DERMAL TOXICITY OF SODIUM LAURYL SULFATE 139 four were maintained with intact integument. In the control group, the distribution of the abraded and intact animals was one and two, respectively. Dosage was incorporated to provide 6, 60, and 125 rag. SLS per kg. in 0.5 mi. of water. Dosage was applied daily, five days a week, for a total of 65 applications using a syringe for delivery of the required volume. Animals were kept in stocks for six hours and allowed food and water ad libitum each day. They were removed from the stocks and returned to their cages at the end of six hours. Clinical blood values including total erythrocyte counts, hematocrit, hemoglobin, total and differential leukocyte counts, blood glucose and urea nitrogen concentrations, and urine analyses were conducted initially prior to start of dosage and at 21 and 90 days. All the abraded rabbits and one male and one female each of the intact skin group were sacrificed at 21 days and the remainder of the intact animals at 90 days. Those that died and the survivors were autopsied and all major tissues fixed in 10% formalin. Nine tissues including thyroid, pancreas, heart, liver, kidneys, adrenals, skin, brain and bone marrow were processed, stained with hematoxylin and eosin and examined microscopically. RESULTS ./tcule Dermal Studies in Rabbits. The data for the acute derreal L.D.50 value in rabbits are shown in Table I. Additional information shown in this table includes the mean primary irritation score, body weight changes and appearance of the skin at the site of application after 14 days. The acute derreal L.D.50 value, determined by the method of Miller and Tainter (3), was 580 4- 138 rag. per kg. of body weight. Tremors, tonic-clonic convulsions and respiratory failure were characteristically seen. TABLF• I--AcvTv. DE•tMAL TOXICITY O}' SODIUM LAURYL SOLFATE (SLS) IN RABBITS* Primary Net Change Dose, Irritation in , --Mortality------ Terminal Skin mg./kg. Scorer Body Weight % days Appearance 150 4.0 q-0.02 10 11 Slight scaling 300 4.0 -0.10 20 3, 11 Scaling, wrinkling 600 3.0 --0.13 40 2, 3, 4, 14 Scaling, wrinkling 1200 4.2 ... 80 2 to 6 Leathery 2000 3.8 ... 100 1 to 4 * Mean data for 10 male rabbits. p Scored at 24 and 72 hr. Atcute Derreal Studies in Other Species. The results of studies in rats and gu'inea pigs are shown in Table IIa. Mortality at the doses shown generally confirm the order of magnitude of the lethal dose and the signs observed following SLS administration in rabbits. The comparison using SLS derived from different sources is shown in Table IIb. lntravenous Study in Rabbits. Attempts to administer a dosage

140 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS TABLE IIa--CoNFIRMATORY TOXICITY STUDIES OF SLS IN OTHER SPECIES Number Mortal- Dose, of ity, Species Route mg./kg. Animals % Symptoms Guinea pig Dermal 1200 4 Guinea pig Dermal 2000 4 Rat Dermal 2000 5 Rabbit Dermal 1200 4 (Transected) Rabbit Intravenous 121.2* 4 0 None 100 Tremors, convulsions, prostration, death 16-20 weeks 100 Hyperpnea, tremors, tonic-clonic con- vulsions 100 Respiratory failure-- no other symptoms 100 Tremors, convulsion in 3.5-5.8 min. * Animals died during the administration of material by slow intravenous injection dosage was calculated from volume injected (117.6, 161.3, 133.3 and 72.7 mg./kg.). TABLE lib--ACUTE DERMAL TESTS IN GUINEA PIGS WITH SLS DERIVED FROM DIFFERENT SOURCES Number Mortal- Dose, of ity Source mg./kg. Animals % Symptoms A complete formulation 2000 6 SLS (U. K.) 2000 6 SLS (U.S.) 2000 6 SLS (U.S.) 2000 6 100 Convulsions and respiratory failure 100 Convulsions and respiratory failure 100 Convulsions and respiratory failure 100 Convulsions and respiratory failure equivalent to the derreal L.D40 by slow intravenous injection resulted in typical tremors and tonic-clonic convulsions, followed by respiratory failure. It was impossible to administer the anticipated dose, death occurring during the infusion process. The volume given was noted and the dosage equivalent calculated. These likewise confirm both the events seen and the order of magnitude ot the toxic dose. The mean L.D400 value for the animals dosed was 121.2 rag. per kg. Spinal Transected Rabbits. Administration of an acute L.D.80 dose of SLS to the operatively prepared animals resulted in the death of the rabbits (Table IIa). The characteristic tremors and convulsions seen in the intact animals were not seen in the spinal transected rabbits, indicat- ing that the ascending central phenomena were controlled however, respiratory failure followed. At autopsy extensive dilation of the right auricle was noted, indicating right side failure commensurate with type of respiratory death. Subacute Ninety-Day Study in Rabbits. No untoward behavioral •nanifestations were seen in this group. Evidence of central nervous system involvement was lacking, even at the highest dosage levels. The growth responses of the rabbits exposed five days a week are shown in 'Fable III, together with their fate and primary irritation scores.