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Toxicological information

Basic toxicokinetics

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Administrative data

basic toxicokinetics
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP study performed according to acceptable scientific method.

Data source

Reference Type:
study report
Report date:

Materials and methods

Objective of study:
Test guideline
equivalent or similar to guideline
OECD Guideline 417 (Toxicokinetics)
Principles of method if other than guideline:
Yes, see description of method below.
GLP compliance:
yes (incl. QA statement)
Midwest Research institute

Test material

Constituent 1
Reference substance name:
Bis(2-ethylhexyl) adipate
EC Number:
EC Name:
Bis(2-ethylhexyl) adipate
Cas Number:
bis(2-ethylhexyl) adipate
Details on test material:
- Name of test material (as cited in study report): DEHA
- Analytical purity: >99.7%
- Impurities (identity and concentrations): no data
- Composition of test material, percentage of components:
Radiolabeled material was prepared by NEN (Boston), and supplied through the CMA. Lot No. 1679-109, specific activity 32.2 mCi/mmol. Radiochemical purity 98.9% (TLC). HPLC analysis by MRI showed >97%.

Test animals

Fischer 344
Details on test animals or test system and environmental conditions:
- Source: Charles River Breeding Lab. (Wilmington, Massachusetts).
- Age at study initiation: 54 days
- Weight at study initiation: 90-117 gram
- Fasting period before study: 18 hr prior to dosing
- Individual metabolism cages: yes
- Diet: ad libitum
- Water :ad libitum
- Acclimatisaton period: at least 7 days

- Temperature (°F): 68-72:
- Humidity (%): 40-60
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
corn oil
Details on exposure:
The rats were dosed orally with 14C-DEHA at 500 mg/kg.
Duration and frequency of treatment / exposure:
Doses / concentrations
Doses / Concentrations:
500 mg/kg
No. of animals per sex per dose / concentration:
Control animals:
Positive control reference chemical:
no data
Details on study design:
Three male and three female rats were treated orally with 14C-DEHA at the mid (500 mg/kg) dose level, and were placed in individual glass metabolic cages (Delmar-Rath type).
Expired air, urine, and feces were collected during 0-6, 6-12, and 12-24 hr intervals following dosing.
The expired 14 C02 was trapped with 5-Methol- amine in 2-methoxyethanol. Other volatile products were collected in
methanol:water (50:50).
Urine was collected in containers kept on dry ice. After each collection, the cages were rinsed and the cage washings were measured
and analyzed.
At 24 hr, the rats were anesthesized with ether, blood was withdrawn by cardiac puncture, and the following tissues and organs were
removed, weighed, and assayed for 14-C content: Liver, Spleen, Urinary bladder, Kidneys, Adrenals, Skeletal muscle, Lungs, Testes,
Retroperitoneal tissue, Brain, Epididymides, GI tract plus contents, Heart, Skin, pancreas, ovaries and uterus.

Portions of blood were centrifuged to separate plasma and red blood cells (RBC's). Bladder contents were removed and the bladder was
washed thoroughly with 0.9% saline. The contents and washings were combined with the final urine samples and analyzed.
Blood and tissues were kept on ice during the necropsy procedures. Sample preparation and analyses were performed immediately after collection, or the samples were frozen until analyzed. The remaining tissues and excreta were stored frozen.
Details on dosing and sampling:
PHARMACOKINETIC STUDY (Distribution, excretion)
- Tissues and body fluids sampled : Expired air, urine, and feces, cage washes, and:
blood, Liver, Spleen, Urinary bladder, Kidneys, Adrenals, Skeletal muscle, Lungs, Testes ,
Retroperitoneal tissue, Brain, Epididymides, GI tract plus contents, Heart, Skin, pancreas, and ovaries and uterus.
- Time and frequency of sampling: Expired air, urine, and feces and cage washings during 0-6, 6-12, and 12-24 hr intervals following dosing.
Other tissues at sacrifice after 24 hrs.

- Tissues and body fluids sampled : urine, GI-content
- Time and frequency of sampling: 24 hrs
- From how many animals: samples pooled
- Method type(s) for identification: HPLC-MS-MS

The means ± standard errors were calculated for each test group with a programmable calculator. Data were subjected to analysis of variance.
Significant F-ratios were then analyzed by Dunnett's procedure. Significant differences were indicated when p < 0.05.

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on distribution in tissues:
Approx. 0.2/1.4% (m/f) was recovered in blood, about 4% was remaining in the GI tract (m/f) and tissue contained only 2.2% . Levels in liver and adrenals were higher than in other tissues, with males showing significantly higher tissue contents than females.
Details on excretion:
Dose mg/kg: 500
Urine +expired air+ feces (24h following dosing) : 95% (males and females)

Metabolite characterisation studies

Metabolites identified:
Details on metabolites:
The GI tract contained the diester, monoester ,and the alcohol, and traces of the polar material.
The liver contained primarily the oxidation products.
The urine contained 2-ethylhexanoic acid (EHA), its glucuronic acid conjugate, a hydroxy acid (5-hydroxy-2-ethylhexanoic acid, 5-OH EHA), and the diacid (2-ethyl-1,6-hexanedioic acid, DiEHA).
Although the liver profiles did not contain appreciable amounts of the less polar metabolites, these products may have been excreted shortly following formation.

Metabolites identified:
MEHA : monoethylhexyladipate
EH: ethylhexanol, and EH glucuronide trace amounts
EHA: ethylhexanoic acid , and EHA glucuronide
DiEHA: ethylhexanedioic acid , and DiEHA glucuronide
5-OH EHA: 5-hydroxyethylhexanoic acid , and 5-OH EHA glucuronide

Any other information on results incl. tables

Urinary, fecal, and respiratory elimination: Urinary exeretion of 14C was rapid and the dominant route of elimination. In males, ~ 19% of the dose appeared in urine at 6 hr after dosing. The largest amount of 14C was eliminated in urine between 12 and 24 hr, a total of ~ 74% being exereted by this time. A total of ~ 20% of the administered radioactivity was exereted in feces during 24 hr, mostly between 6 and 12 hr. Female rats showed similar rates and amounts of 14C in urine and feces. Smaller amounts of radioactivity were recovered in the expired air throughout the 24-hr period; both sexes eliminated a total of ~ 1.4% and 2.1% of the dose. As volatile material, ~ 0.7% of the dose was collected from both sexes. Expired 14CO2 amounted to ~ 0.6 and 1.4% of the dose from both sexes.

Blood and tissue levels: In males, the highest concentrations of radioactivity were found in the GI tract 24 hr after dosing, followed by liver, adrenals, kidneys, fat, and skin. Most of the blood radioactivity was recovered in plasma. Females also demonstrated the highest levels of 14C in GI tract, followed by liver, adrenals, and kidneys. Male rats showed higher 14C levels than females in all tissues. Some of these differences were significant. Particularly apparent were the higher levels shown in pancreas, spleen, muscle, and fat of males.

Tissue-to-blood ratios: In males, the highest ratios were detected in GI tract, followed by liver and adrenals. Ratios higher than 1 were also found for plasma, kidneys, fat, skin and spleen. Females showed the highest ratios for the GI tract, liver, and adrenals. Although the actual concentration of radioactivity was higher in tissues of males, these ratios show no differences in preferential uptake, retention, or storage of 14C-DEHA or its metabolites in both sexes.

Recoveries in excreta and tissue: In males, the majority of the dose was recovered in urine (~ 74%) and feces (~20%). Approx. 1.4% of the dose was collected in the expired air, while ~ 3.7% was remaining in the GI tract at 24 hr after dosing. Tissue contained ~ 2.2% of the dose and only ~ 0.2% was found in blood. Females showed similar results except for slightly lower amounts of 14C in tissue.

Applicant's summary and conclusion