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EC 401-540-3 was investigated for absorption, distribution and excretion after a single gavage application in rats (RCC 1992). This read-across substance differs by an additional chlorine in para-position of both phenyl rings. Therefore, the molecular diameter is slightly larger and the solubility in organic solvents expected to be slightly better. The dominant structural element is the 2,5 -dihydro-pyrrolo(3,4 -c)pyrrole-1,4 dione core. It is the chromophore that is is both poorly soluble in organic and in inorganic solvents. The additional chlorines of the read-across substance may render it slightly better soluble in organic solvents. This is acceptable for the use as read-across substance as better solubility in organic solvents is related to better systemic availability.

As indicated from the discolored feces and from the subacute oral toxicity studies with both pigments, the core is neither metabolised by bacteria nor hydrolysed by gastrointestinal fluids during passage of the gastro-intestinal tract.

The toxicokinetic study was performed under GLP and followed the principles outlined in OECD testing guideline 417.

14C-labelled test compound was administered at two target dose levels of 100 mg/kg (low dose) and 1000 mg/kg (high dose) to male rats and radioactivity appearing in urine, feces, blood/plasma and organs/tissues was measured for various intervals up to 168 hours. In plasma, values which exceeded the limit of quantitation by less than 1.5fold were found around 2h after dosing. This is considered to related to the 0.2% extractable radioactive impurity in the test material and not to indicate uptake of the pigment.

At both dose levels minimal amounts (<0.6% of the total dose) were excreted via the urine. This was considered to be caused by contamination with feces, but it may also be related to the radioactive impurity in the test material. Excretion of 14C-labelled pigment proceeded exclusively via the feces and amounted after 168 hours, on average, to 119.7 % and 96.0 % at the low and high dose level, respectively.

EC no. 401-540-3 is not bioavailable after single oral administration to rats and the same is predicted for CAS no. 54660 -00 -3.