Saliva as an analytical tool to measure occupational exposure to toluene.

OBJECTIVE: To describe a sensitive and rapid method for the determination of toluene in saliva. Biomonitoring of toluene exposure is commonly performed by determination of urinary hippuric acid, o-cresol or toluene itself. The analysis of blood toluene has been verified as another method for biomonitoring. However, drawing blood is invasive and can often not be performed at the workplace for hygienic reasons. Sampling of saliva may be non-invasive, easy to perform and a viable alternative for biomonitoring in the workplace. METHODS: We measured the solvent concentration in saliva specimens of 5 healthy volunteers studied in the laboratory and a group of 36 workers exposed to toluene in the synthetic leather industry. Saliva was collected into Salivette (Sarstedt, Germany) devices by sterile cotton rolls placed in the mouth and then squeezed into pre-weighted vials. Environmental toluene was collected for the duration of a work-shift by Radiello (FSM, Italy) passive samplers. Toluene in urine and saliva (head space analysis) and in environmental samples was measured by GC-MS. RESULTS: Environmental toluene levels ranged from 0.22 to 57.20 mg/m(3), while the concentrations of the solvent in saliva and urine ranged from 0.12 to 18.30 microg/L, and from 0.47 to 26.64 microg/L, respectively. The correlation coefficients (r) between biological and environmental levels of toluene were 0.77 and 0.93, respectively, for saliva and urine samples. CONCLUSION: This preliminary study suggests that saliva may offer many advantages over 'classical' biological fluids such as blood as it is readily accessible and collectible: therefore saliva toluene may be considered as a possible biomarker of exposure to toluene.

[Characteristics, use and toxicity of fluorochemicals: review of the literature]. / Caratteristiche, uso e tossicità dei fluorurati: revisione della letteratura.

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are perfluorinated surfactants used to produce polymers and telomers whose carbon chain can be differently long. Polytetrafluoroethylene (PTFE), namely Teflon, is the chief fluoropolymer and it has been widely utilised over the last decades and all over the world. Indeed, its particular physical and chemical properties make it difficult to replace this substance in several industries (textile, paper, chemical, fire-fighting foam industry). Perfluoroalkyl-compounds may be considered ubiquitous and, in particular, it has been shown that PFOS may be concentrated in the food chain. Concerns about possible toxic effects of these chemicals date back to seventies, but only in 2000 the Environmental Protection Agency (EPA) stated PFOA and PFOS withdrawal to avoid environmental pollution. In 2002 the Organisation for Economic Co-operation and Development reported that these substances are bio-persistent, tend to accumulate in different tissues of living organisms and are toxic to mammalians. In 2006 EPA established that every PFOA emission will be eliminated not later than 2015. Actually, health effects of perfluoroalkyl-compounds on humans remain controversial, in spite of a number of experimental and epidemiological studies. Research focuses on possible endocrine disruption, thyroid and liver carcinogenicity, and development alteration. Our article reviews the main studies concerning PFOS and PFOA industrial and environmental toxicology.

[Recent prevention strategies and occupational risk analysis: Control Banding and Sobane]. / Recenti strategie per la prevenzione e l'analisi dei rischi in ambito occupazionale: Control banding e Sobane.

Employers are responsible for the prevention of risks and must provide for the safety and health of their workers. They are obliged to apply the general principles of prevention: to avoid, where possible, any risk; to characterize and hence to estimate residual risks; to eliminate risks at the source; to adjust jobs to the needs of workers and not workers to the jobs. When we pass to the practical performance of these shared principles we introduce many problems: problems concerning terminology; problems in estimating the nature of the risks that are faced; coordination problems between the subjects that preside over prevention; problems arising from the different typology of the companies investigated In order to answer these questions the "Industrial Hygienists" have long since created various strategies for the prevention and control of risks. Among different models the methods Control Banding and Sobane-Deparis are undoubtedly the most promising. Control Banding is designed to assist especially Small and Medium Enterprises in complying with the chemical safety regulations, the scheme uses the R phrases that in Europe must be assigned to potentially harmful chemicals by the manufacturer of the chemical. R phrases describe the most important harmful effects of a chemical and have been adopted in many non European countries also. The combination of the hazard classification of the chemical and assessment of the exposure potential will allow understanding of the level of risk thus leading the person carrying out the assessment to an appropriate control method. Occupational hygienists with experience of assessing occupational exposure to chemicals agreed parameters that could be used to give reasonable indications of exposure potential. One of them is quantity being used and three categories--small, medium and large--are defined. The likelihood of the chemical becoming airborne has been addressed by defining solids according to levels of dustiness and liquids according to volatility. A simple graph that uses the boiling point of the chemical and the process operating temperature assigns the chemical a high, medium or low volatility rating. The user now has enough information to identify the control approach required to adequately reduce exposures to the chemical Occupational hygienists agreed on three broad control approaches: General Ventilation; Engineering Control; Containment. However it is recognised that in some cases specialist advice will be needed. The user takes the hazard group, quantity and level of dustiness/volatility and matches them to a control approach using a simple table. The controls are described in control guidance sheets, which comprise both general information and, for commonly performed tasks, more specific advice. The second section of the document describes a risk-prevention strategy, called SOBANE, in four levels. These four levels are: screening, where the risk factors are detected by the workers and their management, and obvious solutions are implemented; observation, where the remaining problems are studied in more detail, one by one, and the reasons and the solutions are discussed in detail; analysis, where, when necessary, an occupational health (OH) practitioner is called upon to carry out appropriate measurements to develop specific solutions; expertise, where, in very sophisticated and rare cases, the assistance of an expert is called upon to solve a particular problem. The method for the participatory screening of the risks, Deparis, is proposed for the first level screening of the SOBANE strategy. The aim of Sobane strategy is to make risk prevention faster, more cost effective, and more effective in coordinating the contributions of the workers themselves, their management, the internal and external OH practitioners and the experts.

[The significance of enviromental and biological monitoring in workers employed in service stations after the elimitation of tetraethyl lead from gasoline]. / Il significato del monitoraggio ambientale e biologico nei lavoratori addetti alle stazioni di servizio dopo la eliminazione del piombo tetraetile dalle benzine.

The chemical risk in service stations may be due to toxic compounds present in fuel (particularly benzene and additives) and to the emission of exhausts and fine particulate from vehicles. Owing to the elimination of lead (Pb) from fuel and to the necessity of lowering CO emission, several oxygenated additives have been added to fuel, in particular methyl-tert-butyl-ether (MTBE), whose toxic properties are at present under investigation. The introduction of reformulated gasoline (RFG) and the use of catalytic converters (with possible release of platinum (Pt) in the environment) may have modified the risks for workers employed in service stations. The paper shows data collected from 26 subjects (divided into three specific tasks, namely: fuel dispenser, "self-service" attendant and controller, and cashier) to estimate the actual chemical risk and to compare it with the previous data taken from literature. For this purpose, besides performing the usual medical surveillance, we measured the environmental concentrations of benzene, MTBE and formaldehyde, the urinary levels of benzene metabolites S-phenylmercapturic acid (S-PMA) and t,t-muconic acid (MA) and of unmodified MTBE, and the blood concentrations of Pb and Pt for each subject. Mean values of these compounds were, respectively: 38.81 microg/m3; 174.04 microg/m3; 10.38 microg/m3; 2.36 microg/g creatinine; 96.57 microg/g creatinine; 1.41 microg/L; 7.00 microg/100 mL; 0.0738 ng/ml. The above values were much lower than the corresponding limit values reported by ACGIH and DFG. In particular, after the introduction of vapour recycle systems and the widespread use of "self-service" systems, airborne benzene concentration dropped from 300/400 microg/m3 to lower than 100 microg/m3, without noticeable increasing of exposure to formaldehyde. The disappearing of Pb from gasoline leads to a progressive lowering of its blood levels, while the possible risks due to the very low amounts of Pt released from catalytic converters have still to be defined exactly. Taken all in all, our results seem to indicate that, after the elimination of tetraethyl lead, the chemical risk for workers employed in service stations is now lower than in the past.

[Indoor air quality in an Italian military submarine]. / Qualità dell'aria in una nave sommergibile della marina militare Italiana in condizioni operative.

In recent years there has been increasing interest on studies concerning indoor air quality and focusing on risk factors for exposed subjects. Particularly, airborne chemicals, whose adverse effects are well known, have been identified and determined in means of transport as in other indoor places. As concerns chemical air concentrations in submarines, only a limited number of studies have been published. This paper reports measured concentration data for organic compounds (total volatile organic compounds, substances with a chemical bond S-O, nitrogen compounds, carbon monoxide, carbon dioxide, and different organic solvents) in the air sampled during an 8-h period in an Italian Military submarine, under routine operations. We observed that a periodicalfresh-air intake operation (snorkel) might cause temporary increase of contaminants levels in indoor air. Moreover, we could find that pollutants sometimes reach notable peak concentrations being potentially able to induce adverse health effects in crewmembers. Our data highlight the need to promote further investigations.

Genetic polymorphisms influence variability in benzene metabolism in humans.

The role of genetic polymorphism in modulating urinary excretion of two benzene metabolites, i.e. trans,trans-muconic acid (t,t-MA) and S-phenylmercapturic acid (PMA), has been investigated in 59 non-smoking city bus drivers, professionally exposed to benzene via vehicle exhausts. Exposure to benzene was determined by personal passive samplers (mean +/- SD = 82.2 +/- 25.6 micrograms/m3), while internal dose and metabolic rate were evaluated by measuring urinary excretion of unmodified benzene (mean +/- SD = 361 +/- 246 ng/l), t,t-MA (mean +/- SD = 602 +/- 625 micrograms/g creatinine), and PMA (mean +/- SD = 5.88 +/- 4.76 micrograms/g creatinine). Genetic polymorphism at six loci encoding cytochrome-P450-dependent monooxygenases (CYP2E1 and CYP2D6), glutathione-S-transferases (GSTT1, GSTP1 and GSTM1) and NAD(P)H:quinone oxidoreductase (NQOR) was determined by polymerase chain reaction-based methods. No evidence emerged for a possible role of CYP2E1, GSTM1 and GSTP1 polymorphisms in determining the wide differences observed in the rate of benzene biotransformation. Conversely, a significantly higher t,t-MA urinary excretion was found to be correlated to, GSTT1 null genotype, and a significantly lower PMA excretion was detected in the subjects lacking NQOR activity and in the CYP2D6 extensive-metabolizers. Many biological (i.e. age and body burden) or lifestyle factors (i.e. rural or urban residence, use of paints and solvents, medication, alcohol and coffee intake), also taken into account as potential confounders, did not influence the correlations found. These findings suggest that CYP2D6, GSTT1 and NQOR polymorphisms contribute in explaining the metabolic variability observed in our sample. Therefore, these polymorphisms should be regarded as potential risk factors for benzene-induced adverse health effects.

Determination of S-phenylmercapturic acid in urine as an indicator of exposure to benzene.

S-phenylmercapturic acid (S-PMA) was measured in urine from 145 subjects exposed to low benzene concentrations in the air (C(I), benzene). The 8-h, time-weighted exposure intensity of individual workers was monitored by means of charcoal tubes and subsequent gas-chromatographic analysis after desorption with CS2. S-PMA excretion level in urine was determined by high-performance liquid chromatography with fluorescence detection. The following linear correlation was found between S-PMA concentrations in urine and benzene concentrations in the breathing zone: log(S-PMA, microg/g creatinine) = 0.712 log (C(I)-benzene, ppm) + 1.644 (n = 145, r = 0.74, P < 0.001). The geometric mean (GSD) of S-PMA concentrations in urine from 45 subjects occupationally not exposed to benzene but smoking more than 20 cigarettes/day was 7.8 microg/g creatinine (2.11), the corresponding value among non-smokers being 1.0 microg/g creatinine (2.18). It is concluded that the urinary level of S-PMA can be regarded as a useful indicator of exposure to benzene.

Metabolic polymorphisms and urinary biomarkers in subjects with low benzene exposure.

The effect of some common metabolic polymorphisms on the rate of trans,trans-muconic acid (TMA) and S-phenylmercapturic acid (SPMA) excretion was investigated in 169 policemen exposed to low benzene levels (<10 microg/m3) during the work shift. End-shift urinary concentrations of TMA and SPMA, normalized to unmetabolized blood benzene concentration, were used as indicators of individual metabolic capacity. CYP2E1, NQO1, GSTM1, and CSTT1 polymorphisms were analyzed in all subjects by polymerase chain reaction (PCR) restriction fragment length (RFL). The results obtained show significantly elevated levels of TMA and SPMA in urine of smokers compared to nonsmokers, whereas no correlation with environmental benzene was observed. TMA/blood benzene ratio was partially modulated by glutathione S-transferase (GST) genotypes, with significantly higher values in null individuals (GSTM1 and GSTT1 combined). However, a greater fraction of total variance of TMA/blood benzene in the study population was explained by other independent variables, that is, season of sampling, smoking habits, and gender. Variance in SPMA/blood benzene ratio was only associated with smoking and occupation, whereas no significant role was observed for the metabolic polymorphisms considered. These results suggest that in a population exposed to very low benzene concentrations, urinary TMA and SPMA levels are affected to a limited extent by metabolic polymorphisms, whereas other factors, such as gender, lifestyle, or other confounders, may account for a larger fraction of the interindividual variability of these biomarkers.

Urinary elimination of styrene in experimental and occupational exposure.

Twenty human volunteers were exposed to styrene vapor at 273-1 654 mumol/m3 (28.4-172.3 mg/m3) for a period of 1 to 3 h at rest (15 cases) and during light physical exercise (5 cases). Subsequently 51 workers occupationally exposed to styrene were studied during a workweek (median value 1 138 mumol/m3, geometric standard deviation 2.23). As expected, the relative uptake averaged about 65%, and the ratio of the alveolar concentration to the time-weighted average of the environmental concentration averaged about 0.15. Both in the experimentally exposed subjects and in the occupationally exposed workers the urinary styrene concentration showed a linear relationship to the corresponding environmental time-weighted average concentration. The correlation coefficients of the regression lines ranged between 0.88 (occupationally exposed group) and more than 0.93 (experimentally exposed groups). The regression coefficients were closely linked to the amount of styrene taken up and to the exposure times. The findings show that the urinary styrene concentration can be used as an appropriate biological exposure indicator whose meaning differs from that of other suggested indices. As an example, in occupationally exposed subjects performing moderate work the urinary styrene concentration corresponding to the time-weighted average of the threshold limit value is 815 nmol/l, and the 95% lower confidence limit (biological threshold) is 740 nmol/l.

Urinary elimination of acetone in experimental and occupational exposure.

Fifteen volunteers were exposed to an acetone vapor concentration of 964-8, 610 mumol/m3 (56-500 mg/m3) for 2-4 h in an exposure chamber. Ten subjects were at rest during the exposure, and five were exposed at alternate rest and light physical exercise. Subsequently 104 workers occupationally exposed to acetone were studied. The relative uptake averaged about 53%, and the ratio of the alveolar concentration to the environmental concentration averaged about 0.28. Both for the experimentally exposed subjects and the occupationally exposed workers the urinary acetone concentration showed a linear relationship to the corresponding environmental time-weighted average concentration. A linear equation also existed between urinary concentrations and the amounts of acetone absorbed. The findings enable a consideration of the urinary concentration of the unaltered acetone as an appropriate exposure indicator and the proposal of a "biological equivalent threshold" to be used in the field of biological monitoring.

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.

The urinary excretion of solvents and gases for the biological monitoring of occupational exposure: a review.

'In the field' application of the measurement of urinary excretion of unmodified solvent for the biological monitoring of exposed workers has been investigated in many recent papers. The results obtained for several solvents are reviewed. The values of correlation coefficients (r) and regression lines obtained for benzene, toluene, xylene, styrene, n-hexane, cyclohexane, 2- and 3-methylpentane, methyl chloride, tetrachloroethylene, carbon tetrachloride, methyl chloroform, p-dichlorobenzene, nitrous oxide, halothane, isoflurane, enflurane, acetone, methyl ethyl ketone and methyl isobutyl ketone are presented. The correlations observed were generally good: r values range from 0.50-0.97, and the majority are between 0.84 and 0.90. The regression lines reported for the same solvent in different studies present some variability: this is possibly due to an inadequate control of factors influencing the relationship between external dose and absorption, such as differences in body burden, work load, individual characteristics, etc. These factors are discussed. As a whole, results reported in the literature show that measuring of urinary excretion of unmodified solvents provides a highly sensitive and specific exposure index, and can also be applied for the biological monitoring of occupational exposure to low levels of solvents or to solvent mixtures. Nevertheless, for an adequate assessment of biological limit values, further studies evaluating the reproducibility of regression lines are needed, given that the aspects influencing the correlation between external dose and urinary excretion are fully controlled. Another crucial aspect is the correlation with early effects: even though this has yet to be evaluated for several solvents, for others such as styrene and perchloroethylene a good correlation was obtained, further supporting the usefulness of the measurement of urinary excretion of solvent for the biological monitoring of occupational exposure.

Excretion of N-acetyl-S-(1-phenyl-2-hydroxyethyl)-cysteine and N-acetyl-S-(2-phenyl-2-hydroxyethyl)-cysteine in workers exposed to styrene.

Styrene (S) has been shown to be responsible for neurotoxic effects, including behavioural changes and neuroendocrine disturbances. The initial step of S metabolism is conversion to styrene 7,8-epoxide (SO), which is present in two enantiomeric forms [(R)(+)-SO and (S)(-)-SO]; this electrophilic intermediate is considered to be directly responsible for most toxic effects of S. The major urinary metabolites derived from the biotransformation of SO in man are mandelic acid (MA) and phenylglyoxylic acid (PGA). In rats an alternative pathway has been demonstrated, which involves the conjugation of SO to glutathione (GSH), leading to the excretion of two specific mercapturic acids, N-acetyl-S-(-(1-phenyl-2-hydroxyethyl)-cysteine [M1] and N-acetyl-S-(2-phenyl-2-hydroxy-ethyl)-cysteine [M2]; a close relationship has been found between exposure to S and urinary excretion of M1 and M2 in rats. As a consequence of the chiral nature of SO, both M1 and M2 consist of two diastereoisomers (M1-'R', M1-'S', M2-'R' and M2-'S'). Early reports have shown that the conversion of S to mercapturic acids is much lower in man (below 1% of the absorbed dose) than in rats (about 10%). We propose an analytical method for the determination of urinary M1 and M2 in man, which involves a urine clean-up by a chromatographic technique with a short reversed-phase pre-column; purified samples are then deacetylated with porcine acylase and deproteinized by centrifugal ultrafiltration. A derivatization is then performed with o-phthaldialdehyde and 2-mercaptoethanol and the fluorescent derivatives are separated on a reversed-phase analytical column. The mobile phase consists of acetate buffer and methanol mixed at variable proportions, the fluorescence detector is set at 330 nm (exc.) and 440 nm (em.). M1-'S' and M1-'R' are separated (retention times = 52.8 and 73.7 min, respectively) while the diastereoisomers of M2 coelute as a single peak at 70.5 min. The detection limit is about 7 micrograms/l, the coefficients of variation are below 7% and the error percentages are less than 6%. The method was applied to 25 urine samples from workers exposed to S: significant correlations were found between mercapturic acids and MA and PGA, the best correlation being between M2 and PGA (r = 0.79). Urine samples form unexposed subjects showed no detectable amounts of the analytes. A high stereoselectivity is shown by the enzymes involved in the metabolism of S to mercapturic acids: M1-'S', which derives from (S)-SO, is excreted in much higher amounts than M1-'R', which derives from (R)-SO.

Determination of specific mercapturic acids as an index of exposure to environmental benzene, toluene, and styrene.

Methods were developed for the determination of urinary phenylmercapturic acid (PMA), a metabolite specific for benzene, benzylmercapturic acid (BMA), a metabolite of toluene and phenylhydroxyethylmercapturic acids (PHEMAs), specific for styrene, in human beings. Methods involved sample clean up followed by deacetylation and derivatization of the compounds with o-phthaldialdehyde and 2-mercaptoethanol. The fluorescent derivatives were separated on reversed-phase columns with gradient runs and detected by a fluorescence detector. The detection limits were 0.5 microgram/l for PMA and BMA, and 7 micrograms/l for PHEMAs. The background levels of PMA were higher in smokers than in nonsmokers, while no difference was found in the levels of BMA and PHEMAs. Coexposure to ethanol enanched the excretion of BMA in subjects experimentally exposed to toluene. Correlations were found between environmental benzene (r = 0.74, log transformed data), toluene (r = 0.74) or styrene (r = 0.56) and specific mercapturic acids in workers. The usefulness of PMA, BMA and PHEMAs as biomarkers is critically evaluated.

Acetone in urine as biological index of occupational exposure to isopropyl alcohol.

In order to investigate a role of acetone in urine (AcU, mg/l) as an indicator of occupational exposure to isopropyl alcohol (IPA, ppm), AcU was measured in 80 male workers exposed to this substance in a plastic factory. The exposure concentration of solvent was also monitored personal diffusive sampling in the individuals during morning 4-hr shift. Urine samples were collected near the end of the shift and were analyzed for acetone by head-space gas chromatography. The correlation between airbornre concentration of IPA and its urinary metabolite acetone was significant: AcU (mg/l) = 0.031 x IPA (ppm) + 0.608, r = 0.75, n = 80, P < 0.001. We established 44 ppm as the lowest airborne concentration of IPA that caused excessive urinary excretion of acetone which could be discriminated from the endogenous production of acetone in non-exposed people. This concentration was as low as one ninth to one tenth of the current exposure limit of 400 ppm. At higher concentrations than 44 ppm, AcU was found to be a useful index for monitoring occupational exposure to IPA.

Trichloroethylene in urine as biological exposure index.

Occupational exposure to trichloroethylene (TRI) was studied by analysis of environmental air and urine from 49 workers operating in a special printing house on glass. For the measurement of environmental concentration of TRI (Cenv), the ambient air was sampled using personal passive dosimeters. The activated charcoal was desorbed with carbon disulfide and injected into a gas-cromatograph - mass spectrometer (GC-MSD). The biological monitoring of exposed workers was conducted by determining the concentration of TRI in urine (Curine) Urine concentration of TRI was determined by headspace analysis using GC-MSD. Significant correlation was found between the environmental TRI concentration and urinary TRI concentration. The use of a regression equation between Curine (microg/l) and Cenv (mg/m3) (Curine = 0.081 x Cenv + 4.27) resulted in a value of Curine corresponding to Threshold Limit Value-Time Weighted Average (TLV-TWA) exposure value (269 mg/m3) of 26.0 microg/L.

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.

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.

Effects of dimethylformamide (DMF) on coagulation and platelet activity.

The effects of dimethylformamide (DMF) on hemostatic functions, especially on platelet activity, were examined both in vitro and in vivo in 15 workers exposed to DMF (27 mg/m3, median value). Twenty-eight control subjects who were not exposed to DMF, but comparable for age, anthropometric data, and smoking habits, were also studied. Workers exposed to DMF showed a decrease in the number of platelets and had longer coagulation times, probably due to a change caused by DMF on the membrane receptor of platelets and on the phospholipid components of the clotting system.

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.