The committee concludes, from its assessment of the epidemiologic literature, that there is limited/suggestive evidence of association between chronic exposure to unspecified mixtures of organic solvents and adult leukemia.

TABLE 6.40 Selected Epidemiologic Studies—Adult Leukemia and Exposure to Organic Solvents

Reference

Study Population

Exposed Cases

Estimated Relative Risk (95% CI)

Benzene

Cohort Studies—Mortality

Crump, 1994

Male US Pliofilm workers

14

2.9 (1.61–4.95)a

 

Cumulative exposure

 

 

0–45 ppm-years

3

1.2 (0.26–3.64)a

 

45–400 ppm-years

4

2.7 (0.73–6.83)a

 

400–1,000 ppm-years

2

3.1 (0.37–11.11)a

 

>1000 ppm-years

5

28.1 (9.00–64.83)a

Yin et al., 1996a

Chinese factory workers

 

 

Mortality, total

38

2.3 (1.1–5.0)

 

Males

25

2.1 (1.0–5.3)

 

Females

13

2.8 (0.8–17.6)

 

 

42

 

 

Incidence, total

 

2.6 (1.3–5.7)

Hayes et al., 1997

Chinese factory workers

 

 

All exposed workers

38

2.5 (1.2–5.1)

 

Exposed workers, year of hire

 

 

<1972

25

2.4

 

≥1972

13

3.4

 

Exposed workers, average ppm

 

 

<10

15

2.0 (0.9–4.5)

 

10–24

13

3.7 (1.6–8.7)

 

≥25

10

2.3 (0.9–5.7)

 

p trend=0.02

 

Exposed workers, duration

 

 

<5 years

14

4.0 (1.7–9.6)

 

5–9 years

11

3.1 (1.3–7.5)

 

≥10 years

13

1.5 (0.6–3.6)

 

p trend=0.98

 

Exposed workers, cumulative exposure

 

 

<40 ppm-years

11

1.9 (0.8–4.7)

 

40–99 ppm-years

8

3.1 (1.2–8.0)

 

≥100 ppm-years

19

2.7 (1.2–6.0)

 

p trend=0.04

Ireland et al., 1997

Male US chemical-plant workers

 

 

<12 ppm-months

2

2.5 (0.3–8.9)

 

12–72 ppm-months

0

0.0 (0.0–5.4)

 

≥72 ppm-months

3

4.6 (0.9–13.4)

Rushton and Romaniuk, 1997

Male UK petroleum marketing and distribution workers

 

Cumulative exposure

 

 

<0.45 ppm-years

22

1.00

 

0.45–4.49 ppm-years

47

1.42 (0.77–2.61)

 

4.5–44.9 ppm-years

20

2.48 (0.73–3.00)

 

≥45 ppm-years

1

1.35 (0.14–12.8)



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