Worms unearth key to better soil contamination test

Exposing invertebrates such as worms to toxic chemicals for longer can give a more accurate test of soil contamination, a dutch researcher has found.

Dr Miriam León Paumen exposed soil and sediment invertebrates to toxic Polycyclic Aromatic Compounds (PACs) and found they had "large and unpredictable effects" on their life cycles, "very different from the effects of short-term exposure".

The Netherlands Organisation for Scientific Research (NWO), which funded the research, said: "These chronic effects can be very different from the effects of short-term exposure to PACs.

"Therefore, assessments of soil and sediment contamination are more reliable when they are based on the effects of prolonged exposure of soil and sediment fauna to toxic substances."

PACs are a group of chemicals found in crude oils, mineral oils, bitumen and tars.

They are also created during the incomplete burning of fossil fuels and oil products.

They are found in air, water and soil.

Their effects on terrestrial and benthic invertebrates - those living on the bottom of a body of water - is used to estimate soil and sediment contamination risk and the need for any clean up or remediation.

But risk limits are determined by calculations based on the short term effects of PACs.

Now, León Paumen's research has shown longer exposure gives more reliable assessments.

She examined the effects of two 'standard' (regulated) and four 'new' (non-regulated) PACs on one or more generations of these invertebrates.

The animals she used included two species of worm, a springtail, a tiny insect found in soil, and a chironomid species, known as non-biting midges found near water.

They showed "highly predictable" arrested development in 70% of cases when when subjected to soil and sediment artificially contaminated with PACs.

But extended exposure, mainly to the new PACs, also showed frequent "large and unpredictable effects on their life cycles, the NWO revealed.

A multigenerational experiment showed the influence of these toxic chemicals over several generations is unpredictable.

"León Paumen has now demonstrated that the effects of prolonged exposure can be very different and so risk assessments based on such measurements are more accurate," the NWO said.

A dutch firm has already used some of the techniques born out of her research at contaminated locations, it is understood.

David Gibbs



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