01.04.2005

Heavy Stuff - by Jeremy Hill

Despite leaded petrol and paint being banned for sale in Australia, lead poisoning is still a big health issue, and one that is generally overlooked by those who are exposed to lead daily - everyone.

A few decades ago, the high incidence of lead poisoning in Australia through widespread use of leaded fuels and paints, was considered enough of a health problem to warrant increasing public lead awareness. Leaded fuels were banned in 2002 and leaded paints have not been sold for many years.

The risk has markedly reduced and the lack of dynamic media-based reminders of this important health issue has allowed lead poisoning to slip into relative obscurity, putting public awareness of the problem dangerously "out of sight and out of mind".

Since the elimination of lead in petrol, the average serum blood level has decreased by about 400 per cent. Meanwhile, the blood limit deemed to indicate lead poisoning in a child has been adjusted to one sixth of the limit set in the 1960s. Some experts say problems occur at even smaller levels and, in reality, no lead exposure is acceptable.

Unfortunately, environmental contamination by the heavy metal lead has made such a level impossible - we all have some degree of lead poisoning. The legacy of leaded fuels and paints, plus cigarette smoking, leadlight windows, car batteries, fishing sinkers, diving belts, industrial metal mining and smelting, leaves lead as a persistent assault on our health.

I recently witnessed the lack of understanding of the significant dangers of lead when I went for a swim at a local public swimming pool. Walking through the gate, I noticed a large lead scuba diving weight had been strategically placed to stop the gate fully closing. As each person walked through, the gate swung back, creating a fine layer of very toxic lead shavings for everyone to walk through. This was also right next to the kiosk, where babies crawled and small children played, transferring lead to their mouths as they ate the treats their mothers had bought them. I immediately brought this to the attention of the attendant who acted quickly and was most grateful for the warning - I hope not too late for some.

Children are at the greatest risk from lead poisoning, with lead absorption rates five times that of adults. They also face greater exposure through picking up lead in dust as they play on the ground and floor, frequently putting their contaminated hands and feet into their mouths. Soils and house dust around old houses, or near busy roads, can have quite high levels of lead. So, how can we combat this risk? Covering affected soils with more soil, lawn or paving, along with weekly wet dusting and mopping of floors, window frames and sills with a high phosphate solution such as automatic dishwashing detergent are very efficient ways of dramatically lowering a child's lead exposure, as are washing toys and pacifiers, and hands before eating. Washing vegetables before cooking also reduces lead intake, as does a diet high in minerals such as zinc, magnesium, calcium and iron via competition for absorption sites.

The booming home renovation market is a frequent contributor to lead poisoning, with accumulated dust in ceilings and the removal of old lead-based paint by chipping, scraping, sanding or peeling, or with the help of a heat gun, creating toxic lead-laden dust or fumes - and a normal dust mask won't protect you.

Unfortunately, lead poisoning can occur without any immediate symptoms. By the time health problems start to appear, the damage can be quite severe, with especially disturbing consequences in the young. Because adult brains are already fully developed, they are far less susceptible to the neurological damage incurred from lead poisoning than children, whose fragile developing neurological tissue is easily affected. This has the devastating effect of lowering the IQ and promoting behavioural disorders. In adults, reproductive difficulty, failing memory, digestive pains, anaemia and high blood pressure can be signs of lead poisoning.

Long term, the risk of dying prematurely has been shown to increase considerably in adults with even mildly elevated blood lead levels, due to the inflammatory and free radical inducing nature of the metal causing more cancers and cardiovascular diseases.

Lead has a high affinity for several tissues of the body, including the liver, kidneys and bones, which can store lead for decades, releasing it back into the system slowly and insidiously over time. The rate of release can then abruptly increase during times of rapid bone loss, as in post-menopause, osteoporosis and extended periods of immobility due to illness, injury or old age, thus inducing further toxic effects.
While things definitely aren't as bad as they were back in the time of the Roman Empire, when lead was actually added to wine and food, this heavy metal's damaging legacy lives on.

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