THE INULA. RUBBER WORLD 



Poisons in the Rubber Industry. 



The Rash Produced by Hexamethylene-Tetramine and a Means of Prevention." 



By Norman A. Shepard and Stanley Krall. 



TiiiiuGH THE OCCURRENCE OF .\ RASH among rubber workers has 

 long been observed it is only recently, since the introduc- 

 tion of organic accelerators of vulcanization, that the skin 

 eruption or dermatitis has been at all serious or prevalent. By 

 1917. however, the problem had become so general that the Rub- 

 ber Section of the American Chemical Society requested its 

 Committee on Organic Accelerators to investigate the toxic 

 properties of the more commonly used accelerators. The report' 

 of this committee which was presented in September. 1918, at 

 the Cleveland meeting of the Society brought out the fact that 

 most of the common accelerators had distinctly poisonous 

 properties. The report covered aniline, paraphenylenediamine, 

 thiocarbanilide, p-nitroso dimethylaniline and hexamethylene- 

 tetramine ; it emphasized the necessity of studying accelerators 

 not only from the standpoint of the accelerating action but also 

 as regards poisonous properties. 



In the study of accelerators, the Firestone Research Laboratory 

 has devoted much attention to the question of toxicity, with the 

 purpose of finding an accelerator combining excellent acceleration 

 with a minimum of toxic action. Knowing that many rubber 

 companies are using hexamethylene-tetramine or "Urotropin," it 

 was thought that a study of the to.xicology of this substance 

 would be of interest not only to ourselves, but also to those who 

 are already using this accelerator. The investigation has been 

 extended to cover the probable cause of its action and to find, 

 if possible, an antidote or simple means of prevention. 



The action of hexamethylene-tetramine was summarized in the 

 Report of the Committee on .\ccclerators as follows : 



SvMPTo.MS OF PoisoxiNG. — Rash and inflammation of skin 

 which has been in repeated contact with stock containing this 

 material. In severe cases, blisters filled with watery fluid result. 



Antidote. — Cleanliness and care in regard to clothing are the 

 best preventatives. Change of occupation will cause the rash to 

 disappear, leaving no permanent effects. 



This description agrees closely with that taken from the 

 United States Dispensatory' in which it is stated that, "Locally, 

 hexamethylene-tetramine is mildly irritant and feebly antiseptic. 

 A measles-like rash with much itching has been noticed after 

 its continuous use." 



In order to study the nature of the irritation ascribed to this 

 accelerator, the tetramine was applied in powdered form and in 

 water solution of various concentrations to different parts of the 

 body. Five men from the Research Laboratory were selected 

 for these tests and applications were made on the wrist, fore- 

 arm, chest and thigh. These applications were repeated several 

 times each day for several days, yet there was no irritation or 

 indication of rash in any case and not even the slightest itching. 

 Thinking that possibly the perspiration might function in the 

 production of this rash, applications were made on the feet and 

 even under the arm-pit, where the perspiration flows most 

 freely, .^gain, no action could be observed. Even applications 

 following a very hot bath, thoroughly opening the pores and 

 causing a typical "sweat," resulted in no irritation whatsoever. 



As a result of these negative experiments, it was decided to 

 introduce this accelerator into a factory compound in order to 

 study its effect under actual working conditions. The workmen 

 handling this particular experimental stock were carefully 

 observed, .^t the time this test was begun the weather was 



'Contribution from the Research T^boratory or the Firestone Tire & 

 Rubber Co.. Akron. Ohio. 



* "Journal of Industrial and EngineerinR Chemistry," Volume 10, 1918, 

 page 865: Tne India Rubber WoRJ-n. November I, 1918, page 82. 



quite cool and for some time no deleterious effect was observed. 

 However, with the approach of warmer weather the action of 

 hexamethylene-tetramine began to manifest itself. It usually 

 appeared first as a rash on the wrist or forearm, and in many 

 cases was confined to these parts. The action became more 

 pronounced, however, when really warm weather arrived ; not 

 only the forearms, but also the face and neck became involved 

 and to such an extent in certain cases that a large portion of 

 the face was affected, especially around the eyes. In general the 

 inflammation was confined to the exposed parts, though occa- 

 sionally it appeared on the shoulders, legs and even across the 

 stomach. There seemed, however, to be no tendency for this 

 rash to spread to any great extent beyond the parts which 

 actually came in contact with the stock ; the cases on the face 

 and neck probably resulted from contact with the hands. 



The dermatitis produced by contact with the stocks containing 

 hexamethylene-tetramine was indentical with that described by 

 Kratz* in an article on the "Control and Prevention of a Rash 

 Among Rubber Factory Employes," though his paper mentions 

 no particular accelerator or other substance as the cause of the 

 rash. Quoting from this article, "The rash almost invariably 

 the heat. This condition is closely followed by the appearance 

 appears as a simple erythema, such as is generally attributed to 

 of sac-containing eruptions or vesicles similar to those charac- 

 teristic of ivy poisoning. These vesicles are quite small, seldom 

 being larger than pin-heads and are grouped in varying arrange- 

 ments, from being widely disseminated, to quite closely aggre- 

 gated. They rarely retain their integrity for more than 48 hours, 

 being broken by friction from the clothes or by the jjatients' 

 rubbing and scratching, or, if this does not occur they soon be- 

 come filled with a watery serum and rupture spontaneously in 

 consequence of the exuded fluid." 



The perspiration undoubtedly plays an important part in the 

 production of this rash. It becomes almost epidemic with rise 

 in temperature. Following a few hot or sultry days productive of 

 profuse perspiration, a marked wave of rash will spread among 

 the men handling the raw hexamethylene-tetramine stocks; a 

 few cool days and it subsides, only to reappear again when the 

 hot weather returns. This observation also agrees with that of 

 Kratz, who writes, "Though the rash is most prevalent during 

 hot weather, particularly in humid midsummer, it certainly can- 

 not be attributed solely to the heat ; nevertheless the abnormal 

 perspiration produced by the heat undoubtedly does play a part 

 in rendering the skin most tender and susceptible to infection. 

 Throughout the factory the fundamental cause of the rash will 

 probably be traced to the irritation produced by the careless 

 handling of green stocks or liners." 



On studying the situation closely for several months and dur- 

 ing the hottest weather, a marked immunity to the action of the 

 hexamethylene-tetramine was observed. Only a small per- 

 centage of those handling the stock was afTected. One would 

 find right next to an especially virulent case, men performing 

 exactly the same operations and handling the same stock, abso- 

 lutely free from any sign of irritation. This undoubtedly ex- 

 plains the negative results which were obtained in the laboratory 

 when the strong solutions of hexamethylene-tetramine were first 

 applied. In order to prove that the hexamethylene-tetramine 

 was really responsible for the trouble, a patient was selected for 

 experimentation from among those who had shown themselves 

 susceptible to this rash. This patient had had the rash very 



'The India Ri-bber World, Volume 5", 1917. page H5. 



