There has recently been considerable discussion on the risk from lead pollutants. The effects of direct poisoning are well-known, such as occur when children chew lead toys or paints, resulting in abdominal pain and vomiting, drowsiness, perhaps, leading to coma, paralysis or convulsions, and possible brain damage.
In adults, suffering from severe poisoning, lead has usually been absorbed at work, and, at first, it causes only colic, constipation and malaise, but continued exposure can lead to cramps, paralysis of some muscles and various neurological effects, including loss of concentration, poor memory, increased excitability, insomnia and impotence.
Since the most drastic and obvious effects are on children, a great stress has been laid on the” control of products, likely to contain large doses of lead, but much less is known about the results of chronic low exposure on either children or adults.
Image Source : 1.bp.blogspot.com
ADVERTISEMENTS:
The earliest symptoms are rather vague, and so, it has been suggested that those, at risk, should be regularly monitored, since there is a fairly straightforward test-a blood enzyme is very sensitive to lead poisoning, and shows changed activity before there are any obvious clinical signs.
This kind of survey clearly has a role to play in the control of lead smelters, with respect to those who work in them, and those who live nearby. There is, however, another more controversial issue.
A substantial amount of lead is released into the atmosphere, as organic or inorganic lead by petrol engines, using tetraethyl lead as anti-knock additives, and while there is no question of this being present in severely toxic doses, it has been suggested that the current levels might themselves cause some detriment.
ADVERTISEMENTS:
A notable protagonist, in this field, Professor Bryce-Smith of Reading, has forcefully argued that lead pollution may already be having long term adverse effects on human behaviour. Available evidence may be summarized briefly.
First, Russian research work has shown that conditioned reflexes (a standard test in the country of Pavlov) are slowed down by imbibing very small amounts of lead, and, as a result, smaller levels of atmospheric lead are tolerated there than in the test.
Secondly, children who have suffered acute lead poisoning, but subsequently recovered, may have a later history of poor education progress, and exhibit behavioural difficulties like violent tendencies.
Thirdly, a survey in Switzerland has shown that inmates of a reformatory prison had abnormally high blood lead levels. Clearly, very much more work needs to be done to establish an association between current intake of lead and behavioural disturbances, as the symptoms, being complained of, are rather general, and the fact that behaviour is affected by a large number of social and medical factors cannot be discounted.
ADVERTISEMENTS:
Nonetheless, however ill-established the connection between lead poisoning and anti-social activity is, the matter is worthy of investigation. It has even been suggested, though speculatively, that plumbism may have been a factor in the decline of the Roman Empire after lead conduits were introduced to carry drinking water.