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Dear regulators, policymakers, and responsible authorities,
In 2024, 4,330 calls were registered with the Belgian Poison Control Center concerning household cleaning products. In addition, there were a further 1,218 exposures to household disinfectants, so-called biocides - products specifically developed to kill microorganisms. Half (!) of these cases involved children. In a very high percentage - 73% - of these incidents, victims developed actual symptoms, mainly respiratory irritation, eye injuries, and skin complaints.
These are not marginal figures. These are largely preventable incidents involving products that are routinely used in the home.
Yet disinfectants have been actively promoted for daily use in normal households for years. A central role in this promotion is played by the marketing claim “Kills 99.9% of bacteria.” This claim dominates packaging and advertisements and influences how millions of people clean. It suggests that a home is only truly clean when bacteria are eliminated en masse. Since the coronavirus period, the use of killing agents has become further normalized, even in situations where this provides no demonstrable health benefit.
This norm not only influences behavior but also has concrete consequences for health, safety, and public health. We therefore address you with the request to critically reassess this marketing norm and better protect consumers.
A Misleading Norm
The claim “Kills 99.9%” is based on laboratory tests conducted under controlled conditions. But a home is not a laboratory.
In a normal living environment, surfaces are repopulated within minutes via hands, air, clothing, pets, and the human body. The effect of disinfection is therefore temporary by definition.
Yet the claim creates the impression that a household can or should remain bacteria-free for long periods. It also suggests that bacteria in general are dangerous. This image is scientifically incorrect. Only a very small fraction of all bacteria are pathogenic. The overwhelming majority are harmless or even essential for ecosystems, soil health, and the human body.
By failing to distinguish between harmful and beneficial microorganisms, this marketing claim creates a simplistic and fear-driven view of hygiene that does not align with microbiological reality.
Consequences in Daily Life
Health
A growing body of research shows that an overly sterile living environment can disrupt the microbiome and therefore the immune system. This has been linked to increases of up to +300% in common allergies and sensitivities, as well as generally reduced resistance to disease. This is known as the hygiene hypothesis.
Safety
Household chemicals cause thousands of accidents each year. Young children are at additional risk because they put objects in their mouths and because some products appear attractive.
Biocides account for over a thousand additional incidents. Oral contact is the primary exposure route (>70%), followed by contact with the eyes (17%). Poisonings in adults often occur during normal use. Many disinfectants contain aggressive substances that can cause harm through inhalation or skin contact alone.
Research among domestic cleaners has even shown that frequent exposure can negatively affect lung function to a degree comparable to smoking a pack of cigarettes per day.
Public Health
Unnecessary antimicrobial use contributes to resistance, making antibiotics increasingly ineffective. Antimicrobial resistance is recognised by the WHO as one of the five greatest threats to public health and already causes more than 35,000 deaths annually in the EU. Normalising “killing” as the default solution in marketing contradicts the principles of responsible antimicrobial use.
A Structural Cause: Lack of Basic Knowledge
Many consumers do not know what “99.9%” actually means in practice. The distinction between cleaning, disinfecting, and proportional hygiene is rarely explained.
This knowledge gap makes people vulnerable to simplistic marketing claims that appeal to fear rather than understanding.
What We Ask
We ask policymakers and regulators to critically reassess the use of the marketing claim “Kills 99.9%” for household cleaning products.
Specifically, we ask for:
• Stopping or strictly limiting the use of the marketing claim in consumer advertising and packaging where it creates a misleading impression of necessity or effectiveness.
• Developing clear guidelines distinguishing professional disinfection from routine household cleaning.
• Better protecting consumers through clear warnings and proportional antimicrobial-use principles.
• Investing in basic education about microorganisms from primary school onward.
In Closing
We do not advocate for less hygiene.
We advocate for honest, proportional, science-based hygiene.
For consumer protection without misleading claims.
Respectfully,
The Signatories
Initiator
YOKUU
Belgian pioneer in microbiologically inspired cleaning innovation and advocate for proportional, science-based hygiene.
Experts
Marc Van Ranst
Virologist and professor at KU Leuven, head of the Laboratory for Clinical and Epidemiological Virology. Prominent scientific voice during the COVID-19 pandemic.
Sam Proesmans
Emergency physician and Deputy Chief Medical Officer responsible for critical care clusters and diagnostics within a hospital group of more than 2,500 beds; former advisor to the Belgian Prime Minister during the COVID-19 pandemic.
Frédéric Weekers
Engineer specialized in industrial microbiology and microbial ecology. Expert in Bacillus production and development of microbial applications for agriculture, environment, and cleaning industries. Former Managing Director of an industrial microbiology SME.
Ellen Jansen
Senior clinical project leader with over 16 years of experience in international Phase I–III clinical trials, specializing in study design, execution, and quality control in pharmaceutical and biotech environments.
Dr. Vincent Janssens
General practitioner; former chairman of the Brussels GP Association; former Medical Department Director at Doctors Without Borders.
Dr. Tine Dusauchoit
General practitioner; former chair and Managing Director at Doctors Without Borders.
Dr. Bruno De Gendt
General practitioner, sports physician, and specialist in tropical medicine; former chairman of the Dendermonde GP Association.
Dr. Hilde De Nil
General practitioner and specialist in tropical medicine.
Organizations
SamenFerm – Ferm Household Help
Large Flemish domestic support organization employing more than 2,600 household assistants and supporting approximately 50,000 families daily.
Start it @KBC
One of Europe’s largest startup accelerators supporting sustainable and future-oriented entrepreneurship.
Vogelbescherming Vlaanderen
Nature and environmental organization dedicated to biodiversity protection and ecological balance.
Political Representative
Meyrem Almaci
Belgian politician and former party leader of Groen, recognized for her work on climate, health, and sustainable policy.
Public Figures
Elma Dalhuijsen
Known in Belgium as a household cleaning expert and public face of Tante Kaat, sharing practical cleaning guidance with broad audiences.
Martine Prenen
Television personality and health ambassador promoting healthy lifestyles and preventive care.
Eva Daeleman
Media figure and author recognized for public engagement around mental and physical wellbeing and sustainable living.
Scientific References
Misleading Norm
Kwan, S. E., et al. (2018). Journal of Applied Microbiology.
Balloux, F. et al. (2017). BMC Biology.
Bartlett, K. et al. (2022). Clinical Microbiology and Infection.
Locey, K. J. and Lennon, J. T. (2016). Nature Microbiology.
Health
Scudellari, M. (2017). PNAS.
Martinez, F.D. (2001). Respiratory Research.
Braun-Fahrländer, M. et al. (2002). New England Journal of Medicine.
Safety
European Commission — Poison Centres
Kennisnetwerk Biociden (2025)
VRT NWS (2014)
Chang, A. et al. (2020). MMWR (CDC).
Svanes, O. et al. (2018). American Journal of Respiratory and Critical Care Medicine.
Archangelidi, O. et al. (2021). Occupational and Environmental Medicine.
Salonen, H. et al. (2024). Environment International.
Public Health
Maillard J.Y. and Pascoe M. (2024). Nature Reviews Microbiology.
ECDC (2024). Annual Epidemiological Report.
