It was rather of the nature of the savagetaboo, the outcome of totemistic beliefs or a mode of averting the contaminating presence of djinns and demons.
The men who manipulate the stirring bars are therefore changed at short intervals, while the bars themselves have also to be changed at somewhat longer intervals, as they rapidly become oxidized, and accumulated scale would tend to fall off them, thus contaminating the glass below.
Monkey viruses contaminating batches of oral polio vaccine were carcinogenic.
Landfills are lined with clay and flexible synthetic membranes intended to prevent leachate escaping and contaminating the groundwater.
Even at 15 min, Virkon S is still able to significantly lower the titer of the contaminating bacteria by at least 10 6.5.