Safety evaluation of certain food additives - ipcs inchem

CALCIUM LIGNOSULFONATE (40–65) 17
recondensation steps in water/methanol and filtration. Radioactivity in the samples
was determined after incubation times of 0.5, 1, 1.5, 2 and 3 h. Permeation of
radioactivity was low, at 1.7 ± 0.25% per hour, and essentially the same for all
concentrations. Molecular weight distribution of the absorbed radiolabelled products
as determined by size exclusion chromatography revealed that less than 1% of the
permeated compounds had molecular weight higher than 200. Most of the
radioactivity permeated was present in tritiated water formed by radiolysis from
[ 3 H]lignosulfonate groups. The apparent permeability coefficient of lignosulfonate
with molecular weight higher than 200 calculated from these data is lower than
0.005 × 10 6 cm/s. From these results, no intestinal absorption of calcium
lignosulfonate (40–65) and no systemic exposure are expected in vivo.
The absorption, distribution and excretion of 3 H-labelled calcium
lignosulfonate (40–65) were studied in male and female rats following administration
of a single oral dose (Beck & Rossi, 2005). Owing to the continuous formation of
low molecular weight compounds by radiolysis prior to application, the substance
was purified by ultrafiltration using centrifugal filter devices. The test substance was
administered by oral gavage in a single dose of 10 mg/kg body weight (bw). Plasma
kinetics of radioactivity were studied in a pilot study with three male rats from which
blood samples were taken at 1, 2, 4, 6 and 24 h. The overall fate of the radioactivity
was examined in these three animals and in the main study involving three males
and three females. For this purpose, urine and faeces were collected at two intervals
(0–24 h and 24–48 h). Animals were sacrificed by exsanguination at 48 h, blood
was collected, animals were dissected, and the weights of organs and tissues were
determined. Radioactivity was determined in all biological materials obtained after
sacrifice. Aliquots of samples from urine, faeces, blood and tissues were analysed
twice, before and after drying, in order to determine the presence of tritiated water.
The molecular weight distribution of radiolabelled substances in urine and plasma
was analysed by size exclusion chromatography.
The purity of the 3 H-labelled test substance was analysed by size exclusion
chromatography, and a significant amount of radioactivity (>25%) in molecules of
low molecular weight was observed in radiolabelled samples as received from the
supplier. These small molecules were removed by repeated ultrafiltration steps, the
last of which was performed immediately before administration to the animal.
The test substance applied in the main study contained 2.71% of the
radiolabel in molecules of lower molecular weight. An analysis of purified samples
stored for 3 weeks showed release of approximately 25% of radioactivity from the
substance into molecules that elute at the retention time of tritiated water. It was
concluded that radiolysis of 3 H-labelled lignosulfonate leads to the formation of
mainly tritiated water, which needs to be accounted for when considering the results
of the study.
The plasma kinetics of absorbed tritium activity in three male rats showed
that radioactivity levels peaked at 6 h, reaching 0.0015% of the administered dose
per gram of blood. This level remained almost unchanged until sacrifice at 48 h.
Size exclusion chromatographic analysis of the molecular weight distribution
showed that 98.5% of the radioactivity co-eluted with tritiated water (retention time