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Emerging chemicals pose environmental concerns

11 September, 2011

There is growing scientific concern over the combined impact of novel toxic chemicals on the environment worldwide, according to leading international scientists.

Control of emerging chemicals and their discharge into the environment must become a high priority in order to limit or prevent adverse environmental health consequences, according to Professor Ravi Naidu, organiser of the CleanUp 2011 Conference in Adelaide this week. 

"The new toxics, known as Emerging Contaminants (ECs), have already been wildly distributed in Earth’s water, air, soil and in living organisms. Worldwide, there is currently little or no regulation or monitoring of their impact," Professor Naidu cautioned.

The new contaminants occur in day-to-day consumer items such as cosmetics and pharmaceuticals, meat and dairy products, fragrances, insect repellents and laundry detergents.

They also occur as industrial surfactants, lubricants, plasticizers and building materials, pesticides, fire retardants and as substances made from nanomaterials.

"These contaminants are predominantly unregulated man-made chemicals that occur in air, soil, water, food, and human/animal tissues in trace concentrations, are persistent in the environment, and are capable of perturbing the physiology of any organism or person exposed to them," Professor Naidu said.

"They include a diverse collection of thousands of chemical substances that have until now been largely outside the scope of monitoring and regulation.

"Many of these emerging chemicals have been recognised as endocrine disrupting chemicals (EDCs). EDCs interfere with the function of the endocrine system, a system present in nearly all animals.

"The high mobility of some of these compounds also makes them potentially hazardous as contaminants of groundwater, and is, therefore, of concern with respect to drinking water quality."

A particular category of emerging contaminants are nanomaterials, which contain particles ranging in size from 1 to 100 nanometers. Nanoparticles typically consist of minute spheres, rods, tubes and other geometric chemical shapes and are so small they can easily be inhaled, absorbed through the skin or consumed in food.

The behaviour of nanoparticles in environmental systems and the human body is highly complex and largely unknown, according to Professor Naidu.

"The environmental fate and behaviour of all these ECs is still poorly understood though a significant amount of work has been done on a few out of the many thousands that have been produced by industry worldwide in recent years," he said.

Professor Naidu said there was also a current lack of appropriate policies worldwide for dealing with emergent contaminants - including nanoparticles. This may be due to limited knowledge on the fate and dynamics of such contaminants in the environment.

"There is a need to investigate the mechanisms that underlie the fate of these substances in the environment and how environmental variables affect their behaviour. This is because the chemicals that result from the break-down of the original substances can sometimes be even more toxic," he explained.

There is also the largely unresolved question of how these toxic substances may combine with one another to affect human health over a lifetime of exposure to minute quantities.

"It is important to establish systems for widespread monitoring of ECs in the air and precipitation," he said.

"Considerable research is needed for evaluation of the effects of management practices on concentrations and transport of these compounds; a careful and comprehensive assessment of the environmental impacts of ECs on agriculture and natural ecosystem is also needed."

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