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Pulmonary function response and effects of antioxidant genetic polymorphisms in healthy young adults exposed to low concentration ozone.
Citation:
KIM, C. S., H. R. KEHRL, A. G. RAPPOLD, M. W. CASE, M. T. SCHMITT, R. B. DEVLIN, D. DIAZ SANCHEZ, AND M. HAZUCHA. Pulmonary function response and effects of antioxidant genetic polymorphisms in healthy young adults exposed to low concentration ozone. Presented at American Thoracic Society (ATS) Meeting, Denver, CO, May 13 - 18, 2011.
Impact/Purpose:
Exposure to 0.06 ppm ozone for a 6.6 hour causes a small but significant decrement of spirometric lung function in healthy young adults.
Description:
Rational: Ozone is known to induce a variety of pulmonary effects including decrement of spirometric lung function and inflammatory reaction, and antioxidant genes are known to play an important role in modulating the effects. It is unclear, however, if such effects may occur at low concentrations below the current ground level ozone standard of 0.075 ppm. We tested if airway effects occur below the current standard and if they are more pronounced in individuals deficient in antioxidant genes. Methods: A group of 59 healthy young adults (age = 18-35 years) was exposed to 0.0 (clean air) and 0.06 ppm ozone for 6.6 hours with moderate exercise (Ve=20 l/min/body surface area) in an environmental chamber. Spirometric lung function (FEV 1 and FVC) was measured and symptoms were assessed (in the scale of 0-4) immediately before and after exposure. All subjects were genotyped for GSTM1, GSTP1 and NQOl polymorphisms. Changes in lung function and symptom scores after ozone exposures were compared with those after clean air exposure using a two-factor mixed effects model with repeated measures for the whole group and subgroups of GSTM1 null (N=29), GSTP1 val105 variants (N=34) and GSTM1 nulll NQOl wt combination (N=20). Results: For the whole group, FEV 1 and FVC decreased significantly by 1.75+/-0.64% and 1.19+/-0.51% (mean+/-SE), respectively (p<0.05 for both) after 0.06 ppm ozone exposure relative to clean air (ozone-clean air). Among the subgroups, significant changes in FEV 1 were shown only by GSTM1 positive (-1.98+/-0.90%) and GSTP1 val105 variant groups (-2.02+/-0.87%). However, there was no difference between counterpart pair groups: GSTM1 null vs. positive, GSTP1 wt vs val105 variants and GSTM1 null/NQOl wt combination vs. all others. A few symptoms were reported but the nature and score of the symptoms were similar between clean air and ozone. Conclusions: Exposure to 0.06 ppm ozone for a 6.6 hour causes a small but significant decrement of spirometric lung function in healthy young adults. Antioxidant genes studied in this study appear to have no role on modulating the effects. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.