PCBs and PCDD/FS in fish and fish products and their impact on the human body burden in Belgium.

The concentrations of marker PCBs (28, 52, 101, 118, 138, 153, 180) in fish have been assessed with GC-MS: an average concentration of 540 ng-PCB g(-1) fat (5.02 ng-PCB g(-1) wet weight) was observed. The average concentration of PCDD/Fs, assessed with the CALUX bioassay, amounted to 64 pg-CALUX-TEQ g(-1) fat (0.58 pg-CALUX-TEQ g(-1) wet weight) and that of PCDD/Fs + dioxin-like PCBs amounted to 131 pg-CALUX-TEQ g(-1) fat (1.18 pg-CALUX-TEQ g(-1) wet weight). Results of the PCB congeners analyses show that PCB-153 is the most abundant congener in almost all samples, with also main contributions of the 138- and 180-congeners. For some species such as the sand sole and lemon sole, a fairly constant PCB content, independent of the fat percentage, was observed. For a second group of species such as whelks, cod, and whiting, a positive correlation was observed between their PCB concentration (ng g(-1) fat) and their % of fat. The relationship between marker PCBs and PCDD/Fs concentrations, when plotted on a log scale, fits a straight line (correlation coefficient r = 0.83). With our results on fish and literature data for other food products, intake of marker PCBs and PCDD/Fs could be calculated for the adult population in Belgium (19-60 years old). The Total Daily Intake (TDI) of marker PCBs (ng-PCB day(-1)) ranges between 1690 and 2210. The TDI of PCDD/Fs (pg-CALUX day(-1)) ranges between 80.5 and 122, that of PCDD/Fs + dioxin-like PCBs amounts to 151. When PCDD/Fs in fish are assessed with GC-HRMS, the TDI can be lower. The relative importance of fish regarding marker PCB intake amounts to 15-19%, while regarding PCDD/Fs intake it amounts to 34-51%. Using TDI, the body burden evolution of marker PCBs and PCDD/Fs, with age has been calculated.

Thermal ecology of the smooth snake, Coronella austriaca Laurenti, during spring.

Thermo sensitive transmitters were used in a study on free-ranging smooth snakes (Coronella austriaca). Except on cold cloudy days, this snake shows a daily tripartite pattern of body temperatures. The pattern consists of a quick rise in body temperature in the morning, a subsequent stable phase during which body temperatures vary between 29 and 33° C, and finally a drop of body temperatures in the evening. The, consistency of the stable phase over the study period indicates that this range represents the thermal preferendum of this species. During the succesive study months a time shift in daily activity pattern was observed.