Childhood Blood Lead Levels and Symptoms of Attention Deficit Hyperactivity Disorder (ADHD): A Cross-Sectional Study of Mexican Children

http://dx.doi.org/10.1289/ehp.1510067



Table 1. Characteristics of parents and children participating in Mexican birth cohort study of lead exposure and behavior.
Characteristicsa Original data Imputed data n = 578
n Percent missing Mean ± SD or n (%) Mean ± SD or n (%)
SES, socioeconomic status.
aBehavior assessments were conducted at the follow-up visit when children were 6 to 13 years old. Children’s blood lead levels, parental information, and SES level index were assessed at the behavior assessment. SES level index was calculated by summarization of household assets at follow-up visit.
Behavior assessment
CRS-R
Cognitive Problem/Inattention 561 2.9 54.0 ± 10.6 54.1 ± 10.5
Hyperactivity 561 2.9 55.5 ± 10.8 55.6 ± 10.7
ADHD Index 560 3.1 54.1 ± 10.5 54.1 ± 10.4
CGI Restless-Impulsive 561 2.9 54.5 ± 10.3 54.6 ± 10.3
CRS-R DSM-IV
CRS: DSM IV Inattentive 561 2.9 53.3 ± 10.2 53.4 ± 10.2
CRS: DSM IV Hyperactive-Impulsive 561 2.9 57.1 ± 10.7 57.1 ± 10.6
CRS: DSM IV Total 561 2.9 55.4 ± 10.4 55.5 ± 10.3
Child characteristics
Blood lead level (μg/dL) 412 28.7 3.4 ± 2.9 3.4 ± 3.1
Children’s age (years) 578 0 9.1 ± 1.3 9.1 ± 1.3
Children’s sex, female 578 0 289 (50.0) 289 (50.0)
Birth weight (kg) 577 0.2 3.1 ± 0.4 3.1 ± 0.4
Parental characteristics
Maternal age (years) 578 0 26.0 ± 5.4 26.0 ± 5.4
Maternal education (years) 578 0 10.9 ± 2.8 10.9 ± 2.8
Mothers’ marital status, married 578 0 421 (72.8) 421 (72.8)
Smoking during pregnancy, smoked 577 0.2 18 (3) 18 (3)
Paternal education (years) 534 7.6 10.7 ± 3.5 10.6 ± 3.5
SES level index 553 4.3 8.7 ± 3.2 8.8 ± 3.3