TABLE 4—

Associations Between Duration of Exposure to Secondhand Smoke in a Single Workshift and Changes in the Level of Total NNAL, Nicotine, and Cotinine in the Urine of Nonsmoking Food Service Workers: Oregon, November 2004–August 2005

	Multiplicative Increase per Hour (95% CI)a
Total NNALb	1.06c (1.02, 1.10)*
Total nicotineb	1.33 (1.27, 1.39)**
Total cotinineb	1.12 (1.07, 1.16)**

Notes. NNAL = 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol; CI = confidence interval. The mean level of total NNAL in the exposed workers was 0.03 pmol/mL in the preworkshift urine and 0.04 pmol/mL in the postworkshift urine. Their mean levels of nicotine and cotinine, respectively, were 7.21 ng/mL and 16.63 ng/mL in the preworkshift urine and 44.36 ng/mL and 20.20 ng/mL in the postworkshift urine.

^aMultiplicative increase was based on linear mixed model, and adjusted for participant age, gender, and minutes exposed to secondhand smoke outside the workplace in the past week.

^bA value of half the limit of detection was used for nondetectable values. Limit of detection: cotinine, 2 ng/mL; nicotine, 2 ng/mL; NNAL, 0.007–0.01 pmol/mL depending on recovery. Total NNAL was based on 158 pre- and postworkshift urine samples from 82 participants (50 exposed). Total nicotine and cotinine were based on 166 pre- and postworkshift urine samples from 84 participants (52 exposed).

^cInterpretation: Each hour of exposure was associated with about a 6% increase in total NNAL.

* P < .01; **P < .001.