According to Dr. Bùi Lê Minh, kits containing sodium azide can be toxic if ingested or if they come into contact with the body.
Recently, there have been several reports in the United States about accidents resulting from exposure to solutions used in rapid antigen test kits for Covid-19 that contain sodium azide (NaN3). This is a colorless, odorless, and tasteless substance that dissolves well in water.
In an interview, Dr. Bùi Lê Minh, Head of the Biotechnology Department at the Institute of High Technology Engineering, Nguyễn Tất Thành University, Ho Chi Minh City, stated that some companies use NaN3 in rapid antigen test kits to preserve the protein components in the test samples from degrading quickly in the testing solution. In addition to NaN3, other substances such as Triton-X, phosphate salts, and Pro-Clin 300 can also be used for this purpose. However, unlike NaN3, these other substances do not pose a risk of toxicity if ingested, except for potential allergic reactions causing itching.
Kits containing NaN3 must describe this component.
NaN3 has long been known to be toxic to humans; if ingested, it can cause cardiovascular issues and even death. However, NaN3 toxicity only manifests at a threshold of 0.3 mg absorbed through the gastrointestinal tract (for a person weighing 70 kg). This is a very high level compared to the total amount of NaN3 present in test kits.
According to Dr. Minh, some brands like Abbott (BinaxNOW, Panbio kits) and Acon (Flowflex kit) available in Vietnam contain small amounts of NaN3 ranging from 0.04 to 0.08 mg, which is about 1/10 or less of the level that could cause dangerous effects on the body.
All kits containing NaN3 must describe this component and provide warnings about potential toxicity if ingested or if they come into contact with the body. The solution within the kit is divided into small portions and is not intended for contact with the body through any means.
Therefore, issues of exposure to this chemical are purely accidental, such as children playing with it or adults mistaking it for other solutions. Additionally, it is very unlikely that large volumes of the solution would come into contact with someone.
“Some kits have relatively high amounts of NaN3 (approximately 0.3 mg), such as the BD Veritor or Celltrion DiaTrust kits, so the risk of poisoning is higher if ingested or if there is direct contact with the body. These kits have not yet appeared on the Vietnamese market, but in general, families should be careful to keep rapid test kits out of reach of children. If an accident occurs, parents should monitor for signs of low blood pressure or cardiovascular and metabolic disorders,” Dr. Minh advised.
From June 2021 to January 2022, there were 153 reports of direct exposure to solutions in kits or directly to NaN3 through the US POISONCONTROL website. However, most of these cases did not result in serious consequences and did not show significant toxicity.
Some typical cases involved users mistaking the solution for eye drops, accidentally allowing the solution to contact their skin, incorrectly following instructions for inserting swabs into the nose, or children ingesting it. This led to issues such as red eyes, itching, burning, or swelling. Symptoms disappeared after rinsing with water for 10-15 minutes.
“We can see that the risk of toxicity from this kit component exists, but it is usually not serious; users just need to be cautious to avoid incidents,” Dr. Lê Minh remarked.
This expert provided guidance on waste disposal after using rapid test kits as follows:
- If the solution has not been used for testing, people can dispose of it as regular waste.
- If it has been used for testing, people need to collect all components of the kit and dispose of them as medical waste.
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