Benzyl butyl phthalate

Dermal absorption

Administrative data

Endpoint:

dermal absorption in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

no data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, reasonably well-documented publication which meets basic scientific principles

Data source

Reference

Reference Type:

publication

Title:

Dermal absorption of phthalate diesters in rats

Author:

Elsisi AE, Carter DE & Sipes IG

Year:

1989

Bibliographic source:

Fundamental and Applied Toxicology, 12, 70-77

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 427 (Skin Absorption: In Vivo Method)

Deviations:

yes

Remarks:

(only 3 animals tested (guideline recommends 4); only 1.3 cm2 skin area of application (guideline recommends 10 cm2); expired air not collected; some omissions in reporting but no indication whether or not these related to omissions in practice)

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Benzyl butyl phthalate

EC Number:

201-622-7

EC Name:

Benzyl butyl phthalate

Cas Number:

85-68-7

Molecular formula:

C19H20O4

IUPAC Name:

1-benzyl 2-butyl benzene-1,2-dicarboxylate

Details on test material:

- Name of test material (as cited in study report): benzyl butyl phthalate (BBP)
- Substance type: laboratory reagent
- Physical state: no data
- Analytical purity: no data
- Impurities (identity and concentrations): no data
- Composition of test material, percentage of components: no data
- Isomers composition: no data
- Purity test date: no data
- Lot/batch No.: no data; non-radioactive BBP obtained from Pfaltz and Bauer, Inc., Research Chemicals Division, Stamford, CN, USA; radioactive BBP obtained from Midwest Research Institute, Kansas City, KS, USA
- Expiration date of the lot/batch: no data
- Radiochemical purity (if radiolabelling): >96%
- Specific activity (if radiolabelling): no data
- Locations of the label (if radiolabelling): ring
- Expiration date of radiochemical substance (if radiolabelling): no data
- Stability under test conditions: no data
- Storage condition of test material: no data
- Other: no data

Radiolabelling:

yes

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Division of Animal Resources of the University of Arizona Health Sciences Center
- Age at study initiation: no data
- Weight at study initiation: 180-220 g
- Fasting period before study: no data
- Housing: no data
- Individual metabolism cages: yes
- Diet (e.g. ad libitum): Purina Lab Chow, ad lib
- Water (e.g. ad libitum): ad lib
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12 / 12

IN-LIFE DATES: no data

Administration / exposure

Type of coverage:

semiocclusive

Vehicle:

ethanol

Duration of exposure:

7 days

Doses:

- Nominal doses: 157 µmol/kg bw (49 mg/kg bw ) at 40 µCi/kg bw
- Actual doses: 7.7 mg/cm2
- Actual doses calculated as follows: applied to a circular area of 1.3 cm internal diameter, i.e. area of 1.3 cm2; at a body weight of 200 g, total dose ~10 mg; 10/1.3 = 7.7 mg/cm2
- Dose volume: no data
- Rationale for dose selection: 0.01x oral/intraperitoneal LD50

No. of animals per group:

3

Control animals:

no

Details on study design:

DOSE PREPARATION
- Method for preparation of dose suspensions: no data
- Method of storage: no data

APPLICATION OF DOSE:

VEHICLE
- Justification for use and choice of vehicle (if other than water): no data
- Amount(s) applied (volume or weight with unit): no data
- Concentration (if solution): no data
- Lot/batch no. (if required): no data
- Purity: USP grade

TEST SITE
- Preparation of test site: middle of back clipped using electric clipper 1 hour prior to application of test material
- Area of exposure: 1.3 cm2
- % coverage: no data
- Type of cover / wrap if used: no dressing or wrap (but see 'site protection' below)
- Time intervals for shavings or clipplings: once, single application

SITE PROTECTION / USE OF RESTRAINERS FOR PREVENTING INGESTION: yes
- site protection: skin covered by circular plastic cap with an internal diameter of 1.8 cm, perforated with 10 needle holes to allow aeration, secured with Krazy-Glue cyanoacrylate glue
- restrainers: thick-walled rubber tubing wrapped around chest behind front legs and around abdomen in front of hind legs; held in place with wire placed through centre of tubing; animal could walk freely and access food and water, but could not twist its body or wipe or lick its back

REMOVAL OF TEST SUBSTANCE
- Removal of protecting device: 7 days
- Washing procedures and type of cleansing agent: not required
- Time after start of exposure: 7 days

SAMPLE COLLECTION
- Collection of blood: at study termination only
- Collection of urine and faeces: yes
- Collection of expired air: no
- Terminal procedure: necropsy
- Analysis of organs: brain, spinal cord, lung, liver, spleen, intestine, kidney, testis, fat, muscle, skin (from area of application and a distant site)

SAMPLE PREPARATION
- Storage procedure: no data
- Preparation details:
- Urine: pH adjusted to 4.5-5.5 using glacial acetic acid
- Faeces: digested in 0.5 N NaOH, sample air dried and combusted in a sample oxidizer
- Tissues: samples air dried for 24 hours and combusted
- Skin from area of application: digested in 2 M KOH/methanol; aliquot adjusted to pH 4.5-5.5 with glacial acetic acid
- Plastic cap: washed with 95% ethanol

ANALYSIS
- Method type(s) for identification: Liquid scintillation counting
- Liquid scintillation counting results (cpm) converted to dpm as follows: no data (radioactivity presented as 14C-equivalents)
- Validation of analytical procedure: no data
- Limits of detection and quantification: no data

OTHER:
- Data analysis: one-way analysis of variance, Student's t-test, level of significance p<0.05

Results and discussion

Signs and symptoms of toxicity:

not specified

Dermal irritation:

not specified

Absorption in different matrices:

Mean (+- SD) % of dose in 14C-equivalents 7 days after application to the skin:
- Non-occlusive cover + enclosure rinse: 6.3 (+- 0.8) %
- Skin wash: not done
- Skin test site: 44.9 (+- 6.2) %
- Skin, untreated site: 0.08 (+- 0.03) %
- Blood: no separate data (see 'other tissues' below)
- Carcass: no data
- Urine: no separate data; urine and faeces combined: 30% excreted by 7 days
- Cage wash + cage wipe: not done
- Faeces: see urine
- Expired air (if applicable): not done
- Serial non-detects in excreta at termination: no data
- Other:
- adipose tissue: 0.17 (+- 0.08) %
- muscle: 4.6 (+- 3.7) %
- 'other tissues' (summation of brain, lung, liver, spleen, small intestine, kidney, testis, spinal cord and blood): <0.5%

Total recovery:

- Total recovery: 86 (+- 2) % (sum of percentage dose found in urine, faeces, tissues and plastic cap in 7 days)
- Recovery of applied dose acceptable: no data
- Results adjusted for incomplete recovery of the applied dose: no data
- Limit of detection (LOD): no data
- Quantification of values below LOD or LOQ: no data

Percutaneous absorption

Dose:

49 mg/kg bw (7.7 mg/cm2)

Parameter:

percentage

Absorption:

ca. 35 %

Remarks on result:

other: 7 days

Remarks:

30% of dose excreted in urine and faeces, 4.6% recovered from muscle, 0.17% from adipose tissue, <0.5% from brain, spinal cord and testis, and 0.08% from skin distant from the application site.

Conversion factor human vs. animal skin:

no data

Applicant's summary and conclusion

Conclusions:

Covered application of 14C-benzylbutylphthalate on the shaved skin of rats (to an area of 1.3 cm2) at 49 mg/kg bw (7.7 mg/cm2) for 7 days resulted in approximately 35% dermal absorption over this period, equivalent to 5% per day.

Executive summary:

In a reliable dermal absorption study, ¹⁴C-labelled benzylbutylphthalate was applied to the shaved skin of three male rats at a dose of 49 mg/kg bw on an area of 1.3 cm². The application was semi-occluded for 7 days during which time urine and faeces were collected. At study termination, samples of a number of tissues were taken. Radioactivity was determined in all these tissues and excreta.

The proportion of the administered dose found in the tissues and excreta after 7 days was

30% in urine and faeces, 4.6% in muscle, <0.5% in brain, spinal cord and testis, 0.17% in adipose tissue and

0.08% in skin distant from the application site, making a total of about 35%. Total recovery (including site of application and covering) was 86%.

Covered application of 14C-benzylbutylphthalate on the shaved skin of rats (to an area of 1.3 cm2) at 49 mg/kg bw (7.7 mg/cm2) for 7 days resulted in approximately 35% dermal absorption over this period, equivalent to 5% per day.