«We have to distinguish between health-related limits and politically set limits. This is always mixed up», says Rex FitzGerald, Regulatory Toxicologist at the Swiss Centre for Applied Human Toxicology (SCAHT) in Basel. Health-related limits define the dose that has no harmful effect despite lifelong and daily consumption. There are also legal limits that have nothing to do with health risk.

The value of 0.1 micrograms per litre set for drinking water is not based on a risk assessment, but expresses the political will to have no residues for precautionary reasons. This value is not suitable for assessing the health risk. «If we speak of toxic water because it exceeds 0.1 micrograms per litre, this is fundamentally wrong», says the toxicologist, who carries out risk assessments on behalf of the authorities. He is perplexed as to why this is nevertheless repeatedly reported in the media.

On the right track

Dr Manfred Röttele, project manager of the European water protection initiative TOPPS, explained just how low the limit value for pesticides in water is: «To dilute one gram of an active ingredient to the existing limit value of 0.1 micrograms per litre, you need a stream one metre wide, 30 centimetres deep and 33 kilometres long.» It goes without saying that undesirable inputs into groundwater should be avoided wherever possible. Good agricultural practice is essential. TOPPS supports users and offers the relevant expertise. In this way, pesticide inputs into the groundwater can be significantly reduced. «The direction is right. The contamination of groundwater by pesticides is decreasing», says Röttele.

Discrepancy between perception and danger

Jo Riehle, food chemist and pesticide expert from Hamburg, dares to explain why the public often senses danger at the slightest residue. In his opinion, the heated debate has to do with the so-called uncertainty avoidance index. This is very high in Germany – but probably also in Switzerland. The fear of the unknown leads to the establishment of rigid rules, regulations and laws.

«One driver of the discussion, however, is the vastly improved analytics. Today, we can find anything if we look for it», says Riehle. «The fact that fewer different active substances were found in the past also has to do with resistance management. There are fewer ‹one-fits-all› products today. Today's pesticides have a much more specific effect.» From an ecological point of view, this makes sense. At the same time, however, a greater number of different substances are found. This in turn would be perceived as «dangerous» by the public, says Riehle. There is also the fear of «multiple residues». «However, the mere detectability of different substances does not mean a higher health risk», says the pesticide expert.

The topic is complex. The speakers would like to see a more objective debate and call for common sense. This is precisely the aim of swiss-food.ch.