Children brain development

Basing their views upon an examination of the biochemical evidence for adverse effects of lead rather than upon studies of child brain development, the US Environmental Protection Agency (EPA) [4] and the World Health Organization (WHO) [5] have recommended upper limits to the population median blood lead level. In consequence, the US EPA has promulgated an ambient air quality standard designed to limit the exposure of the general population to airborne lead [4]. This standard will necessitate tight control over emission of lead into the atmosphere. 

Prevention alone is often not enough. Children still become jaundiced even after careful assessment. When this occurs.it is important to assess the risk of developing significant hyperbilirubinemia. The main concern is that the child will develop acute bilirubin encephalopathy, which is caused by the toxicity of bilirubin on the basal ganglia and other brain stem nuclei. There are early, middle, and late stages of acute bilirubin encephalopathy (Table 22-3). The term kernicterus is applied to chronic... 

Acute lead toxicity produces appetite loss and vomiting. Chronic toxicity leads to renal malfunction, anemia, gout, and nervous system disorders, including brain damage in children. (Lead inhibits development in fetal and child brains.) The effects are more serious for a patient deficient in calcium, zinc, or iron (see Figure 2). Available Pb + affects the structure and function of the bone marrow, where it inhibits several enzymes involved in heme synthesis. It also affects mitochondrial functions in diverse ways. It has proven difficult, however, to specify critical interactions in lead toxicity. Pb + is not particularly carcinogenic but quite toxic. Acute toxicity is dealt with by infusion of Ca +-EDTA,... 

A lack of iodine can cause other problems too. For example, thyroid hormones are needed for normal brain development in an unborn child. They are also needed to continue that development after birth. People who do not include enough iodine in their diet do not develop... 

With this tool, the investigators were able to establish a relationship between maternal methylmercury exposure and indices of child development. Statistical analyses of the correlation between maternal hair levels and delayed walking, for example, suggested that even slightly elevated methylmercury consumption by a pregnant woman might pose a risk for fetal brain development. 

A developing fetus is much smaller than an adult or even young child. The effects of chemical exposure are, therefore, much greater for the fetus. An exposure of 10 ppb of PCBs will have a negligible effect on an adult but will impair the brain development of a fetus. 

And the child with a BLL of only 1 unit isn t safe either. In fact, as far as we can tell, there s no threshold of safety for lead in the blood, no concentration below which lead is harmless to the child s developing brain. The only safe concentration is zero. That s the consensus of clinical researchers and pediatricians in America and around the world. 

Each year in America, the national consumption of alcohol by women of child-bearing age adds approximately 100,000 more mentally retarded children to the population. How many more children not diagnosed as mentally retarded are affected by prenatal exposure to alcohol We know only that this exposure is related to atypical brain development, neuropsychological deficits, academic difficulties, emotional dysfunction, and social dysfunction.39 Is this constellation of problems acceptable collateral damage of the alcoholic beverages industry ... 

For the first time, we watched the human brain develop from birth to adulthood...at birth, the areas that were functioning in the newborn child were, not surprisingly, the phylogenetically older parts of the brain the cerebellum, the central structures of the brain the thalamus, and the old motor cortex... as you watch (the child grow) one structure after the other matures,... 

Ethyl alcohol is found in alcoholic beverages and is a known teratogenic material, which is the reason doctors tell pregnant women not to drink alcohol. When a mother drinks, the unborn child drinks as well. Ethyl alcohol causes growth failure and impaired brain development. Unborn children exposed to alcohol may suffer the effects of Eetal Alcohol Syndrome when they are bom. Symptoms of Fetal Alcohol Syndrome include sleep disturbance, jitteriness, a higher incidence of impaired vision and hearing, lack of motor coordination, balance problems, abnormal thyroid function, and a decrease in immune system effectiveness. Additional teratogens include heavy metals, methyl mercury, mercury salts, lead, thallium, selenium, penicillin, tetracyclines, excess Vitamin A, and carbon dioxide. 

The most alarming danger of lead is the damage it can do to a child s developing brain and nervous system. Even amounts of lead that were considered harmless a few years ago have been shown in scientific studies to cause learning disabilities and behavioral problems. A number of studies have found that for each 10 micrograms per deciliter over the threshold of 10 or 15 micrograms per deciliter of lead in a child s blood,... 

Bidirectional brain-behavior links exist (e.g., brain development mediates changes in behavioral competence, but the child s interactions with his or her environment also can influence brain development). 

Rao R, Georgieff MK. 2000. Early nutrition and brain development. In Nelson C, ed. The Minnesota Symposia on Child Psychology. The Effects of Adversity on Neurobehavioral Development. Vol. 31. Mahway, NJ Lawrence Erlbaum Associates. Pp. 1-30. 

Michael K. Georgieff, M.D., is a professor in the Departments of Pediatrics and Child Development and codirector of the Center for Neurobehavioral Development at the University of Minnesota School of Medicine. His expertise and research interests are in fetal and neonatal nutrition and neurodevelopment, with special emphasis on the effect of fetal/ neonatal iron nutrition on brain development and neurocognitive function and the effect of illness on neonatal protein-energy metabolism. Dr. Georgieff received his M.D. from the Washington University Medical School. He is a member of the Perinatal Research Society, the American Academy of Pediatrics, the Society for Pediatric Research, and the American Pediatric Society. 

We have collected much, often redundant, data, and are now able to examine them systematically to determine which measures are the most useful in predicting a child s mental development. We really do not know how or when low levels of lead contamination disturb brain development. Thus, without imposing any prior restrictions, we should evaluate many measures of lead burden. In the absence of an assay for the bioactive species (ionic ) of lead at the target organ (brain) at the critical time(s), blood lead measurements (which are mostly erythrocyte bound lead, and which represent a very small fraction of the body s total lead level) were used to assess the child s body burden. 

AdinolfiM. 1985. The development of the human blood-CSF-brain barrier. Dev Med Child Neurol 27 532-537. 

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