Isolated Chicken Eye Test Research Articles

Inter-laboratory performance of ICE histopathology scoring to identify UN GHS Category 1 surfactants and non-extreme pH detergents

The inter-laboratory performance of Isolated Chicken Eye (ICE) histopathology scoring was assessed for predicting EU CLP/UN GHS Cat. 1 surfactants. Furthermore, the predictive capacity of ICE histopathology was evaluated for the combined dataset of surfactants and existing data for non-extreme pH (2 < pH < 11.5) detergents. Use of ICE histopathology led to increased sensitivity compared to the ICE test method alone for surfactants. When combined with the existing dataset of detergents, use of histopathology in addition to the standard ICE test method decreased the false negative rates from 64% (14/22) to 27% (6/22); increased accuracy from 53% (16/30) to 77% (23/30); and led to acceptable level of false positives (from 0/8 to 1/8 (12.5%). Moreover, good reproducibility of ICE histopathology predictions conducted on the same slides was found between pathologists and peer-reviewers from three independent laboratories (10/12 or 83%) and over time. Use of ICE histopathology was therefore found suitable to predict EU CLP/UN GHS Cat. 1 surfactants and non-extreme pH detergents. In addition, appropriate reproducibility of ICE histopathology was found, provided that i) an internal peer-review system was in place; ii) original slides were assessed to enable evaluation of three dimensional effects; and iii) appropriate training and proficiency appraisal were conducted.

Methods for Testing Ocular Toxicity: Current Status

The developed ophthalmic formulations should be tested for ocular toxicity testing like draize eye test. Rapid growth in the field of ocular toxicity testing replaces the usage of animals and to adopt the modified protocols. The researchers have to develop properly validated and regulatory approved options to animal testing. Alternative ocular toxicity testing is based on corneal structure and mechanism through which the specific ocular formulation causes irritation to the eyes. Several alternative assay methods have been introduced in the field of ocular toxicity testing like in vitro organotypic model for testing ocular toxicity and several other methods like Bovine Corneal Opacity and Permeability Assay (BCOP Assay), isolated chicken eye test, isolated rabbit eye test and Hen's egg-test on the chorioallantoic membrane. The ultimate aim of alternate methods of ocular toxicity testing is to develop properly validated and regulatory approved best practices. Hence this review highlights the development in the field of alternative ocular toxicity testing methods.

Analysis of the adverse impact of an iron-based combustion modifier for liquid fuels on human health

The combustion of liquid fuels–first of all, heavy crude oils–leads to the formation of pollutants such as nitrogen oxides (NOx), sulfur dioxide and hydrocarbons. Specific modifiers are used to reduce harmful emissions of products arising in the combustion of liquid fuels. Such modifiers include organic metal salts which are soluble in the fuels: under combustion process conditions they form metal oxides which improve the fuels in terms of oxidation properties. In this paper, an iron modifier based on fatty-acid organic iron salts dissolved in fuel oil is presented. The modifier described in this paper was used in liquid fuel combustion tests, showing a desirable effect on reducing hydrocarbon, CO and NOx emissions. Because iron at high concentrations is potentially harmful to humans, the effect of the iron-based modifier on human health is discussed in the paper. Since ingestion and skin absorption are the two main routes whereby the heavy metals enter the human body, the results of the following tests are presented in this paper: acute oral toxicity tests, acute skin irritation/corrosion tests in rabbit, and isolated chicken eye tests for identifying ocular corrosives and severe irritants. In the acute oral toxicity test the iron-based modifier was found to be a non-hazardous substance, posing no risk to human health. The results of the isolated chicken eye test indicate that the test material is not an ocular corrosive or severe irritant. The results of the acute dermal irritation/corrosion test in rabbits indicate that the iron-based modifier is a skin irritant. This leads us to the conclusion that particular attention in handling the iron-based modifier should be paid to contact with the skin.

The Isolated Chicken Eye test to replace the Draize test in rabbits

In 1944, Draize et al., published a paper entitled “Methods for the study of irritation and toxicity of substances applied topically to the skin and mucous membranes”. The Organization for Economic Co-operation and Development published their first guideline on eye irritation in 1981, using rabbits. In the early eighties the development of alternative non-animal tests to replace the Draize eye test started. The first attempts to validate alternative tests for eye irritation were considered to be relatively simple by comparing in vitro and in vivo irritation index scores. In the early nineteen-eighties, we introduced the use of isolated eyes as an alternative test for the Draize eye irritation test. What was expected to be a process of several years, however, turned out to be a decades spanning process still not fully completed. For a large part, this can be attributed to the nature of the in vivo test in rabbits, which is more complicated and compromised than originally believed. This paper describes, most chronologically, the development, performance, validation and application of the Isolated Eye Test and, in broader perspective, the international validation and acceptance of this alternative test by regulatory authorities and agencies.

Lacking applicability of in vitro eye irritation methods to identify seriously eye irritating agrochemical formulations: Results of bovine cornea opacity and permeability assay, isolated chicken eye test and the EpiOcular™ ET-50 method to classify according to UN GHS

In vitro methods have gained regulatory acceptance for the prediction of serious eye damage (UN GHS Cat 1). However, the majority of in vitro methods do not state whether they are applicable to agrochemical formulations. This manuscript presents a study of up to 27 agrochemical formulations tested in three in vitro assays (three versions of the bovine corneal opacity and permeability test (BCOP, OECD TG 437) assay, the isolated chicken eye test (ICE, OECD TG 438) and the EpiOcular™ ET-50 assay). The results were compared with already-available in vivo data. In the BCOP only one of the four, one of five in the ICE and six of eleven tested formulations in the EpiOcular™ ET-50 Neat Protocol resulted in the correct UN GHS Cat 1 prediction. Overpredictions occurred in all assays. These data indicate a lack of applicability of the three in vitro methods to reliably predict UN GHS Cat 1 of agrochemical formulations. In order to ensure animal-free identification of seriously eye damaging agrochemical formulations testing protocols and/or prediction models need to be modified or classification rules should be tailored to in vitro testing rather than using in vivo Draize data as a standard.

Suitability of the isolated chicken eye test for classification of extreme pH detergents and cleaning products

A.I.S.E. investigated the suitability of the regulatory adopted ICE in vitro test method (OECD TG 438) with or without histopathology to identify detergent and cleaning formulations having extreme pH that require classification as EU CLP/UN GHS Category 1. To this aim, 18 extreme pH detergent and cleaning formulations were tested covering both alkaline and acidic extreme pHs. The ICE standard test method following OECD Test Guideline 438 showed good concordance with in vivo classification (83%) and good and balanced specificity and sensitivity values (83%) which are in line with the performances of currently adopted in vitro test guidelines, confirming its suitability to identify Category 1 extreme pH detergent and cleaning products. In contrast to previous findings obtained with non-extreme pH formulations, the use of histopathology did not improve the sensitivity of the assay whilst it strongly decreased its specificity for the extreme pH formulations. Furthermore, use of non-testing prediction rules for classification showed poor concordance values (33% for the extreme pH rule and 61% for the EU CLP additivity approach) with high rates of over-prediction (100% for the extreme pH rule and 50% for the additivity approach), indicating that these non-testing prediction rules are not suitable to predict Category 1 hazards of extreme pH detergent and cleaning formulations.

Microscopical evaluation of the cornea in the isolated chicken eye test: the most common histopathological changes

and zDepartment of Dermatology, Venerology and Allergology, Charit eeUniversit€atsmedizin Berlin, Germany Introduction: Nanoparticles (NPs) are widely used in everyday products as well as biomedical applications and intended or unintended contacts between NPs and the skin are likely. It is still unclear, however, whether pre-existing skin diseases may predispose to unwanted NP penetration or whether NPs may even aggravate hypersensitivity reactions. The aim of this study was to investigate whether AHAPS-functionalized silica NPs penetrate inflamed skin or affect the course of allergic contact dermatitis (ACD). Materials and Methods: SKH1 mice (n 5 5 per group) with oxazolone-induced ACD were treated topically with 250 mg silica NPs of 55 6 nm in diameter and N-(6-aminohexyl)(3-aminopropyl) trimethoxysilane (AHAPS)-functionalization or ultra pure water for 5 consecutive days. Mice were examined clinically, histopathologically and for several molecular parameters. NPs were visualized by fluorescence and transmission electron microscopy. Results: The AHAPS-silica NPs were only identified in the superficial layers of the stratum corneum of the epidermis, but not in deeper epidermal or dermal layers, despite severe inflammation and barrier disruption. Furthermore, the NPs did not affect the course of ACD. Conclusions: In contrast to previous general apprehensions about NPs and experimental data on other NPs, AHAPS-functionalized silica NPs seem not to penetrate inflamed skin or affect the course of ACD in this model. Whether they may serve as suitable drug carriers in different skin conditions remains to be studied.

Suitability of histopathology as an additional endpoint to the isolated chicken eye test for classification of non-extreme ph detergent and cleaning products

A.I.S.E. investigated the suitability of histopathological evaluations as an additional endpoint to the regulatory adopted ICE in vitro test method (OECD TG 438) to identify non-extreme pH detergent and cleaning products that require classification as EU CLP/UN GHS Category 1 (serious eye damage). To this aim, a total of 30 non-extreme pH products covering the range of in vivo classifications for eye irritation, and representing various product categories were tested. Epithelium vacuolation (mid and lower layers) and erosion (at least moderate) were found to be the most relevant histopathological effects induced by products classified in vivo as Category 1. Histopathology criteria specifically developed for non-extreme pH detergent and cleaning products were shown to correctly identify materials classified as Category 1 based on in vivo persistent effects, and to significantly increase the overall sensitivity of the standard ICE prediction model for Category 1 identification (to 75%) whilst maintaining a good concordance (73%). In contrast, use of EU CLP additivity approach for classification of mixtures was considerably less predictive, with a concordance of only 27%, and 100% over-predictions of non-Category 1 products. As such, use of histopathology as an addition to the ICE test method was found suitable to identify EU CLP/UN GHS Category 1 non-extreme pH detergent and cleaning products and to allow a better discrimination from Category 2 products.

Suitability of histopathology as an additional endpoint to the Isolated Chicken Eye Test for classification of non-extreme pH detergent and cleaning products

A.I.S.E. investigated the suitability of histopathological evaluations as an additional endpoint to the regulatory adopted ICE in vitro test method (OECD TG 438) to identify non-extreme pH detergent and cleaning products that require classification as EU CLP/UN GHS Category 1 (serious eye damage). To this aim, a total of 30 non-extreme pH products covering the range of in vivo classifications for eye irritation, and representing various product categories were tested. Epithelium vacuolation (mid and lower layers) and erosion (at least moderate) were found to be the most relevant histopathological effects induced by products classified in vivo as Category 1. Histopathology criteria specifically developed for non-extreme pH detergent and cleaning products were shown to correctly identify materials classified as Category 1 based on in vivo persistent effects, and to significantly increase the overall sensitivity of the standard ICE prediction model for Category 1 identification (to 75%) whilst maintaining a good concordance (73%). In contrast, use of EU CLP additivity approach for classification of mixtures was considerably less predictive, with a concordance of only 27%, and 100% over-predictions of non-Category 1 products. As such, use of histopathology as an addition to the ICE test method was found suitable to identify EU CLP/UN GHS Category 1 non-extreme pH detergent and cleaning products and to allow a better discrimination from Category 2 products.

Histopathology in the isolated chicken eye test and comparison of different stainings of the cornea

The isolated chicken eye (ICE) test, developed at our Institute, is accepted by the OECD for identification of severe eye irritants. The OECD ICE Guideline (No. 438) encourages preservation of the treated eyes for possible histopathology of the cornea, which is believed to strengthen evidence of absence or presence of irritation and to help clarify borderline effects by assessment of the corneal Depth-of-Injury. Histopathology of the cornea in addition to the normal slit-lamp microscope assessment of corneal effects has already been performed routinely in ICE tests at our Institute, using two standard stainings (H&E and PAS). In this study, three other stainings (AZAN, EVG and Trichrome), more specific for collagen-rich membranes such as basement- and Bowman’s membranes were examined with corneas exposed to four model compounds ranging from non- to severely irritating (corrosive). PAS appeared to be the superior staining method. Surprisingly, the well-known eye corrosive sodium hydroxide (NaOH, solid) did not visibly compromise the integrity of Bowman’s or the basement membrane. Based on our experience, histopathology of the treated cornea is confirmative in relation to the standard assessment of eye irritation by slit-lamp observation in the ICE and in certain cases can help to evaluate borderline effects. Besides establishing the depth of injury, additional investigation of corneal limbal stem cell damage after chemical exposure might be appropriate to determine reversibility or irreversibility of eye effects.

The isolated chicken eye test as a suitable in vitro method for determining the eye irritation potential of household cleaning products

Eye irritation is an important endpoint in the safety evaluation of consumer products and their ingredients. Several in vitro methods have been developed and are used by different industry sectors to assess eye irritation. One such in vitro method in use for some time already is the isolated chicken eye test (ICE). This investigation focuses on assessing the ICE as a method to determine the eye irritation potential of household cleaning products, both for product safety assurance prior to marketing and for classification and labeling decisions. The ICE involves a single application of test substances onto the cornea of isolated chicken eyes. Endpoints are corneal swelling, corneal opacity and fluorescein retention. The ICE results were compared to historic LVET data in this study due to availability of such in vivo data and the ability to correlate LVET to human experience data on the outcome of accidental exposures to household cleaning products in general. The results of this study indicate that the ICE test is a useful in vitro method for evaluating the eye irritation/corrosion potential and establishing classification and labeling for household cleaning products. For new product formulations, it is best used as part of a weight-of-evidence approach and benchmarked against data from comparable formulations with known eye irritation/corrosion profiles and market experience.

Irag Working Group 1: Organotypic models for the assessment/prediction of ocular irritation

The brief of the Organotypic Models Working Group was to review data submitted to the Interagency Regulatory Alternatives Group on the use of isolated eyes and components of the eye used to predict eye irritation potential. Data submissions were received on four test systems: the isolated rabbit eye (one submission), the isolated chicken eye (one submission), the bovine cornea (eight submissions) and the cultured bovine lens (one submission). On the basis of the data submitted on each test it was concluded that the isolated rabbit eye test as performed was capable of screening for severe eye irritants, but overall was of no practical value for determining irritation potential across the full range; that the isolated chicken eye test as performed showed promise as a method of predicting eye irritation potential, but the database was too small and needed expanding; that the bovine corneal opacity test had an extensive database and overall performed reasonably at screening out severe irritants and performed well for assigning relative potencies; and that the bovine lens test should be researched further to demonstrate its utility. The overall conclusion drawn was that the isolated eye tests and the bovine corneal opacity test can be used now to screen for severely irritating materials. However, it would be unwise to rely solely on these organotypic methods to provide evidence of lack of eye irritation hazard.