The New Straits Times, December 6, 1996
Q: What are the dangerous of lead poisoning?
A: Lead has no biological value in human body even in trace amounts unlike other elements, for example, iron and zinc.
Thus, the ideal wholeblood lead level (BLL) should be zero. In fact, lead can displace other metals from the normal binding sites to produce some of its biochemical effects.
As such, when introduced into the body either by ingestion or inhalation, the lead pigments are able to fool the body into accepting them as normal useful elements, such as calcium and iron.
Since lead serves no useful physiological functions, its accumulation is often potentially toxic to several organ systems,
Once incorporated into the body's chemistry, it can inhibit the normal function of the various organs in the body, especially those of a child.
Because it is not possible for the body to dispose the lead that has entered it by itself, the metal will remain stored in the body, particularly the bones and kidney. The effect of exposure is therefore cumulative.
The toxic effects of lead in children are evident across a broad range of exposures to environmental lead sources can be serious.
Symptoms of lead poisoning at all ages are not specific and often go unrecognised.
In the toddler, anorexia (loss of appetite) is the earliest symptom. Other emerging problems may include occasional vomiting, irritability and unwillingness to play.
More serious signs include persistent vomiting, peripheral nerve weakness, convulsions and coma.
Children who are poisoned by lead can also sustain damage to the brain and nervous system that may cause behaviour and learning problems.
Lead also retards physical development of children. Other problems linked with lead poisoning are hearing difficulties and kidney damage.
In large doses, lead can cause blindness, brain damage and death.
There are also reports to show that blood concentration of lead in pregnant women, below 25 micrograms per deciliter (mcg/dl), can affect early cognitive development in the off-spring.
If a women is exposed to high levels of lead before or while pregnant, the foetus could be harmed.
Given that the foetus is even more sensitive to the toxic effects, of lead, the maximum acceptable level has been recommended to be not more than 10mcg/dl. The most hideous effect of lead is on the nervous system.
Recent work has documented a relationship between BLL in children with a slight decrease in IQ.
Impairment of cognitive function and a progressive decrease in IQ have also been demonstrated with increasing lead levels.
Most lead poisoning, however, is slow on the onset and results from gradual accumulation of lead from sources of low solubility.
