Children who were exposed to increased levels of lead decades ago could now face a middle age with lower IQ and learning capacities compared to the ones they would have normally had without facing the lead exposure. According to medical opinions, there is no safe level of lead exposure for children.
A new study, published in the Journal of the American Medical Association, underlines the negative consequences of childhood exposure to lead.
High Lead Blood Levels Associated With A Lower IQ
The scientists analyzed 565 subjects in New Zealand who were enrolled in a study of people born between 1972 and 1973. Each of the participants had the blood lead levels measured at the age of 11, then decades later, at the age of 38.
Exposure to lead during childhood was directly linked to a lower IQ as adults. The researchers also suggest that high blood lead levels at the age of 11 were correlated with becoming adults with a lower overall socioeconomic status, compared to subjects with low blood lead levels at that age.
According to the study, the decline in IQ was responsible for 40 percent of the link and caused by the fact that the children with high blood lead levels never got to reach their full intellectual potential because of the exposure.
"Associations of childhood blood lead level with deficits in verbal comprehension and processing speed were not statistically significant. After adjusting for confounders, each 5 micrograms per deciliter higher level of blood lead in childhood was associated with a 1.79-unit lower score in socioeconomic status," noted the study.
Nowadays, doctors alert parents that no amount of lead exposure is safe for their children, especially during the ages when the nervous system is still developing, as the toxin can massively affect this process.
According to the World Health Organization, as few as 5 micrograms of lead per deciliter of blood could lower the child's intelligence quotient. The study participants had average blood lead levels more than twice as high when they were 11, back in the early 1980s, with an average of 10.99 micrograms per deciliter of blood.
"It's toxic to many parts of the body, but in particular in can accumulate in the bloodstream and pass through the blood brain barrier to reach the brain," noted Aaron Reuben, first author of the study and graduate student in clinical psychology at Duke University.
Additionally, every 5 micrograms of lead per deciliter of blood during childhood was associated with a 1.61-point lower IQ by the time the subjects reached the age of 38. Additionally, the subjects had lower levels of working memory and perception reasoning.
Lead Poisoning: A World Health Organization Priority
"The Institute for Health Metrics and Evaluation estimated that lead exposure accounted for 9.3 percent of the global burden of idiopathic intellectual disability, 4 percent of the global burden of ischemic heart disease and 6.6 percent of the global burden of stroke", according to the World Health Organization.
The WHO has identified lead as being one of the 10 chemicals that pose a major public health concern. Given this decision, the organization also urged its member states to protect the health of their citizens, from children and women of reproductive age to workers who may be exposed to the substance.
