Exposure to a Fungal Volatile Compound: Walinder et al. respond.There are different opinions on the use of Bonferroni's corrections. Everitt (1995) stated that it gives too conservative estimates if there are more than five tests performed. In environmental medicine, one exposure can have different health effects, so it is reasonable to test for different types of effects on different organs. We prefer to perform conventional statistical tests, without Bonferroni correction In statistics, the Bonferroni correction states that if an experimenter is testing n independent hypotheses on a set of data, then the statistical significance level that should be used for each hypothesis separately is 1/n , and look at the pattern of significant effects and their biologic plausibility. We did not perform 76 comparisons (Walinder et al. 2005); we actually performed 25 tests on 13 physiologic variables based on differences before and after exposure. A fourteenth variable (vital staining) was tested only after exposure. Repeated measurement analysis was performed on blink frequency (60 consecutive measurements of 2 min each) and one questionnaire with 10 questions was administered at six different times. This is a total of 37 tests performed on 25 variables, having five significant values, of which one was highly significant (p < 0.001). Moreover, all tests point in the same direction--mucosal effects of the exposure. We did not find the same effects over time for control exposure. There is, of course, the possibility that some of the significant effects were due to chance, and we were quite modest in our conclusions, using the words "may" or "might be." Because our study is the first exposure-chamber study on 3-methylfuran (3-MF), more studies are needed to determine final conclusions. Blink frequency was measured only during the 2 hr of exposure in the chamber. Therefore, there is no preexposure baseline data available at time 0. Eye effects occur quickly; a rapid effect of the exposure on blinking frequency can occur during the first 2 min of exposure to 3-MF inside the chamber, possibly followed by later adaptation (8.8 blinks/min during the first 2 min, compared with a mean of 7.6 blinks/min during the whole period of exposure). It is true that there was a numerical increase in break-up time at exposure, which could be in agreement with increased blink frequency. The fatty layer on the tear film is produced by the glands of the eyelids eyelids, n.pl a moveable fold of thin skin over the eye. The orbicularis oculi muscle and the oculomotor nerve control the opening and closing of the eyelid. . Therefore, an increased blinking frequency could produce more secretion from the meibomian glands the slender sebaceous glands of the eyelids, which discharge, through minute orifices in the edges of the lids, a fatty secretion serving to lubricate the adjacent parts. See also: Meibomian and therefore a longer break-up time. Regarding lung function, transient effects of environmental exposure (as well as diurnal diurnal /di·ur·nal/ (di-er´nal) pertaining to or occurring during the daytime, or period of light. di·ur·nal adj. 1. Having a 24-hour period or cycle; daily. 2. variation, which we controlled for by performing the experiment at the same time) may affect either forced vital capacity forced vital capacity n. Abbr. FVC Vital capacity measured with subject exhaling as rapidly as possible. forced vital capacity, n a measure of the maximum rate of exhalation. (FVC FVC forced vital capacity. FVC abbr. forced vital capacity FVC, n See forced vital capacity. FVC forced vital capacity. ) or forced expiratory volume forced expiratory volume n. Abbr. FEV The maximum volume of air that can be expired from the lungs in a specific time interval when starting from maximum inspiration. in 1 sec (FE[V.sub.1]), or both. Physiologically and numerically, the decrease was of the same order, but statistically the outcome was different. The decreases were 0.1 L for FVC and 0.08 L for FE[V.sub.1] after exposure to 3-MF. The magnitude of the effect was clinically small, but it was significant at group level for FVC. Small pulmonary effects may have large health effects in a population (Kunzli et al. 2000.) The authors declare they have no competing financial interests. Robert Walinder Dan Norback Gunilla Wieslander Department of Medical Sciences/Occupational and Environmental Medicine University Hospital Uppsala, Sweden E-mail: robert.walinder@medsci.uu.se Lena Ernstgard Gunnar Johanson Division of Work Environment Toxicology toxicology, study of poisons, or toxins, from the standpoint of detection, isolation, identification, and determination of their effects on the human body. Toxicology may be considered the branch of pharmacology devoted to the study of the poisonous effects of drugs. Institute of Environmental Medicine Karolinska Institutet Karolinska Institutet (often translated from Swedish into English as the Karolinska Institute, and in older texts often as the Royal Caroline Institute) is one of Europe's largest medical universities. Stockholm, Sweden REFERENCES Everitt BS. 1995. The Cambridge Dictionary of Statistics in the Medical Sciences. Cambridge, UK: Cambridge University Press Cambridge University Press (known colloquially as CUP) is a publisher given a Royal Charter by Henry VIII in 1534, and one of the two privileged presses (the other being Oxford University Press). . Kunzli N, Ackermann-Liebrich U, Brandli O, Tschopp JM, Schindler C, Leuenberger P. 2000. Clinically "small" effects of air pollution on FVC have a large public health impact. Eur Respir J 15:131-136. Walinder R, Ernstgard L, Johanson G, Norback D, Venge venge tr.v. venged, veng·ing, veng·es Archaic To avenge. [Middle English vengen, from Old French vengier; see vengeance.] P, Wieslander G. 2005. Acute effects of a fungal volatile compound. Environ Health Perspect 113:1775-1778. |
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