Cockroaches cause allergies, we knew that. What we didn't know is that they are also systematically poisoning the air in our homes with bacterial endotoxins. Researchers at North Carolina State University They measured for the first time the quantity of these toxins in infested apartments: very high levels, especially in the kitchens.
Endotoxins are fragments of Gram-negative bacteria that live in the gut of cockroaches. When inhaled, they cause respiratory inflammation and can worsen asthma. The most significant discovery? Completely eliminating the infestation reduces both allergens and toxins. Pest control isn't just a matter of hygiene: it's a matter of respiratory health.
What are endotoxins and why do cockroaches produce them?
Endotoxins are fragments of bacterial cell walls that are released when the bacteria die. Cockroaches eat just about anything, from food scraps to carrion. This allows them to harbor a rich and diverse gut microbiome, full of Gram-negative bacteria. When these insects defecate, they release enormous amounts of endotoxins into the domestic environment.
A single female cockroach deposits approximately 5.000 units of endotoxin per day. In an average infestation, with hundreds or thousands of specimens, we're talking about millions of toxic units accumulating in house dust. Females produce twice as many toxins as males, simply because they eat more.
“Female cockroaches eat more than males, so more endotoxins are released through their feces,” he explains. Madhavi Kakumanu, researcher at NC State and co-author of the study published in Journal of Allergy and Clinical Immunology: Global.
The study that measured cockroach pollution
The research was conducted in residential complexes in Raleigh, North Carolina. Scientists measured the extent of cockroach infestations and the concentrations of allergens and endotoxins in each home. Before any treatment, they collected both settled and airborne dust samples to establish baseline levels.
The results were unequivocal: The infested houses contained extremely high amounts of endotoxins, with particularly high concentrations in kitchens., where cockroaches find the most food. Bedrooms, although contaminated, had lower levels.
The infested apartments were divided into two categories: untreated homes and homes that had received professional disinfestation. The researchers also included a control group of homes without infestation. Dust and insect samples were collected again after three and six months.
Homes that remained untreated showed consistently elevated levels of both allergens and endotoxins throughout the study. In contrast, most units that received disinfection were cleared of cockroaches and showed substantial reductions in both contaminants.
Removing roaches really cleans the air.
"When you eliminate cockroaches, you eliminate their allergens. Small decreases in cockroach numbers don't reduce allergen levels because the remaining live cockroaches deposit more allergens," he explains. Coby Schal, professor of entomology at the NC State and co-author of the study.
“Endotoxins decreased significantly in homes where cockroaches were eliminated. This study demonstrates that cockroaches are the most important endotoxin depositories in infested homes.”
It is important to point out that Humans and pets can also produce endotoxins, but researchers found that a majority of those detected in house dust came from cockroach feces.
Why endotoxins are dangerous to your health
Inhalation of endotoxins causes allergic responses and can aggravate pre-existing respiratory conditions. Cockroaches release allergens through their saliva, droppings, parts of their exoskeleton during molting, and egg casings.Bacterial endotoxins are now added to this cocktail.
“Endotoxins are important for human health, as inhalation of these components has been shown to provoke allergic responses,” says Schal.
Previous household surveys have found significantly higher endotoxin levels in homes with self-reported evidence of cockroaches. This association is stronger in low-income homes than in single-family homes.
The indoor pollution problem we ignore
The study adds an important piece to our understanding of household air pollution. Indoor air quality has become a central issue after the pandemic, but we tend to focus on viruses and fine dust, ignoring the role of pests.
Kakumanu adds a worrying detail: "We've also seen that allergens and endotoxins can become airborne." It's not just dust deposited on furniture. These particles rise into the air and are constantly breathed in.
The next steps of the research will include examining the interactions between cockroach allergens and endotoxins in animal models of asthma, such as mice. "There's a hypothesis that asthma can be worsened by interactions between allergens and endotoxins," says Schal. "We want to see if this is the case in mice."
The lesson is clear: In the presence of cockroach infestations, simply opening windows isn't enough. Professional extermination is the only effective solution for restoring indoor air quality and protecting respiratory health, especially in children and asthmatics. Cockroaches aren't just a hygiene problem: they're a documented health risk.
If you've seen even a single cockroach in your home, act immediately. What you don't see could be worse than what you do: millions of bacterial endotoxins floating in the air you breathe every day.
