli-TK 200) and analyzed by desorption with a mixture of methylene chloride and ethyl acetate followed by quantification using HPLC-Fluorescence detector. The method used did not detect aliphatic or alicyclic hydrocarbons. The HPLC-Fluorescence method is compared with a gas chromatographic method that uses capillary column and flame ionization detection after a collection of air sample on a Carbotrap 100 tube and following thermal desorption.