4-methyl-m-phenylene diisocyanate

Dermal absorption

Administrative data

Endpoint:

dermal absorption in vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: OECD 427 guideline study (GLP)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 427 (Skin Absorption: In Vivo Method)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

4-methyl-m-phenylene diisocyanate

EC Number:

209-544-5

EC Name:

4-methyl-m-phenylene diisocyanate

Cas Number:

584-84-9

Molecular formula:

C9H6N2O2

IUPAC Name:

2,4-diisocyanato-1-methylbenzene

Details on test material:

Unlabeled
- Name of test material (as cited in study report): Toluene-2,4-diisocyanate (2,4-TDI)
- Physical state / Appearance: liquid, colorless, clear
- Analytical purity: 99.5%
- Lot/batch No.: 6213X
- Expiration date of the lot/batch: 01. Aug 2009
- Storage condition of test material: room temperature, under argon; light sensitive and sensitive to humidity

Labeled:
- Name of test material (as cited in study report): 2,4-diisocyanato-1-methylbenzene (14C-2,4-TDI)
- Lot/batch No.: 919-1002
- Radiochemical purity (if radiolabeling): 95.6%
- Specific activity (if radiolabeling): 24.1 MBq/mg
- Locations of the label (if radiolabeling): Phenyl-U-C-14
- Storage condition of test material: at low temperatures and in the dark

Radiolabelling:

yes

Remarks:

14C labeled

Test animals

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Sulzfeld, Germany
- Age at study initiation: 10-12 weeks
- Weight at study initiation: 324 + / - 13 g
- Housing: individually in all-glass metabolism cages type Metabowl
- Individual metabolism cages: yes
- Diet: Kliba lab diet ad libitum
- Water: tap water ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24°C
- Humidity (%): 30-70%
- Photoperiod (hrs dark / hrs light): natural day/night rhythm

Administration / exposure

Type of coverage:

semiocclusive

Vehicle:

unchanged (no vehicle)

Duration of exposure:

0.5, 1, 8 h

Doses:

Nominal concentration:
12 mg/cm2 (10 µl/cm2) this corresponds to 375 mg/kg bw.
Actual concentration:
0.5 h exposure group: 351.3 mg/kg bw (11.5 mg/cm2)
1 h exposure group: 359.9 mg/kg bw (11.6 mg/cm2)
8 h exposure group: 311.6 mg/kg bw (10.0 mg/cm2)

No. of animals per group:

4 animals per exposure period (12 in total)

Control animals:

no

Details on study design:

- dose and exposure time were chosen in a way that no corrosive effects in skin were expected

DOSE PREPARATION
- A respective amount of the cooled radiolabeled test substance was dissolved in pure 2,4-TDI. The target amount of radioactivity per animal was about 2MBq/animal
- The homogeneity and concentration of the TS was demonstrated analytically.

TEST SITE
- Preparation of test site: 24 h before treatment, a part of the dorsum of the animal was thoroughly clipped and then cleaned with acetone
- Area of exposure: 10 cm2
- Type of cover: a permeable (gauze) dressing containing a charcoal filter which was further protected by a semi-occlusive adhesive bandage

REMOVAL OF TEST SUBSTANCE
- Washing: with Lutrol E400
- Time after start of exposure: 0.5, 1 or 8 h after exposure

SAMPLE COLLECTION
- Collection of blood: at the end of the exposure period
- Collection of urine and feces: during exposure period
- Collection of expired air: no
- Additional collections: charcoal filter, gauze with bandage, tape strips (representing stratum corneum of the application site), skin (application site and surrounding skin), carcass and skin wash
(At the end of the exposure/collection period animals were sacrificed and skin stripping was performed to seperate stratum corneum from epidermis and dermis)

ANALYSIS
- Method typ for identification: Liquid scintillation counting for determination of overall radioactivity

Results and discussion

Signs and symptoms of toxicity:

no effects

Dermal irritation:

no effects

Absorption in different matrices:

Skin washes after 0.5 and 1 h contained the largest amount of recovered radioactivity. In the 8 h group the largest proportion was recovered from the protective cover. No correlation between the amount of radioactivity in protective cover and the amount of radioactivity absorbed could be detected (table 2).

ABSORPTION IN DIFFERENT MATRICES IN MORE DETAIL (% of the administered dose)

- Skin wash: 54.3%, 37.9%, 28.34% (0.5 h, 1h, 8 h after application)
- Surrounding skin: 15.13%, 15.84%, 17.57% (0.5 h, 1h, 8 h after application)
- Stratum corneum: (i.e tape strips): 3.28%, 3.61%, 1.51% (0.5 h, 1h, 8 h after application)
- Protective cover: 21.34%, 25.62%, 38.48% (0.5 h, 1h, 8 h after application)
- Application site: 5.82%, 7.48%, 17.14% (0.5 h, 1h, 8 h after application)
- Charcoal filter: 0.43%, 0.70%, 3.55% (0.5 h, 1h, 8 h after application)
- Blood cells: 0.01%, 0.02%, 0.01% (0.5 h, 1h, 8 h after application)
- Plasma: 0.01% (0.5 h, 1h and 8 h after application)
- Carcass: 0.25%, 0.44%, 0.52% (0.5 h, 1h, 8 h after application)

- Urine: 0.01%, 0.02%, 0.33% (0.5 h, 1h, 8 h after application)
- Cage wash + cage wipe: 0.01%, 0.01%, 0.03% (0.5 h, 1h, 8 h after application)
- Feces: 0 % (0.5 h, 1h and 8 h after application)

Total recovery:

- Total recovery: 91.65% - 107.49%

Percutaneous absorption

Percutaneous absorption 1

Dose:

375 mg/kg bw

Parameter:

percentage

Absorption:

0.3 %

Remarks on result:

other: 0.5 h

Remarks:

(actual concentration: 351.3 mg/kg bw)

Percutaneous absorption 2

Dose:

375 mg/kg bw

Parameter:

percentage

Absorption:

0.5 %

Remarks on result:

other: 1 h

Remarks:

(actual concentration: 359.9 mg/kg bw)

Percutaneous absorption 3

Dose:

375 mg/kg bw

Parameter:

percentage

Absorption:

0.9 %

Remarks on result:

other: 8 h

Remarks:

(actual concentration: 311.6 mg/kg bw)

Any other information on results incl. tables

EXCRETION:

0.01%, 0.02% and 0.33% of the administered dose was recovered in urine 0.5, 1, 8 h after application, respectively. No radioactivity was detected in feces (see table 2).

Table 1: Absorption and recovery of 14C-2,4 -TDI after dermal application.

Exposure time [h]	Sacrifice time [h] = time of skin wash	Mean percentage of radioactivity absorbed	Mean percentage of radioactivity in carcass	Cumulative percentage of radioactivity in urine, cage wash, blood cells and plasma
		% absolute	% administered dose	% of the administered dose
0.5	0.5	0.27	0.25	0.04
1	1	0.5	0.44	0.07
8	8	0.9	0.52	0.38

Table 2: Mean excretion and retention of radioactivity after a single dermal administration of 14C-2,4-TDI to rats at a nominal dose level of 12 mg/cm2. The results are expressed as % of the radioactivity administered.

	0.5 h exposure	1 h exposure	8 h exposure
Urine	0.01	0.02	0.33
Feces	0.00	0.00	0.00
Cage wash	0.01	0.01	0.03
Blood cells	0.01	0.02	0.01
Plasma	0.01	0.01	0.01
Carcass	0.25	0.44	0.52
Percentage absorbed	0.27	0.50	0.90
Surrounding skin	15.13	15.84	17.57
Protective cover	21.34	25.62	38.48
Application site	5.82	7.48	17.14
Skin wash	54.30	37.90	28.34
Charcoal filter	0.43	0.70	3.55
Tape strips	3.28	3.61	1.51
Total	100.57	91.65	107.49