A. Bluthgen et al., INVESTIGATIONS ON THE TRANSFER OF SELECTE D DIBENZODIOXINS AND DIBENZOFURANES (PCDD F) AFTER ALL SUPPLEMENTATION INTO THE MILK OF LACTATINGCOWS/, Milchwissenschaft, 50(9), 1995, pp. 508-513
Approaches for determining the carry over rate of polychlorinated dibe
nzodioxin- and furan congeners are possible by comparing coherent data
as regards feedingstuff and milk fat by assuming a typical feed ratio
n. However, controlled experiments with individual lactating cows kept
under environmental conditions are burdened with methodical error sou
rces. In this study carry over trials on the relevant congeners of the
PCDD/F-expositions originating from the environment were performed. U
sing specially labelled congeners (13 C-6, 37 Cl-4) they show, besides
the individual carry over rate, also the kinetics of depot buildup an
d excretion with the milk fat as a function of supplementation time. W
ith the pattern ''one cow = one congener'' a substance optimized GC/MS
measurement is feasible. The individual carry over rates of the conge
ners (cows orally supplemented on wheat starch: 50 and 100 ng/day) wer
e <1 % for 2,3, 7,8-TCDF and 1,2,4,6,7,8-HPCDF; 1-5 % for 1,2, 3,7,8-P
eCDF; 5-10 % for HxCDF and HxCDD without pos. 6; 10-15 % for 1,2,3,7,8
-PeCDD and 1,2,3,6,7,8-HxCDD; 25-35 % for 2,3,4,7,8-PeCDF and >35 % (u
p to 60 %) for 2,3,7,8-TCDD. As approximately 84 % of the toxic equiva
lents (NATO/CCMS) in milk fat are condensed in 5 congeners, the carry
over rate for this couple of 3 dioxins and 2 furans can be calculated
as much as 19.4 %. On the basis of this value it can formally be concl
uded, that for observing the background value of approximately 0.6 pg
iTE/g milk fat feedingstuffs must not be contaminated with quantities
exceeding 0.15 ng iTE/kg dry matter.