Nature | Editorial

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Toxic influence

Europe must act to stop livestock drugs from wiping out its vulture populations.

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A dead vulture in Spain could herald a crisis for raptor populations, because a drug that has killed hundreds of thousands of birds and driven some species to the brink of extinction in Asia now threatens to do the same in Europe. The European Medicines Agency (EMA) must clamp down on the drug.

The Spanish bird died two years ago. Now, the probable cause has been identified as a drug given to livestock (I. Zorrilla et al. Conserv. Biol. http://doi.org/wf5; 2014). Events in Asia show how serious the consequences could be. In the 1990s, vultures on the Indian sub­continent started dying in huge numbers. Some populations lost more than 95% of their animals. The consequences were catastrophic. As the skies cleared, dead livestock were left to rot in fields.

Research finally pinned the blame on the anti-inflammatory drug diclofenac, which had become widely used in cattle for problems ranging from pneumonia to mastitis. Although harmless to bovines, it is highly toxic to vultures that feed on the carcasses (J. L. Oaks et al. Nature 427, 630–633; 2004).

As a result, India, Pakistan and Nepal placed heavy restrictions on the use of the drug in livestock. And although campaigners say that large vials officially designated for human use are often repurposed by veterinarians, the threat to the vultures of Asia has decreased. Numbers have not yet recovered, and in some cases are still declining, but the birds at least now stand a chance.

Europe is heading in the opposite direction. Despite warnings from scientists, Spain — home to the vast majority of Europe’s vultures — last year licensed diclofenac for livestock use. The EMA is considering the risks posed by the drug, and is scheduled to reach a decision by the end of November.

The discovery that the 2012 vulture was probably felled by a related drug, called flunixin (see Nature http://doi.org/wfx; 2014), is worrying for two reasons. First, it shows that diclofenac is not the only product in the class known as non-steroidal anti-inflammatory drugs (NSAIDs) that has the potential to kill vultures and other birds of prey. Second, it shows that carcasses containing significant quantities of these drugs are reaching the wild-animal food chain in Europe — in this case, probably through the Spanish tradition of wild-animal feeding stations known as muladares.

Two things should now happen. The EMA must move to heavily restrict — if not ban — the use of diclofenac in livestock. An alternative drug that does not harm vultures — meloxicam — is already available, and vets should use this in preference. And, as urged by the researchers who reported the flunixin-killed vulture, regulators should look at the effects of all NSAIDs used in livestock on vultures. Although diclofenac could well be the most deadly, we must know what other drugs also pose a threat to birds that feast on carrion, and how they might be managed.

In the longer term, regulators in Spain and the rest of the European Union need to ask how a drug with such evidence of environmental damage was allowed to come onto the market.

Spain is an important stronghold for vultures, and this alone would be reason enough to look seriously at restricting the use of diclofenac. But the European Union needs to set an example for the rest of the world. If it allows diclofenac use to continue, countries such as India could well decide to ease their restrictions, and African nations may rethink their plans to ban it.

Journal name:
Nature
Volume:
514,
Pages:
404
Date published:
()
DOI:
doi:10.1038/514404a

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