NASAL CYTOLOGY IN SOUTHWEST METROPOLITAN MEXICO-CITY INHABITANTS - A PILOT INTERVENTION STUDY

Southwest metropolitan Mexico City (SWMMC) inhabitants have been expos ed several hours per day for the last 6 years to photochemical smog, o zone being the most important oxidant pollutant. Subjects exposed to t he SWMMC atmosphere develop several histopathological changes in their nasal mucosa: dysplasia is the most significant, affecting 78.72% of adult individuals within 60 or more days of residence in SWMMC. This s tudy was originally designed to explore whether chemical intervention could modify nasal dysplasia, as determined by nasal cytology, in a de fined adult population. In a placebo-controlled, randomized, double-bl ind trial, 177 healthy male subjects were divided into 5 groups to who m 5000 IU of vitamin A, 100 IU of vitamin E, a combination of vitamins A and E (5000 IU + 100 IU), 16 mg of beta-carotene, or placebo were a dministered daily for 4 months. Sixteen clinical and cytological varia bles were monitored. No effect on dysplasia was seen at the end of the 4-month trial; however, an apparent reversibility as well as progress ion of the dysplastic nasal lesions and high correlation coefficients between dysplasia and nasal cytology of polymorphonuclear leukocytes ( PMNs; 0.85), squamous metaplasia (SM; 0.50), and nasal mucosa atrophy (NMA; 0.41) were found. A mathematical theoretical nasal dysplasia (tD ) predictor equation for SWMMC adult male inhabitants is proposed (tD = 0.85 DELTA PMNs + 0.50 DELTASM + 0.41 DELTANMA + 0.98), in which PMN s are the best single dysplasia predictor, and all variables are indep endent. We suggest that the nasal cytological changes in SWMMC inhabit ants may constitute an adaptative response to environmental pollutants , and long-term follow-up of these subjects will be necessary to estab lish the possible outcomes of the nasal abnormalities.