A new study by researchers at North Carolina State University has revealed that cockroach infestations can seriously degrade indoor air quality by spreading harmful allergens and bacterial endotoxins. The findings, published in The Journal of Allergy and Clinical Immunology: Global, show that cockroach-infested homes contain much higher levels of these toxins than homes without them.
The study took place in multi-unit apartment complexes across Raleigh, North Carolina. Scientists collected air and dust samples to measure both allergens and endotoxins. Apartments were divided into three groups: homes with no infestations, infested homes that received professional pest control, and infested homes that remained untreated. Samples were collected before the study began and again after three and six months to measure the changes.
Researchers found that female cockroaches released nearly twice as many endotoxins as males, mainly because they eat more food. These toxins are small fragments that come from bacterial cell walls when bacteria die. Cockroaches carry many types of bacteria in their digestive systems because they consume all kinds of materials, including food waste and trash. As they move around and leave droppings, they spread these bacterial fragments into the air and onto household surfaces.
According to the research team, kitchens had the highest concentration of toxins because food sources attract the most cockroaches. “Female cockroaches eat more than males, so they shed more endotoxins through their droppings,” explained Dr. Madhavi Kakumanu, a research scholar at NC State and one of the study’s authors. “Kitchens usually have the highest levels because that’s where food and moisture are most available.”
Endotoxins are dangerous because they can cause inflammation when inhaled. They are known to trigger allergic reactions and even worsen asthma symptoms. These toxins mix with other allergens found in dust and air, making the indoor environment unsafe especially for children and people with respiratory problems.
The research also showed a clear difference between treated and untreated apartments. Homes that received professional extermination saw a sharp drop in both allergens and endotoxins, proving that pest control plays a role in improving indoor air. In contrast, apartments that did not receive treatment continued to show high contamination levels even after six months.
“When you eliminate cockroaches, you eliminate their allergens,” said Dr. Coby Schal, the Blanton J. Whitmire Distinguished Professor of Entomology at NC State and co-author of the paper. “Small decreases in cockroach numbers don’t help because the remaining ones keep producing allergens and toxins. The key is complete elimination. Endotoxins significantly decreased in homes where cockroaches were fully removed.”
Dr. Schal added that the connection between cockroach infestations and endotoxin levels has been seen before, especially in low-income housing. “Past surveys in U.S. homes found endotoxin levels much higher in places with signs of cockroaches, and that link is even stronger in low-income areas than in single-family homes,” he said. “This shows that indoor air pollution can also be a social issue, not just an environmental one.”
Dr. Kakumanu also noted that both allergens and endotoxins can become airborne, which means that people can breathe them in even when they don’t see the insects themselves. “We also saw that allergens and endotoxins can be airborne,” she said. “That makes the risk even greater because these particles can easily travel from kitchens into other parts of the home.”
The NC State team now plans to continue their research to explore how cockroach allergens and endotoxins interact in asthma models. “There is a strong possibility that asthma gets worse when allergens and endotoxins combine,” said Dr. Schal. “We want to see if that is true in lab tests with mice.”
Cockroach infestations are not only an issue of cleanliness but also a serious public health problem. Endotoxins and allergens produced by these pests can harm anyone who lives in the same environment. Simple steps such as regular cleaning, sealing food containers, and hiring pest control professionals can make a difference in improving indoor air quality.
“Cockroaches aren’t just creepy; they pollute the air we breathe,” said Dr. Kakumanu. “Removing them is not only about comfort—it’s about health. A clean, pest-free home means cleaner air and fewer health risks.”
