Table 4.
Exposure-dependent effect of FA on development of nasopharyngeal cancer in the three formaldehyde exposure metrics in the US National Cancer Institute Cancer Cohort; the reference group was the lowest exposure category in each exposure metric (Beane Freeman et al. 2013)
| Peak exposure | Average intensity | Cumulative exposure | |||
|---|---|---|---|---|---|
| ppm | RR (95 % CI) (N) | ppm | RR (95 % CI) (N) | ppm × year | RR (95 % CI) (N) |
| 0 | 4.4 (0.3–54) (2) | 0 | 6.8 (0.5–84) (2) | 0 | 1.9 (0.3–12) (2) |
| >0 to <2.0 | RR = 1 (1) Reference |
0.1–0.4 | RR = 1 (1) Reference |
>0 to <1.5 | RR = 1 (4) Reference |
| 2.0 to <4.0 | NAa (0) Apparent NOAEL |
0.5–0.9 | 2.4 (0.15–39) (1) Apparent NOAEL |
1.5 to <5.5 | 0.86 (0.1–7.7) (1) Apparent NOAEL |
| ≥ 4.0 | 7.7 (0.9–62) (7) | ≥1 | 12 (1.4–97) (6) | ≥5.5 | 2.9 (0.6–13) (3) |
| P (trend FA groups) = 0.005 | P (trend FA groups) = 0.09 | P (trend FA groups) = 0.06 | |||
| P (trend FA groups + controls) = 0.10 | P (trend FA groups + controls) = 0.16 | P (trend FA groups + controls) = 0.07 | |||
The cohort comprises 25,619 workers. Number of NPC cases is indicated by N, and a significant increase is indicated in bold
aNot applicable (NA)