Occupational exposure to endocrine disrupting substances and the risk of breast Cancer: the Singapore Chinese health study

Table 2 Hazard Ratios and 95% CI for breast cancer according to EDC exposure level for each occupational domain: The Singapore Chinese Health Study

		Model 1^a		Model 2^b
Parameter	Cases % (Case N/ Overall N)	HR	95% CI	HR	95%CI
Median (IQR) of Substance Index: 0 (0–2.5)
No Exposure through job/substance/industry	3.0% (550/18,138)	1	Ref	1	Ref
No Exposure to substance type	2.8% (334/11,524)	0.95	0.83–1.10	0.95	0.82–1.09
Tertile 1 (Substance)	2.2% (22/1023)	0.74	0.48–1.14	0.74	0.48–1.13
Tertile 2 (Substance)	3.0% (50/1631)	1.05	0.78–1.40	1.03	0.77–1.38
Tertile 3 (Substance)	2.8% (32/1142)	0.95	0.66–1.36	0.94	0.66–1.35
Median (IQR) of Job Title Index: 0 (0–0)
No Exposure through job/substance/industry	3.0% (550/18,138)	1	Ref	1	Ref
No Exposure via Job Title	3.0% (134/4381)	1.02	0.84–1.24	1.02	0.84–1.23
Tertile 1 (Job Title)	2.4% (75/3039)	0.84	0.66–1.08	0.84	0.66–1.07
Tertile 2 (Job Title)	3.0% (124/4165)	0.98	0.80–1.20	0.97	0.80–1.19
Tertile 3 (Job Title)	2.8% (105/3735)	0.92	0.74–1.13	0.91	0.74–1.13
Median (IQR) of Industry Index: 0 (0–0)
No Exposure through job/substance/industry	3.0% 550/18,138	1	Ref	1	Ref
No Exposure via Industry type	2.7% 263/9635	0.91	0.78–1.05	0.91	.78–1.05
Tertile 1 (Industry)	3.1% 61/1939	1.05	0.80–1.37	1.05	0.80–1.37
Tertile 2 (Industry)	2.7% 42/1579	0.88	0.64–1.21	0.87	0.64–1.20
Tertile 3 (Industry)	3.3% 72/2167	1.08	0.84–1.38	1.07	0.83–1.38

*The index = the sum of the quantity x median duration of years of each individual exposure for the reported substance and reflects the estimated number of years of exposure to occupational related EDCs. Those with non-zero scores were ranked into tertiles
^aModel 1 included age, dialect, enrollment year, education, smoking, alcohol use, BMI, birth control use, hormone therapy use, physical activity, dietary pattern score
^bModel 2: Model 1 + parity, age at first birth, menarche age and menopausal status

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