Table 4.13 Cohort studies of breast cancer and occupational exposure to EMF

Reference, country	Cohort description	Exposure classification	Males		Females		Comments
			No. of cases	RR (95% CI)	No. of cases	RR (95% CI)
(Tynes et al., 1992); Norway	37,945 male workers (aged 20-70) followed 1961-85 in the Cancer Registry of Norway	12 electrical occupations 170 2.1 (1.1-3.6) NA Electric transport work(ISCO codes 631-632, 641, 693) 4 4.0 (1.1-10)					SIR
(Guénel et al., 1993); Denmark	All actively employed Danes (aged 20-64) in 1970 followed 1970-87 in the cancer registry. 172,000 men and 83,000 women in jobs exposed to magnetic fields were compared with reference workers in unexposed jobs.	Jobs with intermittent field exposure 23 1.2 (0.77-1.8) 1526 0.96 (0.91-1.0) Jobs with continuous exposure 2 1.5 (0.16-4.9) 55 0.88 (0.68-1.2)					SIR relative to economically active subjects
(Floderus et al., 1994); Sweden	Male railway workers (aged 20-64) in the 1960 census compared with all employed men (17,150,940 person-years in 1960-69). Cancers for 1960-69 and 1970-79 obtained from Cancer-Environment Registry.	Engine drivers 2 8.3 (2.0-34) NA Conductors 1 2.7 (0.4-20) Railway workers (and station masters, dispatchers & linemen) 4 4.3 (1.6-12)					SIR adjusted for age. All cases occurred in 1960-69 follow up period (none in the 1970s)

RR, relative risks; CI, confidence interval; NA, not applicable; SIR, standardized incidence ratio; SMR, standardized mortality ratio; PIR, proportional incidence ratio