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- Nihlén, Annsofi, et al.
(författare)
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Experimental exposure to methyl teriary-butyl ether : II. Acute effects in humans
- 1998
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Ingår i: Toxicology and Applied Pharmacology. - : Elsevier BV. - 0041-008X .- 1096-0333. ; 148:2, s. 281-287
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Tidskriftsartikel (refereegranskat)abstract
- Methyl tertiary-butyl ether (MTBE) is widely used in gasoline as an oxygenate and octane enhancer. Acute effects, such as headache, nausea, and nasal and ocular irritation, have been associated with the exposure to gasoline containing MTBE. The aim of this study was to assess acute health effects up to the Swedish occupational exposure limit value, both with objective methods and a questionnaire. Ten healthy male volunteers were exposed to MTBE vapor for 2 h at three levels (5, 25, and 50 ppm), during light physical work (50 W). All subjects rated the degree of irritative symptoms, discomfort, and CNS effects before, during, and after all three exposure occasions using a questionnaire. Answers were given on a 100-mm visual analog scale, graded from "not at all" to "almost unbearable." Ocular (redness, tear film break-up time, self-reported tear film break-up time, conjunctival epithelial damage, and blinking frequency) and nasal (mouth and nasal peak expiratory flow, acoustic rhinometry, biochemical inflammatory markers, and cells in nasal lavage) measurements were performed mainly at the highest exposure level. The ratings of solvent smell increased dramatically (ratings up to 50% of the scale) as the volunteers entered the chamber and declined slowly with time (p < 0.05, repeated-measures ANOVA). All other questions were rated from "not at all" to "hardly at all" (0-10% of the scale) with no significant relation to exposure. The eye measurements showed no effects of MTBE exposure. Blockage index, a measure of nasal airway resistance calculated from the peak expiratory flows, increased significantly after exposure; however, the effect was not related to exposure level. In addition, a nonsignificant tendency of decreased nasal volume was seen in the acoustic rhinometry measurements, but with no clear dose-effect relationship. In conclusion, our study suggests no or minimal acute effects of MTBE vapor upon short-term exposure at relatively high levels.
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| 2. |
- Wålinder, Robert
(författare)
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Nasal reactions and the school environment : Nasal patency and lavage biomarkers in relation to ventilation, cleaning and some indoor air pollutants
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In Sweden, 2 million persons are exposed to the school environment, and there has been reports on insufficient cleaning, and inadequate ventilation. The nasal mucosa is more easy to study than the lower airways, and rhinitis is common and possibly related to asthma. The main aim was to study nasal symptoms, nasal patency, and biomarkers in nasal lavage (NAL), in relation to exposures in schools. Acoustic rhinometry and nasal lavage were performed in 234 school personnel in 12 randomly selected schools in Uppsala. An extended study was made, including 89 office workers, and 88 hospital workers. The technical investigations comprised a building survey and measurements of ventilation flow, settled dust, respirable dust, formaldehyde, nitrogen dioxide (NO2), molds, and bacteria in the classroom air. A ventilation flow below current Swedish standard was found in 92% of the schools, and 42% did not follow the recommendation of daily cleaning. Nasal patency was decreased in schoolswith lower air exchange rate. In schools with older mechanical ventilation, based on dilution, there were more nasal symptoms than in naturally ventilated schools, and decreased nasal patency and increase of eosinophil cationic protein (ECP) and lysozyme in NAL. One school with a new type of displacement ventilation had the highest air exchange rate, increased nasal patency and lower ECP and lysozyme. Nasal symptoms were more common in schools with more settled dust. Beneficial effects on nasal patency, ECP and lysozyme in NAL were observed for higher cleaning frequency, particularly desk cleaning. Dry cleaning methods seemed preferable. Decreased nasal patency and higher concentrations of ECP and lysozyme were observed at higher indoor concentration of formaldehyde, NO2 and molds, particularly Aspergillus sp. This indicate increased eosinophil and glandular activity, and mucosal swelling, related to these exposures. In conclusion, the school environment may affect the nasal mucosa, with mucosal swelling and increase of specific inflammatory and secretory biomarkers. Acoustic rhinometry in combination with the determination of specific nasal biomarkers seems to be useful tools for the study of nasal physiological reactions to the indoor environment. Finally, the results implicate that there is a potential to reduce possible airway inflammation in relation to the school environment, by improving cleaning and ventilation.
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