To the Editor.
—Dr Pirkle and colleagues1 suggest that further research is needed to determine the health relevance of ETS exposures that result in serum cotinine concentrations of approximately 1 ng/mL. However, Pirkle et al fail to discuss that we reported data2-4 that show animals exposed to smoke repeatedly for 6 hours per day, with resultant mean cotinine concentrations at the end of the exposures up to 165 ng/mL, had effectively no toxicologic changes. Importantly, the particulate concentrations we used (up to 10 mg/m3) were large exaggerations of ETS concentrations (approximately 30 μ/m3) that have been reported in areas where smoking is allowed.5
Coggins CRE. Estimating Exposure to Environmental Tobacco Smoke. JAMA. 1996;276(8):603. doi:10.1001/jama.1996.03540080025013