If you haven’t been paying attention to where your seafood comes from, this news might make you want to start. A laboratory in North Carolina that tested seafood in Greensboro, North Carolina supermarkets found that 4 out of 15 samples of imported fish contained unnaturally high levels of formaldehyde—a chemical used for preserving corpses. Nationwide follow-up tests by the US Food and Drug Administration produced similar results.
The primary offenders are Chinese tilapia and Vietnamese swai, which may also be labeled as basa, tra, or pangasius. Vietnamese fishermen reportedly add the chemical to their catch to keep it looking fresh.
Standards in Vietnam and China are notoriously ignored and there are frequent scandals involving food safety. Many of the ponds where fish are raised are overcrowded cesspools. To stave off disease, the fish are given veterinary medicines and fungicides that have been outlawed in the US.
The FDA doesn’t regularly test imported seafood for formaldehyde and it can be difficult to detect. However, while only 3% of shipments from Vietnam are singled out for testing, one out of six are rejected.
Appealing Products, a company that makes food test kits, first sounded the alarm in 2013 after finding high levels of the chemical in 25% of Vietnamese and Chinese fish imports at supermarkets in the Raleigh area.
Formaldehyde is highly toxic, and ingestion of a mere 30ml is enough to kill an adult male. The Agency for Toxic Substances & Disease Registry reports that ingestion can cause corrosive injury to the gastrointestinal mucosa, nausea, vomiting, bleeding, and renal failure.
The best way to avoid chemicals such as formaldehyde in fish is to stick to ones labeled wild caught. Eating fish can provide numerous health benefits, so don’t cut back. Just beware of the ones that might have unwanted chemicals.