Surprising Findings Following a Belgian Food Contamination with Polychlorobiphenyls and Dioxins

Article excerpt

We found that 12.1% of Belgian export meat samples from chicken or pork, unrelated to the PCB/dioxin crisis from 1999, contained more than 50 ng polychlorinated biphenyls (PCBs)/g fat and that 6.5% of samples contain more than 20 ng/g fat for the sum of 1,1,1-trichloro-2,2-bis(pchlorophenyl)ethane (DDT) and its metabolites. Part of this background contamination stems from imported animal feed ingredients (fish flour and grains), sometimes contaminated by recent use of DDT, as can be deduced from the ratio between DDT and its main metabolite, 1,1-dichloro-2,2-bis (p-chlorophenyl)ethylene (DDE). However, after comparing PCB concentrations in fish flour and grains with those found in meat, we suggest that the high concentrations stem from recycled fat. This is the first paper describing background concentrations of PCBs in animal meat from Belgium. Key words: animal fat, contamination, DDT, food, polychlorinated biphenyls (PCBs). Environ Health Perspect 109:101-103 (2001). [Online 10 January 2001] http://ehpnet1.niehs,nih.gov/docs/2001/l09p101-l03schepens/abstract.html

The Belgian PCB/Dioxin Crisis

In 1999, about 50 kg polychlorobiphenyls (PCBs) and 1 g dioxins were introduced into the animal food chain through approximately 1,500 tons of animal feed containing 60 tons of contaminated fat from a Belgian fat-melting company. This incident caused widespread concern both in and outside Belgium and obliged the Belgian government to take drastic measures to protect public health, including a large-scale food-monitoring program with measurements of PCBs and dioxins in, respectively, over 20,000 and 450 samples from animal feed, animal fat, and various fat-containing food items (1). All samples were analyzed in officially accredited laboratories.

Analysis of contaminated foodstuff showed a pattern of PCBs closely matched with a mixture of Aroclor 1254 and 1260 and a consistent pattern of dioxin-like compounds, dominated by polychlorodibenzofurans. These patterns were virtually identical to that in the 1969 Yusho rice poisoning, caused by heat-degraded PCBs (2).

Sampling and Methods

Because most of the suspected animal food suppliers and their clients could be traced, all implicated livestock arriving in slaughterhouses were carefully checked and sampled by officially approved veterinarians. All samples were registered, sealed, and labeled. Nonsuspected farms (those that did not obtain animal feed from producers who might have incorporated ingredients from the incriminated fat-melting company) needed for export official governmental certificates. Animals from these farms were checked and sampled in the same manner.

From September to November 1999, the Toxicological Center received and analyzed 1,850 samples of Belgian meat for export (chicken and pork) containing PCBs. Feed ingredients (e.g., grains and fish flour) were provided by the Belgian Federation of Animal Food Processing, the Belgian Ministry of Agriculture, and the only company importing fish flour in Belgium (Comanima NV, Antwerp, Belgium). All feed samples were imported from other countries.

The analysis included three main steps: isolation of lipids and PCBs from the raw material (a matrix-dependent procedure), clean-up on acidified silica gel (44% concentrated sulfuric acid), and determination by gas chromatography with electron capture detection (ECD; HT-8 capillary column) or mass spectrometric detection (DB-5 capillary column). The last two steps were similar for all matrices.

After homogenization, the fish flour, grains, and animal feed (2-5 g) were spiked with 5 ng internal standard (PCB 143) and Soxhlet-extracted with hexane for 4 hr. The extracts were concentrated to 2 ml and cleaned on acidified silica gel.

A representative sample of animal (chicken or pork) fat was cut into small pieces and melted at 80 [degrees] C for 10 min. An aliquot of 0.5 g fat was weighed, solubilized in hexane, and spiked with 5 ng internal standard (PCB 143). …