Take care of your pet and protect nature
Study Provides Insight: Toxic Substances in Flea Control Products Remain in the Home
Last spring, at the initiative of the Hollands Noorderkwartier Water Board (HHNK), the municipality of Uitgeest, and the municipality of Heemskerk, the campaign “Take Care of Your Pet and Your Garden, and Protect Nature” was launched. The campaign helps residents become more mindful of their use of products such as flea treatments for dogs and cats. Many people are unaware that the toxic substances in these products can linger in their homes and indirectly end up in surface water. A preliminary study of nearly fifty households in Uitgeest and Heemskerk shows that toxic substances do indeed linger in homes.
One component of the campaign was an exploratory survey of households to determine which substances pets carry on their bodies—for example, through the use of flea control products. These substances can end up in surface water via hair and dust. By gaining a better understanding of this, we can work more effectively toward clean surface water for people, animals, and nature. Residents of Heemskerk and Uitgeest who own a dog or cat could participate in the citizen science study by submitting a dust and hair sample.
Survey Results
The Velt association conducted the study. The results show that chemicals from flea and tick treatments remain indoors. The five chemicals most commonly found indoors are imidacloprid, fipronil, dinotefuran, pyriproxyfen, and selamectin. These chemicals 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, which causes bee mortality, 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.
Every contribution to cleaner water counts
The substances detected are of concern to the water board because previous studies have shown that veterinary drugs can enter surface water through hair, fur runoff, and treated animals swimming. This study shows that such substances are present in homes and can therefore serve as a source for further dispersal into the environment. Water Board Member Jos Beemsterboer, portfolio holder for integrated water management in rural areas: “We often encounter these toxins in water quality measurements, sometimes in concentrations that are too high. Many residents are unaware that these types of substances are also found in consumer products.”
“We’ve raised awareness of this issue through this campaign. Use resources wisely and only when necessary, and choose products that have the least possible impact on the environment. Only if everyone—the water authority, other government agencies, the agricultural sector, industry, and residents—does their part can we improve water quality.”
Webinar
Those interested can also register for a webinar with a veterinarian on responsible parasite control for pets. It will take place on November 10, 2026, at 8:00 p.m.
Tips for Pet Owners
Controlling fleas and ticks remains important when necessary. Through regular checkups, a clean environment, and careful use of treatments, pet owners can protect their pets and limit the spread of harmful substances.
Treat only when necessary
Use flea and tick treatments only if your pet has an infestation or is at increased risk of one. Talk to your veterinarian to determine whether preventive treatment is necessary, for example, in the case of a flea allergy or a trip to Southern Europe.
Prevent a flea infestation
Vacuum and mop regularly, wash blankets and pillows from sleeping and resting areas at 60 °C, and check dogs and cats weekly with a flea comb. Black specks that turn reddish-brown when wet may be flea droppings. Treat an infestation immediately and thoroughly clean the surrounding area to prevent reinfestation.
Check for ticks
Avoid tall grass, low shrubs, and ferns whenever possible. Check dogs after every walk (within 24–36 hours) and cats regularly. Remove ticks as soon as possible using tick tweezers. Ticks are most active from spring through fall, but can also be found during mild winter weather. Using a tick preventative is not necessary if your dog or cat only occasionally has a tick. Consult your veterinarian to determine if treatment is needed if your dog or cat regularly has ticks.
Choose an appropriate remedy
Ask your veterinarian if a short-acting chewable tablet is a suitable alternative to a pipette or collar. Chewable tablets work from the inside out, so less of the active ingredient comes into direct contact with the skin and fur. Be sure to clean up your pet’s feces outdoors and dispose of it with the general waste. Otherwise, the active ingredients from the chewable tablet could still end up in the environment. Whenever possible, choose a product with a single active ingredient and avoid combination products if the additional ingredients are not necessary.
Be careful with collars
Flea and tick collars pose an additional risk to water quality: when animals swim, the collars can release active ingredients directly into the water. They can also come loose and remain in the water or the surrounding environment for long periods of time, where they continue to release these substances, which can be harmful to the environment.
Use medications carefully and according to the package insert
Be sure to use the correct product for the specific animal species and dosage. Wear disposable gloves when applying the product and dispose of them in the general waste afterward. Do not let dogs swim for the first few days, and do not bathe your pet after administration. Do not let your children pet the dogs and/or cats after treatment. Consult the package insert for the exact instalments regarding swimming, bathing, and touching.
Pick up loose hairs
It's best to brush your pet outdoors. Collect your pet's hair while brushing and dispose of it with the general waste. Don't leave it lying around outside or let it blow away.