Laboratory tests showed that eggs sold by a distributor in Miaoli County had dioxin levels exceeding allowable limits, with the eggs traced to three chicken farms in Changhua County, the administration reported on Friday.

Taipei Times reports that the administration issued a recall, with all vendors required to comply by 3pm on Saturday.

As of 2pm Sunday, 23 April, the agency said 688 retailers and eateries that had purchased the eggs from the three farms and their four down-stream distributors had been inspected, and 6.785 tonnes of eggs had been removed from shelves.

Dioxins are highly toxic compounds that include 75 types of polychlorinated dibenzodioxins and 135 types of dibenzofurans and are formed in the burning or production of chlorine-based chemical compounds, the administration said.

Dioxins can be spread in the air and settle on soil or underwater sediment, where they can enter the food chain and be absorbed by plants, eventually ending up in the bodies of animals and humans, it said, adding that 90 per cent of dioxins detected in humans are attributable to food consumption, including dairy products, fish and eggs.

“Long-term exposure to dioxin can increase the risk of developing several types of cancer, including lymphoma and lung cancer,” Linkou Chang Gung Memorial Hospital nephrologist Yen Tzung-hai said.

Dioxins are fat-soluble and accumulate in fat, so if people lose weight and avoid food high in fat or oil, they are likely to reduce their levels of dioxins, and also reduce their risk of developing cardiovascular disease, Taipei Veterans General Hospital toxicologist Yang Chen-chang said.

The administration said that since 2004 it has began inspecting food products that are more likely to accumulate dioxins, including meat, eggs and dairy products.

Dioxins were detected in goose eggs in Changhua County in 2005, but last week’s case was the first time dioxin residues exceeding legal limits have been found in chicken eggs.

As the agency is focused on tracing the origin of the dioxins found in the latest case, it will also consider expanding its eggs inspections, administration Director-General Wu Shou-mei said.