Document LpNv2gNBE81gvQQMRJRpBwrqX

On the Absorption of Tetraethyl Lead Out of Lubricating Oil A brief report of experimental observations carried out to determ ine the general magnitude of the potential hasard of lead absorption among persons who may handle lubricating oil containing sm all am ounts o tetraethyl lead by Robert A , Kehoe In consideration of the fact that a d istrib u to r of lubricating oil has expressed a v?ioh to purchase tetraeth y l lead from the Ethyl Gasoline Corporation for use in the preparation of a special lubricating oil, it has seemed desirable to investigate various aspects of the potential health hazards which may be hypothecated as an outgrowth of the addition of tetraethyl lead to m otor lubricants. The problem which is the subject of discussion and experim ents h erein , has to do only with the absorption of tetraethyl lead out of lubricating oil. This problem has been investigated by methods sim ilar to those which were employed to determ ine the extent of the absorption of tetraethyl lead out of gasoline. Experim ental Methods ... ' * Healthy full grown rabbits were selected. A fter a brief period of observation in order to establish the healthiness of the anim als, they were p rep ared fo r the experim ental procedure by clipping the h a ir from their fore legs. On successive days, each anim al was held with a fore leg dipped in a known concentration of tetraethyl lead in oil, (Stanavo, Viscosity 120, as supplied by Standard Gil Company of Ohio), for a period of half an hour. A fter the exposure,the skin of the animal was cleansed as thoroughly KE 00034S N6626 2 which th e Ida was generously coated with, white p arrafin oil In o rd e r to prevent undue injury from it contact with the kerosene. The viscosity of the oil and its tendency to spread beyond die treated area* as well ae the necessity for gentle handling of the animals m ilitated against the complete cleansing of the skin. Thus a certain skepticism existed with regard to the quantitative removal of the lead-oil solution. The data will dem onstrate that such skepticism was fully justified. Nevertheless since such technical difficulties could confidently be expected to bring about high results rather than low* it was believed th at such e r r o r s a s m ight o ccu r would be on the aide of an increased severity in the te st conditions. The animals were fed in the usual m anner and kept under observa tion. Necropsies were perform ed soon after the death of anim als that died in the course of the experim ent. Certain surviving anim als were killed at suitable tim es and examined for pathological changes. The tissues of the anim als were analysed to determ ine th eir lead content by means, of methods which we have employed previously in sim ilar experim ents on the absorption of lead out of leaded gasoline* Experimental Observations _ ' I. T hree rab b its w ere subjected to contact with oil containing 10 p er cent of tetraethyl lead by volume. Rabbit #388 was so subjected on 2 succes sive days. He became ill and died on the second day after the second period of contact further manipulation having been suspended because of bis apparent illness. Rabbit #38? was subjected to such periods of contact on 5 succes sive days. He was only slightly ill until the day after the fifth period of K? 0003482 W t: j 3. ' . . ened and died th ree day* after the la st (fifth) period of contact. Babbit 386 becam e lit with in te rc u rre n t sin u sitis and o titis daring the course of the experiment* after having been subjected to three periods of contact. The experimental manipulations were^us pended, the animal recovered* and is apparently well a t p resen t, (Two and a half months a fte r the la st period of contact.} The analyses of the tissues* carried out in such a way as to differ entiate alim entary lead from that in the rem ainder of the carcass* appear in Table l . Attention is directed to two points in the data; (a) the gross amounts of lead found in the tissues a re sm all a s com pared to those found in the tissu es of an anim al subjected to s im ila r contact with a 10 p e r cent solution of te tr a ethyl lead in gasoline (after 3 half-hour periods of contact with such gasoline* a rabbit was found to have 36.46 m gs. of lead in its tissu es); (b) the amounts of lead a re especially high (Cf, Babbit #387) in the alim entary tract* indicating that the anim als swallowed lead in licking the grease cream from th eir con tam inated skins, as they were seen doing regularly after being returned to th eir cages. It seem s apparent* therefore* that the oil was absorbed m ore slowly through the skin of the anim als from this oil than it had been from gasoline. Additional evidence that this was the case is derived from the fact that one out of three anim als survived* while all th ree of tho rabbits previously reported a s having been subjected sim ilarly to contact with gasoline containing 10 p e r cent tetraethyl lead* died as the resu lt of th ree such contacts. X2. T hree rab b its w ere subjected to a corresponding type of contact with oil containing 1 p e r cent of tetraethyl lead in oil. This experiment* con sidered as of m ore significance than that previously described* was carried out over a longer period of tim e. Thirty periods of contact of half an hour HE 0003483 each, ^ ^ - r w ere ca rrie d oat. On account of the evidence of lead ingestion obtained in the first set of observations, m ore tim e and atten tion was given to cleansing the skin after each period of contact. After the period of contact, th irty -first / the anim als were killed, and th eir tissues were prepared for analysis by separation in accordance with the lis t shown in Table 2. The skin was removed and discarded with the utm ost precaution against contamination of the tissues beneath it. The other tissues were analysed in their entirety. The analytical resu lts a re recorded in Table 2. The amounts of lead found in the tissues are not g reater than those which a re found commonly in those of norm al an im als. One re su lt (the h e a rt of Rabbit # 3891 was a b e rra n t, apparently the resu lt of contamination of the sample either in process of preparation o r in the course of the analysis. This resu lt can be ignored entirely as irrelevant, since it is not possible that it could have been due to the absorption of lead during the experim ent, in view of the otherw ise negative findings. Attention should be called especially to the absence of lead in the tissues of the central nervous system . Summary and Conclusions (l) The foreleg of each of th ree rabbits 'was im m ersed in a ten p er cent solution of tetraethyl lead in lubricating oil. One anim al died as a K 0003484 resu lt of two such im m ersions, each continued fo r half an hour on successive days; another died after five such periods of contact; another survived after three such periods of contact, despite a complicating intercurrent illness (an acute suppurative sinusitis and otitis). Analytical evidence indicated that a portion of the lead found in the bodies of the anim als was the result of ingestion due to the practice of the anim ats of licking them selves after the lad found wr conoid rably loss than those which resulted from sim ilar i contacts of the skin with a 10 p er cent solution of tetraeth y l load in geeoline. (} Sim ilarly, th re e rabbits w ere subjected to contact, repeatedly, asiti* a i p er cent solution <ti tetraeth y l lead in o il. The anim als did not sicken, but rem ained healthy through the period of 6 weeks during which they were subjected to contact with the oil for half an hour per day on each of 30 days (5 days per week). A nalyses of th e ir tissue at the end of th is period failed to disclose evidence that lead had been absorbed through their skin. It is concluded that the rate of the percutaneous absorption of i tetraethyl lead out of lubricating oil is mateyaily less than that out of gasoline, and th at no appreciable absorption occurs when the concentration of tetraethyl lead in the oil Is equivalent to 1 per cent or less, by volume. The experim ents have failed to yield evidence ci the likelihood of the uasard of percutaneous .hoxpile of lead among parsons who m ay handle lubricating oil containing loss than 1 per coat oi tetraethyl lead. A p ril - June 1933 to ^ 000348 Table I Lead In T issues of Animals Subjected to Contact oi Their Skin with Oil Con 10 p er cent o f Tetraethyl Lead Tissues Entire leg subjected to contact, including skin Intestinal tract and contents Remainder of carcass exclusive of skin Total lead found in tissues* Lead Found in MUdigram s Rabbit #387 S-half hour periods of contact Died 3 flays afte r la s t period of contact R 2-half hour Died 2 days c 0.40 11.19 4.12 15.62 * All the skin of the body with the exception of that on the leg subjected to contact was disca Tabi 2 Lead la T issues o f A nim als Subjected to Contact with Oil Containing i P er Ge Tetraethyl lea d Tissues Kidney* Liver Spleen C.N .S. bluscle H eart1 1 1 Lungs Bone Intestinal Tract' Remainder Total ' * Obviously a contaminated sample ** Exclusive o f the aberrant result Rabbit #389 0. IS 0.02 0.00 0.00 0.03 1.17 * 0.00 0.23 0.34 0.29 * 1.06 ** Lead Found in MilUgraras, isabbit I39 -* 0.09 0.06 o.oo 0. 00 0.03 0.00 o.co 0.12 ' *9* o* 0 . 16 0.71 i