Know These Signs to Avoid Eating Rice Vermicelli Containing Borax and Harmful Chemicals

By understanding the warning signs below, consumers can avoid accidentally eating rice vermicelli (bún) that contains borax or other harmful chemicals, thereby better protecting their health and that of their families.

How to Check Clean Rice Vermicelli Using Fish Sauce

How to do it:

Step 1: Pour a small amount of fish sauce into a bowl.

Step 2: Place a few strands of rice vermicelli into the bowl, mix gently, and observe what happens.

If the vermicelli absorbs the fish sauce quickly and becomes soft, this is a sign of clean vermicelli. Pure rice-based vermicelli is made from natural starch, which absorbs liquid easily and softens after soaking.

On the other hand, if after several minutes the strands still appear shiny, dry, and only absorb a small amount of liquid, this strongly suggests the presence of chemicals, including borax. Borax makes vermicelli unnaturally chewy, firm, and resistant to absorbing moisture.

Other Ways to Identify the Quality of Rice Vermicelli

1. Based on Color and Texture

Vermicelli made from pure rice flour usually has a slightly opaque or dull white color. In contrast, vermicelli containing borax or preservatives often looks bright white, translucent, and glossy.

Clean vermicelli tends to be slightly fragile, easy to break, and feels soft, slightly sticky, and powdery when touched—typical characteristics of natural rice starch. Vermicelli containing borax, however, is noticeably chewier and more elastic, difficult to break, and feels smooth rather than sticky due to the added chemicals that enhance firmness and crispness.

2. Based on Smell and Taste

Normally, vermicelli without borax has a mild, natural sour aroma. This faint sourness comes from the fermentation of soaked rice during the production process and is completely normal.

Vermicelli containing borax usually lacks this natural sour smell. If vermicelli is left at the market all day in warm temperatures without developing any sour odor, there is a high chance that preservatives or borax have been used. Although certain food preservatives are permitted by regulation, they must be used strictly within allowed limits.

When eaten, clean vermicelli has a clear rice flavor similar to cooked rice. If stored for too long or overnight, it will naturally become sour and spoil. Vermicelli that remains unspoiled for two to three days, has no rice taste when chewed, or feels strangely rubbery is very likely to contain excessive amounts of borax or chemicals. In some cases, applying turmeric powder as a test may cause the vermicelli to turn gray, indicating chemical contamination.

Warnings About Fluorescent Whitening Agents

Experts advise consumers to be especially cautious of fresh noodles and vermicelli that appear excessively white and shiny under light. When possible, consumers can use a UV light (such as a banknote detector). If the vermicelli glows under ultraviolet light, it may contain Tinopal, a fluorescent whitening agent.

When fluorescent substances accumulate in the human body, they can cause serious and unpredictable health risks. One of the earliest effects of Tinopal exposure is damage to the digestive system, particularly irritation of the intestinal lining, leading to indigestion, stomach inflammation, and ulcers.

In addition, prolonged exposure to these chemicals may harm the liver, kidneys, and nervous system. Even more concerning, some studies suggest they may contribute to genetic mutations and increase the risk of cancer over time.

Final Advice for Consumers

For these reasons, homemakers and consumers should be alert and informed when choosing rice vermicelli, fresh noodles, or phở for their families. Careful selection helps prevent unintentional exposure to toxic substances and ensures safer, healthier meals for everyone.