Reaction mass of (2,4,6-trioxo-1,3,5-triazine-1,3,5(2H,4H,6H)-triyl)tri-2,1-ethanediyl triacrylate and 2-Propenoic acid, 1,1'-[[dihydro-5-(2-hydroxyethyl)-2,4,6-trioxo-1,3,5-triazine-1,3(2H,4H)-diyl]di-2,1-ethanediyl] ester

Endpoint summary

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

basic toxicokinetics in vivo

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Data on target substance not available. Thus, read-across has been applied using data from the source substance TMPTA (S2).
See further read-acoss justification in attached document to section 13.

Reason / purpose for cross-reference:

read-across source

Type:

absorption

Results:

dermal (rat): 55.1%(1.7mg/kg), 32.7% (15.2mg/kg), 18.7% (130 mg/kg) absorption increases if preexposure to 25.4% (151mg/kg); dermal (male mice): 75.0% (1.2mg/kg)

Type:

distribution

Results:

Tissue to blood ratio were below 1 with exepetion of kidney. Kidney:blood ratios of radiolabel (approximately 3.3-11.1) were elevated in dermal dosed rats but not in i.v. dosed. Intravenous application showed tissue:blood ratio below 0.7 for all tissues.

Type:

excretion

Results:

i.v. injection (rats, 9.4mg/kg): 77.4% was excreted in the urine (48.6%) , feces, and exhaled CO2 (20.1%); dermal application (rats): urine (28.0% (1.7mg/kg) - 3.0% (130mg/kg), exhaled CO2 (13.1% (1.7mg/kg) - 1.4% (130mg/kg), skin (8.0-10.4%)

Details on absorption:

Absorption of dermally administered trimethylolpropane triacrylate was inversely related to dose; a total of 18.7% of the
130 mg/kg dose was absorbed, while 32.7% of the 15.2 mg/kg and 55.1% of the 1.7 mg/kg dose were absorbed. Most of the radiolabel remaining in the animals 72 hours after dermal application was associated with the skin at the dose site. Preexposed rats absorbed 1.33 times as much [14C]-trimethylolpropane triacrylate as animals that were not preexposed.
In mice, a total of 75% of the dermally applied [14C]-trimethylolpropane triacrylate was absorbed 72 hours after a single dose of 1.2 mg/kg approximately 1.4 times as much as was absorbed by rats administered a similar dose.

Details on distribution in tissues:

Elevated kidney:blood ratios of radiolabel (approximately 3.3-11.1) were noted in rats after dermal exposures, but the kidney:blood ratio of radiolabel after intravenous bolus administration was not elevated. Tissue to blood ratio were below 1 with exepetion of kidney. It was shown that kidney:blood ratios in dermally dosed rats were not due to covalent binding of radiolabeled compounds to kidney proteins.
Intravenous application showed tissue:blood ratio below 0.7 for all tissues.

Transfer type:

other: kidney blood ratios were elevated (after dermal application). But in general less test item was found in the tissues.

Observation:

slight transfer

Remarks:

kidney

Details on excretion:

Intravenous application:
A total of 77.4% of the radiolabel was excreted in the urine, feces, and exhaled CO2. Urine and exhaled CO2 accounted for the largest percentages (approximately 48% and 20%, respectively)
Large amounts are excreted wi

Dermal application:
Most of the radiolabel remaining in the animals 72 hours after dermal application was associated with the skin at the dose site. Acetone extracted 8%, 10%, and 9%, respectively, of the dose from the site of application of rats administered single doses of 15.2, 130 or 151 mg/kg. Large amounts of TMPTA also excreted via urine 28.0%, 12.1%, 3.0% (1.7 mg/kg, 15.2 mg/kg and 130 mg/kg, rats) and exhaled 13.1%, 4.9%, 1.4%. A compareable distribution could also be seen for mice.

Metabolites identified:

no

Details on metabolites:

Following 72 hours of exposure, acetone extracts of the stripped, sliced skin were prepared and analyzed by HPLC; the major peak, accounting for approximately 73% of the radiolabel, was associated with trimethylolpropane triacrylate. Two more peaks accounted for 14% and 10% of the radiolabel. Parent trimethylolpropane triacrylate was therefore the major xenobiotic in the skin at the dosing site and most likely the major xenobiotic
available to the systemic circulation throughout the studies.

Executive summary:

No data is available for Reaction mass of THEICTA and THEICDA (T). Thus read-across has performed from TMPTA (S2).

A study to investigate the absorption, distribution and excretion of Trimethtylolpropane triacrylate was performed within the scope of an NTP toxicity profile. The study was conducted with rats and mice according to guidelines for toxicokinetics studies within the National Toxicology Program. Therefore rats and mice received different dosages of TMPTA via dermal application or tail vein injection. Excreta, blood and tissue samples were collected using different techniques.

In male F344/N rats, 18.7% of a single dermal dose of 130 mg/kg [14C]-trimethylolpropane triacrylate was absorbed and an average of 76% of the administered radiolabel was recovered unabsorbed 72 hours after dosing (Appendix L). In rats administered a 24-hour preexposure dose of nonradiolabeled trimethylolpropane triacrylate, 25% of a subsequent 151 mg/kg radiolabeled dose was absorbed and 65% was recovered unabsorbed from the dose site 72 hours after dosing. The absorption of dermally administered trimethylolpropane triacrylate was inversely related to dose; a total of 18.7% of the 130 mg/kg dose was absorbed, while 32.7% of the 15.2 mg/kg and 55.1% of the 1.7 mg/kg dose were absorbed. In mass terms, approximately five times more trimethylolpropane triacrylate was absorbed as the dose concentration increased by one order of magnitude. An average of less than 5% of the dose was recovered in the excreta of rats 72 hours after dermal application of 130 mg/kg, compared to an average of approximately 19% of the 15.2 mg/kg dose and 45% of the 1.7 mg/kg dose (Appendix L). Very little radioactivity was associated with most of the tissues 72 hours after exposure; however, the kidney had elevated tissue:blood ratios at each dose concentration. In male B6C3F1 mice, a total of 75% of dermally applied [14C]-trimethylolpropane triacrylate was absorbed 72 hours after a single 1.2 mg/kg dose. A much larger percentage of the applied radioactivity remained at the site of application in mice than in rats (31% in mice, 9% in rats). The collected tissues and residual carcass contained less than 2% of the administered dose. Approximately 21% of the dose remained unabsorbed, and approximately 42% was excreted in the urine, feces, and exhaled carbon dioxide after 72 hours. Very little radiolabel was associated with most of the tissues 72 hours after dosing; the non-application site skin, however, had an elevated tissue:blood ratio. During the 72 hours following an intravenous bolus dose of 9.4 mg/kg [14C]-trimethylolpropane triacrylate to rats, a total of 77.4% of the radiolabel was excreted in the urine, feces, and exhaled carbon dioxide, with urine and exhaled carbon dioxide accounting for the largest percentages. Total radiolabel (but not parent trimethylolpropane triacrylate) was measured in the blood, and only slight changes in radiolabel concentrations were observed in blood after 1 hour. Among the tissues collected 72 hours after dosing, the highest radiolabel concentration was in the blood, and the average total recovery of radiolabel was 90% during the 72 hours after the intravenous dose.

See justification for read-across attached in section 13.

Reference 2

Endpoint:

dermal absorption in vivo

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

No data available on toxicokinetic for Reaction mass of THEICTA and THEICDA (T). Therefore, readacross has been made from source substance 2 (S2), TMPTA.

Reason / purpose for cross-reference:

read-across source

Parameter:

percentage

Absorption:

0.6 %

Executive summary:

No data is available for Reaction mass of THEICTA and THEICDA (T). Thus read-across has performed from TMPTA (S2).

Both TMPTA and Reaction mass of THEICTA and THEICDA are - based on the physico-chemical information - believed to be absorbed via skin (molecular weight points to absorption, lipophilicity lays at the lower range for increasing the absorption and water solubility lays in the upper range leading to moderate skin absorption).

For TMPTAin vivoin rats a dose depended, inverse dermal absorption rate was found. A total of 18.7% of a 130 mg/kg dermal dose was absorbed, while 32.7% of a 15.2 mg/kg and 55.1% of a 1.7 mg/kg dose were absorbed.

The percutaneous absorption of TMPTA through human skin membranes was evaluated in accordance to OECD 428. Using radioactive labelled TMPTA ([14C] TMPTA) for evaluation of penetration through human skin, the mean total absorption, defined as the compound-related radioactivity present in the receptor fluid, the receptor compartment wash and the skin membranes (excluding tape strips) was 0.32 ± 0.12% of the applied dose. The mean potentially absorbed dose, which is defined as the compound-related radioactivity present in the receptor fluid, the receptor compartment wash, the skin membranes and the stratum corneum (except for the first 2 tape strips) was 0.60 +/- 0.26 % of the applied dose.

Due to the close structural relation and the comparable physicochemical properties these values are considered to be applicable for the assessment of the dermal absorption in rats and humans for Reaction mass of THEICTA and THEICDA as well.

See justification for read-across attached in section 13.

Reference 3

Endpoint:

basic toxicokinetics in vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: well conducted published NTP study

Objective of study:

absorption

distribution

excretion

Qualifier:

no guideline followed

Principles of method if other than guideline:

Information concerning the used methods can be found at NTP homepage or under J Robert Buchanan, Leo T. Burka, Ronald L. Melnick. Purpose and Guidelines for Toxicokinetics Studies within the National Toxicology Program. Environmonmental Health Perspectives, Vol. 105, No. 5, pp. 468-471, 1997.

GLP compliance:

not specified

Radiolabelling:

yes

Remarks:

14 C material used

Species:

other: rats and mice

Strain:

other: male F344/N (rats) and B6C3F (mice)

Sex:

not specified

Details on test animals or test system and environmental conditions:

Young adult male F344/N rats (240-306 g) and adult B6C3F1 mice (25-35 g) were obtained from Charles River Laboratories (Raleigh, NC, and Kingston, NY). Animals were coded by ear tags and quarantined for approximately 1 week. Purina Rodent Chow No. 5002 and tap water were available ad libitum. Prior to the experiments, rats and mice were housed up to a maximum of four animals per cage in polycarbonate cages. During the excretion studies, animals were housed individually in glass metabolism chambers that allowed for separate collection of urine, feces, and exhaled CO2 beginning at least 1 day before the studies.

Route of administration:

other: dermal (occlusive) and i.V.

Vehicle:

other: acetone for dermal and a mixture of absolute ethanol, Emulphor®, and phosphate-buffered saline for i.V.

Details on exposure:

Rats received a single intravenous injection of 9.4 mg [14C]-trimethylolpropane triacrylate/kg body weight or a single dermal dose of 1.7, 15.2, or 130 mg/kg (13.3, 7.2, 10.5, and 10.5 μCi, respectively)
In a dermal-tape stripping experiment in rats, successive strips of the washed application site skin were analyzed following a single 124 mg/kg dose of [14C]-trimethylolpropane triacrylate (3.8 μCi).
In a preexposure study, rats were given a dermal dose of 151 mg/kg unlabeled trimethylolpropane triacrylate followed 24 hours later by a single dermal dose of 151 mg/kg [14C]-trimethylolpropane triacrylate (8.9 μCi).
Mice received a single dermal dose of 1.2 mg/kg [14C]-trimethylolpropane triacrylate (2.1 μCi)

Animals in dermal dosing experiments were sedated with an intramuscular dose of 60 mg/kg ketamine:xylazine (7:1) approximately 24 hours before dermal doses were applied, and the fur on the back of each animal was clipped. The clipped area was wiped with acetone, dried, and examined; animals with broken skin in the clipped area were excluded from the study. The doses were applied to 1 square inch (rats) or 0.5 square inch (mice) previously outlined with a permanent, felt-tip marker.

The intravenous injection dose was formulated in a mixture of absolute ethanol, Emulphor®, and phosphate-buffered saline by adding appropriate quantities of trimethylolpropane triacrylate. All dermal doses were prepared by dissolving appropriate quantities of trimethylolpropane triacrylate in acetone.

Duration and frequency of treatment / exposure:

single treatment for all experiments excluding preexposure study
72h duration
In a preexposure study, rats were given a dermal dose of 151 mg/kg unlabeled trimethylolpropane triacrylate followed 24 hours later by a single dermal dose of 151 mg/kg [14C]-trimethylolpropane triacrylate

Remarks:

Doses / Concentrations:
intravenous injection:
- Nominal doses (rats) [14C]: 9.4mg/kg bw

dermal:
- Nominal doses (rats) [14C]: 1.7, 15.2 and 130 mg/kg bw
- Nominal doses (mice) [14C]: 1.2 mg/kg bw

dermal strip experiment:
- Nominal doses (rats) [14C]: 124 mg/kg bw

preexposure dermal study:
- Nominal doses (rats) [unlabeled]: 151 mg/kg bw

- Actual doses: stability was confirmed during an dermal carcinogenicity experiment; using GC, recovery rates were (with minor exception) in the range above 85% (mostly near 100).
- Actual doses calculated as follows: Nominal doses were used
- Dose volume: no data

No. of animals per sex per dose / concentration:

- 5 animals per dose group according to raw data

Control animals:

no

Positive control reference chemical:

no

Details on study design:

1. dermal, rats and mice
APPLICATION OF DOSE:

VEHICLE
All dermal doses were prepared by dissolving appropriate quantities of labeled and/or nonlabeled trimethylolpropane triacrylate in acetone.

TEST SITE
Animals in dermal dosing experiments were sedated with an intramuscular dose of 60 mg/kg ketamine:xylazine (7:1) approximately 24 hours beforedermal doses were applied, and the fur on the back of each animal was clipped. The clipped area was wiped with acetone, dried, and examined; animals with broken skin in the clipped area were excluded from the study. The doses were applied to 1 square inch (rats) or 0.5 square inch (mice)
previously outlined with a permanent, felt-tip marker. Before dosing, a self-adhering protective foam appliance Libertyville, IL). Doses were administered with either a ball-tipped gavage needle and glass syringe equipped with a Teflon®-tipped plunger or a silylated glass wiretrol (Drummond Scientific Co., Broomall, PA) to the square inch of skin exposed through the window in the foam appliance. After dosing was complete, a cloth cover was attached to the foam appliance, and a protective metal cover was secured over the appliance with either Elastoplast® or Coban® adhesive bandage (3M Medical-Surgical Division, St. Paul, MN).After dosing the mice, a halved tissue capsule (Fisher HistoPrep; Fisher Scientific Company, Pittsburgh, PA), the latticed top of which was covered with 50/50 polyester/cotton sheeting, was glued over the dosing site with Dura Quick Gel super glue (Loctite Corp., Rocky Hill, CT). Doses were administered to the shaved skin of mice with a 50 μL wiretrol.

SITE PROTECTION / USE OF RESTRAINERS FOR PREVENTING INGESTION: yes: (see above)

REMOVAL OF TEST SUBSTANCE
At 72 hours postdosing the dosing appliances were removed from the anesthetized animals.The dosing site skin was washed and collected for analysis of acetone-extractable and nonextractable radiolabel
- Time after start of exposure: 72h

SAMPLE COLLECTION
To measure cumulative excretion of radiolabel, collection flasks and traps were changed at 8, 24, 48, and 72 hours postdosing
- Collection of blood:Blood was withdrawn from the animals into a heparinized syringe by cardiac puncture
- Collection of urine and faeces:Urine and feces were collected separately into round-bottom flasks cooled with dry ice
- Collection of expired air:Exhaled 14CO2 was collected by passing air from the metabolism cages through two traps containing room temperature 1 N sodium hydroxide
- Terminal procedure:The animals were sacrificed by intracardiac injection of Euthanasia-6® (Sparhawk Veterinary Laboratories, Inc., Lenexa, KS) or by carbon dioxide asphyxiation. Bladder urine was removed from each animal and added to the final urine collection.
- Analysis of organs: yes

SAMPLE PREPARATION
- Storage procedure: Selected tissues were removed from the carcasses and the blood, urine, and tissues were stored at –20° C for subsequent analysis of total radiolabel.
- Preparation details:Aliquots of urine, cage rinse, skin wash, and breath trap contents were mixed with scintillation cocktail and directly assayed for 14C content by liquid scintillation spectrometry (LSS); aliquots of blood, feces, and tissues were digested in Soluene 350® (Packard Instrument Company, Meriden, CT), neutralized, decolorized with perchloric acid and hydrogen peroxide, and assayed for total radiolabel. Skin samples and the residual carcass were digested in 2 N ethanolic sodium hydroxide prior to analysis for radiolabel. The dosing appliances were cut into eight pieces, added to scintillation vials containing 2 mL methanol, and analyzed by LSS. Appropriate background samples containing the same combination of reagents as the corresponding biological samples were prepared for all sample types
For mice urine, feces, breath, cage rinse, skin wash, appliance, and tissue samples were collected, digested,and analyzed as in the definitive dermal studies in rats, except the skin samples were not extracted with acetone prior to digestion.

2. intravenous, rats
APPLICATION OF DOSE :
In the intravenous injection study, a group of five male rats was given a single bolus dose of 9.4 mg [14C]-trimethylolpropane triacrylate/kg.

SAMPLE COLLECTION
- Collection of blood:Serial blood collections were taken at 0.08, 0.5, 1, 3, 6, 24, and 48 hours from the indwelling cannula and at 72 hours by cardiac puncture to analyze for blood concentrations of radiolabel
- Collection of urine and faeces:Urine, feces, cage rinse, and exhaled 14CO2 were collected and analyzed for cumulative excretion of radiolabel as
in the definitive dermal rat studies except that collections were made at 3, 6, 24, 48, and 72 hours postdosing
- Collection of expired air: see above
- Tissue samples were collected at 72 hours postdosing and digested and analyzed for radiolabel as described for the definitive dermal studies in rats.

3. general
ANALYSIS
- Method type(s) for identification: Liquid scintillation counting

please refer to the orginal NTP Protocol (which is published) for more detailed informations

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled (delete / add / specify): urine, faeces, blood and selected tissues (Adipose, Bladder, Brain, Heart, Kidney, Liver, Lung, Muscle, Skin, Spleen, Testis, Residual carcass) , cage washes,exhaled CO2.
- Time and frequency of sampling:To measure cumulative excretion of radiolabel, collection flasks and traps were changed at 8, 24, 48, and 72 hours postdosing. At 72 hours postdosing, the cages were rinsed.

Statistics:

Common statistics

Type:

absorption

Results:

dermal (rat): 55.1%(1.7mg/kg), 32.7% (15.2mg/kg), 18.7% (130 mg/kg) absorption increases if preexposure to 25.4% (151mg/kg); dermal (male mice): 75.0% (1.2mg/kg)

Type:

distribution

Results:

Tissue to blood ratio were below 1 with exepetion of kidney. Kidney:blood ratios of radiolabel (approximately 3.3-11.1) were elevated in dermal dosed rats but not in i.v. dosed. Intravenous application showed tissue:blood ratio below 0.7 for all tissues.

Type:

excretion

Results:

i.v. injection (rats, 9.4mg/kg): 77.4% was excreted in the urine (48.6%) , feces, and exhaled CO2 (20.1%); dermal application (rats): urine (28.0% (1.7mg/kg) - 3.0% (130mg/kg), exhaled CO2 (13.1% (1.7mg/kg) - 1.4% (130mg/kg), skin (8.0-10.4%)

Details on absorption:

Absorption of dermally administered trimethylolpropane triacrylate was inversely related to dose; a total of 18.7% of the
130 mg/kg dose was absorbed, while 32.7% of the 15.2 mg/kg and 55.1% of the 1.7 mg/kg dose were absorbed. Most of the radiolabel remaining in the animals 72 hours after dermal application was associated with the skin at the dose site. Preexposed rats absorbed 1.33 times as much [14C]-trimethylolpropane triacrylate as animals that were not preexposed.
In mice, a total of 75% of the dermally applied [14C]-trimethylolpropane triacrylate was absorbed 72 hours after a single dose of 1.2 mg/kg approximately 1.4 times as much as was absorbed by rats administered a similar dose.

Details on distribution in tissues:

Elevated kidney:blood ratios of radiolabel (approximately 3.3-11.1) were noted in rats after dermal exposures, but the kidney:blood ratio of radiolabel after intravenous bolus administration was not elevated. Tissue to blood ratio were below 1 with exepetion of kidney. It was shown that kidney:blood ratios in dermally dosed rats were not due to covalent binding of radiolabeled compounds to kidney proteins.
Intravenous application showed tissue:blood ratio below 0.7 for all tissues.

Transfer type:

other: kidney blood ratios were elevated (after dermal application). But in general less test item was found in the tissues.

Observation:

slight transfer

Remarks:

kidney

Details on excretion:

Intravenous application:
A total of 77.4% of the radiolabel was excreted in the urine, feces, and exhaled CO2. Urine and exhaled CO2 accounted for the largest percentages (approximately 48% and 20%, respectively)
Large amounts are excreted wi

Dermal application:
Most of the radiolabel remaining in the animals 72 hours after dermal application was associated with the skin at the dose site. Acetone extracted 8%, 10%, and 9%, respectively, of the dose from the site of application of rats administered single doses of 15.2, 130 or 151 mg/kg. Large amounts of TMPTA also excreted via urine 28.0%, 12.1%, 3.0% (1.7 mg/kg, 15.2 mg/kg and 130 mg/kg, rats) and exhaled 13.1%, 4.9%, 1.4%. A compareable distribution could also be seen for mice.

Metabolites identified:

no

Details on metabolites:

Following 72 hours of exposure, acetone extracts of the stripped, sliced skin were prepared and analyzed by HPLC; the major peak, accounting for approximately 73% of the radiolabel, was associated with trimethylolpropane triacrylate. Two more peaks accounted for 14% and 10% of the radiolabel. Parent trimethylolpropane triacrylate was therefore the major xenobiotic in the skin at the dosing site and most likely the major xenobiotic
available to the systemic circulation throughout the studies.

Conclusions:

Interpretation of results (migrated information): no bioaccumulation potential based on study results
TMPTA is absorpt dermal inversely related to dose. Large amounts of the dose can be found unabsorpted or in skin. Main route of excretion is via inhalation, urine and faeces. Only small amount were distributed to the tissue and carcass. No accumulation in tissue was observed. A large part of the applied dose is excreted after 72h.

Executive summary:

A study to investigate the absorption, distribution and excretion of Trimethtylolpropane triacrylate (TMPTA) was performed within the scope of an NTP toxicity profile. The study was conducted with rats and mice according to guidelines for toxicokinetics studies within the National Toxicology Program. Therefore rats and mice received different dosages of TMPTA via dermal application or tail vein injection. Excreta, blood and tissue samples were collected using different techniques.

In male F344/N rats, 18.7% of a single dermal dose of 130 mg/kg [14C]-trimethylolpropane triacrylate was absorbed and an average of 76% of the administered radiolabel was recovered unabsorbed 72 hours after dosing (Appendix L). In rats administered a 24-hour preexposure dose of nonradiolabeled trimethylolpropane triacrylate, 25% of a subsequent 151 mg/kg radiolabeled dose was absorbed and 65% was recovered unabsorbed from the dose site 72 hours after dosing. The absorption of dermally administered trimethylolpropane triacrylate was inversely related to dose; a total of 18.7% of the 130 mg/kg dose was absorbed, while 32.7% of the 15.2 mg/kg and 55.1% of the 1.7 mg/kg dose were absorbed. In mass terms, approximately five times more trimethylolpropane triacrylate was absorbed as the dose concentration increased by one order of magnitude. An average of less than 5% of the dose was recovered in the excreta of rats 72 hours after dermal application of 130 mg/kg, compared to an average of approximately 19% of the 15.2 mg/kg dose and 45% of the 1.7 mg/kg dose (Appendix L). Very little radioactivity was associated with most of the tissues 72 hours after exposure; however, the kidney had elevated tissue:blood ratios at each dose concentration. In male B6C3F1 mice, a total of 75% of dermally applied [14C]-trimethylolpropane triacrylate was absorbed 72 hours after a single 1.2 mg/kg dose. A much larger percentage of the applied radioactivity remained at the site of application in mice than in rats (31% in mice, 9% in rats). The collected tissues and residual carcass contained less than 2% of the administered dose. Approximately 21% of the dose remained unabsorbed, and approximately 42% was excreted in the urine, feces, and exhaled carbon dioxide after 72 hours. Very little radiolabel was associated with most of the tissues 72 hours after dosing; the non-application site skin, however, had an elevated tissue:blood ratio. During the 72 hours following an intravenous bolus dose of 9.4 mg/kg [14C]-trimethylolpropane triacrylate to rats, a total of 77.4% of the radiolabel was excreted in the urine, feces, and exhaled carbon dioxide, with urine and exhaled carbon dioxide accounting for the largest percentages. Total radiolabel (but not parent trimethylolpropane triacrylate) was measured in the blood, and only slight changes in radiolabel concentrations were observed in blood after 1 hour. Among the tissues collected 72 hours after dosing, the highest radiolabel concentration was in the blood, and the average total recovery of radiolabel was 90% during the 72 hours after the intravenous dose.

Reference 4

Endpoint:

dermal absorption in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study performed in accordance to OECD 428 without any deviations to study plan (See attached study report)

Qualifier:

according to guideline

Guideline:

OECD Guideline 428 (Skin Absorption: In Vitro Method)

Deviations:

no

Principles of method if other than guideline:

NA

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Remarks:

[14C]TMPTA

Species:

other: In vitro

Strain:

other: human skin samples

Sex:

not specified

Details on test animals or test system and environmental conditions:

Preparation of skin membranes:
Human skin membranes were prepared from frozen skin samples, present at TNO Triskelion. Human skin, all derived from the breast, was obtained from four female donors directly after surgery.
Donor 1: H15/05, born in 1966, arrival on 15 January 20151
Donor 2: H15/25, born in 1985, arrival on 7 April 20151
Donor 3: H15/26, born in 1969, arrival on 7 April 2015
Donor 4: H15/35, born in 1952, arrival on 26 June 2015

Duration of exposure:

TMPTA was topically applied to the skin membranes. The exposure time was 8h and receptor fluid samples were collected from 0-24 h.

Doses:

Two skin membranes from four donors in each test group was used (a total of 8).

Total concentration measured was 910 g/L. Mean dose applied was 9098 +/- 108 ug/cm2 (a net volume of ca. 6.4 μL of the dose preparations was applied on each skin membrane (0.64 cm2).

The dose preparations were prepared within one day prior to application as follows:
- Amount of [14C] TMPTA was 586 uL (~1.3 MBq, ~10.4 mg)
- Non-radiolabelled TMPTA was 0.5644 g
- Total concentration measured was 910 g/L
- Radioactive concentration measured was 2.49 MBq/mL

No. of animals per group:

NA

Control animals:

no

Remarks:

NA

Details on study design:

NA

Details on in vitro test system (if applicable):

SKIN PREPARATION
Human skin, all derived from the breast, was obtained from four female donors directly after surgery from hospital. The transportation of the skin to the laboratory was carried out as soon as possible after dissection, while the skin was placed in a plastic container that was kept on ice. Subcutaneous fat was removed and the skin was stored at < −18 °C until use (For logistic reasons, the skin was kept in the refrigerator (2-10 ºC) overnight or over the weekend. Prolonged storage at 2-10 ºC is considered not to have affected the quality of the skin tissue, which was confirmed by the
data from the integrity test). In agreement with the hospital, only skin tissue for which informed consent was given by the donor, was provided to TNO Triskelion. Upon thawing, the skin was cut to a target thickness of ca. 0.2-0.4 mm (i.e. splitthickness skin membranes) using a Dermatome (25 mm, Nouvag GmbH, Germany). The thickness of all skin preparations was measured with a digimatic micrometer (Mitutoyo Corporation, Japan).

PRINCIPLES OF ASSAY
Flow-through diffusion cells and receptor fluid:
Approximately 20 h before the start of exposure to the test preparation, the split thickness skin membranes were placed in 9 mm flow-through automated diffusion cells (PermeGear Inc., Riegelsville, PA, USA) to hydrate the skin. The mean skin surface temperature was 32 ± 1 ºC and exposure was at ambient humidity. Following application of the test preparations, the actual temperature was recorded at 15-minute intervals during the study in one diffusion cell containing a non-exposed skin membrane. The receptor fluid was pumped at a flow rate of ca. 1.8 mL.h-1 and consisted of phosphate buffered saline (PBS, containing 0.01% sodium azide, w/v), supplemented with 6% polyoxyethylene 20-oleyl ether (w/v),pH 7.2.

After placing the skin membranes in the diffusion cells, membrane integrity was assessed. To this purpose, the permeability coefficient (Kp) for tritiated water was determined as follows: 200 μL saline (supplemented with 0.01% sodium azide) containing [3H]H2O (17.2 kBq.mL-1) was applied in the donor compartment of the flowthrough diffusion cells. The compartments were covered with a glass slide. Samples of the receptor fluid (ca. 1.8 mL per hour) were collected every hour up to three hours after application. Tritiated water remaining at the application site was then removed and the skin was dried with cotton swabs. Membranes were kept overnight to allow wash-out of the tritiated water from the skin.

Absorption in different matrices:

See below

Total recovery:

See below

Parameter:

percentage

Absorption:

ca. 0.6 %

Remarks on result:

other:

Conversion factor human vs. animal skin:

See below

Key parameters:

- Prior to the determination of the percutaneous absorption of TMPTA, the permeation coefficient (Kp) for tritiated water was determined in human skin membranes. Skin membranes with a Kp value below the cut-off value of 2.5×10-3 cm.h-1 were selected for the study.

- The solubility of TMPTA in water was reported to be ca. 500 mg.L-1. In the study, the receptor fluid, PBS containing 0.01% sodium azide (w/v), was supplemented with 6% PEG (w/v), pH 7.2 to improve solubility of the test substance in the receptor fluid. The solubility of TMPTA in the receptor fluid was determined in this study and found to be ca. 93 μg.mL-1. The maximum absorption into the receptor fluid was 14.5 μg (i.e. 22.6 μg.cm-2, replicate A-3) in ca. 40 mL over 24 h, i.e. 0.36 μg.mL-1. Therefore, the solubility of TMPTA in the receptor fluid was considered sufficient. Furthermore, in the flow-through cells used, the volume of the receptor fluid in the receptor chamber beneath the skin was ca. 0.2 mL, which at a flow rate of ca. 1.8 mL.h-1, was replenished continuously (9 times per hour). Thus, it was assured that the rate of diffusion into the receptor fluid did not become a rate-limiting step (i.e. sink conditions were maintained).

- The mean absorption of TMPTA from the test group A into the receptor fluid over the 24 h study duration was 14.6 μg.cm-2, representing 0.16% of the applied dose.

- The mean maximal flux for the absorption of TMPTA through human skin was 0.77 μg.cm- 2.h-1 and the lag time was 0.2 h.

- The mean total absorption, defined as the compound-related radioactivity present in the receptor fluid, the receptor compartment wash and the skin membranes (excluding tape strips) was 0.32 ± 0.12% of the applied dose. The amount in tape strips 3 -15 was 0.28 +/- 17. The mean potentially absorbed dose, which is defined as the compound-related radioactivity present in the receptor fluid, the receptor compartment wash, the skin membranes and the stratum corneum (except for the first 2 tape strips) was 0.60 +/- 0.26 % of the applied dose.

- The mean recovery of TMPTA in human skin was 101.9 +/- 1.1%. For the dose formulation tested on human skin, less than 75 % of the absorption of TMPTA in the receptor fluid over 24 hours occurred within half of the study duration (i.e. 12 hours).

- For risk assessment, in agreement with the EFSA Scientific Opinion behind the revision of the Guidance Document on Dermal Absorption (2012), it is considered appropriate to include the tape strips (except the first 2 tape strips) in the calculations of the total absorption values (i.e. the potentially absorbed dose).

Conclusions:

The percutaneus absorption of TMPTA through human skin membranes was evaluated in accordance to OECD 428. Using radioactive labelled TMPTA ([14C] TMPTA) for evaluation of penetration through human skin, the mean total absorption, defined as the compound-related radioactivity present in the receptor fluid, the receptor compartment wash and the skin membranes (excluding tape strips) was 0.32 ± 0.12% of the applied dose. The mean potentially absorbed dose, which is defined as the compound-related radioactivity present in the receptor fluid, the receptor compartment wash, the skin membranes and the stratum corneum (except for the first 2 tape strips) was 0.60 +/- 0.26 % of the applied dose.

Executive summary:

The percutaneus absorption of Trimethylolpropane triacrylate (TMPTA) through human skin membranes was evaluated in accordance to OECD 428. TMPTA was tested as neat compound, which represents the maximal concentration possible when handling the neat compound. The objective of the study was to elucidate the extent of percutaneous absorption of the compound-related radioactivity. The contact time was 8 hours, i.e. a normal working day and the post exposure time was 16 hours (sampling duration was 24h). In addition to the amount of radioactivity in the receptor fluid, the residues remaining in/on the skin membranes and in the stratum corneum (16 h post exposure) were determined. The study was performed in flow-through diffusion cells.

Using radioactive labelled TMPTA ([14C] TMPTA) for evaluation of penetration through human skin, the mean absorption of TMPTA into the receptor fluid over the 24 h study duration was 14.6 μg.cm-2, representing 0.16% of the applied dose. The mean maximal flux for the absorption of TMPTA through human skin was 0.77 μg.cm- 2.h-1 and the lag time was 0.2 h.

The mean total absorption, defined as the compound-related radioactivity present in the receptor fluid, the receptor compartment wash and the skin membranes (excluding tape strips) was 0.32 ± 0.12% of the applied dose. The mean potentially absorbed dose, which is defined as the compound-related radioactivity present in the receptor fluid, the receptor compartment wash, the skin membranes and the stratum corneum (except for the first 2 tape strips) was 0.60 +/- 0.26 % of the applied dose.

Description of key information

No data available on toxicokinetic for Reaction mass of THEICTA and THEICDA (T). Therefore, readacross has been made from source substance 2 (S2), TMPTA. 

 

Absorption:

Oral absorption

No specific data is available for neither Reaction mass of THEICTA and THEICDA nor fro THIECTA as a mono-consitutent substance or TMPTA. As for TMPTA a default absorption rate is used for Reaction mass of THEICTA and THEICDA. Thus, when making route to route extrapolation from oral dosing to inhalation an oral absorption rate of 50% will be used.

Dermal absorption:

In vitro data on TMPTA indicate a very low absorption rate of 0.6% in humans while an absorption rate of 55% has been found in rats in vivo.

Inhalation, absorption:

No specific data is available for neither Reaction mass of THEICTA and THEICDA nor TMPTA, and as for TMPTA a default absorption rate has to be used for Reaction mass of THEICTA and THEICDA as well. Thus, when making route to route extrapolation from oral dosing an inhalational absorption rate of 100% will be used.

 

Metabolism/ elimination

Non-specific esterase activity in the gastrointestinal tract (including from gastrointestinal microorganisms) and in liver and plasma may result in hydrolysis of THEICTA into di-and mono-acrylates of tris(2-hydroxyethyl) isocyanurate and eventually in free tris(2-hydroxyethyl) isocyanurateand acrylic acid/ acrylate. No specific data as to the extent and rate of this type of metabolism is available but it may be anticipated that the unspecific esterase activity may be rather similar for Reaction mass of THEICTA and THEICDA and TMPTA yielding similar amount of “free” acrylic acid/ acrylate.

For further details see justification for read-across attached in section 13.

Key value for chemical safety assessment

Absorption rate - oral (%):

50

Absorption rate - inhalation (%):

100