Fd Chem. Toxic. Vol. 22, no. 2, pp. 157 161, 1984 0278-6915/84 $3.00+0.00 

Printed in Great Britain. All rights reserved Copyright (~ 1984 Pergamon Press Ltd 

Review Section 

PREDICTION OF OCULAR IRRITANCY POTENTIAL FROM 

DERMAL IRRITATION TEST RESULTS 

S. J. WILLIAMS 

Central Research and Development Department, E.I. du Pont de Nemours & Company, 

Haskell Laboratory for Toxicology and Industrial Medicine, Elkton Road, P.O. Box 50, 

Newark, DE 19711, USA 

(Received 12 April 1983) 

Summary In a survey of the test files of Haskell Laboratory, it was found that of the materials that had 

been tested on rabbit skin for primary irritation or corrosivity, 60 were severe irritants or corrosive on 

the skin and had also been tested for ocular irritancy. Of these 60 materials only 39 were severe eye 

irritants, while 15 were mild irritants or non-irritants and the remainder were considered to be moderate 

irritants. Thus, to suggest that materials are eye irritants solely on the basis of their skin-irritation 

properties may be misleading, even when severe dermal irritants are considered. 

Introduction 

The use of animals, particularly rabbits, in the evaluation of chemical and cosmetic safety has been 

criticized in the past few years. Criticisms have been 

based upon a number of factors: the lack of reproducibility of eye and skin irritation test results 

between and within laboratories (Weil & Scala, 1971), 

the numbers of animals used in such tests, and the 

testing of materials that elicit extreme responses such 

as pain or death. 

The replacement of animals by in vitro or other 

predictive systems of safety evaluation for possible 

human exposure is not yet possible. However, it may 

be possible to reduce the numbers of animals used in 

such tests and to decrease the likelihood of causing 

severe reactions in test animals (Griffith, Nixon, 

Bruce et al. 1980; Williams, Graepel & Kennedy, 

1982). Alterations of test design, predictive screens 

based on chemical behaviour in other test systems, or 

evaluation of physico-chemical properties of test 

materials may prove useful to this end. 

One suggested method by which the numbers of 

rabbits used in ocular irritancy evaluation might be 

reduced is to pre-test material for primary skin 

irritation (Interagency Regulatory Liaison Group, 

1981) or other properties (e.g. pH, partition 

coefficients), so that further testing might not be 

required. This recommendation, which seems reasonable, has been restated recently (Murphy, Osterberg, 

Seabaugh & Bierbower, 1982) but has never been 

systematically tested. 

The purpose of this report is to test the hypothesis 

that materials found to cause severe primary skin 

irritation can reliably be predicted to cause a similar 

degree of response in the eye. This was done using 

Abbreviations: CFR = Code of Federal Regulations; 

FHSA = Federal Hazardous Substances Act. 

historical data for materials shown in our laboratory 

to be either severe primary irritants or corrosive to 

the skin. 

Method 

Literature search 

The test files of Haskell Laboratory, dated from 

1968 to the present, were searched for all materials 

that had been tested at the Laboratory for either 

primary skin irritation or skin corrosion. This list was 

condensed to include only those materials that were 

found to be either severe primary skin irritants or 

corrosive to the skin and has also been tested for 

ocular irritation. 

For each of the final 60 materials that were selected, the test reports or original data were used to 

evaluate the relative responses of each tissue. In 

making these comparisons, the ocular responses were 

categorized as follows: 

Class 1--Severe: severe injury of any ocular tissue 

at any time, or any degree of damage that persisted 

for 21 days or longer; 

Class 2--Moderate: mild to moderate injury of any 

ocular tissue that resolved in 5-14 days; 

Class 3 Mild or non-irritant: mild injury of any 

ocular tissue that resolved in 3 days or less, or no 

observable change. 

Skin-testing procedures 

Unless otherwise indicated, the following procedures, which are used internally at Haskell Laboratory for material evaluation, were used to evaluate 

primary skin irritation. Six male albino rabbits 

(2-3 kg) were clipped free of hair on the trunk and 

lateral areas and placed in stocks. Doses of 0.5 ml of 

undiluted test material (0.5 g of moistened solids) 

were applied to intact skin under 1.5 × 1.5 in. 12-ply 

157 
158 S. J. WILLIAMS 

gauze patches. The patches were secured with adhesive tape and occluded with rubber sheeting wrapped 

loosely around the trunk. After 24hr, the rabbits 

were taken out of the stocks, the patches were 

removed and the skin reactions were scored for 

erythema and oedema (16 CFR 1500.41: 1973) immediately and at 48 (sometimes 72) hr after the initial 

application. A composite score was not calculated. 

When the test systems described under the Federal 

Hazardous Substances Act (16 CFR 1500.41: 1973) 

or the Department of Transport Skin Corrosion Test 

(49 CFR 173.240: 1975) were used, these are indicated (Table 1). Only the results obtained on intact 

skin have been used for the comparisons. 

Eye-testing procedures 

Unless otherwise indicated, the procedures used to 

assess ocular irritation were those used routinely at 

Haskell for material evaluation. A dose of 0.1 ml of 

liquid or 0.1 g of solid material was instilled into the 

lower conjunctival sac of the right eye of each of two 

albino rabbits (2-2.5 kg, free of ocular lesions). 

Twenty seconds after contact, the treated eye of one 

rabbit was washed for 1 min with a constant stream 

of tap-water. Test rabbits were observed both grossly 

and with a hand slit-lamp at 1 and 4 hr after dosing. 

On days 1, 2 and 3, gross observations and biomicroscopic examinations were made followed by 

hand slit-lamp examination of the eye stained with 

fluorescein. The observations were graded using a 

modified Draize system (Draize, 1959), but a composite score was not calculated. Assessment of injury 

was based largely upon descriptive notation and 

duration of effect. Where noted in Table 1, the FHSA 

procedure for eye irritation evaluation was used (16 

CFR 1500.42: 1973). Only the test results obtained in 

Table 1. Ocular responses to materials found to be severe primary skin irritants or to be corrosive on the skin 

Eye 

Material Skin response Response 

Irritancy 

class* 

1. Triphenylborane DOTt--corrosive 

2. Triphenylboron NaOH complex Necrotic erythema; severe 

oedema 

3. Car wash, liquid FHSA:~ (+)--severe erythema 

and oedema 

4. Chrome polish and cleaner FHSA$ (+)--severe erythema; 

moderate oedema 

5. Cyanamide, sodium salt Necrotic erythema; severe 

oedema 

6. p-Aminodicyclohexylmethane, acetate Necrotic erythema; moderate 

oedema 

7. 1,4-Dimercapto-2,3-butanediol Necrotic erythema; mild 

oedema 

8. Hand cleaner FHSA$ (+) necrotic 

erythema; moderate to 

severe oedema 

9. 1,2-Diaminocyclohexanol/ 1,6-hexanediamine DOTt~orrosive 

10. Mixture A FHSA:~ (+)--necrotic 

erythema; mild oedema 

11. 1,l-Dichloroethene polymer with Necrotic erythema; moderate 

1,1-difluoroethene and oedema 

1-chloro-l-fluoroethene 

12. Mixture B Severe to necrotic erythema; 

mild oedema (85~ solution) 

13. Mixture C Severe, necrotic erythema; 

severe oedema 

14. Mixture D Blanching, necrotic erythema; 

moderate oedema 

15. Mixture E Severe erythema and oedema 

16. Mixture F Severe, necrotic erythema; 

severe oedema 

17. Mixture G Necrotic erytbema; severe 

oedema 

18. Mixture H Severe erythema and oedema 

19. Fixer Moderate necrotic erythema; 

moderate oedema 

20. Mixture I Moderate to severe erythema 

and oedema 

Severe, permanent corneal opacity 

with vascularization; necrotic 

Corrosive; permanent corneal opacity 

FHSA§ (+ ~severe corneal opacity; 

eversion of eyelids 

FHSA§ (+) moderate corneal 

opacity at 72 hr 

Severe, generalized, penetrating 

corneal opacity 

FHSA§ (+) severe, irreversible 

corneal and conjunctival effects; 

corrosive 

Mild corneal opacity, reversible in 3 

days; eye normal in 14 days 

FHSA§ ( ) 

Generalized, permanent, penetrating 

corneal opacity 

Severe, permanent corneal opacity 

Severe, permanent corneal opacity 

Moderate, permanent corneal opacity l 

(6% solution) 

Permanent, penetrating, moderate 1 

corneal opacity 

Severe, permanent corneal, iritic and 1 

conjunctival effects 

Minimal, transient conjunctival 3 

redness 

Mild, transient conjunctivitis 3 

Mild, generalized corneal opacity; 1 

severe conjuntivitis; normal in 14 

days 

Persistent, moderate corneal opacity; 

moderate to severe conjunctivitis 

Severe generalized corneal opacity; 

perforation with haemorrhage 

Slight, reversible after 2 days 

1 

l 

3 

[contd] 
Prediction of ocular irritation 159 

Table l--continued 

Material Skin response 

Eye 

Irritancy 

Response class* 

21. Mixture J 

22. Mixture K 

23. Mixture L 

24. N,N'-Bis-(3-aminopropyl)- 1,6-hexanediamine 

with 

N-(3-aminopropyl)- 1,6-hexanediamine 

(1:1) 

25. N-Butyl- 1,6-hexanediamine 

26. N.N'-Dibutyl- 1,6-hexanediamine 

27. 2-"Cocoyl"- 1 -(sodium 

carboxymethyl)- l-(2-hydroxyethyl)-2- 

imidazolinium hydroxide 

28. Sulphonated glycerol trioleate 

29. Paint, antifouling marine 

30. Paint stripper 

31. 2-Met hylpentanediamine 

32. Mixture M 

33. 50% Solution of mono- and diphosphate 

esters of mixed alcohols in kerosine 

34. 6-tert-Butyl-3-ethylphenol 

35. Mixture N 

36. e-Tridecyl-og-hydroxy-poly(oxy- 1,2- 

ethanediyl) 

37. Mixture O 

38. Mixture P 

39. 2,2,3-Trinuoro-3-oxopropanoic acid, 

methyl ester 

40. 3-(Methylsulphonyl)acrylonitrile 

41. 2-Ethylpyridine 

42. 5-Ethenyl-2-methylpyridine 

43. Polynactin (84%) 

44. Mixture Q 

45. Polishing compound 

46. Hindered phenol antioxidant 

47. Mixture R 

48. Gas booster 

Necrotic erythema; severe 

oedema 

Severe erythema; moderate 

oedema 

DOTt~orrosive 

Severe erythema and oedema 

Necrotic erythema; severe 

oedema 

Necrotic erythema; severe 

oedema 

Severe erythema with 

sloughing; moderate oedema 

Severe blanching and necrotic 

erythema; severe oedema 

Necrotic erythema; severe 

oedema 

Necrotic erythema; mild 

oedema 

DOTt--corrosive 

Moderate increasing to severe 

erythema at 5 days 

DOTt--corrosive 

DOTt--corrosive 

Severe erythema; mild oedema 

Necrotic erythema; mild 

oedema 

Necrotic erythema; severe 

oedema 

Necrotic erythema; severe 

oedema 

DOTt --vorrosive 

Severe to necrotic erythema; 

moderate oedema 

Severe erythema; mild oedema 

Severe erythema; mild oedema 

FHSA$ (+)---necrotic 

erythema 

Severe erythema; blanching 

FHSA~: (+)--blanching; 

necrotic erythema 

DOTt--corrosive 

Severe erythema and oedema 

FHSA:~ (+)--moderate to 

severe erythema and 

oedema 

Mild to moderate conjunctivitis: 

normal in 3 days 

Slight, transient conjunctivitis 

Permanent corneal opacity with 

vascularization 

Persistent, severe corneal opacity and 

conj unctivitis 

Severe corneal opacity; corrosive 

Severe, permanent, penetrating corneal 

opacity 

Moderate corneal opacity with 

vascularization; severe conjunctivitis 

Severe conjunctival blanching; corneal 

opacity at 14 days with some 

vascularization 

Moderate corneal opacity decreased to 

slight by 7 days; moderate, 

reversible conjunctivitis 

Severe corneal opacity and 

conjunctivitis 

Opalescent cornea; conjunctival 

necrosis 

Slight corneal cloudiness; normal in 1 

day 

Severe corneal opacity and 

conjunctivitis; reversible in 3 days 

Mild to moderate corneal opacity; 

severe iritis and conjunctivitis 

Slight corneal clouding; mild 

conjunctivitis; reversible in 2-3 days 

Permanent, general, moderate corneal 

opacity with vascularization; severe 

conjunctivitis 

Slight, transient corneal opacity; mild 

to moderate conjunctivitis; reversible 

in 3 days 

Mild corneal opacity and 

conjunctivitis; reversible in 3 days 

Corrosive; corneal perforation 

FHSA~ (+~irreversible, corrosive 

Persistent general corneal opacity and 

moderate conjunctivitis 

General, moderate permanent corneal 

opacity; moderate conjunctivitis 

Moderate corneal opacity and 

conjunctivitis; normal in 7 days 

Slight transient microscopic corneal 

opacity; moderate conjunctivitis; 

normal in 7 days 

Slight but persistent corneal opacity; 1 

severe conjunctivitis 

Moderate, penetrating corneal 2 

opacity; moderate conjunctivitis; 

normal in 5 days 

Slight conjunctivitis, normal in 2 days 3 

FHSA§ (-)~slight, transient 3 

conjunctival redness 

[contd] 
160 S. J. WILLIAMS 

Table 1 continued 

Material Skin response 

Eye 

lrritancy 

Response class* 

49. Zinc chloride (10% solution) 

50. Zinc ammonium chloride galvanizing 

flux A (10% solution) 

51. Zinc ammonium chloride galvanizing 

flux B (10% solution) 

52. Wax, cream 

53. Ultraviolet curing lacquer A 

54. Ultraviolet curing lacquer B 

55. Ultraviolet curing lacquer C 

56. Ultraviolet curing lacquer D 

57. Ultraviolet curing lacquer E 

58. Ultraviolet curing lacquer F 

59. Varnish A 

Necrotic erythema; severe 

oedema 

Necrotic erythema 

Necrotic erythema 

FHSA+ + (+)--necrotic 

erythema 

Moderate erythema and 

oedema, necrotic at 6 days; 

localized haemorrhaging 

Moderate to severe erythema, 

necrotic and sloughing at 6 

days; haemorrhaging 

Necrotic at 11 days; localized 

haemorrhaging 

Necrotic at 11 days; localized 

haemorrhaging 

Moderate erythema with 

severe oedema, necrotic at 

11 days; localized 

haemorrhaging 

Moderate erythema, severe 

oedema, localized 

haemorrhaging, necrotic at 

6 days 

Moderate erythema and 

oedema; necrotic at 6 days 

60. Varnish B Moderate erythema with 

moderate to severe oedema 

Moderate, penetrating corneal 2 

opacity; mild 

conjunctivitis reversible in 7 14 

days 

Mild, transient conjunctivitis 3 

Mild, transient conjunctivitis 3 

FHSA§ (-)--transient, mild 3 

conjunctivitis 

Moderate corneal opacity; persistent I 

conjunctivitis 

Severe, permanent corneal l 

opacification; moderate 

conjunctivitis 

Severe, permanent corneal 1 

opacification 

Moderate to severe corneal opacity 1 

and conjunctivitis; normal in 21 

days 

Severe, permanent corneal opacity 1 

Severe, permanent corneal oedema 1 

with vascularization 

Severe, permanent corneal opacity 1 

with superficial vascularization; 

severe conjunctivitis 

Generalized, permanent, moderate to 1 

severe corneal opacity; moderate 

conjunctivitis 

*See text for description of eye-irritancy class designation. 

tDepartment of Transportation test for skin corrosion (49 CFR 173.240: 1975). 

:~Dermal irritation test protocol specified by the Federal Hazardous Substances Act (16 CFR 1500.41: 1973). 

§Ocular irritation test protocol specified by the Federal Hazardous Substances Act (16 CFR 1500.42: 1973). 

unwashed eyes are used for comparison with dermal 

irritation test results. In all except a few indicated 

instances, the concentrations of materials tested for 

ocular irritation were the same as those tested for 

dermal irritation. 

Results and Discussion 

The results in Table 1 demonstrate that as a general 

principle, primary skin irritation test results are not 

predictive of ocular irritancy potential. We started 

with the hypothesis that severe or corrosive dermal 

irritants would also be severe ocular irritants. This 

clearly is not the case. Fifteen of 60 severe primary 

dermal irritants were classified as mild irritants or 

non-irritants when tested in the eye; another six 

materials were classified as moderate irritants. Also, 

it should be noted that the definition of a severe eye 

irritant used here was conservative and would be 

consistent with the definition of a substantial irritant 

as defined in the NAS criteria document (National 

Academy of Sciences---National Research Council, 

1977) and by Griffith et al. (1980). If the FHSA 

criteria were used to classify these materials as eye 

irritants, prediction of eye irritancy on the basis of 

skin responses would still be correct for only 45 of 60 

materials. 

While a direct relationship between primary dermal irritation and ocular irritancy is not apparent 

from this retrospective study, it is possible that some 

subclass of the materials examined here could be 

found that would yield a positive correlation between 

skin and eye irritation. This subclassification might 

be based upon some set of physico-chemical properties, such as pH, octanol-water partition coefficients 

or others (Williams, 1982), which might yield a tiered 

screening system with better predictability. However, 

good physico-chemical data are very difficult to obtain for complex formulations such as some of those 

that have been tested or must be tested at Haskell 

Laboratories as a part of product safety evaluation. 

Moreover, it has been demonstrated recently that 

there is no simple relationship between ocular irritancy and easily obtainable chemical parameters such 

as pH (Murphy et al. 1982) even with chemically 

well-defined samples. 

Another possible reason for the lack of correlation 

between the results of the two tests is that the current 
Prediction of ocular irritation 161 

methods for evaluating primary skin irritation may 

be too rigorous a model for probable exposure. For 

example, two materials studied here (Table 1, nos 45 

and 52) were also evaluated by the proposed revision 

test for primary skin irritants (Federal Register, 1972) 

and were found to be non-irritants, as defined. In this 

test, material is applied in a similar manner to that 

described for the FHSA test, but test patches are held 

in place for 4 rather than 24 hr. In the eye tests it can 

be argued that, while exposure may be exaggerated, 

the protective responses of the eye remain physiological. This is not the case for current dermal test 

procedures since occlusion of the contact area allows 

for an extended time of intimate dermal exposure 

under conditions of abnormal hydration. A better 

correlation between severe primary skin irritation 

and eye irritation might be obtained if the skin 

irritation test were performed using non-occluded 

conditions. In a review of the acute toxicity of 300 

materials (Smyth, Carpenter, Weil et al. 1962) in 

which a non-occluded method of dermal-irritation 

evaluation was used, only four out of 63 severe skin 

irritants (score /> 6) were classified as less than severe 

irritants when tested in the eye (score ~< 4). Therefore, 

the lack of predictability of ocular responses based 

upon dermal irritancy may be related to overestimation of the latter by current test procedures. 

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Safety of Chemicals in Foods, Drugs and Cosmetics. p. 46. 

Association of Food and Drug Officials of the United 

States, Austin, TX. 

Federal Register (1972). Proposed revision test for primary 

skin irritants. Fed. Reg. 37, 27635. 

Griffith J. F., Nixon G. A., Bruce R. D., Reer P. J. & 

Bannan E. A. (1980). Dose-response studies with chemical irritants in the albino rabbit eye as a basis for 

selecting optimum testing conditions for predicting 

hazard to the human eye. Toxic. appl. Pharmac. 55, 501. 

lnteragency Regulatory Liaison Group (1981). Recommended Guideline for Acute Eye Irritation Testing. 

IRLG Testing Standards and Guidelines Work 

Group, Washington, DC. 

Murphy J. C., Osterberg R. E., Seabaugh V. M. & 

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various pH's of acids and bases with and without irrigation. 7bxicology 23, 281, 

National Academy of Sciences-National Research Council 

(1977). Principles and Procedures for Evaluating the Toxicity of Household Substances. p. 41. National Academy 

of Sciences, Washington, DC. 

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skin irritation tests. Toxic. appl. Pharmac. 19, 276. 

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(Abstract 622) Toxicologist 2 (1), 178. 

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