European developments following incidents with dioxins and PCBs in the food and feed chain

From dioxin to dioxin congeners: understanding the differences in hydrophobic aggregation in water and absorption into lipid membranes by means of atomistic simulations

Molecular dynamics simulations indicate that dioxin likely accumulates in cell membranes more than its congeners (anthracene, tetrahydrodioxin, 3,3′,5,5′-tetrachlorobiphenyl, and 1,2-dihydroxytetrahydrodibenzo-p-dioxin).

Carry-over of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in dairy cows fed smoke contaminated maize silage or sugar beet pulp

Fires and improper drying may result in contamination of feed with PCDD/Fs and PCBs. To predict the impact of elevated feed levels, it is important to understand the carry-over to edible products from food producing animals. Therefore, a carry-over study was performed with maize silage contaminated by a fire with PVC materials, and with sugar beet pulp contaminated by drying with coal, containing particles from a plastic roof. Levels of PCDD/Fs and dl-PCBs in the maize silage were 0.93 and 0.25 ng TEQ kg(-1), those in beet pulp 1.90 and 0.15 ng TEQ kg(-1) (both on 88% dry matter (DM)). Dairy cows (3 per treatment) received either 16.8 kg DM per day of maize silage or 5.6 kg DM per day of sugar beet pellets for a 33-d period, followed by clean feed for 33 days. This resulted in a rapid increase of PCDD/F levels in milk within the first 10 days with levels at day 33 of respectively 2.6 and 1.7 pg TEQ g(-1) fat for maize silage and beet pulp. Levels of dl-PCBs at day 33 were lower, 1.0 and 0.5 pg TEQ g(-1) fat. In the case of the maize silage, the carry-over rates (CORs) at the end of the exposure were calculated to be 25% and 32% for the PCDD/F- and dl-PCB-TEQ, respectively. For the dried beet pulp the CORs were 18% and 35%. This study shows that the carry-over of PCDD/Fs and dl-PCBs formed during drying processes or fires can be substantial.

Dioxins, PCBs and heavy metals in Chinese mitten crabs from Dutch rivers and lakes

Chinese mitten crab is an invasive species in many European rivers and lakes. Data from the UK indicated high levels of dioxins and PCBs, in particular in the brown meat in the body. This was confirmed by studies in the Netherlands, showing average levels of dioxins and PCBs in the meat in the body of 43 pg TEQ g(-1) ww in crabs caught in the large rivers. Levels in crab of lakes in the Northern part of the Netherlands were on average 3.7-fold lower. Consumption of crabs from polluted areas results in a relatively high dose of dioxins and dl-PCBs and could significantly increase the intake above the TWI. However, in general consumption of these crabs is low, even in the Asian sub-population in the Netherlands. Cadmium and lead levels were higher in crabs from contaminated areas, but for mercury and arsenic there was no clear difference. Consumption of crabs would not result in significant risks for cadmium and mercury. For lead the daily intake could be raised above the BMDL01 for neurodevelopmental toxicity, but this would only occur on a limited number of days. For arsenic the exposure would exceed the lower end of the BMDL01 values for certain cancers, but again, the infrequent consumption by most consumers reduces this risk. Furthermore, speciation showed that most arsenic in crabs was probably not a toxic inorganic form, but likely to be in an organic form.