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One key toxicokinetic study was identified for poly alpha olefins. This study, conducted with 1-decene, homopolymer, hydrogenated, included four experimental procedures designed to assess the toxicokinetic profile of orally or intravenously administered3H-Nexbase 2006 FG in male rats (Runacres, 1999). Three rats/ dose were used for each time point and endpoint measured.

 

In experiment #1, male Fischer rats were administered a single oral dose of3H-Nexbase 2006 FG at doses of 30, 210, or 1500 mg/rat. Maximum plasma radioactivity was measured at 8, 4, and 72 hours, respectively, with mean concentrations of 0.893, 2.243 and 6.720 µg equivalents/ml. Terminal rate constants of 81 and 93 hours could only be estimated for the 210 and 1500 mg/rat doses. The majority of the dose remained in the gastrointestinal (GI) tract and was excreted in the faeces by 168 hours with ≥ 92% of the dose recovered. Excretion was rapid with nearly all radioactivity collected by 48 hours for animals dosed with 30 or 210 mg3H-Nexbase 2006 FG.  Excretion of the 1500 mg/rat dose took longer with radioactivity still collected at 168 hours. Urinary excretion were low (<1%). Although the majority of the dose was found in the gastrointestinal tract, radioactivity was also found in the liver, lymph nodes, fat, kidneys, and spleen.  Rats administered 210 or 1500 mg/rat3H-Nexbase 2006 FG had oily fur shortly after dosing (this was also noted by increasing amounts of radioactivity in the fur). While the oil was gone by morning in the 210 mg/rat group, it took 48-72 hours to decline after exposure to 1500 mg/rat. Very little of the administered oral dose of3H-Nexbase 2006 FG was considered absorbed in this experiment. 

 

In experiment #2, male Fisher rats were administered a single intravenous dose of3H-Nexbase 2006 FG (30 mg/rat). No pharmacokinetic analysis of plasma radioactivity was possible because the measured plasma radioactivity in 2 of the 3 rats was below the limits of quantification 4 hours post-dosing. 

 

In experiment #3, male Fischer rats were orally administered Nexbase 2006 FG (210 mg/rat/day) for 14 days followed by a single dose of3H-Nexbase 2006 FG. Mean overall recovery of radioactivity following repeated exposure to Nexbase 2006 FG was 94.88% (almost exclusively in the faeces) at 168 hours following the final dose of3H-Nexbase 2006 FG. The pattern of excretion of radioactivity at the 210 mg/rat level was almost identical to the single dose excretion study (Experiment 1).

 

In experiment #4, rats had bile duct-canulation surgery prior to oral administration of3H-Nexbase 2600 FG (210 mg/rat). The majority of the administered dose was recovered in the faeces (70.03%) and GI tract (24.76%) at sacrifice (48 hours post-dosing). Very little of the dose (mean 0.01%) was recovered in the bile. 

 

Collective analysis of the results from the toxicokinetic experiments with Nexbase 2006 FG indicates that it is not extensively absorbed from the gastrointestinal tract of rats following oral administration and the predominant route of excretion is via the faeces. Any material that is absorbed is likely to be cleared rapidly from the blood. These experimental findings correlate well with the predicted low degree of oral absorption of poly alpha olefins, such as 1-decene, homopolymer hydrogenated, with large molecular weights, low water solubility(< 0.1 mg/L), and large partition coefficient (log Kow > 6.5) (Walker and Mullee, 2006, ECHA Guidance Chapter R.7C).