When young children attend their annual checkup, a blood test is administered that includes testing for existing blood lead levels. While a blood test can monitor whether a child has recently been exposed to lead, it does not show whether any past exposure has occurred. It only takes one incident of being exposed to lead to permanently affect a child’s development and cognitive functions. If the child had been exposed to lead months prior, an ordinary blood test may not show any existing lead levels. The only way to detect if a child has been exposed to lead previously would be to receive a bone sample.
A pediatrician in Philadelphia, Herbert Needleman, worked at a community health center’s psychiatry outreach program. After meeting one teen in particular, he began wondering how many children attending the clinic were there due to missed cases of lead exposure. Dr Needleman decided to research childhood lead exposure to generate some answers.
Lead is extremely toxic due to the fact that the body misreads it as calcium, and immediately begins storing it throughout the body. Because of this, it is absorbed directly into not only the bloodstream, but also the bones, residing in the bones for decades. Children are at a greater risk of lead poisoning because they absorb about 50% of all ingested or inhaled lead, while adults only absorb about 10%. Because Needleman would be testing children for their past exposure to lead, he realized the only harmless way to receive a bone sample from each child would be to collect their baby teeth after they fell out. Collecting their teeth would be an easy way for Needleman to gather the data he needed, and discover the irreversible damage lead exposure caused on these children’s lives.
Preliminary testing showed lead in both inner city and suburban children’s teeth. Unfortunately, the inner city children had a lead level 5 times higher than those living in the suburbs, averaging a 51.1 ppm bone reading. The next step in the study was to prove that heightened lead levels had an impact on the child’s psychological functioning.
In a three year span, first and second graders living in Chelsea and Somerville Massachusetts were recruited for the study. Their parents collected their baby teeth, while their teachers rated their behavior in the classroom on an 11-item scale. Many other tests were conducted as well to rule out any other factors, and monitor their development.
Ultimately, more than 2,100 children submitted at least one tooth to be examined. The children were then divided into six groups, depending on their bone lead level. 58 children were in the highest lead level group (27 ppm or greater) and 100 children were in the lowest level (5 ppm and below.) These two groups were compared in the analysis. All variables were similar when it came to race, birth weight and parent’s IQ.
From the study results, Needleman concluded the highest lead level group performed less well on the Weschler Intelligence Scale, particularly on verbal ability and attention. The teacher’s ratings were also different when it came to the behavior of the two groups. For every item on the 11-item scale rated by the children’s teachers, the high lead level group scored significantly poorer than the low lead level group. This data shows a correlation between high levels of lead, and behavioral and developmental problems in children.
Needleman went on to do much more research focused on lead exposure, as he was passionate about the topic. The findings from this study are extremely significant, and prove without a doubt that any and all lead exposure is detrimental to a child’s development.
