Registration Dossier

Administrative data

basic toxicokinetics in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
2 (reliable with restrictions)

Data source

Reference Type:
Percutaneous absorption of polycyclic aromatic compounds from bitumen fume condensate
Roy, T. A., Kriech, A. J. and Mackerer, C. R.
Bibliographic source:
J. Occup. and Env. Hygiene, Volume 4, No. 81, Pages 137-143

Materials and methods

Objective of study:
Test guideline
no guideline available
Principles of method if other than guideline:
Test material applied to sections of isolated human back skin mounted in a Franz diffusion cell. Dermal uptake was monitored by diffusion of material from the skin surface through to a receptor fluid.
Sections of human back skin were sliced with a dermatome to a thickness of ~250 µm, and 1-inch circular pieces were mounted in 6 Franz diffusion  cells.  Tissue integrity was assured by measurement of electrical resistance.  Neat condensate was applied to the stratum corneum at "infinite dose" (200 µl) while the dermis was in direct contact with a receptor fluid  vessel consisting of an aqueous solution of polyoxyethylene 20 oleyl  ether.  
Receptor fluids were sampled at 12 intervals over 48 hours, and  analyzed by an HPLC system equipped with a variable wavelength detector  and a fluorescence
detector connected in series.  The UV detector was operated at 254 nm, and the fluorescence detector at  ex630nm/em400nm, 18 nm bandpass. 
The mobile phase was a 60-100%  acetonitrile/water gradient. 
Penetration rates of anthracene,  fluoranthrene-pyrene, and total 3-6 ring polycyclic aromatic compounds (PAC) were measured.
GLP compliance:
not specified

Test material

Constituent 1
Reference substance name:
mixture of 64742-93-4 (70%) and 64741-56-6 (30%)
mixture of 64742-93-4 (70%) and 64741-56-6 (30%)
Constituent 2
Reference substance name:
Paving grade bitumen fume condensate (mixed air-rectified and vacuum residue)
Paving grade bitumen fume condensate (mixed air-rectified and vacuum residue)
Test material form:
other: low viscosity liquid hydrocarbon
Details on test material:
fume condensate collected from a heated storage tank containing paving grade bitumen - mixture of air-rectified bitumen (70%) and vacuum residue (30%).
Bitumen fume condensate was obtained from the headspace of a bitumen  storage tank containing a lightly oxidised paving-bitumen for the purpose  of developing an in vitro procedure to estimate the percutaneous  absorption, through human skin, of the very low levels of polycyclic  aromatic compounds found in the condensate. 
The neat condensate contained 32.7 µg/g anthracene, 7.4 µg/g fluoranthene, 7.3  µg/g pyrene, and 1.8 mg/g total 3-6 ring PAC.

Test animals

not specified

Administration / exposure

Route of administration:
unchanged (no vehicle)
Details on exposure:
neat bitumen fume condensate (200ul) applied to the surface of skin samples (n=6) held in a Franz diffusion cell.
Duration and frequency of treatment / exposure:
Single application
Doses / concentrations
Doses / Concentrations:
200 ul
No. of animals per sex per dose / concentration:
6 skin samples
Control animals:
Details on study design:
six skin samples used for the study. Aliquotes of the test material applied to the surface of skin samples mounted in Franz diffusion cells. The receptor fluid was sampled at 0, 2,4,8,12, 16, 20, 24, 30, 36 and 48 hrs after application and analysed for the presence of polycyclic aromatic hydrocarbon by HPLC.
Details on dosing and sampling:
test material applied (200 ul) using a positive displacemnt pipette.

Results and discussion

Toxicokinetic / pharmacokinetic studies

Details on absorption:
The rates of dermal penetration (ng/cm²/hr±SD) were: 
anthracene 6.5 ± 0.9;  
fluoranthene-pyrene 1.8 ± 0.3;
3-6 ring PAC 120 ± 30.  

Percentages of  applied dose absorbed were: 
anthracene 5.3%, 
fluoranthene-pyrene 3.3%,
 3-6 ring PAC 1.8%.  

The apparent permeability coefficient Kp (Kp =  flux rate/applied concentration) for anthracene was 2 x 10-4 cm/hr.

Bioaccessibility (or Bioavailability)

Bioaccessibility (or Bioavailability) testing results:
 These results demonstrate that dermal penetration of PAC, at low concentrations  found in bitumen fume condensates can be measured by an 
appropriately designed in vitro method.

Applicant's summary and conclusion

Interpretation of results (migrated information): other: These results demonstrate that dermal penetration of PAC occurs, at  low concentrations  found in bitumen fume condensates.
Dermal penetration of PACs found in low concenetrations in bitumen fume condensate can occur. The amount amd rate of dermal uptake was relatively low.
Executive summary:

In an in-vitro dermal absorption study, 200 ul aliquots of neat bituen fume condensate, containing low concentrations of PACs, was applied to the surface of human skin samples fixed in a Franz Diffusion cell. Samples of the receptor fluid were analysed at time intervals ovr a 48hr period following application.

Results show that PACs present in bitumen fume condensate can penetrate the skin.

The rate of dermal flux (ng/cm²/hr±SD) for selected PACs was:

anthracene  6.5 ± 0.9;  fluoranthene-pyrene 1.8 ± 0.3; whilst the rate for total 3-6 ring PAC was 120 ± 30.  

The amount absorbed over a 48hr period was relatively low; measured values compared to aapplied dose were

anthracene 5.3%, fluoranthene-pyrene 3.3% and  3-6 ring PAC 1.8%.  

The permeability coefficient Kp (Kp =  flux rate/applied concentration) for anthracene was calculated to be 2 x 10-4 cm/hr.