JOURNAL OF APPLIED TOXICOLOGY, VOL. 12(4), 281-284 (1992)
Relationship between Eye and Skin Irritation in Rabbits using a Series of Textile Fiber Finishes Gerald L. Kennedy,
Jr.'*t and Asit K. Banerjee'
IHaskell Laboratory for Toxicology and Industrial Medicine. Du Pont Central Research and Development, PO Box 50. Elkton Road, Newark. D E , USA. 'Quality Management and Technology Center, D u Pont Engineering, PO Box 6091, Newark, D E , USA
Key words: finish, eye irritation; finish. skin irritation; prediction of irritability; eye irritation; skin irritation
A series of 76 fiber finishes, typically composed of blends of lubricants, emulsifiers, antistatic agents and fatty acid soaps, were tested in rabbits to determine both the eye and the skin irritation potential. Each finish was classified as being either non-, slightly, mildly, moderately or severely irritating to the target tissue during a 48-h post-treatment period. Seven (9.2%) of the finishes tested were severely irritating to both the skin and the eye; two (2.6%) were determined to be non-irritating to both tissues. While occasionally finishes produced equal degrees of damage resulting in similar irritancy classifications, seven (9.2%) finishes were found to be severely irritating to the skin without producing any irritation in the eye. Conversely, one finish was found to be a severe eye irritant without producing any skin irritation. The suggested use of the skin irritation data to predict the ocular reaction needs to be carefully examined, particularly with materials such as these fiber finishes. The prediction that a severe skin irritant is also a severe eye irritant was demonstrated to be in error with 8 of 75 (10.5%) of the finishes studied. Further, there is little predictive association between the skin and eye irritation for these compounds.
INTRODUCTION The need to evaluate the skin and eye irritation potential of materials likely to come in contact with the skin and eye is obvious. Screening programs prior to use of these materials in the workplace include evaluation in an animal model to determine the reactive irritancy for the purpose of establishing appropriate control(s). Results of these studies also are used to develop appropriate procedures for handling accidental human contacts and these procedures can range from rinsing with copious amounts of water to seeking medical attention immediately. Thus, it is important that of these materials, those that elicit severe responses in the eye and skin need to be properly identified. It is agreed that the use of all resources available to the toxicologist be used wisely. To that end, efforts to replace or reduce the species and numbers of animals used in toxicological testing programs need to be made. The relationship between irritancy to these two organs, the skin and the eye, has been demonstrated with strong acids and bases which are, at some concentrations, corrosive to both organs. It has been suggested and is practiced widely that such materials do not need to be tested as they are severe irritants based on pH, and testing is not necessary. The irritancy potential for acids with pK, s 4 appears highly predictive of acute skin irritation for acids in man.' For a series of bases that penetrate through the skin ill vitro at similar rates, the penetrant pK, ( 2 8) was shown to correlate with erythema and edema.s However, it needs to be emphasized that there is no simple rule for predicting irritancy from pH. An example is that acetic acid ( 5 % )
t
Author to whom correspondence should be addressed.
026(M37X/92/040281-04$07.00 Wiley & Sons, Ltd
0 1992 by John
with a pH of 2.7 produces substantial corneal opacity while 0.3% hydrochloric acid (pH 1.3) causes no corneal opacity.h A further suggestion is that these studies should be conducted in series, with skin testing proceeding first. Materials found to be severe skin irritants would then be assumed to be severe eye irritants without actually conducting the test and avoiding the use of any additional animals. 7-9 Our toxicological testing program for all fiber finishes calls for acute skin and eye irritation testing in rabbits. With this program in place, it was possible to study retrospectively the concordance beween eye and skin irritation in the rabbit for a series of fiber finishes. This paper describes an investigation of the relationship between skin and eye irritation in the rabbit for 76 experimental finishes for which we had conducted both an eye and skin irritation test according to the same protocol. Individual studies were conducted between 1985 and 1988.
METHODS Materials tested
The materials (a total of 76) used in these tests were experimental textile fiber finishes prepared by the Fibers Business of the Du Pont Company. Fiber finishes are lubricant and antistatic coatings critical for the production and use of synthetic and natural fibers. These coatings provide protection to the surface of the fiber during texturing, knitting and weaving processes. Without such aids, the fibers can be damaged by the various machine surfaces that come in contact with the fiber surface during manufacture and processing of the Received 14 September 1991 Accepted (revised) 19 December I991
282
G. L. KENNEDY, Jr. AND A. K. BANERJEE
fiber. This damage results in loss of physical properties and ultimately poor performance and quality. The fiber finishes generally will contain 1-15 components, with each component providing a specialized or combination of functions. These components are fatty acid esters for lubrication and fatty alcohol or acid ethoxylates/propoxylates (ethylene and propylene oxide copolymers) for surfactant and wetting of the fiber surface. Finishes often contain antistats, typically anionic and cationic species belonging to the phosphate or quaternary amine family. which are used to control electrical static that will build up during fiber handling. Antioxidants, phenolic or phosphorus-containing, prevent air or NO, oxidation of finish and/or fiber. Fatty acid soaps can also be commonly added to these finish systems for control of pH, bacteria control, emulsification and to assist in the wetting character of the finish on the fiber. Commonly used lubricants include n-butyl stearate, ditridecyl adipate and pentaerythritol tetrapelargonate. Emulsifiers include C12/14 alcohol-(PO) 10-(EO) 10(EO)lO-(PO)l.S-H, C11/15 linear secondary alcohol(E0)7-H, and hepta esters of ethoxylated sorbitol. Tri(monononylpheny1)phosphite and mono and diacid phosphate esters of C12 alcohol are two commonly used antistats. and typical fatty acid soaps used are the potassium or triethanolamine salts of oleic acid and the potassium salt by isostearic acid. Animal husbandry Young adult male New Zealand White rabbits weighing between 2 and 3 kg were used in these studies (Hare Marland, Hewitt, New Jersey). Rabbits were housed singly in suspended stainless-steel wire-mesh cages. Purina Certified Rabbit Chow” 5322 and water were available ad libitum. Rabbits were quarantined, weighed and observed for general health for ca. 2 weeks. Animal rooms were maintained on a timercontrolled 12-h light/dark cycle. Environmental conditions of the rooms were targeted for a temperature of 20°C ? 2°C and a relative humidity of 50% ? 10%. Procedure For the skin irritation tests, on the day prior to study initiation, the hair of six male rabbits was closely clipped to expose the skin from the scapular to the lumbar region of the back. Each rabbit was placed into a stock which had been fitted with a piece of rubber sheeting (ca. 8” X 18”). The rabbits remained in the stocks throughout the exposure period (4 h) and during that time did not have access to food or water. This procedure does not appear to be particularly stressful to the rabbits as they do not generally show signs indicative of unease or discomfort. A 0.5 ml aliquot of the test finish was applied directly to each site beneath a 1-in. gauze square that was held in place with tape. The rubber sheeting was then wrapped around the torso of the rabbit and secured with clips to retard evaporation and to keep the test material in contact with the skin without undue pressure. Up to three other test materials were generally applied to three other sites on the same rabbit. It is theoretically possible that the effect of a material at one of the skin
Table 1. Classification of fiber finishes as skin irritants” Classification None Slight Mild Moderate Severe
Evaluation of skin reaction No erythema, no edema Barely perceptible erythema and/or edema Well-defined erythema; slight edema with the edges of area well defined by definite raising Moderate to severe erythema; moderate edema with area raised ca. 1.0 rnm Severe erythema (beet redness) and slight eschar formation (injuries in depth); severe edema with area raised more than 1.0 mm extending beyond the area of exposure
Description based on highest classification in any one of the six rabbits.
a
sites could affect, perhaps systemically, the local response to a material at another site. However, we have not encountered such a situation in many years of testing, and in an effort to minimize the number of test animals needed, we continue to use multiple sites (spacially removed from each other) for testing. Approximately 4 h after application of the test material, the rubber sheeting was loosened and the skin at the corners of the gauze squares was marked with a waterproof pen; wrappings and gauze squares were then removed. The test sites were gently washed with warm water to remove excess test material and gently wiped dry. Approximately 4, 24 and 48-h after application of the test material, the test sites were evaluated for erythema, edema and other evidence of dermal effects and were scored according to a modification of the Draize (10) scale (Table 1). For the eye irritation tests, the eyes of two male rabbits were examined using fluorescein dye. Rabbits showing pre-existing corneal or conjunctival injury or irritation were not used in these studies. A 0.01 ml aliquot of each fiber finish was introduced into the lower conjunctival sac of the right eyes of two male rabbits, the lids were held together for 1 s and were then allowed to open. We showed with a series of chemicals that when the dose volume administered is reduced from 0.1 to 0.01 ml, the severity of the response is reduced but the rank order of severity of the materials is unchanged.” The left eyes served as controls. The treated and control eyes of one rabbit remained unwashed. Approximately 20 s after the test material was administered, both eyes of the remaining rabbit were rinsed for 1 min with lukewarm tapwater. Approximately 1 and 4 h and 1 and 2 days after treatment, the rabbits were examined for evidence of eye irritation. At each observation the treated eyes were examined using illumination and magnification and scored for ocular reactions using the Draize scale (presented in Table 2). The untreated eye of each rabbit was also examined and used for comparison. Fluorescein dye was used to evaluate corneal ulceration and irritation at the 1- and 2-day observations. Biomicroscopic examinations for corneal injury were also conducted at the 1- and 2-day observation.
283
TEXTILE FIBRE IRRITATION OF EYE AND SKIN
Table 2. Classification of fiber finishes as eye irritants" Ocular findings
Classification None
Slight
Mild
Moderate
Severe
No corneal opacity; no iritic changes; no conjunctival changes (vessels normal, no swelling, no discharge) Scattered or diffuse areas of corneal opacity, details of iris clearly visible (
Relationship between Eye and Skin Irritation in Rabbits using a Series of Textile Fiber Finishes Gerald L. Kennedy,
Jr.'*t and Asit K. Banerjee'
IHaskell Laboratory for Toxicology and Industrial Medicine. Du Pont Central Research and Development, PO Box 50. Elkton Road, Newark. D E , USA. 'Quality Management and Technology Center, D u Pont Engineering, PO Box 6091, Newark, D E , USA
Key words: finish, eye irritation; finish. skin irritation; prediction of irritability; eye irritation; skin irritation
A series of 76 fiber finishes, typically composed of blends of lubricants, emulsifiers, antistatic agents and fatty acid soaps, were tested in rabbits to determine both the eye and the skin irritation potential. Each finish was classified as being either non-, slightly, mildly, moderately or severely irritating to the target tissue during a 48-h post-treatment period. Seven (9.2%) of the finishes tested were severely irritating to both the skin and the eye; two (2.6%) were determined to be non-irritating to both tissues. While occasionally finishes produced equal degrees of damage resulting in similar irritancy classifications, seven (9.2%) finishes were found to be severely irritating to the skin without producing any irritation in the eye. Conversely, one finish was found to be a severe eye irritant without producing any skin irritation. The suggested use of the skin irritation data to predict the ocular reaction needs to be carefully examined, particularly with materials such as these fiber finishes. The prediction that a severe skin irritant is also a severe eye irritant was demonstrated to be in error with 8 of 75 (10.5%) of the finishes studied. Further, there is little predictive association between the skin and eye irritation for these compounds.
INTRODUCTION The need to evaluate the skin and eye irritation potential of materials likely to come in contact with the skin and eye is obvious. Screening programs prior to use of these materials in the workplace include evaluation in an animal model to determine the reactive irritancy for the purpose of establishing appropriate control(s). Results of these studies also are used to develop appropriate procedures for handling accidental human contacts and these procedures can range from rinsing with copious amounts of water to seeking medical attention immediately. Thus, it is important that of these materials, those that elicit severe responses in the eye and skin need to be properly identified. It is agreed that the use of all resources available to the toxicologist be used wisely. To that end, efforts to replace or reduce the species and numbers of animals used in toxicological testing programs need to be made. The relationship between irritancy to these two organs, the skin and the eye, has been demonstrated with strong acids and bases which are, at some concentrations, corrosive to both organs. It has been suggested and is practiced widely that such materials do not need to be tested as they are severe irritants based on pH, and testing is not necessary. The irritancy potential for acids with pK, s 4 appears highly predictive of acute skin irritation for acids in man.' For a series of bases that penetrate through the skin ill vitro at similar rates, the penetrant pK, ( 2 8) was shown to correlate with erythema and edema.s However, it needs to be emphasized that there is no simple rule for predicting irritancy from pH. An example is that acetic acid ( 5 % )
t
Author to whom correspondence should be addressed.
026(M37X/92/040281-04$07.00 Wiley & Sons, Ltd
0 1992 by John
with a pH of 2.7 produces substantial corneal opacity while 0.3% hydrochloric acid (pH 1.3) causes no corneal opacity.h A further suggestion is that these studies should be conducted in series, with skin testing proceeding first. Materials found to be severe skin irritants would then be assumed to be severe eye irritants without actually conducting the test and avoiding the use of any additional animals. 7-9 Our toxicological testing program for all fiber finishes calls for acute skin and eye irritation testing in rabbits. With this program in place, it was possible to study retrospectively the concordance beween eye and skin irritation in the rabbit for a series of fiber finishes. This paper describes an investigation of the relationship between skin and eye irritation in the rabbit for 76 experimental finishes for which we had conducted both an eye and skin irritation test according to the same protocol. Individual studies were conducted between 1985 and 1988.
METHODS Materials tested
The materials (a total of 76) used in these tests were experimental textile fiber finishes prepared by the Fibers Business of the Du Pont Company. Fiber finishes are lubricant and antistatic coatings critical for the production and use of synthetic and natural fibers. These coatings provide protection to the surface of the fiber during texturing, knitting and weaving processes. Without such aids, the fibers can be damaged by the various machine surfaces that come in contact with the fiber surface during manufacture and processing of the Received 14 September 1991 Accepted (revised) 19 December I991
282
G. L. KENNEDY, Jr. AND A. K. BANERJEE
fiber. This damage results in loss of physical properties and ultimately poor performance and quality. The fiber finishes generally will contain 1-15 components, with each component providing a specialized or combination of functions. These components are fatty acid esters for lubrication and fatty alcohol or acid ethoxylates/propoxylates (ethylene and propylene oxide copolymers) for surfactant and wetting of the fiber surface. Finishes often contain antistats, typically anionic and cationic species belonging to the phosphate or quaternary amine family. which are used to control electrical static that will build up during fiber handling. Antioxidants, phenolic or phosphorus-containing, prevent air or NO, oxidation of finish and/or fiber. Fatty acid soaps can also be commonly added to these finish systems for control of pH, bacteria control, emulsification and to assist in the wetting character of the finish on the fiber. Commonly used lubricants include n-butyl stearate, ditridecyl adipate and pentaerythritol tetrapelargonate. Emulsifiers include C12/14 alcohol-(PO) 10-(EO) 10(EO)lO-(PO)l.S-H, C11/15 linear secondary alcohol(E0)7-H, and hepta esters of ethoxylated sorbitol. Tri(monononylpheny1)phosphite and mono and diacid phosphate esters of C12 alcohol are two commonly used antistats. and typical fatty acid soaps used are the potassium or triethanolamine salts of oleic acid and the potassium salt by isostearic acid. Animal husbandry Young adult male New Zealand White rabbits weighing between 2 and 3 kg were used in these studies (Hare Marland, Hewitt, New Jersey). Rabbits were housed singly in suspended stainless-steel wire-mesh cages. Purina Certified Rabbit Chow” 5322 and water were available ad libitum. Rabbits were quarantined, weighed and observed for general health for ca. 2 weeks. Animal rooms were maintained on a timercontrolled 12-h light/dark cycle. Environmental conditions of the rooms were targeted for a temperature of 20°C ? 2°C and a relative humidity of 50% ? 10%. Procedure For the skin irritation tests, on the day prior to study initiation, the hair of six male rabbits was closely clipped to expose the skin from the scapular to the lumbar region of the back. Each rabbit was placed into a stock which had been fitted with a piece of rubber sheeting (ca. 8” X 18”). The rabbits remained in the stocks throughout the exposure period (4 h) and during that time did not have access to food or water. This procedure does not appear to be particularly stressful to the rabbits as they do not generally show signs indicative of unease or discomfort. A 0.5 ml aliquot of the test finish was applied directly to each site beneath a 1-in. gauze square that was held in place with tape. The rubber sheeting was then wrapped around the torso of the rabbit and secured with clips to retard evaporation and to keep the test material in contact with the skin without undue pressure. Up to three other test materials were generally applied to three other sites on the same rabbit. It is theoretically possible that the effect of a material at one of the skin
Table 1. Classification of fiber finishes as skin irritants” Classification None Slight Mild Moderate Severe
Evaluation of skin reaction No erythema, no edema Barely perceptible erythema and/or edema Well-defined erythema; slight edema with the edges of area well defined by definite raising Moderate to severe erythema; moderate edema with area raised ca. 1.0 rnm Severe erythema (beet redness) and slight eschar formation (injuries in depth); severe edema with area raised more than 1.0 mm extending beyond the area of exposure
Description based on highest classification in any one of the six rabbits.
a
sites could affect, perhaps systemically, the local response to a material at another site. However, we have not encountered such a situation in many years of testing, and in an effort to minimize the number of test animals needed, we continue to use multiple sites (spacially removed from each other) for testing. Approximately 4 h after application of the test material, the rubber sheeting was loosened and the skin at the corners of the gauze squares was marked with a waterproof pen; wrappings and gauze squares were then removed. The test sites were gently washed with warm water to remove excess test material and gently wiped dry. Approximately 4, 24 and 48-h after application of the test material, the test sites were evaluated for erythema, edema and other evidence of dermal effects and were scored according to a modification of the Draize (10) scale (Table 1). For the eye irritation tests, the eyes of two male rabbits were examined using fluorescein dye. Rabbits showing pre-existing corneal or conjunctival injury or irritation were not used in these studies. A 0.01 ml aliquot of each fiber finish was introduced into the lower conjunctival sac of the right eyes of two male rabbits, the lids were held together for 1 s and were then allowed to open. We showed with a series of chemicals that when the dose volume administered is reduced from 0.1 to 0.01 ml, the severity of the response is reduced but the rank order of severity of the materials is unchanged.” The left eyes served as controls. The treated and control eyes of one rabbit remained unwashed. Approximately 20 s after the test material was administered, both eyes of the remaining rabbit were rinsed for 1 min with lukewarm tapwater. Approximately 1 and 4 h and 1 and 2 days after treatment, the rabbits were examined for evidence of eye irritation. At each observation the treated eyes were examined using illumination and magnification and scored for ocular reactions using the Draize scale (presented in Table 2). The untreated eye of each rabbit was also examined and used for comparison. Fluorescein dye was used to evaluate corneal ulceration and irritation at the 1- and 2-day observations. Biomicroscopic examinations for corneal injury were also conducted at the 1- and 2-day observation.
283
TEXTILE FIBRE IRRITATION OF EYE AND SKIN
Table 2. Classification of fiber finishes as eye irritants" Ocular findings
Classification None
Slight
Mild
Moderate
Severe
No corneal opacity; no iritic changes; no conjunctival changes (vessels normal, no swelling, no discharge) Scattered or diffuse areas of corneal opacity, details of iris clearly visible (
