Unsafe limits

Even permissible levels of pollutants can damage health

Last Updated: Saturday 04 July 2015

Reality check: health risks no (Credit: Arizona University)if your doctor's assurances about your health are based on 'safe limits' set by premier bodies such as the World Health Organization (who), they may merely lull you into a false sense of security.

A new study conducted by paediatricians from the Children's Hospital Medical Centre, usa, reveals that even the so-called 'safe' amounts of lead in blood have adverse effects on children's intelligence quotient (iq).

Both who and the us Centres for Disease Control state that lead levels in blood only above 10 microgrammes per decilitre (g/dl) put children at risk of cognitive damage. But the fresh research shows that children with lead levels of 10 g/dl of blood had iq that was 7.4 points lower than those with levels of one g/dl. When lead levels rose from 10 g/dl to 30 g/dl of blood, the iq dropped by another 2.4 points. On an average, with an increase in lead levels by 10 g/dl of blood, there was a s4.6-point decline in iq. "Our study shows that there is no discernible threshold for the adverse effects of lead exposure," says Bruce Lanphear, one of the paediatricians. He asserts that who should refine its definition of 'safe'.

Permissible limits for air pollutants are also misconstrued. Current regulations ignore local lung build-ups that lead to cancer, opine researchers from the University of Salzburg, Germany. They have developed a computer model, which shows that certain spots in the lungs accumulate more cancer-causing airborne particles than was previously thought. "Our findings suggest that permissible concentrations of pollutants should be reduced," says Werner Hofmann, one of the researchers.

The model indicates that cells of spurs found between airways have concentration of carcinogens 100 times higher than any other part of the lung. The researchers used the model to simulate the breathing lung and millions of dust, smoke and other particles that are sucked in and out with each breath. The model uses a technology employed in aircraft design. It gives precise predictions of where particles will land in a 3d space. Till now, the researchers puffed fumes into artificial lungs to gauge the effects of pollutants.

But exactly how the hotspots harm lung tissue is still unclear. The researchers are even uncertain about the exact reason for the uneven concentration of the pollutants. For instance, how a pollutant is inhaled affects the distribution. Cigarettes with high tobacco content affect the upper parts of the lungs, while those having less tobacco stain deeper parts of the lungs because smokers suck on them harder.

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