Table 9: Biological Gradient. Numbers of cases (Ca), controls (Co), and odds ratio (OR) with 95% confidence interval (CI) for cumulative use of mobile phone in hours and glioma risk in Interphone [2].

Cumulative call time (hours)Ca/CoOR (95% CI)

Never regular user1,042/1,078(1.0)
<5141/1970.70 (0.52–0.94)
5–12.9145/1980.71 (0.53–0.94)
13–30.9189/1791.05 (0.79–1.38)
31–60.9144/1960.74 (0.55–0.98)
61–114.9171/1930.81 (0.61–1.08)
115–199.9160/1940.73 (0.54–0.98)
200–359.9158/1940.76 (0.57–1.01)
360–734.9189/2050.82 (0.62–1.08)
735–1,639.9159/1840.71 (0.53–0.96)
≥1,640210/1541.40 (1.03–1.89)

≥1,640160/1131.82 (1.15–2.89)

Regular use < 5 h = OR 1.0 (ref).