Breast cancer risk in relation to occupations with exposure to carcinogens and endocrine disruptors: a Canadian case–control study

Table 7 Breast cancer odds ratios for cumulative exposure accruing in time-windows reflecting reproductive status, by conditional multiple logistic regression

Parameter
Window	OR (95% CI)	Wald P
Cumulative Exposure ¹ I
< menarche	1.037 (0.89-1.21)
menarche-first pregnancy	1.018 (0.98-1.06)
first pregnancy – menopause	1.036 (1.01-1.06)	0.012
menopause -	1.012 (0.97-1.06)
Cumulative Exposure ² II
< menarche	1.003 (0.85-1.18)
menarche-first pregnancy	1.037 (0.98-1.09)	0.18
first pregnancy – menopause	1.050 (1.01-1.09)	0.0072
menopause -	1.018 (0.97-1.07)
Selected cumulative exposures ^2,3,4
Farming
< menarche	1.054 (0.88-1.26)
menarche-first pregnancy	0.997 (0.93-1.07)
first pregnancy – menopause	1.046 (0.98-1.12)	0.19
menopause -	1.054 (0.96-1.16)
Bars, gambling
menarche-first pregnancy	1.022 (0.81-1.29)
first pregnancy – menopause	1.141 (0.98-1.33)	0.092
menopause -	1.039 (0.82-1.32)
Metalworking
menarche-first pregnancy	1.161 (0.96-1.40)	0.12
first pregnancy – menopause	1.064 (0.97-1.16)	0.17
menopause -	1.020 (0.92-1.13)
Auto industry: plastics
menarche-first pregnancy	1.297 (1.05-1.61)	0.018
first pregnancy – menopause	1.104 (1.01-1.20)	0.023
menopause -	1.044 (0.92-1.19)
Canning
menarche-first pregnancy	1.262 (0.96-1.66)	0.095
first pregnancy – menopause	1.079 (0.96-1.22)
menopause -	1.041 (0.88-1.24)

All three models include reproductive, demographic risk factors as in Table 4 and employment duration; matching on age in 3-year intervals.
OR for cumulative exposure evaluated at 1.0 year in time-window inhigh-exposed jobs (lagged 5 year).
1. cumulative exposure on transformed ratings: 1 (low), 2 (moderate),3 (high) → 0, 1, 2, as rating-year.
2. cumulative exposure on transformed ratings: 1 (low), 2 (moderate),3 (high) → 0, 1, 10, as rating-year.
3. model includes all major sector exposures;
4. no cases/controls with non-farm exposure in window: < menarche.