We are surrounded by environmental chemical pollutants. Some have been clearly identified and linked to health and developmental problems and others are suspected but not proven.

Now researchers have found that children who are exposed to lead are more likely to have behavioral problems and be suspended from school.

Lead is a well-known toxin which is particularly dangerous for young children. Lead is everywhere — found in air, water and soil.

Children who had been exposed to lead were almost four times more likely to be suspended at least once in the fourth grade than the children who were not.

Because young children operate close to the ground, are prone to putting dirty fingers and lead-contaminated objects in their mouths, and are quite small, they are exposed to particularly high levels of lead.

Common sources of lead include:

  • House paint manufactured before 1978
  • Toys and furniture painted before 1976
  • Painted toys and decorations made outside the U.S.
  • Plumbing including pipes, faucets, and lead solder
  • Soil contaminated from car exhaust or house paint
  • Hobby materials such as stained glass, pottery glaze, some paint and art supplies, pewter ware
  • Storage batteries.

High doses of lead can cause emergency symptoms, such as increased pressure in the brain, but it is more common for lead poisoning to build up slowly over time from ongoing or repeated exposure. As a person's lead level gets higher, problems worsen.

Children with high lead levels may have abdominal pain, headaches, irritability, poor appetite and energy, low blood, constipation and other physical symptoms. They may also demonstrate behavior or attention problems, hearing problems, kidney damage, reduced IQ and slow growth.

The new study adds to the enormous body of literature on the negative impact of lead exposure on our children. Researchers examined the records of 3796 fourth grade students and compared their rate of school suspension as fourth graders to their lead levels in their first three years of life.

Children were categorized as lead exposed — those who had lead levels between 10-20 micrograms per deciliter; and unexposed — those who had never had a lead level greater than or equal to 5 micrograms per deciliter. There were 2687 exposed and 1076 unexposed children.

Previous studies have suggested links between lead exposure and poor school performance. Lead exposure has been associated with attention-deficit-hyperactivity disorder (ADHD) and behavior and learning disorders.

Other studies have shown that lead-exposed students perform more poorly in school.

In this latest study, researchers used school suspensions as a marker for behavior issues since that is the most common disciplinary method employed in public schools.

Lead exposure was most strongly associated with both race/ethnicity and with eligibility for assisted lunch, a measure of household income. The lead exposure rates of their study population were consistent with national statistics: 80% of the lead exposed children were African American; 64% were Hispanic; and 38% were non-Hispanic whites.

Children who had been exposed to lead were almost four times more likely to be suspended at least once in the fourth grade than the children who were not. This result was consistent when race/ethnicity, gender and income were taken into account.

The researchers suggest, based on other studies, that children who are exposed to lead have more difficulty paying attention than their peers and are perceived as being disorderly and disruptive by their teachers. Research on animals has shown that lead is a neurotoxin: exposure disrupts the development of neurologic pathways that are responsible for attention and focus.

School suspension has a very negative impact on a child’s educational trajectory. Suspended students have a higher risk of dropping out of high school. They also have poor reading achievement, increased likelihood of tobacco use, and an increased probability of violent behavior in the year following the suspension.

African American students are three times more likely to receive out of school suspension than their white peers. The researchers suggest that the increased exposure of the African American student population to lead and the attention, behavior, and learning problems that it creates may be an underlying reason for this racial disparity.

This study underscores the need for parents to be vigilant about their children’s potential exposure to environmental lead and to talk with their child’s health care provider about whether screening is indicated.

The study is published online ahed of print in the journal, Environmental Research.