Evaluation of modified methods for determining skin irritation.

The premarket testing of household cleaning products for dermal irritancy is best achieved via human testing. Animal dermal irritation testing is generally limited to screening for possible dermal hazard of totally new or unique products or ingredients prior to human testing or to meeting regulatory requirements of government bodies. Alternatives to animal tests are being sought; however, until such time that these alternatives are identified, validated, and accepted by government bodies, the judicious use of animal testing remains a necessity. Modifications to standard animal skin irritation test procedures have been evaluated against human skin irritation results with the objective of defining one method that could be used in place of current standard procedures that differ slightly from one another, and thereby avoid excessive and redundant use of animals. Hill Top Chambers (19 mm) and standard gauze patches (U.S. Department of Transportation procedure) were used to obtain comparative irritation responses for 24 cleaning products, common caustics, and acids in rabbits and humans. Exposure times were 1 or 4 hr, and responses were graded over a 72-hr period. Results indicate that use of the Chamber offers the potential to (1) reduce the number of animals used for skin irritation screening (smaller group size and up to eight test substances/concentrations per animal); (2) eliminate the need for conducting multiple tests to satisfy different governmental requirements; and (3) reduce animal stress by reducing exposure times without compromising the value of the irritancy patch test as a screening tool. When animal data are required, it is suggested that the use of a Chamber and other modifications of traditional test procedures offers advantages that could result in using fewer animals and/or have less potential for producing unnecessarily severe responses in animals.

Automated office hematology instruments.

Evaluation of an automated hematology instrument begins with analysis of one's practice needs, followed by analysis of initial start-up costs, cost of maintenance, and staffing. In one situation, the decision to purchase an automated instrument may allow personnel working with low-efficiency pipetting and slide chamber counting time to assist in other functions of the clinic. In another practice, an automated counter may permit in-office complete blood counts to be added to the workload of current staff. These instruments are more than time-saving conveniences. They can facilitate clinical decision making and monitoring for complications of disease and therapy by making it easier for the physician to obtain reliable hematologic results. They can generate additional practice income and reduce patient cost by improving the quality and efficiency of medical care.

Human and rabbit eye responses to chemical insult.

Groups of eight human volunteers and eight albino rabbits, under controlled laboratory conditions, were exposed in one eye without subsequent rinsing to the same concentrations and volumes of four prototype consumer products: fabric softener, shampoo, hand soap, and laundry detergent. Dose volume was 0.10 or 0.01 ml. The dose concentrations were selected to produce moderate effects with recovery within 24 to 48 hr. Two irritation scales were employed with both human and animal subjects: the Draize scale by a technician and a medical scale used with slit lamp examination by an ophthalmologist. Eyes were examined by both graders before and after dosing at specified intervals until recovery. Mean and maximum irritation scores are presented for each grading time, method, and exposure, as are the mean hours to recovery (clearing) for each exposure. Recovery times for human eyes were consistent with those reported previously for accidental human exposures to similar materials. Correlation coefficients for time to clear, comparing human vs rabbit for each dose volume-species combination across the four test products, were 0.72, 0.1 ml-human vs 0.01 ml-rabbit; 0.66, 0.01 ml-human vs 0.01 ml-rabbit; 0.40, 0.01 ml-human vs 0.1 ml-rabbit; 0.35, 0.1 ml-human vs 0.1 ml-rabbit. Thus, recovery time obtained under conditions of the "Low-Volume" test (0.01 ml-rabbit) better correlates with human eye recovery time (either dose volume) than does recovery time under Draize test conditions (0.10 ml-rabbit).(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of DNA-strand breaks in rat testicular cells after in vivo treatment with sodium fluoride.

Oral administration of up to 84 mg/kg of NaF to adult male rats did not induce DNA-strand breaks in testicular cells when measured by alkaline elution. Although plasma fluoride levels were as high as 12 ppm is rats given 84 mg/kg of NaF, testicular fluoride levels in most cases were only 10-20% of plasma levels. Fluoride did not accumulate in the testes after 5 daily treatments. Therefore, it is unlikely that NaF, even at high doses, poses a hazard with respect to heritable genetic effects.

New method for determining eye anesthesia in an animal model.

Some chemical which are injurious to the eye may also cause anesthesia. If the eye were unknowingly anesthetized, exposure to an irritant could go undected and cause injury. Techniques for determining whether the eye was anesthetized have been generally unreliable. Usually the technique consists of challenging the cornea with a probe and testing for a blink response. In a new method described herein, an indwelling subpalpebral lavage apparatus was surgically implanted in the dog. Through this apparatus, a test material was instilled into the eye without the animal's anticipation. Responses caused by the materials were monitored by electroencephalography. The normal response to an irritting material was increased frequency and decreased amplitude of the electroencephalogram tracing or a deflection of thepolygraph needle (blink response), or both. The method was evaluated with known eye anesthetic agents and appeared to be a useful way of detecting eye anesthesia.