Tris(2,4-ditert-butylphenyl) phosphite

Endpoint summary

Link to relevant study record(s)

Reference

Endpoint:

basic toxicokinetics

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1981-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Objective of study:

absorption

excretion

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Deviations:

yes

Remarks:

Missing residual radioactivity determination in expired air and bile. No residual radioactivity in individual organs.

GLP compliance:

yes

Radiolabelling:

yes

Remarks:

C14

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Zentralinstitut für Versuchstiere, Hannover Germany
- Weight at study initiation: 143.9 - 179.1 g
- Individual metabolism cages: yes
- Diet (e.g. ad libitum): 15 g. The day before antioxidant application, however, the standard food ration was reduced to 8 g for each animal. Thereafter the animals got again their normal daily ration of 15 g standard food, but the first ration was given 8 hours after antioxidant application.
- Water (e.g. ad libitum): ad libitum- Acclimation period: 14 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 1
- Humidity (%): 55 ± 5
- Photoperiod (hrs dark / hrs light): 12 / 12

Route of administration:

other: gavage and intravenous

Vehicle:

other: olive oil (gavage) and propanediol-1,2 (intravenous)

Details on exposure:

PREPARATION OF DOSING SOLUTIONS
The application solutions A, B, and C were only prepared shortly before administration to the test animals. Calculated amounts of C-labeled test material were weighed in homogenization vessels of glass and dissolved at room temperature by means of an ultrasonic homogenizator within1 minute in also defined amounts of various vehicle substances.

Application solution A for oral application of radiolabelled test material to rats of test group I
- Test substance: 14C-labelled test material with the above mentioned properties
- Vehicle liquid: olive oil
- Specific radioactivity: 37.429 μCi/g solution (1384.87 kBq/g solution) ± 0.961 μCi/g solution; s [%] 2.57 (n = 4)
- Concentration of 14C-test material: 2352.6 μg/g solution

Application solution B for oral application ofradiolabelled test material to rats of test group II
- Test substance: 14C-labelled test material with the above mentioned properties
- Vehicle liquid: olive oil
- Specific radioactivity: 1.610 μCi/g solution (59.57 kBq/g solution) ± 0.004 μCi/g; s [%] 0.26 (n = 4)
- Concentration of 14C-test material: 101.2 μg/g solution

Application solution C for intravenous application of radiolabelled test material to rats of test group III
- Test substance: 14C-labelled test material with the above mentioned properties
- Vehicle liquid: propanediol-(1,2)
- Specific radioactivity: 1.386 μCi/g solution (51.28 kBq/g solution) ± 0.006 μCi/g; s [%] 0.40 (n = 4)
- Concentration of 14C-test material: 87.1 μg/g solution

The application solutions with cold test substance for the control groups 0I/II and 0III were produced in the same way.

Duration and frequency of treatment / exposure:

72 hours

Dose / conc.:

0.051 mg/kg bw/day (actual dose received)

Remarks:

intravenous, single dose

Dose / conc.:

0.26 mg/kg bw/day (actual dose received)

Remarks:

gavage, single dose

Dose / conc.:

5.3 mg/kg bw/day (actual dose received)

Remarks:

gavage, single dose

No. of animals per sex per dose / concentration:

4

Control animals:

other: cold material

Positive control reference chemical:

none

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled: urine, faeces, blood, and carcass
- Time and frequency of sampling: 24 h before dose administration and at 0, 6, 24, 48, and 72 h (urine and faeces). Blood and carcass at 72 h
- Other: storage of the samples of animal materials at -30 °C

Details on excretion:

Average radioactivity excreted after oral administration:
- group I (0.26 mg/kg bw): 72 hours after dosing 0.116 % (urine), 94.51 % (feces), < LOD (about 0.3 ng test substance/g sample) (blood), and - group II (5.3 mg/kg bw): 72 hours after dosing 0.380 % (urine), 97.12 % (feces), 0.030 % (blood), and n.d. (carcass).
Average radioactivity excreted after intravenous administration:
- group III (0.051 mg/kg bw): 72 hours after dosing 0.328 % (urine), 3.67 % (feces), 0.127 % (blood), and 73.7 % (carcass).

Metabolites identified:

not measured

Conclusions:

No bioaccumulation was found by oral route (at least 94.5 % radioactivity was found in feces). 73.7 % radioactivity was instead found in the bodies of the i.v. treated animals after 72 h.
In conclusion, the orally given antioxidant tris(2,4-ditert-butylphenyl) phosphite (and also its possible metabolites) rests only a short time (72 hours) in male rats and is favouredly excreted nearly quantitatively by faeces (> 94.5 %), but also by renal way (< 0.4 %).

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

The data after treatment by gavage show that nearly the entire amount of the labelled test substance applied was excreted. Most of the radioactivity was found in the feces and only a small extend was found in the urine. The residual radioactivity found in the blood and in the homogenized rat carcasses was very small.

The data after intravenous treatment show that some radioactivity was eliminated by feces and by urine, but distinctively slower than after oral application. Whereas the residual radioactivity found in the blood was also very small, the majority of the residual radioactivity was found in the homogenised rat carcasses (74 %).

The data collected show that both the resorption by the intestinal tract and the excretion of resorbed test substance via the bile or the renal way occur relatively slowly. They show also that there is no accumulation of test substance given orally.