Wetenschap - 16 november 2017

‘There’ve been antidepressants in our rivers for years’

tekst:
Didi de Vries

American research has proven that fish in the Niagara ingest antidepressants via the river water. According, to Ivo Roessink, an Environmental Risk Assessment researcher at WUR, this is a global problem.

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Are there antidepressants in Dutch rivers too?

‘Yes, active ingredients in antidepressants largely survive conventional water purification technology and end up in our surface water. Little is known about the effects on the ecosystem. Nor are the effects very obvious: fish don’t go floppy straightaway and plants just keep on growing. The substances can bring about a shift in the ecosystem, but we do not know how big that shift is.’

Why is so little known about this?

‘The alarm bells only started to ring about seven years ago, and that is too short a time to be able to establish a long-term effect. Lab studies have been done on the behaviour of fish which ingest different amounts of antidepressant. Some fish became very relaxed, and others weren’t affected at all. A few years ago researchers discovered that endocrine substances in contraceptive pills were giving male fish in the Dommel female characteristics. You don’t want that, of course.’

How can we prevent medicinal substances getting into surface water?

‘First of all by taking fewer pills. Also, water purification technologies have improved in recent years and you can remove medicines with extra purification stages. That is expensive so we still have to weigh up how necessary we think it is to invest in it. Water boards are giving the issue a lot of attention at the moment: they want to find out whether there is indeed cause for concern. Increasingly often, they measure exactly which pharmacological substances water contains.’

Should we be wary of eating fish?

‘Eating fish can cause you to absorb undesirable substances, as we saw in the case of eel. Whether there is any question of what is called secondary poisoning from drug residues, we don’t know. Theoretically it is a possibility.’


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