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ORIGINAL PAPERSK. DŻAMAN ET AL.it was the only taste that functioned correctly at the firstexamination. Therefore, it appears that the dysfunction ofthe sour taste perception is reversible and that the othertastes are more sensitive to the chronic activity of toxicagents. Changes in taste perception after 8-hour occupationalexposure to toxic chemicals were reported alsoby other researchers [21]. It seems that a reversible, temporarydysfunction of smell and taste may be due to a fatigueof the sensory receptors which is observed even aftershort-term exposure to harmful agents in workplace.Olfactometry performed after work showed an increasedlevel of OPT in each group, but the change was not statisticallysignificant. No differences in olfactometric measurementswere found between particular workplaces.In the analysis, we also considered other factors that couldhave influence on the results. A statistical analysis (testingfor independent variables) was performed to checkthe influence of the differences in the subjects’ age andemployment duration (Table 2). The total duration of employmentdid not differ statistically between the groups.Table 2. Statistical analysis of between-group differences in thesubjects’ age and duration of employmentMeanParameterEmploymentduration (years)Group 1 vs. Group 2 15.167 9.417 1.493 0.148Group 1 vs. Group 3 15.167 14.792 0.083 0.934Group 2 vs. Group 3 9.417 14.792 –1.649 0.113AverageAge (years) t pGroup 1 vs. Group 2 42.800 34.583 2.538 0.018Group 1 vs. Group 3 42.800 44.167 –0.355 0.725Group 2 vs. Group 3 34.583 44.167 –2.863 0.009The statistical analysis revealed age differences betweenparticular subgroups. Thus, we decided to compare the TPTand OPT measurements recorded before and after work inthese groups with the findings for the control group.Some authors postulated that the functions of both thesenses deteriorated with age, but this was not confirmed inother reports. Some researchers suggest that an increasetpin TPT and OPT levels occurs after the age of 60 years,but in our study the oldest worker was 55 years of age (inthe control group there was one worker who was 62 yearsold). Therefore, the age difference did not have any significantimpact on the study results.The number of male and female subjects in the studygroups (gender factor) is related to the specific characterof each workplace. The males are more frequently employedin wastewater treatment plants and landfills whilethe females in laboratories. Therefore, it is very difficultto analyze the impact of the gender factor on the tasteand smell perception in workers at these workplaces. Inthe present study, the TPT and OPT measurements werecompared with those for the control group where the proportionof both genders was similar.The analysis of the study results indicate an increased riskof the smell and taste dysfunctions in workers with a longduration of employment in a sewage treatment plantand/or waste landfill. For a detailed interpretation of thefindings for TPT and OPT in the context of occupationalexposure it would be necessary to carry out measurementsof the concentrations of air pollutants in each workplace,which could be the subject of further studies.There are literature reports on the studies concerning airconcentrations of harmful biological and chemical agents inthe sewage treatment plant and landfill areas [5,18,22–23].Studies investigating the correlation between exposure tohydrogen sulphide and endotoxins and the illnesses diagnosedamong sewage and landfill workers were conductedby Ray [23], Abdou [24] and Lee [19]. They noted a statisticallyhigher rate of irritation of the respiratory system, eyesand skin as well as the neurological and gastric symptoms.This increased rate was found even at exposure to hydrogensulphide below the level of 1 ppm, and endotoxins below91 units per m 3 (EU/m 3 ). Smit et al. [18] observed anincreased frequency of health problems under conditionsof endotoxin exposure above the level of 50 U/m 3 .The technological development and progress in occupationalmedicine makes it possible to monitor and limit occupationalexposure to chemical and biological hazards,thus diminishing their influence on workers’ health [25].The quantitative and qualitative tests of smell and taste232IJOMEH 2009;22(3)
TASTE AND SMELL PERCEPTION AMONG SEWAGE WORKERSORIGINAL PAPERScould serve as indicators that would help detect the hazardsand enhance systematic monitoring of the functionsof sense organs. Performing these tests on workers occupationallyexposed to harmful agents provides an opportunityfor assessment of the compensatory ability of boththe sense organs [26].Own experience in investigating the sensory dysfunctionsprompts a complex nature of the causes of dysfunctionsreported in the present study. Presumably, a dysfunctiontakes place at several stages of the reception of thesense stimulus. It is plausible that even the first stagei.e. reaching the receptor by stimulus, can be hinderedby a mechanical barrier, namely oedema of the mucousmembrane irritated by airborne particulates. The processof dissolving chemical stimulus in the mucus layeroften becomes abnormal because of the changes in themucus composition that result from occupational exposure.This leads to a decrease in the connection betweenthe stimulus and the receptor. The functions ofthe gustatory and olfactory receptors, which are directlyexposed to toxic agents, could also be considered. Thereis a hypothesis that the sensory neuroepithelium is sensitiveto environmental exposure to pollutants [27–29].Finally, the changes can also relate to further parts ofthe sensory tract.The knowledge about the influence of long-term exposureto chemical hazards on the senses of smell and tasteis inadequate. Occupational dysfunctions of the smell andtaste are usually subclinical and can often be found onlyduring the olfactometric and gustometric examinations.Therefore, the findings presented above show a need fora further research in this area.CONCLUSIONThe gustometry and olfactometry results indicate a higherrisk of smell and taste dysfunctions among sewage treatmentand landfill workers. The sense of the sour taste appearedto be most sensitive after short-term exposure, butthis dysfunction is probably reversible in nature. The othertastes were found to be more sensitive to chronic toxicexposure than the sour taste. Occupational dysfunctionof the senses is usually multicausal and subclinical in nature.It can often be found exclusively during professionalexaminations.REFERENCES1. Kuszmider G, Mrowiec B, Kubiesa I, Suschka J. The gasiformorganic substances emission to atmosphere from sludge. ArchOchr Środ 1997;23:79–90 [in Polish].2. Lemasters GK, Zenick H, Hertzberg V, Hansen K, Clark S.Fertility of workers chronically exposed to chemically contaminatedsewer wastes. Reprod Toxicol 1991;5:31–7.3. Thornton I, Butler D, Docx P, Hession M, Makropoulos Ch,McMullen M, et al. Pollutants in urban waste water and sewagesludge. In: European Communities ICON, IC ConsultantsLtd, editors. Final Report. London: Office for OfficialPublications of the European Communities; 2001. p. 1–19.4. Cyprowski M, Krajewski JA. Harmful agents in municipal wastewatertreatment plants. Med Pr 2003;54(1):73–80 [in Polish].5. Laitinen S, Kangas J, Kotimaa M, Liesivuori J, MartikainenPJ, Nevalainen A, et al. Workers’ exposure to airborne bacteriaand endotoxins at industrial wastewater treatment plants.Am Ind Hyg Assoc J 1994;55(11):1055–60.6. Thorn J, Beijer L, Jonsson T, Rylander R. Measurement strategiesfor the determination of airborne bacterial endotoxin insewage treatment plants. Ann Occup Hyg 2002;46(6):549–54.7. Prażmo Z, Krysińska-Traczyk E, Skórska C, Sitkowska J, CholewaG, Dutkiewicz J. Exposure to bioaerosols in a municipal sewagetreatment plant. Ann Agric Environ Med 2003;10:241–8.8. Wlazło A, Pastuszka JS, Łudzeń-Izbińska B. Assessment ofworkers’ exposure to airborne bacteria at a small wastewatertreatment plant. Med Pr 2002;53:109–14 [in Polish].9. Krajewski JA, Cyprowski M, Szymczak W, Gruchała J.Heath complaints from workplace exposure to bioaerosols:a questionnaire study in sewage workers. Ann Agric EnvironMed 2004;11:199–204.10. Scarlett-Kranz JM, Babish JG, Strickland D, Lisk DJ. Healthamong municipal sewage and water treatment workers. ToxicolInd Health 1987;3(3):311–19.11. Thorn J, Kerekes E. Health effects among employees insewage treatment plants: A literature survey. Am J IndMed 2001;40:170–9.IJOMEH 2009;22(3) 233
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