Blood Lead Concentrations and Children’s Behavioral and Emotional Problems

Abstract

Importance The association between lead exposure and children’s IQ has been well studied, but few studies have examined the effects of blood lead on children’s behavior. Objective This study examined the association between blood lead concentrations and behavioral problems in a community sample of Chinese preschool children with a mean blood lead level <10 µg/dL. Design Prospective cohort study. Setting Four elementary schools in Jintan City, Jiangsu Province of China. Participants Participants were 1341 children at ages 3–5 years. Main Outcome Measures Blood lead concentration was measured at ages 3–5 years. Behavioral problems were assessed using Chinese versions of the Child Behavior Checklist and Teacher Report Form when children at age 6 years. Results Mean blood lead concentration was 6.4 µg/dL (SD=2.6), with 75th and 90th percentiles being 7.7 and 9.4 µg/dL respectively. General linear modeling showed significant associations between blood lead concentrations and increased scores for teacher reported behavioral problems. One µg/dL increase of blood lead concentration resulted in a 0.32, 0.25 and 0.30 increase of behavior scores on emotional reactivity, anxiety/depressed and pervasive developmental problems, respectively (p <0.05), while adjusting for parental and child variables,. Spline modeling showed that teacher-reported behavior scores increased with blood lead concentration, particular for older girls. Conclusions and Relevance Blood lead concentrations, even at mean levels of 6.4 µg/dL, were associated with increased risk of behavioral problems in Chinese preschool children, including internalizing and pervasive developmental problems. This association showed different patterns depending on age and gender.

Effects of low level lead exposure on associative learning and memory in the rat: Influences of sex and developmental timing of exposure

“…Considering the known sensitivity of the frontal cortex and hippocampus to the effects of Pb (Schneider et al, 2012b), it is likely that the current effects are related to complex effects of Pb on fronto-hippocampal circuits involved in acquisition, consolidation and recall of memories (Miller et al, 2010), and in particular, emotional memories. In addition to adversely affecting the formation, stabilization and recall of memories, Pb-induced damage to prefrontal/hippocampal circuits may also underlie emotional and behavioral dysregulation frequently seen in Pb-exposed children (Carpenter and Nevin, 2010, Chiodo et al ., 2004, Liu et al , 2014, Nevin, 2007, Nigg et al ., 2008). Additional work in progress will better define the extent to which low level Pb exposure during different developmental periods affects the dynamic modulation of DNA methylation and post-translational histone modifications critical to normal cognitive and behavioral regulation.…”

“…Of the numerous adverse behavioral outcomes from developmental Pb exposure, anti-social and aggressive behaviors are amongst the most common and troublesome. Although anti-social and aggressive/violent behavior can be attributed to a variety of social factors, increased frequency of anti-social and aggressive behaviors as well as other behavioral disorders such as oppositional defiant behavior and anxiety have been shown to be related to developmental Pb exposure (Carpenter and Nevin, 2010; Chiodo et al, 2004; Liu et al, 2014; Nevin, 2007; Nigg et al, 2008). There has been little basic research on these aspects of developmental Pb neurotoxicity and their relationship to disturbed cognitive outcomes.…”

Lead Exposure: Pottery Impact in Tlaxcala, Mexico

“…Lead has originated environmental and human health problems around the world (Braun et al 2014, Jeong et al 2014, La llave et al 2014, McElvenny et al 2015. Various studies suggest that exposure to lead during childhood at levels under 10 µg/dL contributes to learning problems, hearing deficit, and a decline in the intellectual coefficient and cognitive capacities (Carta et al 2013, Liu et al 2014, Sánchez-Villegas et al 2014, Taylor et al 2014.…”

Exposure to Power-Frequency Magnetic Fields and the Risk of Infertility and Adverse Pregnancy Outcomes: Update on the Human Evidence and Recommendations for Future Study Designs

“…As an alternative, splines can be easily added to statistical models to detect associations that normally would not be revealed using a quantile analysis. Splines have been widely used in environmental epidemiology studies (Ashley-Martin et al, 2014; Khalil et al, 2014; Kim et al, 2014; Liu et al, 2014; Wang and Choi, 2014), including those that have focused on magnetic fields (Greenland et al, 2000; Kheifets et al, 2010). While it may be true that splines are sensitive to placement of knots, others investigators argued that quantiles are equally sensitive to the selection of cut-off points (Bennette and Vickers, 2012).…”