EPA's requirements for dermal irritation and sensitization testing.

This paper presents an overview of EPA guidelines for dermal irritation and sensitization testing (part of Subdivision F Guidelines) for the registration of pesticide products [Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)]. In addition, these data and others may be needed for chemicals submitted for the Premanufacture Notification or testing under Section 4 of the Toxic Substances Control Act (TSCA). The EPA periodically reviews its recommended test procedures and revises them when indicated scientifically.

An eye irritation test protocol and an evaluation and classification system.

An in vivo test protocol and an evaluation and classification system for the determination of eye irritation potential of chemicals and mixtures (substances) is proposed. The protocol uses two or three rabbits and reduces distress in test animals. The test substances are classified as non-irritant, irritant or severe irritant to meet regulatory needs. They may be classified on the basis of past experience with similar compounds or mixtures. Screens such as structure-activity relationships, pH extremes, validated and accepted in vitro tests, severe dermal irritation (primary dermal irritation index > or = 5) or severe dermal toxicity (lethality at < 200 mg/kg body weight) should be used to classify irritant or severe irritant materials when one or more of the screens can provide convincing evidence. For suspected severe irritant materials, the proposed in vivo test permits the use of one rabbit and instillation of 0.01 ml (0.01 g) of the test material into the cornea. Materials that are not classified irritant or severe irritant by screens or severe irritant by one rabbit test are tested in two or three rabbits; 0.1 ml (0.1 g) is instilled into the conjunctival sac. The responses (corneal opacity, iritis and conjunctival redness) are scored according to the modified Draize scoring system at 24, 48 and 72 hr and 7 days post-instillation. A rabbit is considered positive when corneal opacity of 1 or above, iritis of 1 or above or conjunctival redness of 2 or above is present at 24, 48 or 72 hr post-instillation. The material is classified as a severe irritant when the rabbit in the one-animal test or two or more rabbits in the standard test have responses of corneal opacity of 3 or above and iritis of 2 at 24, 48 or 72 hr, or positive responses on day 7 after instillation. The material is classified as an eye irritant when two or more rabbits are positive but the responses are not severe and they clear 7 days after instillation. The material is classified as a non-irritant when no more than one rabbit is positive. The opinions expressed in this article are those of the authors and do not necessarily reflect the views of US Federal agencies.

Use of ophthalmic topical anaesthetics.

Pretreatment of the eyes of rabbits with a topical anaesthetic can be viewed as a refinement of the test for eye irritation. It reduces pain at the time of test-material administration, decreases animal distress and permits easier application of the test agent to the eye. In some cases, however, use of an anaesthetic either alone or in combination with the test substance may alter ocular responses or provide little benefit. Although anaesthetic pretreatment may result in decreased pain at the time of test-compound administration, it does not affect possible pain after the effects of the anaesthetic have dissipated. Some anaesthetics are themselves irritating to eyes. In addition, anaesthetics reduce blinking and tearing, thereby maintaining the test-material concentration at the surface of the eye longer. Corneal permeability may also be increased with pretreatment use of an anaesthetic, and may bring the test agent into contact with more structures of the eye. Some anaesthetics delay healing after ocular injury. All of these varied effects may result in increased irritation to the eye. Overall, pretreatment with anaesthetics has usually resulted in a tendency for slightly higher irritation scores; eye irritancy classification is usually unaffected.

Ocular irritancy responses to various pHs of acids and bases with and without irrigation.

Acids and alkalies were instilled into the eyes of 2 groups of rabbits; the eyes of one group were washed with tap water 30 s after exposure. Damage seen in washed and unwashed eyes was not always related to pH. Some strong acids with greater acidity than pH 2.5 produced opacities while 0.3% hydrochloric acid with a pH of 1.28 produced no ocular damage. Phenol (5%) and acetic acid (5%) with pHs greater than 2.5 produced damage equivalent to or greater than that produced by equal concentrations (w/v) of the mineral acids. All alkalies with pHs ranging from 11.5 to 13.5 produced opacities and other ocular damage of different degrees depending upon the alkali and its concentration. For example, low concentrations of some alkalies in the pH range from 11.3 to 12.8 produced no ocular changes. The duration of the corneal opacities produced by phenol, 1% sodium hydroxide, acetic acid and anhydrous sodium carbonate and the onset of corneal opacity produced by 5% sulfuric acid, the weak acids and 1% sodium hydroxide were reduced as a result of washing the test eyes 30 s after instillation of the test material. These data suggest that acidity and alkalinity of the test material are not the only factors to be considered in relation to a substances' capacity to produce severe ocular injury. The concentration of the test chemical and its period of contact with the eye prior to washing are also important.

Potential biological hazards of commercially available cleansers for dentures.

Thirteen representative denture cleansers were selected from among more than 32 retail products to be tested for potential hazard and toxicity to humans. Products were subjected to toxicological analyses by using the biological tests (acute oral toxicity in rats, eye and skin irritation in rabbits) specified in the Federal Hazardous Substances Act Regulations. All products were eye irritants with ranges from slight to severe. Three produced a primary skin irritation response (one was corrosive), while five of the denture cleansers produced oral LD50 values below 5 g/kg. Furthermore, a provisional upper gastrointestinal irritancy test used in rabbits indicated that eight of the denture cleansers produced upper gastrointestinal irritation, which was, in general, dose-related.

Detergent toxicity survey.

A survey of over 249 detergent products involving biological testing, chemical analyses, and product label reviews has been conducted from 1971-1976 for determining compliance with the Federal Hazardous Substances Act. Test results for 145 detergent products having both chemical and biological data were examined. All of the tested detergents were rabbit eye irritants. Forty-seven per cent were also either rabbit primary skin irritants or corrosives. Eighty-one per cent were either rabbit esophageal test irritants or corrosives, and 80 per cent had rat oral toxicities 5g/kg or less.