The level of lead in childrens’ blood corresponds with emotional and behavioral problems, recent research suggests. According to the latest research, emotional and behavioral problems are present even with low exposure to lead, with an increase in related problems directly proportionate to increasing blood lead levels.

The research was funded by the National Institute of Environmental Health Sciences, which is part of the National Institutes of Health. The results were published in the online edition of the journal JAMA Pediatrics on June 30.

Kimberly Gray, PhD, NIEHS Health Scientist Administrator, said in a statement, “This research focused on lower blood lead levels than most other studies and adds more evidence that there is no safe lead level.” She continued, “It is important to continue to study lead exposure in children around the world, and to fully understand short-term and long-term behavioral changes across developmental milestones. It is well-documented that lead exposure lowers the IQ of children.”

The researchers measured blood level concentrations in over 1,300 preschool children in China, and found that the blood levels were linked with an increased risk of behavioral and emotional problems, including depression, anxiety and aggression. The average blood lead level among the children was 6.4 micrograms per deciliter.

According to the National Institute of Environmental Health Sciences, lead is a naturally occurring metal deep within the ground and is used in a wide range of products, from batteries to paint to gasoline and ceramics.