Tobacco Documents Online

INDEX HAS INDICATED GAP IN BATES RANGE HERE

-3- animals from the same experiment exposed to smoke diluted 1:8 with air, but assessed by an independent investigator. The final conclusions to be drawn from these combined results, in relation to the design of relatively short-term irritancy snudies, will be reported separately. BAT Co LTD - MINNESOTA TOBACCO LITIGATION o (..j-i o-,, -,..j

INDEX HAS INDICATED GAP IN BATES RANGE HERE

-4- V V I N'I~, DUCTZON Eerli.er complrat~ve ~nb211eCion toxicicy studies carried out in Chess laboratories have involved the treatment of animals with smoke for approx~matel7 6 weeks (i, 2, 3), as sugiested by guidelines relating to the assessment of smoke toxicity (4). These experiments consistently produced smoke-induced changes Ln rat lunZ structure which wre related Co the duration of exposure end the desree of d~Lut~on of smoke. However, it was not kno~m vhethez an exposure period of 6 weeks was, in fact, optimal for such short-term irrltancy studies. The purpose of the experlmenC described in this report ~ts three-fold: (i) Co determine the C~ne-course of the funs pathology chanses induced over a 6 week period. (il) to determine how such changes developed as smoke-exposure was extended up to 12 weeks. and (iii) to determine the effect of stopping smoke exposure on the changes in lung structure produced by 6 weeks of treatment. ~TERZALS AND METHODS Cigarette Type Filter cigarettes (Code H3gl) used for the exper/~ent were made from a standard flue-cured blend (Blend 72). TPM delivery from this cigarette to the sn~nal exposure chamber, when smoked under standard conditions on the inhalation system, was 19.6 ms/ci2aretce. The cigarette burned to a bucc length of 25 mm in 10 puffs. BAT Co LTD - MINNESOTA TOBACCO LITIGATION c~ ................................................ --"T

INDEX HAS INDICATED GAP IN BATES RANGE HERE

-5- Animals White albino rats (Strain CFH~) were suppl~ed by Angl£a Laboratory Antis. The average weiKhts o£ animals on arrival at the laboratory were; males 200 S, females 170 g. AC chase weights, the animals were approximately 50 days old. Animals were kept 6 per case on autoclaved wood shavinss and had free access to food end water. Exposure System In this experlmant, an/~als were subjected to frmsh, diluted smoke on the 5-port version of the B.A.T exposure sTstem (5). A clean machine, exclusively fOE the "sham-smokinK" of rats, was used to provide appropriate treatment-control animals throuehout the study. Exper imencal DesiEn The b~sic desist of the study is shown in ¥iKure I. i. Groups of animals were exposed for varylnK periods up to a total of 12 weeks (ProKrassion). Ln this part of the exper£ment, an/male were k£11ed on ~he de7 £mmed£ately foILowinK their last exposure to smoke. 2. Ocher groups of rats were exposed to smoke for 6 weeks, and then held for up to 6 weeks without further exposure to smoke Cl~sression). ~t was not possible to expose aLL the Stoups of animals simultaneously, therefore the start of the e~per£maut was staKKered. The animals in Stoups I to 7 and 19, plus those in the approprLate control Eroups, were delivered at the same time. A second delivery of animals, of slm£1ar eke and weisht tense, was made 5 weeks Later. These animals £o~med Stoups 9, iO, Ii and ~heir case conErols. One treatment Stoup (6 weeks cr~ BAT Co LTD - MINNESOTA TOBACCO LITIGATION

INDEX HAS INDICATED GAP IN BATES RANGE HERE

-6- exposure) was duplicated (Group I and Group 9) so chat comparisons can be made between ohm animals of the first delivery and chose o5 the later one. For each o£ these two phases of the whole experiment, groups of animals were exposed Co smoke diluted 1 in 8 or 1 in 12 with air. One mddlcional group (Croup Ig) was exposed at the max/mum toierable smoke concencratlon (dLluc£ou Level I in 7) for g uetks. AC all chess dilution levels, animals were routinely given 2 x i0 mLnuCe exposures (4 hours between exposures) pmr day on weekdays, and I x lO minutes exposure on Saturdays and Sundays. Exposure o£ anneals to smoke began on l~th September 1975 and the experiment was compleced on lath December 1975. Each rime smoke-exposed animals were killed, corresponding sham- smoked end case conCrol cars were also Oaken. All groups comprised 6~ and 6~ rats, except the group exposed ac I in 7 dilut£on, which contained 12c~a~,d 12~ rats. In all 468 animals were used. Observations TPI4 deliveries from the cigarette to the puf£ generation unLt of the inhalation system and to the exposure chamber icsel£ were decermined gray/metrically, alter collection of particulates on Cambridge ££1cer pads. Smoke concentration within the exposure chamber was zmasured regularly £or e~ch o£ the 3 smoke dilutlon levels used in the experiment. Throughout the experi~nent, blood carboxyhaemoglobin levels of samples were measured as soon ms possible alter exposure to smoke. Blood samples £rom anaechetised animals (Ketamine hydrochloride I0 mg/lOO g bodywe£ghc) were taken [rom the orbital s£nus and analysed using an lnscrumentacion Laboratories CO-Ox~mecer. BAT Co LTD - MINNESOTA TOBACCO LITIGATION ¢...,m

X QO BAT Co LTD - MINNESOTA TOBACCO LITIGATION

-7- Growth curves and terminal bodywe£ght data collected from previous studies have shown that exposure to smoke end sham-smoking of animals retard their rate of growth. To investigate this effect further, throuKhou~ this study average food consumption of animals was determined on alternaue days. Food hoppers on the cakes, were filled with weighed amounts (400 g) of dried, pelleted food. The food was reweiEhed on the t following day and the average food consumaptlon per rat per day calculated. Individual bodyweights of animals were routinely recorded three times per week throughout the study and the final bodyweight of each animal was determined iuusedLately before post-aortae examination. All mortalities, with appropriate details, were recorded. This study was the longest experiment to date carried out in our laboratory. Bearing in mind the potential r£ek of infection of animals held for lone periods, it was considered worthwhile to monitor the level of contamination of the air in the downstairs inhalation area of the Life Sciences Building, as an index of the general standard of cleanliness within the animal unit. To do this, 9 cm plates of blood egar were exposed for 15 minutes in the work areas. Plates were incubated at 37°C and counts of colonies made after 2 and 5 days of incubation. Te.rminal Studies Autopsy technique, histological examination and quantitative microscopy have been described (6). The weights of heart, thymus, combined InnK and trachea from each animal were recorded az pos~-mDrcem. The following sections were =ned in dar, a£l for each animal in the study: larynx (transverse to include the central depression and free edge of vocal cords), trachea (transverse to include tracheal and thyroid glands), (single left lobe including the main intrapulmonary bronchus and the maximum amount from the 3 right lobes). BAT Co LTD - MINNESOTA TOBACCO LITIGATION