The enquiry began after the discovery of an egg with reportedly high dioxin concentrations at a retail outlet in Miaoli, in western Taiwan, last week.
Taiwan’s Food and Drug Administration (FDA), its Council of Agriculture (COA) and its Environmental Protection Administration are leading the enquiry. They have collected samples from eight animal feed manufacturers that supplied nine egg farms as part of their investigation, according to local media reports. The results of their tests are due on Friday.
The authorities were said to have immediately sealed off three major egg farms that had supplied the retailer, prohibiting the producers from transporting their hens or selling any eggs until the order is lifted.
While they have yet to rule out other possible causes of the pollution, feed is widely considered as the most likely contamination culprit, noted The China Post.
The egg farms in question are said to raise their hens in cages; local media noted there are no incinerators, burning facilities or bottom ash recycling facilities within three kilometers of the farms.
Egg prices in Taiwan have seen a downward slide because of the contamination scare.
Potentially contaminated eggs pose no serious risk to the public because dioxin is only dangerous if consumed over long periods of time, said German authorities during a similar incident in that country in 2014.
The term dioxin refers to a broad family of chemicals. Of the 210 different dioxin compounds, only 17 are of toxicological concern.
A FAO report noted: "Since the Belgian dioxin crisis in 1999, dioxins have become important considerations for feed safety. Since then, numerous cases of contamination involving dioxin from unexpected sources have been reported. This has shown that dioxins may be inherent to a product (e.g. clay minerals), or introduced during processing (e.g. lime in citrus pulp). Dioxins can be introduced if contaminated fuels are used in the drying of feed products; for example treated wood, poor quality coal or contaminated fuel oil. Dioxins have also been known to contaminate forage crops grown in the vicinity of certain industrial processes (e.g. incinerators).
"It has been postulated that most human exposure to dioxins is as a result of foods of animal origin, which in turn may arise from the presence of dioxins in animal feeds. Dioxins accumulate in fat to a high degree, so even extremely low levels of dioxin in feed can become significant over the lifetime of an animal and result in unacceptable residues in human foods such as meat, milk, and eggs."
PAHs in feed
Three years ago, Taiwan was hit by a waste oil scandal that affected both the feed and food sectors.
A governmental inquiry then found toxic chemicals in feed produced by local manufacturer, Ching Wei.
Analysis by the COA revealed 14 of that company’s feed oil products contained polycyclic aromatic hydrocarbons (PAHs), a known carcinogen, wrote the Taipei Times.
A government official said the fact the products tested positive on PAHs showed there was still much room for improvement in terms of Taiwanese regulatory oversight, as the substances should not appear in oil for either human or animal consumption.