You walk through the market looking for the freshest produce. The cabbage is firm and crisp. The fish looks remarkably fresh. Naturally, these are the ones you choose. But what if that appearance of freshness has been artificially maintained?

This is the uncomfortable question raised by the illegal use of formaldehyde in food — a practice that has been documented internationally in fish, seafood, vegetables and other foods as a way of delaying deterioration or maintaining the appearance of freshness. And just this week, it was back in the international headlines.

Cabbage dipped in formaldehyde

In August 2026, Chinese food safety authorities launched an investigation after reports that buyers in Hebei province were dipping Chinese cabbage in a formaldehyde solution before transportation to help preserve it.

According to China’s State Administration for Market Regulation, the local government confirmed that the practice shown in a widely circulated video had occurred. Police took action against individuals involved, affected cabbage was being traced, and authorities ordered wider inspections of perishable vegetables. Chinese authorities also made one thing very clear: Using formaldehyde to preserve food in this way is illegal.

So why would anyone put this chemical on food? The answer is disturbingly simple. To make perishable food last longer or appear fresher than it really is.

What exactly is formaldehyde?

Formaldehyde is a colourless, highly reactive chemical used for several legitimate industrial purposes. It is used in the manufacture of resins and other materials and can also function as a disinfectant and preservative. Formalin is a concentrated water-based solution of formaldehyde, commonly around 37 per cent. Those preservative properties are precisely what make its illegal use in food attractive.

Formaldehyde can inhibit microorganisms and affect the physical characteristics of food, potentially delaying obvious signs of deterioration. Reports of its misuse have involved foods including fish, soya bean products, mung bean vermicelli, tripe and vegetables. However, there is an important distinction consumers need to understand. Finding formaldehyde in a food does not automatically mean someone added it.

Formaldehyde can occur naturally

It may surprise you to learn that formaldehyde occurs naturally in many foods and is also produced during normal metabolism. Published data, for example, report naturally occurring formaldehyde in foods including fruits, vegetables, meat, fish and mushrooms. In fact, the World Health Organization (WHO) estimates that an average adult may consume approximately 1.5–14 mg of formaldehyde per day through food, with much of it present in a bound and unavailable form.

Formaldehyde is a colourless, highly reactive chemical that can inhibit microorganisms and alter food characteristics, potentially delaying visible signs of spoilage.

Some fish can present a challenge

Concerns about the possible use of formaldehyde to preserve fish are not new to Jamaica. As far back as 2010, the issue made national headlines after fish samples collected from nine vendors at the Mandeville Market were reported to contain traces of formaldehyde. The discovery prompted further investigations and expanded testing of fish from markets and fishing communities. Subsequent government testing returned negative results, with authorities assuring consumers that the fish tested were safe.

More than a decade later, the issue continues to surface in public discussions about fish adulteration. This history makes the Scientific Research Council’s (SRC) current research particularly relevant, as improved scientific methods can help distinguish naturally occurring formaldehyde from deliberate adulteration and provide the evidence needed to determine whether such practices are occurring locally.

The SRC is Jamaica’s representative in a five-year international research project involving approximately 25 to 30 countries and led by the International Atomic Energy Agency in collaboration with the Food and Agriculture Organization.

Importantly, the research should not be interpreted as evidence that Jamaican fish is currently being treated with formaldehyde. The researchers themselves have stressed the need for data before conclusions can be drawn.

When preservation becomes food fraud

Using a chemical to conceal deterioration creates a problem beyond the presence of the chemical itself. It deceives the consumer. Freshness provides information about the quality, handling and condition of food. When deterioration is artificially concealed, consumers may purchase something believing it is fresher than it actually is.

In seafood, the implications can be particularly important. Chemical treatment does not correct poor handling, temperature abuse or inadequate hygiene. Neither does it turn deteriorating food back into genuinely fresh food. Proper preservation depends on controls such as refrigeration, freezing, hygienic handling and maintenance of the cold chain — not secretly treating food with an undeclared chemical. That makes deliberate treatment for the purpose of disguising freshness both a food safety and a food fraud concern.

What about our health?

The International Agency for Research on Cancer classifies formaldehyde as carcinogenic to humans (Group 1). However, that classification tells us that formaldehyde is capable of causing cancer; it does not mean that eating foods containing naturally occurring trace amounts of formaldehyde will cause cancer. Much of the evidence underlying formaldehyde’s established carcinogenicity relates to inhalation and occupational exposure. Food safety authorities have noted that the available evidence does not establish the same cancer risk from ordinary dietary exposure.

Our bodies also handle formaldehyde differently from many chemicals people may imagine “building up” inside us. Formaldehyde entering through food can be absorbed through the gastrointestinal tract but is rapidly metabolised into other substances. At high enough oral exposures, however, formaldehyde is certainly harmful. Concentrated formaldehyde solutions can severely irritate and damage tissues of the mouth, oesophagus and stomach. Significant ingestion can cause nausea, vomiting, abdominal pain and other serious systemic effects. The issue is, therefore, dose and exposure.

Can you tell by looking?

Unfortunately, there is no reliable household test that allows a consumer to look at a cabbage or piece of fish and confidently declare that formaldehyde has been added. Unusual characteristics can raise questions, but they are not proof.

With fish, for example, excessive stiffness or an unusually firm or rubbery texture has sometimes been associated with formaldehyde treatment because formaldehyde can interact with proteins. However, consumers should not attempt to diagnose chemical adulteration based solely on appearance.

Instead, we need to return to the basic principles of safe food purchasing. Buy fish, meat and produce from reputable suppliers and retailers with traceable sources. Be cautious about foods being sold under questionable conditions or where proper temperature control is clearly absent.

For fish, look for the usual indicators of freshness: Clear, bright eyes; firm flesh; appropriate colour; fresh-looking gills; and the absence of strong offensive odours. For fresh produce, avoid items with unexplained chemical odours, visible residues or other unusual characteristics. Nevertheless, remember that food treated to conceal deterioration may have been deliberately manipulated to look acceptable, so appearance alone cannot guarantee safety.

Washing fruits and vegetables thoroughly under clean running water remains good practice. Formaldehyde is water-soluble, and washing can help reduce surface residues. For dried foods, soaking followed by discarding the soaking water may also reduce residues. Cooking can further reduce formaldehyde because it can dissipate with heat. These practices can reduce exposure; however, they should never be interpreted as permission for formaldehyde to be deliberately added to food.

Freshness should not need a disguise

Perhaps the bigger lesson from the cabbage investigations in China and Jamaica’s emerging seafood-fraud research is that modern food safety cannot rely solely on what our eyes tell us. We naturally associate crisp vegetables, firm fish and attractive colour with freshness. However, appearance can be manipulated.

That is why food safety systems need strong supplier controls, traceability, surveillance, laboratory capability and enforcement — particularly as our food supply becomes increasingly global. As consumers, we can reduce our risk by buying from reputable sources, examining food carefully, washing produce, maintaining safe temperatures and reporting foods that appear suspicious.

About the Author

Allison Richards is a food safety communicator, certified trainer and the founder of The Food Safety Girl®, a consumer awareness platform promoting food safety in Jamaica and the Caribbean. She is the Caribbean Chapter Director for Women in Food Safety (WIFS) and host of The Big Bite Food Safety Show®. With over 15 years of experience in food safety regulation, she is committed to public education and consumer empowerment. Through public education initiatives, including free community webinars, she continues to create space for learning, dialogue, and practical food safety awareness.