. 2017 Nov 7;125(11):117003. doi: 10.1289/EHP1691

Table 1.

Main characteristics of mothers and children included in the study by girls and boys ( $n = 1,408$ ) and hair selenium below and above $665 μ g / kg$ ( $n = 1,330$ ).

Characteristic	$n$	All( $n = 1,408$ ) $Mean \pm SD$	Girls( $n = 671$ ) $Mean \pm SD$	Boys ( $n = 737$ ) $Mean \pm SD$	p-Value^a	Hair Se $< 665 μ g / kg$ ( $n = 1,296$ ) $Mean \pm SD$	Hair Se $\geq 665 μ g / kg$ ( $n = 34$ ) $Mean \pm SD$	p-Value^a
Mothers
Parity at GW8^b	1,408	$1.5 \pm 1.4$	$1.5 \pm 1.4$	$1.4 \pm 1.4$	0.30	$1.5 \pm 1.4$	$1.2 \pm 1.6$	0.17
SES at GW8	1,408	$- 0.14 \pm 2.3$	$- 0.17 \pm 2.3$	$- 0.12 \pm 2.3$	0.67	$- 0.14 \pm 2.3$	$0.50 \pm 1.9$	0.11
Ery-Se at GW14 ( $μ g / g$ Hb)	1,408	$0.45 \pm 0.11$	$0.45 \pm 0.11$	$0.45 \pm 0.11$	0.41	$0.45 \pm 0.11$	$0.51 \pm 0.15$	0.012
Ery-Zn at GW14 ( $μ g / kg$ )	1,408	$8156 \pm 2303$	$8190 \pm 2384$	$8124 \pm 2228$	0.70	$8145 \pm 2302$	$8389 \pm 2036$	0.62
Ery-Mn at GW14 ( $μ g / kg$ )	1,408	$20 \pm 7.5$	$20 \pm 7.4$	$20 \pm 7.5$	0.66	$20 \pm 7.5$	$19 \pm 5.1$	0.62
Ery-As at GW14 ( $μ g / kg$ )	1,408	$7.6 \pm 8.1$	$7.4 \pm 7.4$	$7.7 \pm 8.7$	0.55	$7.5 \pm 8.1$	$6.0 \pm 5.4$	0.43
Ery-Cd at GW14 ( $μ g / kg$ )	1,408	$1.1 \pm 0.69$	$1.0 \pm 0.72$	$1.1 \pm 0.66$	0.12	$1.1 \pm 0.69$	$0.96 \pm 0.49$	0.68
Ery-Pb at GW14 ( $μ g / kg$ )	1,408	$77 \pm 45$	$76 \pm 44$	$78 \pm 1.6$	0.59	$77 \pm 45$	$76 \pm 32$	0.77
Raven’s score at 5 y	1,408	$25 \pm 12$	$25 \pm 12$	$25 \pm 12$	0.28	$25 \pm 12$	$27 \pm 12$	0.24
Education at 5 y (y)	1,408	$4.6 \pm 4.0$	$4.6 \pm 4.0$	$4.6 \pm 4.0$	0.73	$4.6 \pm 4.0$	$5.9 \pm 3.9$	0.049
Education at 10 y (y)	1,408	$5.1 \pm 3.7$	$5.1 \pm 3.7$	$5.2 \pm 3.7$	0.63	$5.1 \pm 3.7$	$6.2 \pm 3.4$	0.10
Paternal educationat 5 y	1,399	$5.0 \pm 4.5$	$4.9 \pm 4.5$	$5.2 \pm 4.4$	0.20	$5.0 \pm 4.5$	$6.5 \pm 3.8$	0.045
Paternal education at 10 y	1,408	$5.4 \pm 4.3$	$5.3 \pm 4.3$	$5.5 \pm 4.3$	0.42	$5.4 \pm 4.3$	$6.6 \pm 3.8$	0.075
Children at birth
Birth weight (g)	1,327	$2690 \pm 390$	$2640 \pm 370$	$2740 \pm 400$	$< 0.001$	$2700 \pm 390$	$2700 \pm 460$	0.88
Gestational age at birth (wk)	1,408	$39 \pm 2.1$	$39 \pm 2.1$	$39 \pm 2.2$	0.012	$39 \pm 2.2$	$40 \pm 1.2$	0.027
Children at 5 years
Age (y)	1,408	$5.4 \pm 0.13$	$5.4 \pm 0.13$	$5.4 \pm 0.13$	0.42	$5.4 \pm 0.13$	$5.4 \pm 0.16$	0.41
HAZ (z-score)	1,408	$- 1.6 \pm 0.92$	$- 1.6 \pm 0.88$	$- 1.6 \pm 0.96$	0.77	$- 1.6 \pm 0.92$	$- 1.3 \pm 1.1$	0.17
HOME	1,344	$8.6 \pm 4.8$	$8.7 \pm 4.8$	$8.5 \pm 4.9$	0.37	$8.5 \pm 4.8$	$11 \pm 5.1$	0.0024
Tester (%)	1,408				0.45			0.81
Tester 1		8	9	7		8	6
Tester 2		78	77	79		78	76
Tester 3		14	14	14		14	18
School type (%)	1,408				0.059			0.16
None		20	18	22		20	29
Primary		23	23	23		23	26
Madrasa		5	4	4		5	6
Kindergarten		6	6	6		6	12
Maktab		29	27	31		29	21
Nonformal		17	20	14		17	6
U-Se ( $μ g / L$ )	1,357	$14 \pm 6.6$	$13 \pm 6.3$	$15 \pm 6.7$	$< 0.001$	$14 \pm 6.4$	$17 \pm 9.5$	0.033
U-As ( $μ g / L$ )	1,357	$101 \pm 118$	$100 \pm 115$	$102 \pm 120$	0.66	$102 \pm 119$	$84 \pm 85$	0.33
U-Cd ( $μ g / L$ )	1,357	$0.29 \pm 0.28$	$0.31 \pm 0.33$	$0.27 \pm 0.23$	0.058	$0.29 \pm 0.28$	$0.24 \pm 0.15$	0.46
U-Pb ( $μ g / L$ )	1,357	$4.6 \pm 3.5$	$4.7 \pm 3.7$	$4.5 \pm 3.3$	0.31	$4.6 \pm 3.6$	$4.4 \pm 2.7$	0.92
Full developmental score	1,408	$79 \pm 22$	$80 \pm 22$	$79 \pm 22$	0.29	$79 \pm 22$	$82 \pm 24$	0.46
Verbal score	1,408	$33 \pm 11$	$33 \pm 11$	$33 \pm 11$	0.57	$33 \pm 11$	$33 \pm 18$	0.54
Performance score	1,408	$34 \pm 7.8$	$34 \pm 7.7$	$34 \pm 8.0$	0.69	$34 \pm 7.8$	$35 \pm 8.8$	0.39
Children at 10 y
Age (y)	1,408	$9.5 \pm 0.095$	$9.5 \pm 0.090$	$9.5 \pm 0.10$	0.96	$9.5 \pm 0.095$	$9.5 \pm 0.072$	0.86
HAZ (z-score)	1,408	$- 1.4 \pm 0.94$	$- 1.5 \pm 0.95$	$- 1.4 \pm 0.93$	0.33	$- 1.4 \pm 0.94$	$- 1.2 \pm 1.1$	0.24
HOME	1,408	$27 \pm 4.9$	$27 \pm 4.8$	$27 \pm 5.1$	0.0063	$27 \pm 4.9$	$29 \pm 6.2$	0.15
Tester (%)	1,408				0.14			0.59
Tester 1		26	25	28		27	18
Tester 2		25	27	23		25	32
Tester 3		24	22	25		23	26
Tester 4		25	26	24		25	24
School type (%)	1,408				$< 0.001$			0.93
None		10	5	15		11	9
Madrasa		3	3	3		3	0
NGO		77	84	70		77	79
Primary		9	7	12		9	12
English medium		1	1	0		0	0
Years of schooling	1,408	$3.1 \pm 1.0$	$3.2 \pm 0.97$	$2.9 \pm 1.1$	$< 0.001$	$3.1 \pm 1.0$	$3.3 \pm 1.0$	0.14
SES	1,408	$0.0012 \pm 2.6$	$0.028 \pm 2.6$	$- 0.023 \pm 2.5$	0.98	$- 0.017 \pm 2.6$	$0.79 \pm 3.1$	0.055
U-Se ( $μ g / L$ )	1,403	$15 \pm 6.1$	$14 \pm 5.7$	$15 \pm 6.3$	$< 0.001$	$15 \pm 6.1$	$17 \pm 6.9$	0.0088
U-As ( $μ g / L$ )	1,403	$107 \pm 123$	$110 \pm 125$	$104 \pm 121$	0.96	$106 \pm 123$	$113 \pm 99$	0.47
U-Cd ( $μ g / L$ )	1,403	$0.29 \pm 0.22$	$0.30 \pm 0.23$	$0.28 \pm 0.21$	0.078	$0.29 \pm 0.22$	$0.24 \pm 0.15$	0.13
U-Pb ( $μ g / L$ )	1,403	$1.9 \pm 1.5$	$1.9 \pm 1.3$	$1.9 \pm 1.6$	0.39	$1.9 \pm 1.3$	$2.0 \pm 1.2$	0.54
Hair Se ( $μ g / kg$ )	1,334	$487 \pm 84$	$478 \pm 85$	$496 \pm 82$	$< 0.001$	$482 \pm 77$	$701 \pm 41$	$< 0.001$
Hair Hg ( $μ g / kg$ )	1,334	$799 \pm 684$	$807 \pm 473$	$791 \pm 840$	0.083	$803 \pm 689$	$661 \pm 449$	0.037
Water Mn ( $μ g / L$ )	1,408	$895 \pm 1164$	$942 \pm 1247$	$852 \pm 1082$	0.90	$885 \pm 1144$	$1017 \pm 1459$	0.84
Full developmental score	1,408	$133 \pm 33$	$131 \pm 33$	$134 \pm 34$	0.16	$132 \pm 33$	$138 \pm 44$	0.32
Verbal comprehension	1,408	$37 \pm 11$	$36 \pm 10$	$37 \pm 11$	0.043	$37 \pm 10$	$39 \pm 14$	0.29
Perceptual reasoning	1,408	$32 \pm 12$	$30 \pm 11$	$33 \pm 12$	$< 0.001$	$32 \pm 11$	$34 \pm 16$	0.53
Working memory	1,408	$30 \pm 6.2$	$29 \pm 6.0$	$30 \pm 6.2$	$< 0.001$	$30 \pm 6.1$	$30 \pm 8.5$	0.38
Processing speed^c	1,408	$34 \pm 12$	$36 \pm 12$	$33 \pm 12$	$< 0.001$	$34 \pm 12$	$34 \pm 12$	0.63

Note: Ery-As, erythrocyte arsenic; Ery-Cd, erythrocyte cadmium; Ery-Mn, erythrocyte manganese; Ery-Pb, erythrocyte lead; Ery-Se, erythrocyte selenium; Ery-Zn, erythrocyte zinc; GW, gestational week; Hair Hg, hair mercury; Hair Se, hair selenium; HAZ, height-for-age z-score; HOME, quality and quantity of children’s stimulation at home assessed using a modified version of Home Observation for Measurement of the Environment; NGO, nongovernmental organization; SES, socioeconomic status assessed via a wealth index based on information on family ownership of e.g. assets, housing structure, and dwelling characteristics (Gwatkin DR et al. 2000); U-As, urinary arsenic; U-Cd, urinary cadmium; U-Pb, urinary lead; U-Se, urinary selenium; Water Mn, water manganese.

^{^a}

Mann-Whitney U-test, chi-squared, or Fisher’s exact test.

^{^b}

GW8 corresponds to enrollment into Maternal and Infant Nutrition Interventions in Matlab (MINIMat).

^{^c}

Higher processing speed indicates faster response time.