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Public Radio's Environmental News Magazine (follow us on Google News)

The Secret Life of Lead, part 1

Air Date: Week of

Living on Earth’s hour-long documentary "The Secret Life of Lead" opens with host Steve Curwood visiting the neighborhood around researcher Kim Dietrich’s office. Dr. Dietrich has been following almost 300 young men and women there for the past two decades in an attempt to unravel the effects of childhood lead exposure. Most recently, his research has shown that lead exposure can lead to an increase in juvenile delinquency.




CURWOOD: Welcome to Living on Earth. I’m Steve Curwood in Cincinnati. And we’re here to take you on a journey. But we won’t be boarding the paddle wheelers that cater to tourists along the Ohio River waterfront of this Midwestern city, or the tour buses that frequent the famous Cincinnati Zoo. No, today we embark on a voyage of scientific discovery with a team of researchers at Cincinnati Children’s Hospital and the University of Cincinnati. They have let us into their lives and laboratories to help us learn how cutting edge science does its work; to help us understand how years of hard labor, false starts, and moments of inspiration can lead to scientific breakthroughs.

For more than two decades, the Cincinnati research team has been trying to unravel the scientific secrets relating to childhood lead exposure, and this step-by-step process is far from finished. Our story on this emerging science doesn’t begin in a room filled with test tubes and people with white coats, but in a modest, tidy living room on the outskirts of the city.


DIANA: Tony…you are so disrespectful…enough is enough.

CURWOOD: Tony is in trouble again. His mother Diana says it’s nothing new for her 22-year-old.

DIANA: He can’t hold down a job. He can’t keep a steady girlfriend. His mind, it’s like his mind races.

CURWOOD: And Tony’s troubles today look much like the ones of his early years when his family lived in a gritty neighborhood downtown.

DIANA: It was hard, especially trying to raise three other children who, quote unquote, was pretty normal, but then you’ve got this child you just can’t figure out what’s going on. It was a tear in our marriage. And then you’ve got this kid, every time you turn around you’re getting a phone call to come and get him.

CURWOOD: Diana and I talk while Tony wanders in and out of the house, yakking on his cell phone, meandering up and down the stairs. He says he wants to talk with me but it seems like he just can’t sit down.

DIANA: Tony, are you ready for your interview?

CURWOOD: Finally, Tony sits down to chat. He squirms as he tells me about life in grade school.

TONY: Couldn’t concentrate. I was wild. I wanted to be over here talking but I had to do my work over here. That was rough right there. That was always a concentration thing with me. I guess they thought it was like, well, he has a behavior problem or whatever. It was just I didn’t want to sit down. School, it was just rough, man, from first grade to 11th, it was just rough.

DIANA: He’s very smart. He can be a very sweet child. He’s just not…his attention span--Tony doesn’t have a good attention span at all. And he’s been diagnosed with ADD. And I don’t know if that’s part of him having lead, or it could very well just be part of my genes that he has.

CURWOOD: Indeed, that’s the question scientists who have been following Tony all his life would like to answer. Like millions of American children, Tony spent his early childhood in an apartment that was loaded with dust from lead paint. But unlike most of those children, Tony’s exposure to lead has been carefully documented since he was in his mother’s womb. He’s one of nearly 300 individuals being followed by the research team in Cincinnati that is probing the long-term effects of lead. Neuropsychologist Kim Dietrich has been studying this group for more than twenty years.

DIETRICH: We recruit them prior to birth and then follow them over a period of time, measuring the amount of lead they’re exposed to by measuring the amount of lead in their blood, and their behavior. Sequentially. And thus, we can correlate earlier exposure to lead, which we have a good record of, with later behavioral problems.

CURWOOD: When he was a toddler, Tony had levels of lead in his blood that today would be considered cause for concern. But back then, lead exposure was only officially a cause for concern at levels approaching those that could lead to seizure or death. Still, there were some signs that childhood lead exposure in much smaller doses could have an adverse impact on learning and behavior. Trouble was, most kids who were identified with elevated lead exposures were also poor, and many were black. Some said their problems could be blamed on poverty and race. Many were skeptical that lead was playing any large role, among them Kim Dietrich himself.

DIETRICH: There are certainly children who are not poor that get lead poisoning. We know that for certain. But it is predominantly seen in children living in situations that present other challenges to optimal development, including poor nutrition, perhaps in some cases inadequate caretaking and supervision and stimulation. And so, I was skeptical. I thought that since lead was correlated with these other factors, it was probably these other factors that were responsible for the effects that were observed. And there was only one way to really tease this out. And that was to conduct a different kind of study we call a prospective study.

CURWOOD: In a prospective study, a group of people are followed over a period of time to see who gets sick and why. Lead exposure had never been studied this way before. Most of the 300 people recruited for the study first lived here, in Over-the-Rhine, a neighborhood near downtown Cincinnati that’s seen better days. Its name comes from the German immigrants who moved here in the nineteenth century. Tony spent his first years in an apartment only a few doors away from the clinic where Kim Dietrich has his office. On a snowy day, Dr. Dietrich and I set out for a tour of the neighborhood. Near the front door of the clinic a sign says “BMF.”

DIETRICH: BMF stands for Babies Milk Fund. And it –

CURWOOD: Babies Milk Fund?

DIETRICH: Babies Milk Fund, right. Because it was originally established to provide vitamin D-enriched milk to prevent rickets in children who were not getting adequate nourishment living in the community.

CURWOOD: Today, almost every family here lives below the poverty line and many people still go hungry. They make do in shabby apartment houses that share the streets with abandoned properties. Many of the facades of these decaying buildings are adorned with intricate carvings that recall how grand this neighborhood once was. And as this elegance has faded, it has shed lead paint dust and chips on the ground.

DIETRICH: As a matter of fact, in neighborhoods like this, the soils and other surface areas can have concentrations of lead which are equal to or greater than that which you would find in certain mining communities where lead had been mined for decades.


DIETRICH: Poor people have, many times, no choice but to live in communities like this where the housing is not well-maintained. And, as a result, they are essentially trapped in this world of lead.

CURWOOD: God, look at this place. This one is occupied but next to it is a vacant building where the windows are cracked.

DIETRICH: But it is for rent. And so at some point in time, a family is going to move into this apartment, and I can tell you for certain that there are significant lead hazards in this building just by looking at the exterior. If we were able to get inside we would very likely find base boards and windowsills with peeling and cracking paint. And the thing you have to understand here, or at least appreciate, is that this is one house, but it’s not a question of one house and one child. This lead-contaminated apartment here is going to poison more than just one child because there’s going to be families moving in and out and in and out of this apartment over and over and again.

CURWOOD: Back when Kim Dietrich started his study, the Centers for Disease Control set the official threshold of concern for lead at 30 micrograms per deciliter of blood. Most of the children in his research group, or cohort as it’s called, did not have obvious physical signs of lead poisoning but had exposures around the level of concern. It didn’t take long for Dr. Dietrich to see results.

DIETRICH: We found a number of things. We found that even exposure in the womb was associated with lower birth weight in our cohort. It was associated with a slower rate of early sensory motor development. Later on, we found that earlier lead exposure was associated with lower IQ.

CURWOOD: And this was true even when Dr. Dietrich took into account other factors, such as the mother’s IQ, the quality of childcare, and the child’s nutrition. Kim Dietrich measured other aspects of neurological development through specially designed games and tests.

DIETRICH: We have found over the years that lead exposure is associated with a number of motor symptoms. Children with higher exposure to lead had difficulty in engaging in fine motor tasks. They had poor postural stability. In other words, they were not as coordinated as their peers who were exposed to lower levels of lead.

CURWOOD: In 1991, the work done by Dr. Dietrich and other leading researchers prompted the government to tighten its threshold of concern for children down to 10 micrograms of lead per deciliter. The Cincinnati study was one of several that began in the early 1980s. Today, this is the only long-term study still intact.

DIETRICH: When you follow a cohort for over 20 years, it becomes much more than just a research study. You get personally involved with the families, with the sometimes troubles and crises they may have from time to time.

CURWOOD: Persistence is part of the research protocol here. And to keep people coming in for checkups and testing, Dr. Dietrich and his colleagues have spent many hours knocking on doors, holding holiday parties, even checking out the local laundromat to find no-shows. But the problems of keeping this study cohort together go beyond missed appointments.

DIETRICH: A great many, unfortunately, of the members of this cohort have had problems in terms of the justice system. More than a handful have been incarcerated and, unfortunately, one of the sources of attrition in our cohort is homicide. That is members of the cohort being killed either as a function of a drive-by shooting or engaging in criminal activity themselves.

CURWOOD: This violence and crime that is so much a part of life in this neighborhood may well be connected to their childhood lead exposure, says Dr. Dietrich. Two years ago, he published a study about delinquency and reported that the teens in his group with the highest lead exposures were much more likely to engage in delinquent behavior than teens with the lowest exposures to lead as children. Dr. Dietrich says he doesn’t know exactly how lead exposure can lead to delinquent behavior, but he does know that lead seems to compromise the abilities to focus and control impulses, and that is an important clue.

DIETRICH: For example, we know that children who have attentional deficits, poor impulse control, deficits in an area we call executive functions, that is a lack of ability to plan ahead, to anticipate consequences. We know that children who have these behavior deficits are at higher risk for engaging in anti-social behavior, and, ultimately, behaviors we associate with a high risk of arrests and adjudication for delinquency.

CURWOOD: For Kim Dietrich, lead very well might tip the balance when it comes to the ability to resist temptation.

DIETRICH: I guess the way I think about lead is that the environment these children are living in--the environment of drugs, easy access to guns--I guess I would say that the environment provides the opportunity. Lead may pull the trigger.

CURWOOD: Two decades into this research, Kim Dietrich’s subjects are now young adults. We’ll meet a few of them and hear about their problems with the law, and see how researchers hope to learn more about the secret life of lead, coming up right after this.

[MUSIC: Carl Craig “A Wonderful Life” Back to Mine/Everything but the Girl (Ultra 2001)

CURWOOD: You’re listening to NPR’s Living on Earth.

[MUSIC: DJ Cam “Friends and Enemies” Back to Mine/Everything but the Girl (Ultra 2001)]



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