Table 1. Sample characteristics.

		N‡	%
Sex		1341
	Male	738	55.0
	Female	603	45.0
Age at blood lead test, Mean (SD)		1341	4.84(0.86)
	3 years	316	23.6
	4 years	415	30.9
	5 years	610	45.5
Residence/schools		1341
	City (Jianshe)	538	40.1
	Suburban (Huacheng)	521	38.9
	Rural (Xuebu)	282	21.0
Father's education		1304
	≤Middle school	503	38.6
	High school	420	32.2
	College or higher	381	29.2
Father's occupation		1262
	Unemployed	52	4.1
	Physical worker	718	56.9
	Professional worker	492	39.0
Mother's education		1305
	≤Middle school	657	50.3
	High school	384	29.4
	College or higher	264	20.2
Father smoking		1273
	No	563	44.2
	Occasionally	454	35.7
	Several times/wk	41	3.2
	<10 cigarettes/wk	127	10.0
	10–20 cigarettes/wk	71	5.6
	>20 cigarettes/wk	17	1.3
Iron Status	Mean (SD)	1341	8.13 (0.83)
Blood lead (µg/dL)	Mean (SD)	1341	6.43(2.64)
	<6.0	611	45.6
	6.0 to <8.0	440	32.8
	8.0 to <10.0	185	13.8
	≥10.0	105	7.8

^‡Number of children differs across sample characteristics due to missing values.