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Table 3 Distribution of pharyngeal cancer cases in the NCI-cohort by cumulative exposure to formaldehyde and period of follow-up

From: New insights into the mortality risk from nasopharyngeal cancer in the national cancer institute formaldehyde worker cohort study

Exposure (ppm-yr)

1934–1979

1980–2004

1934–2004

Obs

Exp

SMR (95%CI)

Obs

Exp

SMR (95%CI)

Obs

Exp

SMR (95%CI)

0

2

1.06

1.89 (0.23–6.83)

3

2.43

1.24 (0.25–3.61)

5

3.49

1.43 (0.47–3.35)

(0, 0.5]

8

3.59

2.23 (0.96–4.39)

15

12.25

1.22 (0.69–2.02)

23

15.84

1.45 (0.92–2.18)

(0.5, 5.5]

3

4.13

0.73 (0.15–2.12)

9

9.94

0.90 (0.41–1.72)

12

14.07

0.85 (0.44–1.49)

> 5.5

2

2.56

0.78 (0.09–2.82)

8

5.50

1.46 (0.63–2.87)

10

8.06

1.24 (0.59–2.28)

Total

15

11.34

1.32 (0.74–2.18)

35

30.12

1.16 (0.81–1.62)

50

41.46

1.21 (0.90–1.59)