Environmental Pollutants Make White Worms Even Colder

Certain environmental pollutants are making white worms, which over thousands of years have adapted to the arctic cold, even colder, possibly endangering the species, new research says.

The earthworm Enchytraeus albidus is a so called ectotherm, meaning its body temperature closely follows the temperature of the environment in which it lives, mainly the Arctic. But the toxin nonylphenol, which is found in certain detergents, pesticides and cosmetics, is affecting this natural ability.

Nonylphenol inhibits the worm's ability to protect the cells in its body from cold damage, and researchers worry that this is not only threatening to this earthworm, but that it can impact the rest of the ecosystem as well.

The findings were published in the journal Environmental Science & Technology.

When ectothermal animals are exposed to cold, their cell membranes - composed mainly of lipids, or fat - become stiff, preventing normal flow of molecules and ions. Conversely, heat can also be a problem, because it makes cell membranes too fluid. Lucky for Enchytraeus albidus and many other ectothermal animals, they can adjust the fluidity of membranes by altering the lipid composition of their cell membranes.

Now it turns out that nonylphenol is making life difficult for these white worms, hindering their ability to tolerate the cold.

"Usually, when you make ecotoxicological risk assessments for hazardous substances, you make experiments with different organisms at room temperature, or at the optimal temperature for the organisms. But in nature, the organisms rarely have optimal conditions. They are stressed by high or low temperatures, drought or disease. This gives a risk of underestimating the real effect of substances in nature," research leader Martin Holmstrup explained in a statement.

Researchers from Aarhus University, University of Southern Denmark and Roskilde University tested the effect of nonylphenol and another pollutant called phenanthrene - found in tar - on artificial cell membranes.

As nonylphenol makes the membranes more stiff, phenanthrene makes the cell membranes more fluid and thus the worms more resistant to cold when occurring in the right concentration.

Though the results indicate that these substances could have potentially harmful consequences on this worm population, the researchers say that further study is needed.