CHRONIC EXPOSURE

Background emissions of dioxins in Belgium are high. Although the emissions of primary sources are decreasing, concentrations in the food chain remain among the highest worldwide. In 1995, 1.151 g I-TEQ of dioxins were emitted in Belgium.¹ A comparison of dioxin and furan inventories for 15 countries² shows that the per capita emission in Belgium is the second highest after Japan. Sixty per cent of this value is attributable to emissions into the air.

Quantitative data on PCB fluxes for the country as a whole are not available, but some data point to an important diffuse chronic background contamination of these foodstuffs with polychlorinated biphenyls (PCBs).

In a study that aimed at monitoring Belgian chicken and pork intended for export, produced by farms not suspected of being involved in the PCB/dioxin crisis in early 1999,³ seven marker PCBs (IUPAC numbers 28, 52, 101, 118, 138, 153, and 180) were analysed in 1850 samples. It was found that in 88% of the samples concentrations of PCBs were below 50 ng PCBs/g fat, while 12% of these chicken or pork samples contained more than 50 ng PCBs/g fat. Some 1.2% of the samples even contained more than 200 ng PCBs/g fat. Two per cent of the samples exceeded the limit set by the Belgian authorities.

ACUTE EXPOSURE

To these background emissions are added PCBs and dioxins, which are incidentally admixed to the food chain. During the period 1998–2001, three incidents of contamination of the Belgian food chain through PCB/dioxin contamination of animal feed were reported. The most dramatic one occurred in 1999. In January that year, approximately 50 kg of mineral oil containing PCBs and almost 1 gram of dioxins (the most likely source being discarded transformers originating from a waste recycling centre) was admixed to the fat delivered to 10 animal feed producers. The resulting 500 tons of contaminated animal feed were distributed to poultry farms and, to a lesser extent, also to rabbit, calf, cow, and pig breeding and raising farms, mostly in Belgium, but also in the neighbouring countries. Through the animals the PCBs and dioxins spread over the whole food chain. Chicken, pork, and eggs were the most contaminated products. The authorities only started to act convincingly on the issue after 27 May, when the media made the incident known to the public. One of the actions taken was a large scale monitoring project of PCB and dioxins in food. During the period May to August 1999, 20 491 food samples were analysed. During the period after August 1999, over 40 000 samples were analysed as a direct response to the incident.⁴

The highest dioxin concentrations were found in poultry fat and eggs. In 6.5% of the poultry samples and 8.1% of the egg samples, concentrations above 200 ng PCBs/g fat were found. For dioxins, concentrations above 2 pg/g fat were found in 41.9% of the poultry and 63.6% of the egg samples.⁴ Of core importance is whether these types of separate incidents have an effect on the body burden of the population. Table 1 shows the results of measurements of three marker PCBs in bloodfat for three groups of Belgian women. One group was monitored before the 1999 incident. The two other groups were studied after the crisis. The data suggest that the crisis caused an important increase in PCB body burden. Although these figures need to be interpreted with caution (for example, because the three groups are not directly comparable), any increase is worrisome as body burdens of PCBs and dioxins of the magnitude found in Belgium have been associated with adverse effects both in animals and in humans.³

NEW EU STANDARDS

As a partial response to the 1999 PCB/dioxin incident in Belgium, the Health and Consumer Protection division of the European Commission has established new maximum limits for dioxins in food.⁵ The regulation entered into force on 1 July 2002. Maximum levels range between 0.75 pg WHO-PCDD/F TEQ/g fat (for vegetable oil) to 6 pg TEQ/g fat (for liver and derived products). For fish and fishery products, the standard is 4 pg TEQ/g fresh weight. Through this expression of concentration per gram fresh weight, the sum of dioxins TEQs in fish will exceed 10 to 20 times the maximum residual limits set for animal meat (expressed per gram fat). These new regulations do not take into account the dioxin-like PCBs for which TEQ values have been set.⁶ These PCBs account respectively for 69% and between 41% and 74% of the total TEQ load of fish⁷ and Belgian meat or dairy products.⁸ Recent measurements show that mean PCDD plus PCDF TEQ levels (not taking into account dioxin-like PCBs) in Belgian meat and dairy products are below the limits set by the new regulations (beef: 1.84 pg TEQ/g fat; pork 0.22 pg TEQ/g fat; chicken 0.35 pg TEQ/g fat; butter 0.80 pg TEQ/g fat; milk 0.34 pg TEQ/g fat). Table 2 provides the data that enable the calculation of the maximum daily intake of dioxins taking into account the new EU standards and an average Belgian diet. The calculation shows that up to 280 pg WHO TEQ per day, corresponding to 4 pg/kg body weight per day or to 28 pg/kg body weight per week can be taken in. This is well above the 1 pg/kg body weight per day that is set by the WHO as a limit for the future, and twice the tolerable weekly intake for dioxins and dioxin-like PCBs set by the Scientific Committee for Food at 14 pg WHO-TEQ/kg body weight.⁵

Standards aimed at regulating maximum residual limits of dioxins in foodstuffs show several limitations, including: the high levels permitted in fish; the lack of standards for dioxin-like PCBs; the intakes they permit, which can be above WHO recommendations; the high levels that are tolerated for pesticides (for example, for DDT, the European Council limit is 1000 ng/g fat); the lack of standards for more recently introduced persistant organic pollutants (POPs) such as polybrominated biphenyl ethers (PBDEs); and the current incapability of standards to protect for synergistic effects of these endocrine disrupters.

Much more drastic measures are required to decrease exposure to dioxins, PCBs, and other POPs.