Table 2.

Exposures to nitrate-nitrogen (NO₃-N) and total trihalomethanes (TTHMs) in public water and ovarian cancer risk

	Median	N	Cases	HR (95% CI)
				Age-adjusted	Model 1a	Model 2b
NO3-N (mg/L)
0.01 – 0.472	0.31	3,263	23	1.0	1.0	1.0
0.473 – 1.08	0.75	3,269	32	1.41 (0.82 – 2.41)	1.36 (0.80 – 2.34)	1.27 (0.73 – 2.21)
1.09 – 2.97	1.68	3,504	41	1.66 (1.00 – 2.76)	1.55 (0.92 – 2.59)	1.45 (0.85 – 2.44)
2.98 – 25.34	3.81	3,015	49	2.34 (1.42 – 3.84)	2.14 (1.30 – 3.54)	2.03 (1.22 – 3.38)
ptrend				0.0005	0.002	0.003
Private well water	-	4,165	45	1.50 (0.91 – 2.49)	1.53 (0.93 – 2.54)	-
Years of NO3-N >5 mg/Lc
0	0	9,206	91	1.0	1.0	1.0
1 – 3	1	1,871	22	1.20 (0.75 – 1.91)	1.05 (0.64 – 1.72)	1.08 (0.65 – 1.77)
≥ 4d	8	1,974	32	1.66 (1.11 – 2.49)	1.60 (1.06 – 2.41)	1.52 (1.00 – 2.31)
ptrend				0.01	0.02	0.05
TTHMs (μg/L)
0 – 0.89	0.47	3,112	27	1.0	1.0	1.0
0.90 – 4.59	1.95	3,612	33	1.07 (0.64 – 1.78)	1.10 (0.65 – 1.86)	1.08 (0.64 – 1.82)
4.77 – 14.31	10.67	3,524	55	1.82 (1.15 – 2.89)	1.86 (1.146– 3.00)	1.64 (1.00 – 2.70)
14.50 – 200.88	76.32	2,803	30	1.27 (0.76 – 2.14)	1.31 (0.77 – 2.24)	1.24 (0.73 – 2.13)
ptrend				0.78	0.74	0.80
Years of TTHMs >40 μg/Lc
0	0	9,838	110	1.0	1.0	1.0
> 0 – 35	3	1,442	17	1.05 (0.63 – 1.76)	1.00 (0.59 – 1.70)	0.99 (0.59 – 1.68)
≥36d	40	1,771	18	0.93 (0.56 – 1.53)	0.90 (0.54 – 1.50)	0.91 (0.55 – 1.52)
ptrend				0.84	0.69	0.72

^aAdjusted for age, BMI, family history of ovarian cancer, number of live births (0, 1–2, 3–4, ≥ 5), age at menarche (≤ or >12), age at menopause (< 45, 45–49, 50–54, ≥ 55), age at first live birth (< 20, 20–24, 25–29, ≥ 30), oral contraceptive use (never, ever), estrogen use (never, ever), and history of unilateral oophorectomy.

^bAdditionally mutually adjusted for logarithmically transformed values of NO₃-N or TTHMs levels in public water.

^cHalf the maximum contaminant level (MCL) determined by the U.S. Environmental Protection Agency.

^dThe median years of exposures to a half of MCL among women who exposed during the reported duration of exposure.