The New Straits Times, July 3,1995
Q: What is the relationship between lead and IQ?
A: Lead and its related metallic compounds are known to be very toxic to humans.
Twenty years of research carried out worldwide provides evidence of the following:
exposure to small amounts of lead gives rise to a drop in cognitive functions and behavioral changes of children. In this instance, a negative association between lead levels and intellectual performance is observed.
low levels of lead may also affect children's performance based on the standardised evaluations of cognitive functioning. Lead concentrations of greater than 10mcg/dL were shown to be associated with an average decline of five IQ points
a decrease in lead level was associated with an improvement in IQ in a group of young children.
Currently, values between 15mcg/dL and 25mcg/dL are recognised as having the ability to cause a decline in cognitive function without causing readily identifiable sign and symptoms of toxicity. However, consensus on specific laboratory values and treatment indications or regimes has not been reached. Therapy is only indicated when it has been determined that lead is the cause of the symptoms.
Children are at particular risk since they tend to absorb more than adults and that absorption is further enhances if the children are malnourished. The average blood lead concentration in children worldwide is 3mcg/dL, whereas the average for the US population is 13mcg/dL. Theoretically, there should not be any lead in our children's blood.
When considering the implications for children entering school with this hindrance to learning and the uncertainty of the effectiveness of treatment available, and notwithstanding the possible long-term effects it has on children, we should take note that there may be no safe blood lead level and that every child is at risk. Thus we should try to reduce any possible threat that is present around our child by first identifying possible sources of lead in our environment and removing them.
