TABLE 3.
Odds ratios of ever asthma in relation to blood trihalomethane (THM) concentrations among US adolescents according to tobacco smoke exposure (National Health and Nutrition Examination Survey 2005–2012)
| Blood THM (pg·mL−1) | All (n=2359) | Tobacco smoke exposure (n=378) | No tobacco smoke exposure (n=1981) | pinteraction-value for adjusted model | ||||||
| n/N # | Unadjusted model OR (95% CI) | Adjusted model OR (95% CI) ¶ | n/N # | Unadjusted model OR (95% CI) | Adjusted model OR (95% CI) + | n/N # | Unadjusted model OR (95% CI) | Adjusted model OR (95% CI) + | ||
| TCM | 0.32 | |||||||||
| Q1 (1.48–4.11) | 109/567 | Reference | Reference | 22/95 | Reference | Reference | 87/472 | Reference | Reference | |
| Q2 (4.12–8.34) | 106/566 | 0.73 (0.53–1.01) | 0.76 (0.57–1.03) | 22/86 | 0.89 (0.41–1.94) | 0.82 (0.40–1.73) | 84/480 | 0.71 (0.49–1.01) | 0.73 (0.52–1.03) | |
| Q3 (8.35–16.90) | 106/561 | 0.74 (0.50–1.09) | 0.79 (0.51–1.23) | 23/99 | 0.66 (0.27–1.59) | 0.54 (0.22–1.33) | 83/462 | 0.75 (0.51–1.11) | 0.86 (0.52–1.41) | |
| Q4 (>16.90) | 103/572 | 0.79 (0.53–1.19) | 0.80 (0.53–1.20) | 24/86 | 1.36 (0.52–3.55) | 1.32 (0.53–3.32) | 79/486 | 0.69 (0.47–1.02) | 0.72 (0.48–1.08) | |
| ptrend-value§ | 0.45 | 0.48 | 0.46 | 0.43 | 0.17 | 0.26 | ||||
| BDCM | 0.05 | |||||||||
| T1 (0.44–0.75) | 159/778 | Reference | Reference | 30/136 | Reference | Reference | 129/642 | Reference | Reference | |
| T2 (0.76–2.50) | 148/784 | 0.88 (0.61–1.28) | 0.83 (0.57–1.21) | 26/120 | 1.16 (0.55–2.44) | 0.99 (0.40–2.41) | 122/664 | 0.84 (0.56–1.24) | 0.78 (0.51–1.19) | |
| T3 (>2.50) | 132/780 | 0.94 (0.69–1.29) | 0.94 (0.69–1.29) | 37/118 | 1.74 (0.86–3.55) | 1.66 (0.77–3.57) | 95/662 | 0.68 (0.48–0.94) | 0.82 (0.59–1.14) | |
| ptrend-value§ | 0.25 | 0.95 | 0.12 | 0.14 | 0.02 | 0.35 | ||||
| DBCM | 0.03 | |||||||||
| <50th (0.44–0.65) | 221/1155 | Reference | Reference | 34/198 | Reference | Reference | 187/957 | Reference | Reference | |
| 50–75th (0.66–1.87) | 105/578 | 0.88 (0.59–1.31) | 1.00 (0.65–1.54) | 27/91 | 1.65 (0.80–3.41) | 1.61 (0.77–3.36) | 78/487 | 0.78 (0.50–1.22) | 0.90 (0.54–1.49) | |
| >75th (>1.87) | 107/576 | 1.26 (0.89–1.79) | 1.54 (1.07–2.21) | 29/77 | 3.34 (1.54–7.24) | 3.96 (1.89–8.30) | 78/499 | 1.01 (0.71–1.44) | 1.28 (0.85–1.93) | |
| ptrend-value§ | 0.15 | 0.01 | 0.003 | <0.001 | 0.79 | 0.15 | ||||
| TBM | 0.99 | |||||||||
| <75th (0.71–1.13) | 324/1730 | Reference | Reference | 70/291 | Reference | Reference | 254/1439 | Reference | Reference | |
| 75–87.5th (1.14–2.10) | 58/287 | 1.35 (0.86–2.12) | 1.43 (0.92–2.24) | 13/52 | 1.30 (0.49–3.48) | 1.69 (0.70–4.09) | 45/235 | 1.35 (0.82–2.21) | 1.44 (0.85–2.44) | |
| >87.5th (>2.10) | 48/288 | 1.03 (0.63–1.71) | 1.23 (0.71–2.15) | 9/30 | 1.29 (0.44–3.79) | 1.39 (0.48–4.00) | 39/258 | 1.01 (0.61–1.67) | 1.25 (0.72–2.17) | |
| ptrend-value§ | 0.78 | 0.38 | 0.54 | 0.34 | 0.89 | 0.36 | ||||
| Br-THMs | 0.02 | |||||||||
| Q1 (1.58–1.78) | 105/563 | Reference | Reference | Reference | Reference | 87/462 | Reference | Reference | ||
| Q2 (1.79–3.15) | 116/563 | 1.12 (0.74–1.72) | 1.04 (0.68–1.58) | 18/101 | 1.44 (0.67–3.09) | 1.39 (0.57–3.38) | 95/474 | 1.07 (0.67–1.72) | 0.91 (0.54–1.53) | |
| Q3 (3.16–6.69) | 100/564 | 0.87 (0.60–1.27) | 0.92 (0.62–1.35) | 21/89 | 1.31 (0.48–3.59) | 1.21 (0.41–3.60) | 78/471 | 0.79 (0.54–1.16) | 0.86 (0.55–1.36) | |
| Q4 (>6.69) | 101/563 | 1.23 (0.83–1.85) | 1.46 (0.98–2.17) | 22/93 | 3.08 (1.38–6.84) | 3.28 (1.43–7.53) | 72/485 | 0.99 (0.66–1.51) | 1.19 (0.77–1.82) | |
| ptrend-value§ | 0.34 | 0.04 | 29/78 | 0.005 | 0.003 | 0.87 | 0.25 | |||
| TTHMs | 0.20 | |||||||||
| Q1 (3.07–6.99) | 108/540 | Reference | Reference | 21/85 | Reference | Reference | 87/455 | Reference | Reference | |
| Q2 (7.00–12.97) | 99/541 | 0.57 (0.38–0.84) | 0.58 (0.38–0.88) | 22/91 | 0.67 (0.31–1.47) | 0.52 (0.25–1.10) | 77/449 | 0.55 (0.36–0.83) | 0.57 (0.37–0.90) | |
| Q3 (12.98–25.63) | 99/540 | 0.69 (0.45–1.05) | 0.76 (0.49–1.18) | 19/92 | 0.57 (0.22–1.44) | 0.49 (0.20–1.19) | 80/449 | 0.72 (0.47–1.10) | 0.87 (0.54–1.40) | |
| Q4 (>25.63) | 99/540 | 0.86 (0.58–1.29) | 0.92 (0.59–1.42) | 26/81 | 1.66 (0.72–3.83) | 1.42 (0.65–3.12) | 73/459 | 0.73 (0.50–1.06) | 0.83 (0.54–1.29) | |
| ptrend-value§ | 0.91 | 0.80 | 0.13 | 0.14 | 0.36 | 0.85 | ||||
TCM: trichloromethane (chloroform); Q: quartile; BDCM: bromodichloromethane; T: tertile; DBCM: dibromochloromethane; TBM: tribromomethane (bromoform); Br-THMs: sum of BDCM, DBCM and TBM; TTHMs: sum of TCM and Br-THMs. #: proportions of adolescents with ever diagnosed asthma are absolute, unweighted values; ¶: adjusted for age, sex, race/ethnicity, body mass index (BMI) z-score, family income to poverty ratio, family history of asthma, swimming pool/hot tub/steam room use within 72 h, survey cycle and tobacco smoke exposure; +: adjusted for age, sex, race/ethnicity, BMI z-score, family income to poverty ratio, family history of asthma, swimming pool/hot tub/steam room use within 72 h and survey cycle; §: tests for linear trend were conducted by modelling categories of THM concentrations as ordinal variables using the median values within each category.