Expert opinion

Threat to waterways from parasite treatments for dogs and cats

Assignment

The client had read studies from the United Kingdom that indicated a threat to waterways from parasite treatments for dogs and cats (summary: online webinar by Prof. Goulson (from 28:30 to approx. 45:30)

The question to be answered was whether such a threat to the communities living in our waters could also exist in Switzerland.

Research

In addition to studying the literature and legislation, it was necessary to contact various individuals and organisations. Test purchases were also carried out.

The following organisations were consulted:

EAWAG: provided all the necessary information immediately. However, it became clear that only a few results from water tests were available.

The parasitologists (Faculties of Veterinary Medicine, Universities of Bern/Zurich) were unable to provide any information on the frequency of tick-borne diseases in pets in Switzerland. The diseases that occur are usually mild or can be vaccinated against. faculties at the Universities of Bern/Zurich) were unable to provide any information on the frequency of tick-borne diseases in pets in Switzerland. The diseases that do occur are usually mild or can be vaccinated against.

Swissmedic confirmed that many parasite control products for dogs and cats contain the controversial insecticides. The statement made after being confronted with new toxicological findings regarding the risk to humans was alarming: the manufacturing companies are responsible for informing Swissmedic about new findings so that the drug information can be updated – they do not have time to read toxicological studies.

The Swiss Veterinary Association (GST) has largely failed to respond to various requests for information from the veterinary profession. It was not until November 2025 that a short newsletter was published calling for mandatory approval.

Results of the analysis

a) The insecticides fipronil, imidacloprid and permethrin have been banned in agriculture for years, but are still approved for use as parasite control agents for pets.

b) All of these insecticides are highly toxic to humans, animals and the environment.

c) After application to pets, these substances remain detectable in pet owners' households for weeks and enter waterways either indirectly via laundry, dog grooming salons, etc., or directly, for example when bathing dogs.

d) The few test results already available indicate that limit values have been exceeded in individual water bodies, but estimates of usage suggest a greater impact.

e) Swiss pharmaceutical legislation does not provide sufficient protection against environmental risks.

f) The risks posed by ticks and fleas are low for pets in Switzerland.

g) Prophylactic treatment is rarely necessary, but is heavily advertised (capitalising on fear).

h) There are plenty of alternatives, especially various plant-based substances that are very effective at keeping insects away (no insecticide-based products are approved for use on humans!).

i) During test purchases in chemists and drugstores, warnings about risks were rarely given. Alternative products without toxic insecticides were rarely mentioned.

k) Many parasite control products, including those that require a prescription or are only available in pharmacies, can be easily ordered from abroad via the Internet.

 

The summarised results were sent to the interviewees for comment and any ambiguities were clarified.

The question of whether such a threat to the communities living in our waters could also exist in Switzerland had to be answered with a YES.

In view of the facts and circumstances, it became clear that the issue must be addressed politically.

Political use

After the client made contact and submitted the results of the basic dossier, Council of States member Jakob Stark, Swiss People's Party, TG, finally submitted Interpellation 24.3899 "Must the use of fipronil and imidacloprid be restricted or even banned?" on 18 September 2024.

Political action

The statement issued by the Federal Council on 27 November 2024 was unclear on a number of points and lacked specific promises of action. In-depth research was subsequently carried out.

Based on these facts, the interpellants requested a discussion in the Council of States. In the debate on 6 March 2025, Federal Councillor Baume-Schneider stated that extensive investigations were underway in Swiss waters and that the results should be available by the end of 2025. Action would then be taken depending on the results. Video of the debate on 6 March 2025

Results of water investigations in Switzerland

The results of the investigations published at the end of 2025 Pesticides in streams: There is still much to be done (German) and FIPRONIL CONTAMINATES FLOWING WATERS (English tranlation) confirmed the assumptions.

However, it became clear that only a small number of pesticides could be investigated.

Metabolites such as the highly toxic fiprol, but also growth inhibitors such as methoprene or isoxazoline etc., which are also contained in parasite control agents, were not investigated – or there is no possibility of investigation (EAWAG press release (German)).

 

Demands

a) It makes no sense to apply double standards. If a substance is too toxic for use in agriculture (fipronil, imidacloprid, permethrin) and is banned there, the same must apply in other areas.

b) All insecticide-based parasite control products should at least be subject to prescription – only a vet can carry out the necessary risk analysis before use.

c) In general, substances with an increased risk potential should only be used or dispensed by persons who have the appropriate professional training and are able to competently assess the risks (doctors, veterinarians, farmers, gardeners, pest controllers, etc.).

d) Swiss pharmaceutical legislation must be amended to ensure that all medicines undergo an environmental impact assessment.

e) Water testing should be continued and extended to include other active ingredients in parasite control products.

f) The online trade in medicines subject to authorisation must be prevented.

g) Specialists and the general public should be adequately informed about the risks of insecticide-based parasite control products, and alternatives should be identified.

 

Full report/dossier

The full report was updated in January 2026 and released for further use by the press and for general publication.

Switzerland/ political debate - Risks posed by ectoparasiticides for pets

Press release and background dossier, including basic information, political debate, progress, results, demands, bibliography