Low levels of pollutants may be beneficial: Study

February 14, 2003

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Misty

Asian News International

Washington, February 14

Are we putting too much effort into cleaning our environments? Well,

two US scientists have said that there are safe levels below which

potential pollutants and poisons may actually be beneficial.

According to a report in Nature, the levels at which potentially

toxic substances such as mercury and lead are classified as

dangerous may have been miscalculated.

Risk assessments and regulations on safe limits for these substances

in medicine and the environment may have to be rethought, said

Edward Calabrese and Linda Baldwin of the University of

Massachusetts in Amherst.

For the past 30 years, cancer-causing chemicals and X-rays have been

viewed largely as dangerous whatever their level. " The field of

toxicology has made a terrible blunder. A lot of high-powered people

need to take the time to explore this " , Calabrese was quoted by

Nature as saying.

For example, dioxins, which are industrial by-products that at

certain doses can cause cancer, can actually reduce tumour growth in

some species. Similarly, small amounts of the toxic trace metal

cadmium can promote plant growth.

Having identified over 5,000 similar examples, Calabrese and Baldwin

are among a growing number of researchers who feel that the

hazardous nature of toxic substances has been overstated. The levels

used in studies are not comparable to those normally experienced by

humans, the report said.

The debate also raises the question of how clean our environment

really needs to be. Some argue that billions of dollars are being

wasted in ridding the world of substances that are

dubbed 'hazardous', when low levels could actually be a good thing.

But convincing people that 'safest' is a more meaningful description

of risk than 'safe' and 'dangerous' is notoriously difficult, it

added.

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