ABSTRACT
Lead exposure is a severe public health issue that can adversely affect children's neurocognitive development. A semi-urban community in Mexico has been exposed to lead from food cooked in glazed clay pots. A cognitive intervention was conducted from 2015 to 2016 to minimize this negative impact. This intervention aimed to improve the neurocognitive development of the affected children. METHODS: A quasi-experimental study with a control group was conducted in children aged 7 to 12 years from 2 communities in Morelos, Mexico. Blood lead levels were determined, and the neurocognitive function was assessed pre- and postintervention with the Wechsler Intelligence Scale for Children and Children's Auditory Verbal Learning Test-2. A cognitive intervention was conducted at the school. The difference-in-differences method adjusted for variables known as priori and evaluated the impact of cognitive intervention. RESULTS: The differences-in-differences models indicated a significant average increase in scores on the Verbal Comprehension Index (9.58 points), Processing Speed Index (5.33 points), intelligence quotient (5.63 points) level of learning (7.66 points), interference trial (10.12 points), immediate memory span (7.98 points), and recognition accuracy (1.18 points) subtests after the cognitive intervention. CONCLUSION: The results suggest that cognitive intervention improves neurocognitive development in schoolchildren exposed to Pb.
ABSTRACT
The effects caused by exposure to lead (Pb) are still considered as a relevant health risk despite public policies aimed to restricting the use of this element. The toxicity limit in the blood (10 µg/dL, established by the Center for Disease Control and Prevention) has been insufficient to prevent adverse effects and even lower values have been related to neurobehavioral dysfunctions in children. Currently, there is not a safe limit of exposure to Pb. A large body of evidence points to environmental pollutant exposure as the cause of predisposition to violent behavior, among others. Considering the evidence by our group and others, we propose that Pb exposure induces alterations in the brain vasculature, specifically in nitric oxide synthases (NOS), affecting in turn the serotonergic system and leading to heightened aggressive behavior in the exposed individuals. This review article describes the consequences of Pb exposure on the nitrergic and serotonergic systems as well as its relationship with aggressive behavior. In addition, it summarizes the available therapy to prevent damage in gestation and among infants.
ABSTRACT
OBJECTIVES: Lead exposure remains a significant environmental problem; lead is neurotoxic, especially in developing humans. In Mexico, lead in human blood is still a concern. Historically, much of the lead exposure is attributed to the use of handcrafted clay pottery for cooking, storing and serving food. However, experimental cause-and-effect demonstration is lacking. The present study explores this issue with a prospective experimental approach. METHODS: We used handcrafted clay containers to prepare and store lemonade, which was supplied as drinking water to pregnant rats throughout the gestational period. RESULTS AND DISCUSSION: We found that clay pots, jars, and mugs leached on average 200â µg/l lead, and exposure to the lemonade resulted in 2.5â µg/dl of lead in the pregnant rats' blood. Neonates also showed increased lead content in the hippocampus and cerebellum. Caspase-3 activity was found to be statistically increased in the hippocampus in prenatally exposed neonates, suggesting increased apoptosis in that brain region. Glazed ceramics are still an important source of lead exposure in Mexico, and our results confirm that pregnancy is a vulnerable period for brain development.
