Contamination of Belgian chicken, meat and dairy produce with dioxins and PCBs in 1999 may cause up to 8,000 cancers and result in unquantifiable behavioural and neurotoxic effects on children, one of the first detailed scientific accounts of the incident has concluded. (1) The results contrast with an earlier assessment which suggested the incident was "unlikely" to cause adverse public health impacts.

The study, by scientists from Belgian universities and the Federal Ministry of Agriculture, is one of the first detailed analyses of the incident and it's aftermath to be made public.

The paper reveals that oil containing 40-50 kilograms of PCBs and one gram of dioxins entered edible oil recycling bins in January 1999.  The bins belonged to Verkest, one of 20 Belgian companies recycling household waste fats and oils for use in animal feed. The fat was delivered to 10 animal feed producers and about 500 tonnes of contaminated feed are believed to have resulted - about 5.5% of national weekly production.

Most of the feed probably went to chicken farms, and the first symptoms were noted in poultry farms in early February. Egg production and hatching declined and chickens began to die in an epidemic of oedema. However, the cause was not recognised and samples of food, meat and eggs were sent for analysis on 18th March. Results showing high levels of dioxins arrived on 26 April and the public were not informed until the 27 May. The Belgian government fell following elections three weeks later.

Although at the time the main contaminant was thought to be dioxins, analyses showed that PCB concentrations exceeded dioxins by 50,000 to one. The PCB pattern was consistent with a mixture of Arochlors - products made by Monsanto - of the kind used in transformer oils.

No systematic sampling of food was carried out during the period of exposure from February-May 1999 and the details of who was exposed and how cannot now be worked out. However, the researchers made some estimates of the likely health impacts based on the available information.

They assumed that some 30% of the PCB contamination was consumed by the 10 million people in Belgium, giving an average PCB dose of 25,000 nanograms per kilogram of body weight. This would increase average body burdens of PCBs by 42% and dioxins by 7%.

Using the available risk assessment data for the carcinogenic effects of PCBs and dioxins, they conclude that the incident would  cause 44 - 8316 cancer deaths. However, they acknowledge "huge uncertainties" because of wide variation in risk assessments and the lack of information on individual doses.

The scientists caution that the incident "probably doubled or tripled the body burdens of selected subpopulations who were intensly exposed to contaminated food." They urge that highly exposed individuals be traced and their health status monitored.

They also point to evidence of non-cancer effects from PCB exposure in babies, infants and children. These include neurological changes, changes in thyroid hormones, changes in the immune system and vitamin K deficiency in new born babies.

The conclusions contrast sharply with a study published by a different group of Belgian academics in September 1999 which found it " very unlikely that the isolated episode of contamination....will cause adverse health effects in the general population." (2).  The study said that the increase in body burdens produced would be at least 100 times lower than those in the notorious Yusho or Seveso incidents where there were acute health impacts.

On this point, the latest study agrees that the exposures in Belgium were relatively low - only 0.5ng/kg expressed as a toxic equivalent (TEQ) of the most toxic dioxin, 2,3,7,8 - TCDD, compared  with 16-78ng/kg TEQ at Seveso. However, the notable feature of the Belgian incident is that millions were exposed rather than only a few thousand.

Another conclusion was that the PCB analyses showed up many instances of PCB food contamination unrelated to the transformer oil incident. "Measures are urgently needed to reduce the overall PCB and dioxin burden for the population," it says, pointing to sources such as fish, vegetable products from countries where DDT is still used, recycled animal fat and any waste fats that may contain mineral oil.

(1) Van Larebeke, et al 2001, Env Health Perspectives, Vol 109, - 265 - 273.

(2) Bernard et al. 1999, Nature, Vol 401, pp 231 - 232
 

CANK Addenda
Oedema - 'An excessive accumulation of serous fluid in the tissues'

Dr Roberts
Compare this with the bland reassurance given by Dr Richard Roberts in the Conclusion to his original assessment of the likely health impact of the proposed co-incinerator:
'Individuals living in the area of the works are very unlikely to suffer any harmful effects from authorised emissions of any pollutant, including dioxins, from the proposed kiln'
At the very least the huge variation in academic opinion illustrated above serves to show that Dr Roberts could be very, very wrong.