Pesticides: Better predict biological effects 2

Pesticides: Better predict biological effects

Helmholtz Center scientists want to better predict the biological effects of low concentrations of pollutants.

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Pollutants like Pesticides can already have effects on sensitive individuals at concentrations ten thousand times lower as previously assumed. It could be scientists Helmholtz Center for Environmental Research (UFZ) in its current study published in the journal Scientific Reports. An important role is played by the amount of stress. Surprising at first glance: Not only too much, but too little stress can lead to greater sensitivity to pollutants.

If and to what extent Pollution damages the body or kill it depends primarily on its concentration and the sensitivity of the individual: the dose makes the poison. "But that's not all," says UFZ ecotoxicologist, prof. Dr. Honey. Matthias Liess. "It also depends very much on how much stress the body is exposed to." Concentration of pollutants, individual sensitivity and environmental stress So play together in a kind of action triad. The role of individual components was explored in their current study. They wanted to find out how things could be better in the future, sensitive individuals and effects at very low concentrations in risk assessment. "Earlier calculation models could hardly predict the effects of low concentrations of pollutants on susceptible individuals and species," Liess explains. "But it's in human and in ecotoxicology important. "For vulnerable people – such as children, the sick or the elderly – or more sensitive species of ecosystems, they are clearly damaged at significantly lower concentrations than previously thought.

"Our research was triggered by observations in the lab: At very low pesticide concentrations – well below the concentrations that led to potent effects in previous studies – there were effects susceptible organisms"The ecotoxicologist says. This has hardly been noticed so far, because such low concentrations are only rarely tested. So far, it has been assumed that pollutants show effects in high concentrations only after they exceed the limit value – and so does the theory. extremely low concentrations obviously this is not true. Less: "We found these effects in almost all studies that have studied very low concentrations of pollutants." And in their own research, where they exposed the planktonic cancer Daphnia magna to the lowest concentrations of pesticides – in this case esfenvalerate, as an insecticide with Effects of contact and feeding in pesticides it is used in fruits, vegetables and crops and is EU approved. What is behind the effects in these low concentration areas? The hypothesis of UFZ scientists is: Pollution stress satisfies internal stress. But what does that mean?

Organisms are exposed to environmental stress, e.g., predator pressure, parasites and heat waves are more sensitive to pollutants and die in low concentrations of pollutants. "We've already been able to calculate that ratio in earlier studies," Liess says. "We could show it now Individuals develop internal stressif they are exposed to too little periodic environmental stress. "Obviously Organisms adapted to a certain amount, Laboratory conditions are optimal for planktonic cancers – enough oxygen, optimal water temperature – so they are probably not very optimal. "And as external and internal stress add up, so does the sensitivity to pollutants – and drastically," says Liess. Repercussions: Sensitive individuals are already responding to extremely low concentrations of pollutants. These can be up to a factor of 10,000 below concentrations previously considered harmful. "Accordingly, too much – but too little – stress increases sensitivity to pollutants," UFZ researchers say.

In order to be able to visualize effects in low concentration ranges, scientists have developed a model by which internal stress and related effects can be calculated on the effects of pollutants. Less: "We hope that our study will contribute to a more realistic and detailed risk assessment for environmental and human toxicological issues – especially for vulnerable individuals." (UFG)