Residue is not the same as residue
Painkillers like Voltaren are a blessing for us – yet in our rivers they can harm fish. If these were crop protection products, calls for bans would be immediate. It becomes clear that we are applying double standards.
Monday, March 2, 2026
Back pain? A stiff neck? A dip in the River Aare might help – at least in theory. As reported by the Argauer Zeitung, around a quarter of a tonne of diclofenac flows into the river each year near Brugg.
Diclofenac is the active ingredient that relieves pain for many sufferers, day and night. It has analgesic, anti-inflammatory and fever-reducing properties and is found in well-known products such as Voltaren, Ecofenac and Flector.
For us humans, it is a blessing. A brief swim in the Aare would hardly have any effect, however. For other living organisms, the concentration in the river can be problematic. According to the Swiss water research institute Eawag, diclofenac can damage the liver, kidneys and gills of fish.
According to Eawag, diclofenac is the only chemical substance that regularly exceeds the legal limit at the lowest monitoring station on the Aare. The highest concentrations occur in winter – not because more painkillers are consumed, but because sunlight, which breaks down the active substance, is lacking.
The cantons are responding. Wastewater treatment plants equipped with an additional treatment stage to remove micropollutants can largely filter diclofenac from wastewater. In the canton of Aargau, two plants are already equipped accordingly, and at least five more are to follow by 2035. There are currently 41 municipal wastewater treatment plants in the canton.
Until the upgrades are completed, simple behavioural measures can help. After applying pain relief cream, hands should first be wiped with paper and the paper disposed of in the waste bin. Wipe first, then wash – that is the rule to reduce diclofenac concentrations in water bodies.
It is striking how differently risks are assessed. Farmers applying crop protection products are under constant scrutiny. As soon as residues are detected in water, calls for bans arise. At the same time, agriculture has long-established methods to minimise risks: precision nozzles that reduce spray drift by up to 95%, dedicated washing areas for spraying equipment, covering field drains, planting crops across slopes, and hedges along waterways to reduce runoff. All these measures are part of good agricultural practice and help minimise residues.
The situation looks very different for us. Anyone applying Voltaren to their elbow may at most be advised to wipe their hands with a paper towel afterwards – no one calls for a ban.
Lothar Aicher from SCAHT sums up this schizophrenia: people tend to perceive risks as lower when they personally benefit from them.
Many people fail to see the benefits of crop protection products, although we would immediately feel the consequences of their absence. A 50% reduction in their use would lead to yield losses of up to 30% in certain crops, according to studies. A 2019 study by the European Parliamentary Research Services points to even more drastic figures and consequences: increased land use and prices, and declining food quality. Not only the concerns of those directly affected – farmers – but numerous studies underline the economic and ecological importance of these products. Yet this remains abstract, distant and complex.
A painful back or stiff neck in the morning, by contrast, is very concrete and immediate. One thing is certain: the calm tone with which the media report on pharmaceuticals in our waters would also be welcome in the debate on crop protection.
Life Leaves Residues – and They Show Up in Our Water
Contrary to popular belief, agriculture is not the only source of pollution in our waters – many residues stem directly from everyday life. Active substances such as fipronil, found in tick and flea treatments for dogs and cats, enter rivers and lakes via wastewater. Cleaning agents and detergents also leave traces when we clean or do the laundry.
Cigarettes are particularly problematic: around 75% are carelessly discarded and contain toxic substances such as arsenic, lead, cadmium, ammonia and formaldehyde, which pollute soils and water bodies.
Life leaves residues – and the substances detected in water and soils ultimately reflect our daily lives. An honest discussion about environmental contamination places responsibility on all of us. And often, small actions can make a difference. Properly disposing of a cigarette butt would be a good start.
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