Table 3.

Individual unconditional logistic regression models examining the relationship between each parental toenail metal exposure and spina bifida risk in children (n=278).

	Crude^a			Adjusted^b			Adjusted + Interaction^c

Metal (ln transformed)	β	OR (95% CI)	P	β	OR (95% CI)	P	β	OR (95% CI)	P
Maternal
Aluminum (Al)	0.078	1.082	0.56	0.105	1.110	0.46	−0.156	0.856	0.75
		(0.831, 1.408)			(0.841, 1.466)			(0.331, 2.211)
Arsenic (As)	0.046	1.047	0.71	0.042	1.043	0.74	−0.054	0.947	0.90
		(0.819, 1.338)			(0.812, 1.339)			(0.419, 2.142)
Cadmium (Cd)	0.116	1.124	0.35	0.166	1.180	0.21	0.116	1.123	0.70
		(0.880, 1.435)			(0.909, 1.532)			(0.624, 2.023)
Cobalt (Co)	0.095	1.099	0.49	0.118	1.126	0.41	−0.049	0.952	0.92
		(0.842, 1.435)			(0.850, 1.490)			(0.381, 2.377)
Chromium (Cr)	0.127	1.136	0.40	0.162	1.176	0.30	0.078	1.081	0.88
		(0.845, 1.527)			(0.864, 1.599)			(0.407, 2.871)
Copper (Cu)	−0.896	0.408	0.04	−0.817	0.442	0.07	1.452	4.273	0.24
		(0.176, 0.946)			(0.185, 1.058)			(0.372, 49.134)
Iron (Fe)	0.013	1.013	0.92	0.033	1.033	0.82	0.006	1.006	0.99
		(0.779, 1.318)			(0.783, 1.364)			(0.393, 2.575)
Mercury (Hg)	−0.136	0.873	0.44	−0.155	0.857	0.38	0.194	1.214	0.67
		(0.621, 1.227)			(0.607, 1.21)			(0.502, 2.939)
Manganese (Mn)	−0.117	0.890	0.24	−0.106	0.900	0.31	−0.014	0.986	0.96
		(0.733, 1.080)			(0.735, 1.102)			(0.530, 1.832)
Molybdenum (Mo)	0.229	1.257	0.37	0.266	1.305	0.32	−1.324	0.266	0.16
		(0.762, 2.074)			(0.776, 2.194)			(0.042, 1.679)
Nickel (Ni)	−0.047	0.954	0.62	−0.043	0.958	0.65	0.245	1.278	0.45
		(0.793, 1.148)			(0.794, 1.155)			(0.674, 2.423)
Lead (Pb)	−0.103	0.902	0.51	−0.106	0.899	0.51	−0.403	0.668	0.40
		(0.663, 1.228)			(0.655, 1.235)			(0.262, 1.703)
Antimony (Sb)	0.141	1.152	0.41	0.123	1.131	0.48	−0.294	0.745	0.63
		(0.824, 1.610)			(0.804, 1.591)			(0.225, 2.463)
Selenium (Se)	1.536	4.645	0.02	1.572	4.818	0.02	−1.976	0.139	0.35
		(1.305, 16.536)			(1.319, 17.601)			(0.002, 8.541)
Tin (Sn)	−0.022	0.978	0.86	−0.017	0.983	0.90	0.182	1.199	0.67
		(0.767, 1.248)			(0.766, 1.262)			(0.521, 2.761)
Uranium (U)	0.182	1.200	0.27	0.186	1.204	0.28	−0.501	0.606	0.37
		(0.870, 1.655)			(0.863, 1.680)			(0.201, 1.826)
Vanadium (V)	0.075	1.078	0.56	0.103	1.108	0.45	−0.053	0.948	0.91
		(0.838, 1.388)			(0.847, 1.449)			(0.382, 2.355)
Zinc (Zn)	−2.183	0.113	0.001	−2.220	0.109	0.001	−1.832	0.160	0.35
		(0.031, 0.415)			(0.028, 0.415)			(0.004, 7.290)
Paternal
Aluminum (Al)	0.299	1.348	0.05	0.350	1.419	0.03	0.070	1.073	0.88
		(1.004, 1.810)			(1.045, 1.928)			(0.422, 2.731)
Arsenic (As)	0.525	1.690	0.001	0.555	1.742	0.001	1.415	4.115	0.02
		(1.225, 2.332)			(1.256, 2.417)			(1.247, 13.575)
Cadmium (Cd)	0.187	1.205	0.20	0.195	1.215	0.19	−0.076	0.927	0.87
		(0.908, 1.600)			(0.908, 1.626)			(0.377, 2.278)
Cobalt (Co)	0.320	1.377	0.04	0.381	1.464	0.02	0.124	1.132	0.81
		(1.021, 1.857)			(1.072, 2.001)			(0.413, 3.100)
Chromium (Cr)	0.363	1.437	0.02	0.355	1.427	0.02	0.198	1.219	0.63
		(1.072, 1.927)			(1.059, 1.921)			(0.544, 2.728)
Copper (Cu)	−0.080	0.923	0.82	0.002	1.002	1.00	0.064	1.066	0.96
		(0.457, 1.863)			(0.488, 2.060)			(0.101, 11.280)
Iron (Fe)	0.391	1.478	0.01	0.452	1.572	0.003	0.316	1.371	0.51
		(1.117, 1.957)			(1.171, 2.109)			(0.532, 3.532)
Mercury (Hg)	0.145	1.156	0.52	0.151	1.163	0.51	−0.160	0.853	0.83
		(0.743, 1.799)			(0.741, 1.823)			(0.201, 3.623)
Manganese (Mn)	0.157	1.170	0.14	0.195	1.215	0.08	−0.293	0.746	0.41
		(0.948, 1.445)			(0.975, 1.514)			(0.375, 1.486)
Molybdenum (Mo)	0.237	1.268	0.22	0.299	1.348	0.14	0.111	1.118	0.85
		(0.867, 1.855)			(0.905, 2.008)			(0.367, 3.405)
Nickel (Ni)	0.179	1.195	0.07	0.190	1.209	0.06	0.278	1.321	0.45
		(0.983, 1.454)			(0.991, 1.475)			(0.641, 2.721)
Lead (Pb)	0.112	1.119	0.52	0.105	1.111	0.56	0.037	1.037	0.95
		(0.794, 1.576)			(0.782, 1.58)			(0.360, 2.990)
Antimony (Sb)	0.239	1.270	0.17	0.222	1.249	0.21	0.208	1.231	0.72
		(0.906, 1.782)			(0.881, 1.770)			(0.403, 3.760)
Selenium (Se)	2.488	12.033	<0.001	2.527	12.514	<0.001	1.282	3.604	0.43
		(4.259, 33.999)			(4.329, 36.175)			(0.152, 85.371)
Tin (Sn)	0.141	1.151	0.32	0.152	1.164	0.30	0.549	1.732	0.29
		(0.870, 1.522)			(0.875, 1.550)			(0.628, 4.776)
Uranium (U)	0.213	1.237	0.12	0.235	1.264	0.10	0.100	1.105	0.82
		(0.944, 1.622)			(0.954, 1.675)			(0.458, 2.666)
Vanadium (V)	0.284	1.329	0.05	0.339	1.404	0.02	−0.014	0.986	0.98
		(1.003, 1.760)			(1.047, 1.883)			(0.406, 2.394)
Zinc (Zn)	−0.376	0.686	0.44	−0.364	0.695	0.46	0.069	1.072	0.96
		(0.263, 1.789)			(0.263, 1.834)			(0.090, 12.828)

Note: CI, confidence interval; ln, natural log; OR, odds ratio.

Crude logistic regression models assessed the relationships between each natural log transformed toenail metal and spina bifida case status. Separate models were run for each parent and each metal.

Adjusted logistic regression models examined the relationship between natural log transformed toenail metal concentrations and spina bifida status, adjusting for maternal age (years), paternal age (years), infant sex, place of birth, and maternal serum folate (ng/mL, natural log transformed).

Interaction logistic regression models were the same as the adjusted models, with the addition of an interaction term for the relationship between toenail metals and maternal serum folate.