470 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS LABORATORY METHODS Atcule Oral Toxicity Toxicity when ingested in single doses was evaluated by feeding the mate- rial as 10 per cent aqueous solutions or emulsions to unfasted rats by in- tubadon. Groups of five animals each were fed doses ranging in geometric progression from 0.252 to 7.95 g./kg. body weight. Mortality was estab- lished over a two week post-feeding period. L.D.•0 values were calculated by the Well Modification of the Method of Thompson.* Eye Studies The eyes of all rabbits used in this study were established as being free of corneal injury by selecting those showing no reaction to a 5 per cent aqueous solution of fluorescein disodium salt twenty-four hours prior to use. Two drops of surfactant to be tested were applied to each eye of the rabbit. Within 30 seconds one eye was washed for two minutes with flowing tap water. The other eye was left unwashed. Both eyes were evaluated for immediate effects and again after one hour, twenty-four hours, forty-eight hours and one week for conjunctival and corneal injury and for internal effects such as iritis and lenticular damage. Fluorescein was employed in all cases as an aid in assessing corneal injury. Three animals were used for each concentration studied (25 per cent, 5 per cent and 1 per cent aqueous emulsions or solutions). The type and intensity of reaction were rated according to the following index code: Reaction Pain Evaluation Index (Objective Observations) (Reactions by Animal) 1 No effect. 2 Very slight effect, disappearing within twenty-four hours. May consist of appreciable pain initially and some con- junctival irritation. No corneal injury. 3 Slight effect, disappearing within a week. May consist of appreciable conjunctival irritation and pain but no corneal or internal injury. 4 Moderate effect, consisting of superficial corneal injury which clears within a week. Probably no internal effects on eye. No loss of vision expected. Conjunctival irrita- tion may be severe. 5 Severe effect, consisting of serious corneal injury from which recovery will be prolonged. Some impairment of vision may be expected. Internal injury may be ob- served. Conjunctival irritation may or may not be severe. 6 Very severe effect, consisting of total loss of vision due to serious injury to the cornea or internal structure of the eye. Conjunctival irritation may or may not be severe. No response. No more than a few blinks. Normal in a minute or so. Blinks and tries to open eye. Reflexes close eye. Holds eye shut and puts pressure on lids. May rub eye with paw. Holds eye shut vigor- ously. May squeal. Holds eye shut vigor- ously. May squeal, claw at eye, jump and try to escape. * Weil, C. S., Biometrics, 8, 343 (1952).

TOXICOLOGICAL PROPERTIES OF SURFACTANTS 471 Skin Studies Rabbits were prepared by shaving the bellies free of hair with a straight razor and barber soap. After five days, animals free of hair growth were selected as test subjects. Immediately prior to application, abrasions were made with a sharp instrument on the caudal area of the belly. Abrasions were sufficiently deep to penetrate the stratum corneum but not deep enough to result in appreciable bleeding. The test materials were applied to one inch by one inch cotton pads which in turn were held in intimate contact with the intact and abraded skin areas by means of a cloth bandage taped around the entire trunk of the animal. Ten applications of 5 mi. each were made over a period of fourteen days to intact areas. Three similar applications were made to abraded areas. This procedure resulted in continuous contact for fourteen days to intact skin and three days to abraded skin. A small amount of material was likewise applied daily to the intact ear following the application and evaluation program as de- scribed for the intact belly. In no case were applications continued beyond the production of a substantial burn or eschar formation. Skin reactions were observed and recorded following each application and at subsequent intervals up to three weeks from the beginning of the study. The type and intensity of reactions were rated according to the following index code: Index Reactions Essentially no irritation to intact skin. Very slight hyperemia on intact skin, likely more irritating to abraded skin. Slight hyperemia on intact skin, may or may not burn abraded skin. Moderate hyperemia on intact skin, may or may not burn abraded skin. Burn from two to four twenty-four hour applications to intact skin. Burn from one twenty-four-hour application to intact skin. RESULTS AND CONCLUSIONS Atcute Oral Toxicity All materials tested are moderate to low in acute oral toxicity. In Table 1 the L.D.50 values in rats can be seen to range from 0.71 g./kg. body weight in the case of sodium dodecylated diphenyl ether disulfonate to 3.30 g./kg. for lauryl imidazoline. The toxicity by acute ingestion of both sodium dodecylated diphenyl ether disulfonate and sodium lauryl sulfate appears to be appreciably less when in the form of the triethanolamine salt. It is also significant to note that the toxicity of the 1: 1 mixture of sodium dodecylated diphenyl ether disulfonate and sodium lauryl sulfate is lower than would be expected on the basis of the toxicity of the individual components.