LANOLIN ALLERGY? 153 tests on 50 human subjects indicated they are not primary irritants. Kligman (29) reported another test for irritancy before the SOCIETY OF COSMETro CHEMISTS. Tested with this procedure both lanolin and the liquid lanolin showed "a remarkably low order of irritancy... ex- traordinarily innocuous for human skin" (30). Acute Oral Toxicity This is a basic test for any cosmetic or ingredient which may be in- gested, even if accidentally. Rats are fed successively increasing doses of the materials to determine the minimum amount, if any, required to kill 50% of the animals. In the instance of lanolin, its liquid fraction and other lanolin derivatives relatively massive doses are tolerated (31). Rabbit Eye Irritation The usual method of test for eye irritation is that described by Draize (26). Such tests on lanolin and some of its derivatives consistently show a very low order of irritation (32). Goldemberg (33) pointed out the possibility of formulating with anti-irritants, that is, substances which might reduce the irritancy of other materials. Russell and Hoch (34) reported that the addition of the liquid fraction of lanolin to deter- gent systems seems to reduce the eye irritation of the detergent system. Ser•sitization and Allergenicity One test for sensitization involves the intradermal injection of the test material in guinea pigs over a period of days, followed by a challeng- ing injection. Areas of the wheels resulting from the final injection are compared with average responses in the previous ones. A substantial increase in response to the final injection is considered evidence that the material is a sensitizer. Human testing is generally considered more desirable. Klauder (35) feels that such predictive patch testing using as many as 200 human subjects would only begin to detect allergenicity at about the mid-region of a scale of materials "where at one end of which allergenicity is very rare (lanolin) and at the other end it is fre- quent (paraphenylenediamine)." Regardless of this feeling, the repeated insult test is considered desirable. In the case of lanolin and the liquid fraction of lanolin such tests on 25 human male and 25 human female subjects (36) indicate these materials are not sensitizers. Silverman (37) studying a suppository base containing 40% of the liquid fraction of lanolin reported a similar result.

154 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS CAUSATIVE FACTORS IN LANOLIN ALLERGY With respect to the relatively few cases of allergy attributed to lano- lin it is significant to note the lack of agreement as to the causative factor involved. Some researchers have made fairly definite statements as to the nature of the allergen. However, the results have been at best con- tradictory. Sulzberger and Lazar (9), for example, in their report on four lanolin sensitive patients stated that the allergen was a constituent or constituents of the mixed alcohols. It did not seem to be present in other fractions of lanolin such as the mixed fatty acids, cholesterol, or lanosterol. Then Sulzberger et al. (10) and Warshaw (11) in their con- tinuing studies felt they had isolated the allergen in the mixed aliphatic alcohols. They also got occasional positive reactions from the extracted fatty acids of the same source which could cause some doubt both as to the purification of the fractions and to the nature of the allergen. They also reported that modification of the lanolin and the aliphatic alcohols with acetyl radical reduced the incidence in some but not in all cases. Schwarzreid (8) in his report of ten cases found that two were sensitive to lanolin and Aquaphor, four were sensitive to lanolin alone and four were sensitive to Aquaphor alone. Then, Fanburg (38) cited a case of contact dermatitis due to Aquaphor. This patient gave a positive reac- tion to "purified cholesterol esters" derived from lanolin but gave a negative reaction to lanolin itself. Following the Sulzberger et al. reports, Everall and Truter (13) tested further successive fractions on their one lanolin-sensitive patient--going beyond the Sulzberger experiments. The patient reacted negatively to extracted aliphatic alcohols on the other hand, there was a positive reaction to the crudely extracted cholesterol. Then, on purification of the cholesterol, they got a negative reaction. They finally isolated a yellow, glassy solid which they considered an impurity and to which the patient had a positive reaction. This material was not further identi- fied. Acetylation of the "impurity" gave a negative reaction. Klauder and Ellis (18) tested their five lanolin-sensitive patients with the oil solu- ble liquid fraction of lanolin. All five were negative to the liquid lanolin. They tested four of these patients with the solid waxy fraction* ob- tained from lanolin by the same process and also got negative results. Ellis tested one of the patients with wool wax fatty acids and aliphatic alcohols and got a negative reaction another gave a positive reaction to cholesterol. * Lanfrax©-Malmstrom Chemical Corp.