Benzenesulfonic acid, 2-[(2Z)-2-(2,6-diamino-4-oxo-5(4H)-pyrimidinylidene)hydrazinyl]-3-methyl-

Endpoint summary

Description of key information

Based on measured n-octanol-water partition coefficient of less than -1.3 and the absence of adverse findings in the subacute oral toxicity study, the pigment is predicted to have no potential for bioaccumulation. Indication of urinary elimination (Yellow discoloration of the urine) was reported in mice treated once with 2000 mg/kg bw. No urine discoloration was observed in studies with rats.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

The pigment is of low solubility in water (0.8 mg/L) and very low solubility in n-octanol (< 0.044 mg/L). The n-octanol-water partition coefficient of less than -1.3 indicates that the uptake by the body is low regardless of the route of exposure. This is consistent with the absence of adverse findings in the subacute oral toxicity and the reproductive toxicity screening study up to 1000 mg/kg bw. A greenish content in the gastrointestinal tract was noted for the majority of animals at 300 and 1000 mg/kg/day at the end of treatment, but not at the end of recovery period. Animals at 300 and 1000 mg/kg/day showed yellow faeces during the treatment period and/or day 1 of the recovery period. This is supportive of rapid excretion of the yellow pigment without uptake and destruction of the chromophore. It is concluded that the substance has no risk for bioaccumulation.

The only study giving an indication of systemic uptake (and also elimination) after ingestion is the micronucleus study in mice (BASF 2016). In this study, yellow urine discoloration was observed in animals treated with 2000 mg/kg bw, but not in animals treated with 1000 or 500 mg/kg bw. Since both urine and the test substance have a similar color, urine discoloration is not a sensitive marker of elimination.