Table 5.

Incidence of MN of the breast in 71 185 male and 10 431 female UK Electricity Generation and Transmission workers, by year of hire, period from hire, period from leaving employment, duration of employment, industry sector and type of work, 1973–2015

	Males				Females
	Obs	Exp	SRR	95% CI	Obs	Exp	SRR	95% CI
Year of hire
1926–59	18	12.5	144	88–223	51	38.3	133	100–174
1960–69	19	16.8	113	70–173	145	128.5	113	96–132
1970–82	15	12.8	117	68–189	562	522.1	108	99–117
Test for trend			P = NS				P = NS
Period from hire (years)
0–19	6	4.7	128	52–266	168	152.7	110	94–128
20–29	11	8.2	134	71–233	225	209.0	108	94–122
30–39	13	12.9	101	56–168	267	241.0	111	98–125
≥40	22	16.2	136	87–202	98	86.2	114	93–138
Test for trend			P = NS				P = NS
Period from leaving employment (years)
<10a	16	11.8	136	80–216	179	164.7	109	94–126
10–19	13	14.0	93	52–155	228	194.1	118	103–134
20–29	16	12.3	130	77–207	213	214.7	99	87–113
≥30	7	3.9	180	79–355	138	115.5	120	101–141
Test for trend			P = NS				P = NS
Duration of employment (years)
<10	10	7.9	127	64–226	428	400.9	107	97–117
10–19	16	14.3	112	66–178	240	211.0	114	100–129
≥20	26	19.8	131	88–190	90	77.0	117	95–143
Test for trend			P = NS				P = NS
Industry sector
Power stations	33	28.7	115	80–160	273	253.6	108	95–121
Transmission	2	2.1	95	16–315	11	12.5	88	46–153
Non-operational	16	9.1	176	104–279	417	374.0	112	101–123
Unclassifiableb	Sup.c				57	48.8	117	89–150
Test for heterogeneity			P = NS				P = NS
Type of work
Managers	Sup.c				Sup.c
Engineers	18	10.8	167	102–258	13	13.2	98	55–164
Admin, clerical	5	2.6	192	70–426	566	496.0	114	105–124
Industrial	28	25.7	109	74–155	130	140.0	93	78–110
Building, constr.	Sup.c				Sup.c
Not known	Sup.c				47	38.4	122	91–161
Test for heterogeneity			P = NS				P = *
Total	52	42.0	124	93–161	758	688.9	110	102–118

NS, not significant.

^aIncludes still employed.

^bUnclassifiable work history or no work history.

^cSup = findings suppressed because of confidentiality concerns about ‘disclosive’ data.

*P < 0.05.