RC - What is RC? - Rotterdam Convention

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2
Chicken feed
Chicken meal
a nd = not detected; m = mean of individual values; n = number of
samples; r = range; wwt = wet weight
of
6. KINETICS AND METABOLISM
6.1 Absorption and distribution
Whole body autoradiography of longitudinal sagittal sections
male rats after administration of a single oral dose of 200 mg
uniformly labelled hexachlorobutadiene/kg body weight in corn oil
demonstrated that intestinal absorption of the parent compound was
virtually complete by 16 h. The radioactivity in the
gastrointestinal tract at this point in time was mainly due to
water-soluble metabolites, whereas 85% of the radioactivity in the
small intestine was still present as unchanged hexachlorobutadiene
4 h after the administration. At all points in time radioactivity
levels in the stomach were low compared to those in the intestines.
The autoradiogram showed a specific distribution of radioactivity,
especially in the outer medulla of the kidney (Nash et al., 1984).
Reichert et al. (1985) orally administered 1 or 50 mg of
labelled hexachlorobutadiene/kg body weight in tricaprylin to
female
rats and recovered, at 72 h, approximately 7% of the label in
carcass and tissues, mainly liver, brain and kidneys. Most of the
label was excreted via urine or faeces within this time period
(section 6.4). In mice given 30 mg of labelled hexachlorobutadiene
per kg body weight in corn oil, over 85% of the label was excreted
within 72 h (section 6.4); 6.7-13.6% was found in the carcass,
especially in adipose tissue (Dekant et al., 1988a). This report
on mice supports the study by Reichert et al. (1985) on rats with
respect to the amount of labelled hexachlorobutadiene absorbed.
and
to
6.2 Metabolism
The extent of metabolic transformation and the identity of
excretion products found in studies with rodents are summarized in
Table 8. The available evidence suggests that hexachloro-butadiene
is metabolized in a glutathione-dependent reaction to toxic sulfur
metabolites. The glutathione- S-conjugate 1-(glutathion-S-yl)-
1,2,3,4,4-pentachloro-1,3-butadiene (GPB) is formed in the liver
excreted with bile. GPB is reabsorbed from the gut both intact and
after degradation to 1-(cystein- S-yl)-1,2,3,4,4-pentachloro-
1,3-butadiene (CPB). Finally, these sulfur conjugates and the
corresponding mercapturic acid 1-( N-acetylcystein- S-yl)-
1,2,3,4,4-pentachloro-1,3-butadiene (ACPB) are delivered to the
kidney. In the kidney, high concentrations of CPB are present due