Although recent studies have shown that even low blood levels of lead - 10 to 25 micrograms per decilitre (mcg/dL) - can cause a persistent, dose-related decrease in children's IQ, many are still unware of it. Growing evidence indicates that levels of blood lead in the range of 10-15 mcg/dL and above have adverse neuro-behavioural effects in children.
The impact of lead poisoning to society is real as it silently damages our children's minds and restrict their abilities. The effects of lead poisoning in the organ systems are cumulative. It has been estimated that lead could remain in the bones and kidneys as long as 30 and seven years respectively.
The symptoms and presenting signs of lead toxicity can be described in Table 1.
The answer to this problem is removing lead from the environment. Unfortunately, the removal process may well turn into poilitical, economical, medical as well as emotional issues.
As we all know much of the lead in the atmosphere comes mainly from automobile emissions and industrial waste. Thus, any type of legislation to stop manufacturing or using leaded gasoline may provoke an outcry of anger and protest from users of leaded gasoline.
But perhaps we can learn something from the Americans. In 1991, when the United States started to place restrictions on leaded gasoline, lead-based paints and reduce the use of lead soldering in food cans, the outcome was rather encouraging.
| For Lead Intoxication remember | For Lead Encephalopathy recall |
|---|
A anorexia, apathy and anemia
B behavioural disturbances
C clumsiness
D development skill deterioration
E emesis |
P persistent vomiting
A ataxia
I intermittent stupor
N neurologically intractable convulsions
T tiredness and lethargy |
| (Source: American Pharmacy , November 1993) |
|---|
Table 1.
The average blood lead level in Americans of all ages decreased from 15.8 to 10 mcg/dL. This decrease coincided with the reduction in the use of lead addictives in these products.
The sources of lead poisoning can be unexpected as demonstrated by the examples below:
- In Mexico, a six-month-old boy was admitted to a hospital. He was suffering from abdominal distention, pallor, superficial breathing and nasal flarring. He had mucous diarrhoea for a month prior to the admission. He was found to be on a medication in the form of an orange-coloured powder prescribed by a local health practitioner. The powder was later identified as lead tetraoxide (97.4%).
- A 10-week-old infant was admitted to a hospital in Canada because of a sudden onset of seizure. The infant appeared healthly otherwise and was only fed breast milk and commercial infant formula. It was later confirmed that she had an extremely high blood lead level. Further investigations showed that the water used to prepare the infant formula had been thoroughly boiled in a special container which showed a distinct spot of lead solder.
Knowledge of the danger of lead poisoning keeps most people, especially manufacturers and government, vigilant about the amount of lead that gets into food. Among others, some sectors are still concerned about lead leaching into food from ceramic ware, especially mugs.
Scientists are particularly aware about adult exposure to lead from food in contact with ceramic ware, especially when it involves pregnant women. Besides, potentially harming her own health, lead can damage the developing foetus because it crosses the placental barrier. Toxicologists mostly agree that pregnant women should avoid daily drinking of hot acidic beverages such as tea and coffee from lead-glazed ceramic cups or mugs. The effect could be detrimental as a substantial accumulation of lead may increase the risk to the developing foetus from lead leaching into food from ceramic ware.
Previously, food from lead-soldered cans also seemed to be a major contributor to lead contamination. However, this problem has been kept to a minimum with the elimination of lead solder in cans. The idea now is to switch from lead-soldered cans to unseamed cans and to cans seamed with non-lead solder techniques. Apart from these unusual cases of lead poisoning, most common poisoning is due to lead-based paint.
Basically, the two most common forms of lead used in the paint are lead carbonate and lead oxide. Lead was added to paint because it helped the paint to dry more quickly and gave it a shinier and harder finish. They make up more than 38% of the dried weight of paint. Some paints can contain as much as 50% lead.
Usually, lead paint is favored for use due to its stability and good finishing. Its durability makes it the pigment of choice for use on industrial surfaces. Fortunately, at present, lead-based paint is no longer a problem in residential areas. The paint industry has greatly reduced the lead content of house-paint.
The problem of childhood lead exposure needs effective measures of intervention to minimise the risk of lead exposure. These measures will also benefit the whole community.
Action will be focused on children with lead poisoning severe enough to require medical attention. Public awareness to excessive lead exposure has to be enhanced. Continuing education of children's exposure to other sources of lead in the environment would be a good step in promoting good healthcare in the community.
No treatment can be better than removing sources of exposure when it can be identified. With respect to childhood lead toxicity, two important issues have to be handled wisely. The main issues are the extent of hazard from lead exposure and deciding secondly deciding how to prevent future poisoning.
Government and non-governmental sectors should come up with a comprehensive effort to reduce the major sources of lead. One lesson is clear. Prevention is cheaper than treatment. It is therefore important for us to design a conceivable and forward thinking solution to keep lead and other hazards from robbing us of our most valuable resource - out children.
The writer is a pharmacist at the National Poison Centre, Universiti Sains Malaysia, Penang.
