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P. Novaes, N. Kara-José, M. Macchione, M. Matsuda, P. H. N. Saldiva, I. Marquez, A. Berra; Low Levels of Air Pollution Induce Hyperplasia of Goblet Cells in Human Conjunctiva. Invest. Ophthalmol. Vis. Sci. 2007;48(13):394.
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© ARVO (1962-2015); The Authors (2016-present)
To estimate the effect of different levels of air pollution on the ocular surface by using individual exposure assessment.
A panel study was carried out involving 44 volunteers in a city with high detected levels of air pollution - São Paulo (n=20) and in a city with low levels of pollution - Divinolândia (n=24). Each subject received an individual pollution monitoring device with filters for ozone(O3) and nitrogen dioxide (NO2). The monitors were kept for one week, and daily pollution concentration was estimated by dividing the accumulated dose by 7. Tear samples for determination of lisozyme and IgA levels were collected, as well as impression cytology samples from inferior tarsal conjunctiva and temporal bulbar conjunctiva of both eyes. Subject’s exposure to NO2 was categorized in 4 groups : G1: 3 to 5 µg/mm3, G2: 5.1 to 6.5 µg/mm3, G3: 6.6 to 10 µg/mm3 , and G4: > 10 µg/mm3 .
The levels of NO2 exposure in subjects in São Paulo (11,32 µg/mm3) were significantly higher than those in Divinolândia (5,78 µg/mm3). The individual exposure levels to NO2 in São Paulo were significantly lower than those detected by the city’s monitoring system, which is located outdoors at the vicinity of high traffic locations (57,63µg/mm3) . There were no significant differences in O3 levels, tear lysozyme and tear IgA levels between both groups. In the impression cytology samples of inferior tarsal conjunctiva, goblet cell hyperplasia was detected in 16 of 20 samples of São Paulo and in 4 of 24 samples of Divinolândia. When the intensity of goblet cell hyperplasia was computed across gradients of NO2, a clear dose response pattern was detected: 0%, 10%, 30% and 100% in G1, G2, G3 and G4 respectively.
This study has indicated that personal exposure to pollutants is lower than the values obtained by outdoor standardized measuring systems. The results suggest that low levels of exposure to NO2, a proxy of "fresh" automotive emission, induced a dose dependent goblet cell hyperplasia in inferior tarsal conjunctiva. These findings suggest that this event is an adaptive response of the conjunctival epithelium to chronic environmental injury.
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