Today is World Health Day! The World Health Organization’s goal is “to build a better, healthier future for people all over the world.” Environmental research is crucial in making a healthier future for our children. One of our faculty members, Dr. Kim M. Cecil, PhD, examines how environmental exposures, such as lead, influence brain development using an MRI scanner.
Lead is a naturally occurring substance that is toxic to humans. It can cause damage to almost every organ in the body. Lead poisoning occurs when someone absorbs too much lead by swallowing a substance with lead in it, such as paint, dust, food or water. No safe lead level in children has been identified.
To better understand what lead does to the human brain, Dr. Cecil’s team studied people enrolled in the Cincinnati Lead Study, the longest ongoing study of lead exposure. Pregnant women from Cincinnati neighborhoods with known lead hazards were enrolled in the study between 1980 and 1985. The study followed the development of the children born to these women. When the children were between 18-22 years old, they had a brain MRI.
Dr. Cecil found that those with high blood lead levels had smaller brain sizes, especially in the frontal lobe. The frontal lobe is important for many brain functions, especially decision making, judging right and wrong, and controlling emotions. Almost all of the children from this study had levels exceeding 10 micrograms of lead per deciliter of blood. Today, experts use a reference level of 5 micrograms of lead per deciliter of blood to identify children with high blood lead levels. It is thought that in the US, approximately 1 million children under 6 years of age currently exceed this reference level.
Image: For the 157 Cincinnati Lead Study participants who completed a high-resolution MRI examination, we compared their adult brain volumes with their childhood blood lead histories. The brain rendering (left side of figure) shows gray matter volume loss in regions in red and yellow associated with the average of the childhood blood lead levels. The plot (top right) displays how volume within the frontal lobe cluster is related to individual mean childhood blood lead levels. The frontal lobe gray matter cluster is expanded; age at scan and birth weight are also included in the model as they can also affect brain volume (bottom right of figure).
Our goal as a society is to prevent lead exposure to children before they are harmed. Although there are several exposure sources, lead-based paint is the most widespread and dangerous high-dose source of lead exposure for children. Homes built before 1978 are likely to contain some lead-based paint. You can take action to prevent lead poisoning by eliminating lead paint hazards in your home. Children get lead exposure from swallowing dust on their hands and toys. When old paint cracks and peels, it makes lead dust.
Parents should wash their children’s hands before eating and sleeping. It is also important to regularly wet-mop the floor, wet-wipe around windows and window seals, and seal chipping or peeling paint. As lead competes with calcium and iron in the body, feeding your child healthy foods with calcium, iron and vitamin C is also important to minimize lead exposure. Cities have a responsibility to properly maintain safe water line practices. If you are concerned about your child’s potential exposure, speak to their doctor about getting them tested.
Contributions by Kim Cecil, PhD and edited by Sparkle Torruella.
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