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Description of key information

Short description of key information on bioaccumulation potential result: 
An ADME study was performed in the rat in accordance to GLP and EPA OPP Guideline 85-1. No bioaccumulation potential based on study results. 14C-DMH is well absorbed and rapidly and quantitatively excreted, unchanged, in the urine following oral or intravenous administration. There was no evidence for significant tissue accumulation. HPLC profiles for composited male and female urines collected for the qualitative analysis allowed to conclude that unmetabolised DMH was the only14C-residue found in the urine.

Key value for chemical safety assessment

Additional information

Absorption

Regardless of dosing regimes, more than 90% of the dosed radioactivity in both male and female rats was excreted, unchanged, in the urine (90.50-96.25%) while less than 1.37% was excreted in the faeces. Most of the radioactivity recovered in the urine was excreted within the first 12 hours. Urinary half lives were superimposable, with values of 3.0-3.25h (males) and 2.4-2.8 h (females). Test substance DMH was adsorbed completely and readily.

Distribution in tissues

Tissue residues expressed as ppm 14C-DMH equivalents and percent of administered dose were very low and with the exception of the single oral high-dose group, were similar for all dosage regimens. The slightly higher tissue residue levels in a few tissues in the single oral high-dose group were considered to be a reflection of the higher dose administered to the animals in this group. Only in hair and possibly fat, were residue levels above those found in plasma found with any regularity. The slightly higher residue levels in fat were not of the magnitude to suggest significant bioaccumulation. The residue levels in hair may indicate some preference for 14C-DMH to accumulate in this matrix or may be an artefact of trying to determine 14C residue levels in extremely small samples.

Excretion

Only one substance was excreted in urine (90-96% of initial measured dose); it was identified as unchanged 14C-DMH by HPLC. No metabolites was identified.