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Administrative data

Link to relevant study record(s)

Description of key information

ATBC can be rapidly absorbed via oral route of exposure. Absorption via dermal and inhalation routes is limited. Absorbed ATBC was rapidly metabolized and eliminated in rats.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential
Absorption rate - oral (%):
100
Absorption rate - dermal (%):
100
Absorption rate - inhalation (%):
100

Additional information

Oral aborption

The metabolism of ATBC after oral dosing in male rats was tested in an ADME study (Hiser et al., 1992; Dow Chem. Co., 1992). In this study groups of 4 – 5 male Sprague-Dawley rats were dosed once via gavage with 70 mg [14C]ATBC/kg bw and urine, faeces, cage wash, expired organics and [14C]CO2, blood, tissues (including GI tract and contents) and carcass were analysed for [14C] and/or unchanged ATBC. Absorption of dosed [14C] was rapid (t1/2 = 1.0 h) and extensive (>= 67 %). Absorbed [14C]ATBC was rapidly and completely metabolized and eliminated. More than 87 % of the administered radioactivity was excreted during the initial 24 hrs after dosing. For [14C] in blood an elimination half-life of 3.4 hrs was calculated during this interval. Less than 1 % of the dosed radioactivity remained in tissues and carcass 48 hrs post-dosing. The principleroute of [14C] excretion was via urine (59 – 70 % of the [14C] dose), while 25 – 36 % were excreted via faeces and 2 % as [14C]CO2. At least 9 radiolabeled metabolites were found in urine and 3 in faeces. Urinary metabolites positively identified were acetyl citrate, mono-butyl citrate (tentatively the major metabolite), acetyl mono-butyl citrate, dibutyl citrate, and acetyl dibutyl citrate.

It was concluded that the low oral toxicity of ATBC is not due to poor absorption but is caused by an intrinsic property of ATBC and/or its metabolites or is due to rapid clearance in the rat.

Dermal absorption

No experimental studies on dermal uptake are available for ATBC. An assessment of its penetration ability through the skin is assessed based on the physico-chemical properties. Taken into account molecular weight of 402, logPow of 4.86 and water solubility of 4.49 mg/L, dermal absorption is expected to be low. However, according to the criteria outlined in TGD (Appendix IV, 2003) 100% dermal absorption should be considered for ATBC (worst-case).

Inhalation absorption

Due to the logPow of 4.86, a directly absorption of ATBC across the respiratory epithelium is possible. Water solubility of 4.49 mg/L indicates a certain potential for accumulation. On the other hand, vapour pressure of 0.049 Pa and boiling point of 331°C point to a low volatility. Based on these data, it can be expected that ATBC is marginally available in the air for inhalation. However, 100% for absorption by inhalation is considered due to the absence of substance-specific information on absorption rates.