P. O. Droz

1,1,1-Trichloroethane exposure, biologic monitoring by breath and urine analyses.

SummaryAbsorption and excretion of 1,1,1-trichloroethane, as well as the kinetics of formation and elimination of trichloroethanol (TCE) and trichloroacetic acid (TCA) were simulated by a mathematical model. The results of this model were compared with experimental ones on pulmonary elimination of the solvent and urinary excretion of the metabolites. The influences of duration and repetition of exposure on the pulmonary and urinary eliminations were studied. A tentative method of biologic monitoring is proposed. Theoretically, the most suitable method to estimate the exposure is by two determinations, before and after a work shift. Following this procedure, analysis of TCE in the urine is more sensitive than determination of 1,1,1-trichloroethane in the breath. As an indicator of exposure risk, TCA is not considered sensitive enough if variations in the inspired concentration occur.

Exposition au styrène

SummaryIn order to determine the quantities and percentages of styrène metabolites excreted in urine, five male subjects were given five controlled exposures to styrène, each of 8 h, at 206 and 103 ppm. The experiment showed that about 92 o/o of styrene is metabolized in the body. Of the amount absorbed, 54 o/o is eliminated in the urine as phenylglyoxylic acid and 37 o/o as mandelic acid. Neither differences between the individual subjects nor the exposure concentration seem greatly to influence elimination of the solvent. These urinary metabolites may therefore be used as biological indicators of exposure to styrène.

Effect of Alcohol on the Kinetics of Styrene and its Metabolites in Volunteers and in Workers

Abstract The reliability of mandelic acid (MA) and phenylglyoxylic acid (PGA) in urine as biological indicators of styrene exposure is impaired by the concurrent intake of ethyl alcohol. This has been verified by controlled experiments in the laboratory and in the field. Six males were exposed to styrene at 50 ppm with four concurrent levels of ethyl alcohol intake from 0 to 1 g per kg of body weight during or following exposure. Blood and urine samples were analyzed for MA, PGA, styrene epoxide (SO), and styrene glycol (SG). The MA/SG ratio in blood was found to be the most promising indicator and could be used as a metabolic “check-index.” An MA/SG ratio less than 30 is proposed as a warning level which is indicative of interference by alcohol intake. Similar studies on seven workers in a polyester plant yielded results in agreement with the controlled laboratory findings. Berode, M.; Droz, P. O.; Boillat, M. A.; Guillemin, M. Effect of alcohol on the kinetics of styrene and its metabolites in volunteer...

Pharmacokinetic modeling as a tool for biological monitoring.

SummaryThe relationships between biological indicators and exposure or tissue burdens are determined by the pharmacokinetic behaviour of the chemical. They can be studied by pharmacokinetic models of various types. Simple pharmacokinetic models are used here to describe general relationships valid for large groups of chemicals or situations. Important parameters to consider are the half-life of the biological indicator, the individual variability and the exposure variability. Biological sampling strategies are presented for monitoring of groups of workers, or individual workers. For specific chemicals, mainly solvents, more elaborate models can be developed, i.e., physiologically-based pharmacokinetic models including physiological, metabolic and physico chemical parameters. Such models are useful to describe the influence of confounding factors. Physiologically-based pharmacokinetic models can also be developed for metals and metalloids. Antimony is presented here as an example. In conclusion, pharmacokinetic modeling brings much information on sampling time, sample size, limit values, effect of physical workload and of individual physiological parameters.

Surveillance de personnes exposées au perchloréthylène ou au styrène

ZusammenfassungEine Gruppe von 49 Perchloräthylen exponierten Personen (Trokkenreinigung) und von 41 Styrol bearbeitenden Arbeitern (Polyesterindustrie) werden verglichen mit 68 Personen ohne beruflichen Kontakt mit Lösungsmitteln. Schwindel, trockener Mund, Müdigkeit, Schleimhaut- und Hautreizung fallen bei Lösungsmittelverarbeitenden Personen öfter an, jedoch ohne beobachtete Veränderung der Leber- und Nierenfunktionen. An diesem Beispiel wird gezeigt, wie medizinische Untersuchung, arbeitshygienische Untersuchung und biologische überwachung in der Beurteilung der Arbeitsbedingungen sich gegenseitig ergänzen.SummaryForty-nine employees exposed to perchloroethylene (dry cleaning) and 41 employees exposed to styrene (fiber reinforced polyester) are compared to a control group of 68 persons. Symptoms such as dizziness, mouth dryness, fatigue, mucous membranes and skin irritation appear more frequently among the exposed groups, while liver and kidney functions remain unchanged. This study demonstrates that medical examination, industrial hygiene survey and biological monitoring can complement each other in the evaluation of work conditions.

Application of Pharmacokinetic Modelling to Biological Monitoring

Exposure monitoring is one of the key steps in the assessment of occupational risks. It is further very often used in risk management to monitor the performance of the controls in workplaces. Exposure can occur in workplaces via several different routes: inhalation, ingestion, dermal contact. However it is often perceived as airborne exposure, and is in most cases estimated via air monitoring. Air monitoring has several limitations in the estimation of total exposure: (1) as mentioned, other routes of exposure exist, depending on the chemicals and to the exposure situation; (2) workers often use personal protective equipment and the efficiency of this equipment cannot be estimated by air monitoring; (3) physical activity is known to increase pulmonary ventilation and thus uptake of chemicals, which is not reflected in air monitoring results; (4) occupational exposures fluctuate widely over time, for example from one day to the next, and this requires repeated air sampling to estimate the average long term exposure: (5) individual differences are known to exist between workers, for instance in body build or ability to metabolise chemicals, and these will have an impact on the level of active species at the site of action.