Recipe for disaster


By Debora MacKenzie in Brussels BELGIANS will be reeling from further shocks this week. Food which was last week revealed to have been contaminated with dioxins also contained high levels of PCBs—and all the contaminated produce has probably already been eaten. What’s more, the first estimates of likely doses suggest that young children may be at risk from the poisons. Meat and eggs started reappearing on Belgian grocery shelves this week, after the discovery of high levels of dioxins in chickens and eggs led to the destruction of thousands of tonnes of food. In January, chicken farmers noticed that eggs were not hatching and that chicks had neural disorders. At first, vets suspected nutrient deficiencies. In April, however, a feed manufacturer sent a laying hen and suspect feed to RIKILT, the Dutch State Institute for Quality Control of Agricultural Products based in Wageningen—the nearest laboratory that could measure dioxins. RIKILT found 781 parts per trillion of dioxins in fat in the feed—more than 1500 times the legal limit. The contamination was traced to an 80-tonne batch of fat produced by Verkest, a company near Ghent, which was sold to 12 feed manufacturers. Wim Traag of RIKILT says the batch contained 8 litres of oil containing dioxins and PCBs, which are also toxic. One theory is that used transformer oil, rich in PCBs, was dumped in a public recycling container for used frying oil. The batch would have made 1600 tonnes of feed, enough to feed 16 million chickens for a day, says Traag. The number of people affected depends on how many animals ate the poison and passed it on in meat or eggs. “Either a few people got a large dose, or many people got a small dose,” says Traag. So far only two chickens and two eggs collected from hatcheries in April have been analysed. All were highly contaminated. The contaminated feed may have also been eaten by pigs and cattle, prompting the widespread withdrawal of meat products across Europe. But meat and eggs produced more recently have so far tested clean. “The contamination has probably all been eaten,” says Traag. The two chickens contained 958 and 775 parts per trillion of dioxin in their fat, and one had 400 parts per million of PCBs—400 times the Dutch limit for food. Given the average Belgian diet, says Martin van den Berg of the University of Utrecht, if all eggs and chickens in the affected area contained 900 parts per trillion of dioxin in their fat, people would have consumed forty times the WHO’s recommended daily limit of 1 picogram per kilogram of body weight. As certain PCBs resemble dioxins as well, he says, toxic limits could well have been exceeded a hundred-fold. The impact on the Belgian population—and on people elsewhere who ate Belgian products—depends on how much food was contaminated and how long it was available. “Most people carry 2 to 6 nanograms per kilogram of body weight of dioxins already,” says Rolaf van Leeuwen of the WHO’s European Centre for Environment and Health in Bilthoven, the Netherlands. A single egg containing 900 parts per trillion of dioxin in its fat adds 6 nanograms to that load—an increase of as little as 1.4 per cent for an adult, but as much as 20 per cent for a three-year-old. Like PCBs, dioxins persist in body fat. The doses consumed by the Belgians are probably too low to cause cancer, according to van den Berg, but could affect neural and cognitive development, the immune system, and thyroid and steroid hormones, especially in unborn and young children. “People at risk should be identified now, and followed medically for the next ten years,
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