Experts warn against home use of diatomaceous earth to eradicate bedbugs

"Everyone!!! Diatomaceous earth eradicates bedbugs!!!! (Powder, not a mat)," reads part of a Korean-language post on X, formerly Twitter, from October 18, 2023.

The tweet goes on to claim "insecticides and sprays are meaningless" and that high temperatures above 50 degrees Celsius (122 Fahrenheit) and diatomaceous earth are effective for killing bedbugs.

According to the US National Pesticide Information Center, diatomaceous earth is made from the fossilised remains of tiny aquatic organisms whose skeletons are formed from a natural substance called silica (archived link).

It is used in pesticides as well as a range of items such as skin care products, toothpastes, food and beverages, medicines and bathroom mats.

The post shares another tweet which includes a link to a YouTube video titled: "Bed Bugs - What You've Been Told is Totally False".

A man in the video claims diatomaceous earth was a "superstar" in tests against bedbugs with a 90 percent mortality rate after 10 days. He demonstrates how to apply a thin layer of diatomaceous earth using a powder duster to floors, cracks in furniture as well as around and behind power outlets.

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A screenshot of the post on X, taken November 10, 2023

Bedbugs feed on blood by biting people, creating wounds that can be itchy but do not usually cause other health problems. However, exposure to their droppings can trigger asthmatic attacks, while bites can cause rashes or more severe reactions such as anaphylaxis.

The misleading claim emerged as South Korea grappled with a surge in bedbugs that was first reported in September 2023, triggering panic in a country that has been considered largely free of the pests for decades (archived link).

As of November 21, the Office for Government Policy Coordination said it had received 365 bedbug reports, of which 108 were confirmed (archived link).

South Korean authorities have escalated pest control, dispatching officers to inspect and disinfect affected areas as well as places especially prone to outbreaks such as hotels, dormitories and saunas (archived links here and here).

Similar misleading claims about diatomaceous earth have been viewed more than four million times on YouTube and repeatedly shared on Facebook here and here. They have also been shared on South Korean platforms Naver Blog here and here, Naver Cafe, and MLB Park.

But diatomaceous earth is not safe for home use and could be harmful to humans, South Korean authorities and a pest control expert warned.

Lung damage

Yang Young Cheol, an adjunct professor teaching pestology at South Korea's Eulji University, said the substance can cause lung diseases and does not kill bedbugs immediately (archived link).

"If diatomaceous earth is sprayed indoors and around a bed, its fine particles can be inhaled and cause lung diseases such as silicosis," he told AFP on November 21.

He added that although the substance is used as a long-term measure in the United States and Europe to prevent infestations and curb the spread of bedbugs, it did not apply to the current situation in South Korea where speedy pest control is crucial.

The local government in the southeastern town of Osan similarly warned that inhaled particles of diatomaceous earth can scar the lungs in a November 14 blog post (archived link).

"Please never follow this (false information)," it said in the blog, which introduced proper pest control including preventive measures against bedbugs recommended by the Korea Disease Control and Prevention Agency, or KDCP.

According to the KDCP's guidelines, diatomaceous earth is not a proper method for exterminating bedbugs (archived links here and here).

Heat and pesticides

Instead, the KDCP recommends a combination of chemical and physical extermination methods, such as applying heat to cracks in walls and furniture with a steamer, removal with a vacuum cleaner, running affected fabrics through a dryer and using government-approved insecticides.

It says people should wear protective gear when using insecticides, particularly indoors, and avoid using such substances on anything that comes into direct contact with the body including clothes, mattresses and pillows.

Fumigation and fogging are not recommended as the bedbugs will likely just move to other areas.

When bedbugs are spotted at home, it is best to vacuum them as a first step and then spray a botanical insecticide called pyrethrin directly at the insects collected in the vacuum filter for several seconds, Yang said (archived link).

This should be sealed and thrown away. Affected fabrics should be washed in water hotter than 60 degrees Celsius, he said.

"Alternatively, use a steamer to apply hot steam for more than five seconds to the area where bedbugs are seen," he added. "For narrow areas where a vacuum cleaner or a steamer can't reach, apply pyrethrin sprays with a long, thin spray nozzle."