Table 4.

The Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) cohort consists of over 2000 mother-infant pairs, belonging to a low income population recruited from 1994 onwards from 3 hospitals in Mexico City (Mexican Social Security Institute, Manuel Gea Gonzalez Hospital, and National Institute of Perinatology). For our study, we randomly selected UCB for 24 male children and 24 female children from the 1st and 4th quartiles of Pb levels.

Family ID	Gender	SES score	Gestational age	Smoke Ever	Birth weight	Pb concentration
12	male	6	38	1	3.63	1.2797
15	female	4	38	1	3.05	6.1748
17	female	2	40	1	3.285	1.2036
32	male	1	37	0	2.7	1.3276
41	male	2	38	0	3.1	1.6951
62	female	5	39	1	3.285	1.6714
70	female	3	39	0	2.98	3.8141
76	male	4	37	0	3.3	1.5686
82	male	3	38	0	3.09	1.5404
83	male	4	40	0	3.25	4.8687
88	male	2	40	1	3.47	1.5936
91	male	4	39	1	2.98	1.3482
92	female	2	38	1	3.09	1.7482
99	female	2	39	1	3.025	1.3594
101	female	1	39	1	2.725	6.3513
105	female	3	41	1	2.5	6.4667
120	male	3	40	0	3.85	6.4195
129	male	3	40	1	3.02	4.7712
135	female	2	39	1	3.3	5.0786
141	female	2	40	0	3.15	9.825
144	male	2	40	0	3.105	7.2093
150	male	1	39	1	3.05	5.3881
162	female	4	39	1	2.6	3.7799
163	male	2	39	1	2.805	1.5525
164	male	2	40	0	3.625	1.1279
168	female	1	39	1	3.575	7.8923
184	female	2	40	1	3.125	0.8501
185	female	3	39	1	2.375	4.0317
189	male	3	37	0	2.705	0.5872
196	female	3	38	0	3.005	10.5263
199	male	3	40	1	3.05	1.3602
202	female	6	37	0	3.055	4.3582
203	female	2	41	1	2.705	1.4625
207	male	2	36	1	2.4	1.3162
212	female	3	36	0	3.05	4.6601
215	female	4	39	1	2.8	0.6821
222	male	2	39	0	3.2	6.2375
230	female	3	38	0	2.325	4.5225
235	female	2	40	1	3.06	4.9727
239	male	2	39	1	3	1.0372
247	female	2	39	1	2.7	0.9782
264	female	2	40	0	2.725	1.1936
269	male	4	41	1	4	3.9883
276	male	4	39	1	3.6	5.364
278	male	5	37	0	3.3	0.9199
283	male	2	40	1	2.85	4.5899
287	female	2	40	1	3.25	1.572
305	male	2	38	0	3.425	4.3498