4-tert-butylpyrocatechol

Specific investigations: other studies

Administrative data

Endpoint:

specific investigations: other studies

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Depigmentation from 4-Tertiary Butyl Catechol - An Experimental Study

Author:

Gellin GA, Possick PA, Perone VB

Year:

1970

Bibliographic source:

J Investigative Dermatology, 55(3), 190-197

Materials and methods

Principles of method if other than guideline:

Depigmentation

GLP compliance:

no

Type of method:

in vivo

Endpoint addressed:

not applicable

Test material

Test material information

Constituent 1

Reference substance name:

4-tert-butylpyrocatechol

EC Number:

202-653-9

EC Name:

4-tert-butylpyrocatechol

Cas Number:

98-29-3

Molecular formula:

C10H14O2

IUPAC Name:

4-tert-butylbenzene-1,2-diol

Details on test material:

Viscous 4-tert-butylpyrocatechol (4-TBC), 100%, was supplied by the American Oil Company, Chicago, Illinois.
Pure cristalline 4-TBC was supplied by Dow Chemical Company, Midland, Michigan.
No other data available

Test animals

Species:

guinea pig

Strain:

other: Unspecified (randomly bred, English, short-haired, black Guinea pigs)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Mr Robert Kydd, 71 Elm St., Chelmsford, Mass.
- Age at study initiation: adult
- Weight at study initiation: 675 grams
- Fasting period before study: no
- Housing: individual cage
- Diet: ad libitum, supplemented twice weekly with fresh lettuce
- Water: no data
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS
no data

Administration / exposure

Route of administration:

dermal

Vehicle:

other: acetone, DMSO, assembly oil blend or propylene glycol

Details on exposure:

TEST SITE
- Area of exposure: 9 cm² (3 cm x 3 cm)
- % coverage: no data
- Time intervals for shavings or clipplings: no data

TEST MATERIAL
- Amount(s) applied: 0.1 mL
All concentrations of 4-TBC used were weighed in volume solutions, except for viscous 4-TBC, diluted in solvents as volume in volume solutions.
The materials tested were:
- pure crystalline 4-TBC in acetone, DSMO, propylene glycol or assembly oil blend
- viscous 4-TBC in acetone or assembly oil blend

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

3 weeks

Frequency of treatment:

daily application

Post exposure period:

3 months

No. of animals per sex per dose:

12 animals for all study

Details on study design:

The dorsal skin of unepilated ears was painted daily for three weeks with a glass rod. At least one shaved area was left untreated.
Punch biopsies were performed on treated and control sites.

Concentrations: see Table 1 in part "Results and discussions"

Examinations

Examinations:

The depigmentation observed was classified as follows: absent - no visible depigmentation; definite, but weak - small spots or speckles of hypopigmentation; definite, but moderate - uniform hypopigmenting; very strong - complete depigmentation.

Results and discussion

Details on results:

Depigmentation was induced only when the solvent carriers contained 4-TBC in suitable concentrations. Pigment loss was confined to the skin of test sites when pure crystalline 4-TBC was incorporated into acetone, DMSO, or assembly oil blend, but not in propylene glycol.
When viscous 4-TBC was dissolved in acetone depigmentation was also induced. However, when incorporated into the assembly oil blend, uniform hyperpigmentation was induced at all concentrations.
No pigmentary change developed without antecedent inflammation.

Any other information on results incl. tables

Table 1: Evaluation of depigmenting potency and irritant effects of 4-TBC in different vehicles at various concentrations in twelve black guinea pigs

	Solvent	Concentration grams %	Degree of irritation	Depigmenting potency
4-TBC, crystalline	Acetone	0.005	0	absent
		0.05	0	absent
		0.1	0	absent
		0.5	+	absent
		1	++	absent
		5	++++	definite, but weak*
		10	++++	definite, but weak*
	DMSO	1	+	definite, but moderate
		5	++++	definite, but moderate
		10	++++	strong
	Propylene glycol	1	0	absent
		5	++	absent
		10	+++	absent
	Assembly oil blend	5	++++	strong
		10	++++	strong
4-TBC, viscous	Acetone	0.005	0	absent
		0.05	0	absent
		0.1	+	absent
		0.5	+	absent
		1	++++	strong
		5	++++	strong
		10	++++	strong
	Assembly oil blend	0.005	++++	absent#
		0.05	++++	absent#
		0.1	++++	absent#

		0.5	++++	absent#
		1	++++	absent#

* Hyperpigmentation of the skin followed the inflammatory reaction, but some hairs depigmented.

# Hyperpigmentation of the skin and hairs followed the inflammatory reaction.

Applicant's summary and conclusion

Conclusions:

These findings confirm the ability of 4-tert-butylpyrocatechol (4-TBC) to depigment black guinea pig skin when incorporated into a variety of solvents.
Uniform hyperpigmentation was seen when 4-TBC was incorporated into the assembly oil blend at all concentrations.