Barr et al. during the morning sampling period had sig- whites (p = 0.039) and Mexican Americans Mexican Americans (p < 0.0001). Children had nificantly higher 3PBA concentrations than (p = 0.025) (Figure 3C). 3PBA concentra- higher LSGM 3PBA concentration than did did those collected in the afternoon (p = tions in samples collected during the evening adolescents (p = 0.001) and adults (p = 0.0014); –0.002) and evening (p < 0.001) sampling sampling period were significantly lower than however, we observed no difference between periods (Figure 3B). those collected in the morning (p = 0.001) adolescents and adults. 3PBA concentrations in For the 2001–2002 survey period, race and afternoon (p = 0.007) (Figure 3B). samples collected during the evening sampling (p = 0.008; Figure 3C) and sample collection For combined survey periods (1999–2002), period were significantly lower than those col- time (p = 0.036; Figure 3B) were significant in race, age, and time of collection were all signifi- lected in the morning (p = 0.02) and afternoon the final model, but not age group or sex. The cant in the final model. Non-Hispanic blacks (p = 0.03; Figure 3B). Fasting duration was not LSGM 3PBA concentration of non-Hispanic had a higher LSGM 3PBA concentrations than a significant variable in either survey period or blacks was higher than those of non-Hispanic did non-Hispanic whites (p = 0.0096) and in the combined survey periods. Table 3. Urinary concentrations of cis-DCCA in the general U.S. population, NHANES 1999–2002. Selected percentile (95% confidence interval) Category/survey GM (95% Sample Weighted years confidence interval) 50th 75th 90th 95th size (n) detection (%) Total 1999–2000a NC < LOD 0.27 (0.22–0.34) 0.60 (0.49–0.71) 1.12 (0.77–1.68) 1,951 46.7 2001–2002a NC < LOD 0.17 (0.13–0.23) 0.51 (0.41–0.67) 0.91 (0.80–1.10) 3,048 32.4 1999–2000b NC < LOD 0.26 (0.23–0.29) 0.54 (0.44–0.70) 1.12 (0.69–1.59) 1,951 46.7 2001–2002b NC < LOD 0.23 (0.21–0.25) 0.46 (0.42–0.54) 0.90 (0.75–1.04) 3,046 32.4 Age group 6–11 years 1999–2000a NC < LOD 0.33 (0.21–0.55) 0.74 (0.58–1.53) 1.77 (0.68–3.15) 468 46.6 2001–2002a NC < LOD 0.11 (< LOD-0.20) 0.37 (0.28–0.61) 0.73 (0.49–0.87) 580 26.4 1999–2000b NC < LOD 0.26 (0.19–0.40) 0.63 (0.40–1.38) 1.38 (0.59–1.80) 468 46.6 2001–2002b NC < LOD 0.21 (< LOD-0.25) 0.40 (0.32–0.58) 0.70 (0.54–0.77) 580 26.4 12–19 years 1999–2000a NC < LOD 0.30 (0.20–0.41) 0.67 (0.46–1.11) 1.44 (0.67–2.21) 667 48 2001–2002a NC < LOD 0.16 (< LOD–0.21) 0.44 (0.30–0.63) 0.73 (0.63–0.92) 831 31.7 1999–2000b NC < LOD 0.16 (0.13–0.21) 0.32 (0.25–0.45) 0.57 (0.32–1.24) 667 48 2001–2002b NC < LOD 0.13 (< LOD-0.18) 0.27 (0.21–0.33) 0.38 (0.29–0.56) 830 31.7 20–59 years 1999–2000a NC < LOD 0.26 (0.20–0.33) 0.57 (0.43–0.69) 1.07 (0.67–1.80) 816 46.5 2001–2002a NC < LOD 0.17 (0.12–0.23) 0.51 (0.40–0.74) 0.96 (0.79–1.28) 1,128 32.6 1999–2000b NC < LOD 0.29 (0.26–0.32) 0.55 (0.44–1.06) 1.33 (0.83–1.75) 816 46.5 2001–2002b NC < LOD 0.26 (0.24–0.28) 0.58 (0.44–0.72) 1.05 (0.80–1.46) 1,128 32.6 ≥ 60 years 2001–2002a NC < LOD 0.22 (0.13–0.35) 0.64 (0.38–1.29) 1.77 (0.76–3.10) 509 36 2001–2002a NC < LOD 0.31 (0.24–0.37) 0.68 (0.42–1.23) 1.39 (0.72–2.65) 508 36 Sex Male 1999–2000a NC < LOD 0.25 (0.20–0.31) 0.53 (0.42–0.60) 0.79 (0.60–1.50) 947 46.8 2001–2002a NC < LOD 0.16 (0.12–0.21) 0.49 (0.41–0.64) 1.03 (0.70–1.31) 1,429 31.6 1999–2000b NC < LOD 0.22 (0.18–0.26) 0.41 (0.35–0.57) 0.80 (0.51–1.11) 947 46.8 2001–2002b NC < LOD 0.19 (0.17–0.21) 0.41 (0.33–0.47) 0.74 (0.62–1.05) 1,429 31.6 Female 1999–2000a NC < LOD 0.28 (0.22–0.38) 0.68 (0.49–1.08) 1.47 (0.95–2.54) 1,004 46.6 2001–2002a NC < LOD 0.19 (0.12–0.25) 0.56 (0.40–0.74) 0.90 (0.79–1.13) 1,619 33.2 1999–2000b NC < LOD 0.2 (0.27–0.34) 0.63 (0.47–1.33) 1.55 (1.00–2.03) 1,004 46.6 2001–2002b NC < LOD 0.27 (0.23–0.30) 0.52 (0.46–0.63) 0.96 (0.84–1.20) 1,617 33.2 Race/ethnicity Non-Hispanic white 1999–2000a NC < LOD 0.27 (0.22–0.34) 0.63 (0.46–0.78) 1.13 (0.74–2.35) 591 46.3 2001–2002a NC < LOD 0.16 (< LOD–0.23) 0.51 (0.38–0.76) 0.96 (0.79–1.17) 1,281 29.6 1999–2000b NC < LOD 0.31 (0.28–0.40) 0.83 (0.55–1.33) 1.55 (1.06–1.99) 591 46.3 2001–2002b NC < LOD 0.28 (< LOD–0.32) 0.63 (0.50–0.71) 1.14 (0.96–1.38) 1,280 29.6 Mexican American 1999–2000a NC < LOD 0.20 (0.11–0.24) 0.46 (0.30–0.61) 0.73 (0.47–1.32) 671 35.9 2001–2002a NC < LOD 0.14 (0.11–0.18) 0.30 (0.25–0.39) 0.51 (0.38–0.64) 767 31.3 1999–2000b NC < LOD 0.14 (0.11–0.21) 0.29 (0.23–0.35) 0.40 (0.29–0.67) 671 35.9 2001–2002b NC < LOD 0.16 (0.14–0.19) 0.28 (0.25–0.30) 0.38 (0.33–0.50) 767 31.3 Non-Hispanic black 1999–2000a 0.202 (0.155–0.262) 0.16 (0.12–0.20) 0.38 (0.27–0.52) 0.82 (0.49–1.68) 1.68 (0.91–5.43) 518 61.5 2001–2002a NC < LOD 0.30 (0.24–0.37) 0.67 (0.53–0.78) 0.94 (0.77–1.37) 776 48.5 1999–2000b 0.138 (0.104–0.182) 0.11 (0.08–0.16) 0.23 (0.18–0.28) 0.46 (0.29–0.94) 1.02 (0.52–1.80) 518 61.5 2001–2002b NC < LOD 0.17 (0.14–0.20) 0.35 (0.26–0.48) 0.58 (0.37–1.39) 775 48.5 NC, not calculated (proportion of results below LOD was too high to provide a valid result). < LOD indicates less than the LOD for the uncorrected urine values, which may vary for some chemicals by year. n-Values may differ because some information was missing for a particular subgroup. aVolume-based concentrations (ng/mL). bCreatinine-adjusted concentrations (μg/g creatinine). 746 118 | number 6 | June 2010 • Environmental Health Perspectives ovlume