FACTs About Low Lead Level Exposures

There is no safe level of lead exposure for children; lead affects intelligence even at very low levels. 

  • The rate of IQ loss per 1 micrograms of lead per deciliter of blood (ug/dL or 10 parts per billion) is greatest at lead levels below 10 ug/dL (100 ppb). 
  •  As a child’s blood lead level (BLL) increases from 1 to 10 ug/dL (10-100 ppb), experts estimate a child may lose anywhere from 3.9 to 7.4 IQ points.  
  • Low-level chronic exposure may have an even greater effect on IQ than a single instance of very high BLL. [1]
Low levels of lead ingestion causes decreased academic achievement and behavioral disorders.

Low levels of lead ingestion causes decreased academic achievement and behavioral disorders.

New studies and re-interpretation of past studies demonstrates that it is not possible to determine a threshold below which BLL is not inversely related to IQ. [2]

Elevated BLLs are associated with Attention Deficit Hyperactivity Disorder (ADHD) and antisocial behavior, which in turn increase the likelihood of conduct disorder.[3]

The Center for Disease Control and Prevention (CDC) has gradually lowered the blood lead level of concern (the BLL where intervention is recommended) from 60 ug/dL (600 ppb) in 1960 to 10 ug/dL (100 ppb) in 1991. 

  • Most recently, in January 2012, the Advisory Committee on Childhood Lead Poisoning Prevention (ACCLPP) recommended dropping the term “level of concern” entirely and using a “reference value” to provide a way to compare an individual child’s blood lead level to a population of children the same age.
  • An accumulation of evidence showing negative health effects at very low levels of exposure supported this change.  The current reference value is 5 ug/dL (50 ppb) and will shift with population blood lead levels.

Certain vitamins and minerals, especially calcium, iron and vitamin C, play a specific role in minimizing lead absorption. It is reasonably well-established that iron deficiency is associated with increased BLLs, and that some effects, such as lower IQ, can result from both conditions.

[1] Low Level Lead Exposure Harms Children: A Renewed Call for Primary Prevention, Report of the Advisory Committee on Childhood Lead Poisoning Prevention of the Centers for Disease Control and Prevention dated January 4, 2012

[2] Id.

[3] Issue Brief: Childhood Lead Exposure and Educational Outcomes by the National Center for Healthy Housing