PubMed · 6590456
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1984. Carbon blacks.. https://pubmed.ncbi.nlm.nih.gov/6590456/
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OBJECT: Ambient air and biological monitoring of an occupational toluene exposure was carried out on a group of 33 workers. METHOD: The biological monitoring of the workers was based on determination of the concentration of toluene in blood and on quantification of the urinary metabolites o-cresol and hippuric acid. All blood and urine samples were collected post-shift. RESULTS: The average toluene concentration in the workplace air was 65 ppm, ranging from 13 to 151 ppm. AN average concentration of toluene in the blood of 911 microns/1 was found, corresponding to an average urinary concentration of 2.9 mg/1 (2.3 mg/g creatinine) o-cresol and 2.4 g/l (1.9 g/g creatinine) hippuric acid. Both urinary metabolites can be correlated with the concentration of toluene in ambient air and blood, respectively. CONCLUSIONS: The results of our study indicate that the determination of the urinary o-cresol excretion represents a diagnostically specific and sensitive parameter for the estimation of an individual toluene uptake. In contrast, monitoring of the concentration of hippuric acid in urine cannot be recommended for assessment of individual exposure. To set up a biological tolerance value (BAT) for o-cresol, a urinary concentration of 3 mg/l o-cresol should be in accordance with the current MAK value of 50 ppm toluene.
OBJECT: To quantify the exposure of operating room personnel to sevoflurane and nitrous oxide. DESIGN: Prospective study at a university hospital. METHODS: In 25 patients undergoing elective surgical procedures, anaesthesia was induced with thiopentone/etomidate, vecuronium and fentanyl and maintained with fentanyl, sevoflurance in 35% oxygen and 65% nitrous oxide (N2O). Occupational exposure to sevoflurane and N2O was measured in the breathing zone of one representative of each of three personnel groups (anaesthetist, surgeon, auxiliary nurse) by means of a direct reading instrument using photoacoustic infrared spectrometry. RESULTS: The mean trace concentrations of sevoflurane for the single anaesthetic procedures exceeded the 0.5 ppm level in more than 50% of the measurements. The 2 ppm level was not exceeded in the case of the anaesthetist and the surgeon, but was exceeded in 16% of the measurements for the auxiliary nurse. The level of 25 ppm N2O were exceeded in 28% of the measurements for the anaesthetist and in 16% of these for the surgeon and for the auxiliary nurse. CONCLUSIONS: To keep exposure low, sevoflurane and N2O were used in a modern working environment: a low-leakage anaesthesia machine, high room ventilation rates, scavenging system, no intermittent mask ventilation, low to medium concentrations of sevoflurane, and strict control of the cuff pressure. Nevertheless, exposure could not be kept under NIOSH threshold values in all cases.
Nitrous oxide (N2O) is one of the most common inhalation anesthetics in current anesthesiological practice. Even though artificial ventilation and active scavenging in operating theaters are employed in most of the modern hospitals, potential N2O contamination persists in regular anesthesia, particularly pediatric operation. In order to understand personal exposure during pediatric anesthesia, ambient monitoring for N2O exposure around the breathing zone of the anesthesiologist was conducted by a portable infra-red Miran 1B2 spectrophotometer. The results demonstrated that general mask anesthesia generated greatest N2O contamination, with the mean time-weighted-average (TWA) concentrations of 85 +/- 48.4 (mean +/- S.D.) ppm in 12 cases. Initial mask induction followed by cuffed endotracheal incubation (6 cases) or intravenous induction followed by uncuffed endotracheal intubation (6 cases) also produced significant pollution to the workers, with the mean TWAs of 33.2 +/- 24.0 ppm and 31.9 +/- 18.0 ppm respectively. These procedures provided exposure levels above the 25 ppm Recommended Exposure Limit (REL) of the National Institute of Occupational Safety and Health (NIOSH), U.S.A. Modification with intravenous induction followed with cuffed endotracheal intubation or mask general anesthesia provided with a ventilation hood diminished the contamination apparently, with the resulting mean TWAs of 11.0 +/- 4.7 ppm and 17.9 +/- 9.8 ppm in 7 and 5 cases respectively. The results indicated that excessive N2O exposure to anesthesiologists was not negligible during routine pediatric anesthesia. Significant reduction could be achieved via appropriate industrial modification.