Frequently Asked Questions About the Campaign

Why this campaign?

HHNK has detected harmful substances from pet and garden products in surface water samples. Many people are unaware that these substances can enter the environment and water from their homes and through their pets. With this campaign, we aim to raise awareness and encourage the responsible use of products such as flea treatments.

In how many homes were substances found in the dust and hair samples?

In total, we found substances found in flea and tick treatments in 46 of the 48 homes. In two homes—one in the control group and one in the group with treated pets—we found no such substances in the dust and hair samples.

Which substances were found most frequently?

The five most commonly detected substances indoors are imidacloprid, fipronil, dinotefuran, pyriproxyfen, and selamectin. These substances are commonly found in flea and tick treatments. Imidacloprid and fipronil were banned in agriculture in the European Union years ago because they are too harmful to humans and the environment.

HHNK has observed that imidacloprid is still present in surface water. This study shows that the use of this substance in pets may explain its continued presence in the water. At the same time, further research is needed to better understand the exact extent of its contribution.

Are the substances that were found harmful to the water?

Several active ingredients are known to be harmful to insects and aquatic organisms. Imidacloprid is a well-known example. This substance has long been the subject of public debate due to its effects on insects.

Why is this research important to HHNK?

Previous studies have shown that veterinary drugs can enter surface water through the hair, fur washings, and swimming of treated animals. This study shows that such substances are widely present in homes and can therefore serve as a source for further dispersal into the environment.

Does the study show that flea control products are a source of toxins in the water in Heemskerk and Uitgeest?

Due to its scope and the registration/selection procedure, this study should be considered an exploratory study. Although this study is not representative of all households in the project area, it does show that the substances used in veterinary medicines are found in the living environment of the pets included in the study. This suggests that these substances may end up in the environment and surface water.

What can I do as a pet owner?

See the page Four Tips for Cleaner Water. Will you join us?

What is HHNK doing, in collaboration with other parties, to improve water quality in Heemskerk and Uitgeest?

The study and the campaign are part of the pilot project in the Uitgeester- and Heemskerkerbroek polder, aimed at improving water quality. In February 2023, HHNK, the municipalities of Heemskerk and Uitgeest, the province of North Holland, the KAVB, LTO, Glastuinbouw Nederland, Landschap Noord-Holland, and PWN signed a memorandum of understanding to collaborate on ensuring clean surface water in the Uitgeester and Heemskerkerbroek polder. This led to a package of measures, some of which have been implemented or are currently being implemented. For example, a water retention area with a purification function was recently completed in the Heemskerkerduin. There are also ambitious plans for an ecological corridor from Heemskerk toward Uitgeest and for the redevelopment of a park in Heemskerk’s “ centre ” area to enhance connectivity and the experience of water. In addition, the agricultural sector is taking steps to implement measures within its own operational processes to limit the emission of nutrients and crop protection products. Finally, farmers and land managers have begun maintaining their ditches to provide more space for ecological development within the water system. For more information, see the page Uitgeester- and Heemskerkerbroek Pilot.