Lead Levels Below Federal Guidelines Affect Children’s Cognitive Development

Those at greatest risk of health effects associated with lead exposure are the most vulnerable – fetuses and children under the age of six.  They are particularly at risk because their brains and central nervous systems are still forming.  Lead is a powerful neurotoxin that interferes with the development of these systems.

More than ten years ago, the National Academy of Sciences concluded that “[t]here is growing evidence that even very small exposures to lead can produce subtle effects in humans.”  A study reported in the April 2003 New England Journal of Medicine and funded by the National Institute of Environmental Health Sciences (“NIEHS”) found that blood lead levels below 10 ug/dL produce a significant decrease in IQ.  Importantly, the researchers discovered that the amount of impairment was more pronounced at lower levels.  IQ scores of children who had blood lead levels of 10 ug/dL were 7.4 points lower than for children with levels of 1 ug/dL.  But, an increase in lead blood levels from 10 to 30 ug/dL was only associated with a small additional decline in IQ. 

A report from the Work Group of the Advisory Committee on Childhood Lead Poisoning Prevention to the CDC concluded that the overall weight of available evidence supports the finding that blood lead levels below the supposed “safe” level have a negative impact on children’s cognitive development.

Blood lead levels below 10 ug/dL may also impact children’s health.  Few studies have directly analyzed health effects and blood lead levels below 10 ug/dL.  However, the Work Group found that the available research indicate that blood lead levels below 10 ug/dL impacts children’s health.  Recent research suggests that health effects can occur at blood lead levels as low as 2.5 ug/dL. 

According to the CDC’s figures, almost 1 in 10 children have a blood lead level above 5 ug/dL.  Approximately 11 million children between the ages of 1 and 5, about fifty four percent (54%) of that age group, had blood lead levels of 2.5 ug/dL or greater between 1992 and 1994. 

The most recent studies underscore the importance of preventing children’s exposure to lead.  Lead poisoning symptoms may be subtle and may be take time to appear.  They can be confused with other problems.  Common symptoms include stomach aches and headaches, which may be confused with the flu.  Other symptoms include irritability, appetite loss, impaired hearing, hyperactivity, and learning disabilities.  Lead exposure can lead to slowed growth and damage to the brain and nervous system.

Acute lead poisoning is rare, but can cause vomiting, abdominal pain, diarrhea, weakness in the limbs, seizures, coma and death. 

The only way to determine whether a child has a lead-related problem is to have the child tested.

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