90-Day Inhalation Study with Cigarettes containing G7-25 Calibration of Air Sampling Instruments the calibration period, the diluted smoke will The measurement of flow rates is of be directed to equilibration chambers until a critical importance in inhalation toxicology. steady concentration is achieved. Then the The inhalation exposure system will use diluted smoke stream will be directed to the several different instruments to measure flow inlet manifold on the animal exposure chamber rates. and the exposures will begin. Animals will be Two primary standards will be used : placed on the exposure trays during the soap bubble flow meters (Series 823, Mast equilibration of the smoke generator; during Development Co., Davenport, IA) for flow this time animals will be exposed to an rates up to 5 liters per minute (LPM), and adequate supply of dilution air. certified dry gas meters (Singer DTM 115, During animal exposures, several of the American Meter Company, Philadelphia, PA) ports will be used for monitoring the aerosol for flow rates above 5 LPM. A variety of presented. Two ports will be used for secondary measuring instruments, including collection of WTPM on 44 mm glass fiber pressure differential devices such as the CME filter pads (Model 1021215P1, Cambridge (MIE Corp., Manassas, VA) will be used for Filter Corp., Syracuse, NY). Filter pads will routine measurements; these instruments will be pre-conditioned at 40-60% RH before use. be calibrated against the primary standards. Nicotine on pads will be estimated using Smoke generation. standard analytical techniques. WTPM will The smoking machine has been also be monitored on line from a third port, described previously (Baumgartner & using the output from the RAM-1 instrument Coggins, 1980); it operates under standard (GCA Corp., Bedford, MA). The output from conditions of a 2-second puff with a volume of the RAM-1 will be displayed on a chart 35 ml, taken once per minute. A number of recorder. modifications have recently been incorporated Ports will be used for monitoring CO into the basic design of the machine (Ayres et and oxygen concentrations. The analytical al., 1990), modifications which have been instrument used for CO will be the Horiba included in the latest models (CH PIR-2000 CO-analyzer (Horiba Instruments Technologies, Westwood, NJ) Inc., Irvine, CA), calibrated daily with Separate exposure devices will be used certified gas mixtures of CO in nitrogen for test and reference cigarettes, and for sham (AIRCO Welding Supply, Greensboro, NC). exposures (total of three devices). Each The output from the Horiba will be displayed exposure device will consist of three 24-port as voltage on a chart recorder and logged on circular chambers. The flow rates of the the printer of the computer-control unit as diluting air streams will be adjusted to ensure voltage and calculated parts per million (ppm, flow rates at each of the animal ports of 350 based on prior calibration). Oxygen ml/min (Coggins et al., 1982). concentrations (%) will be monitored by a Pre-exposure characterization Horiba PMA-200 instrument, also calibrated Before the animal exposures begin, with a certified gas mixture. satisfactory achievement of uniformly One port will be used for the distributed concentrations at or near the targets measurement of particle size distribution, will be documented, for test and reference using a cascade impactor (In-Tox Products, cigarettes. The characterization of each Albuquerque, NM) similar to that described in chamber will be made for WTPM, CO and the literature (Mercer et al., 1970). The nicotine, along with a measurement of particle impactor will have cut-off diameters in the size distribution and oxygen. range of 0.4-2.5 um under the conditions of Daily characterization of inhalation use; calculations of mass median aerodynamic exposures. diameter (MMAD) and geometric standard The puff volume produced by the pump deviation will be made by the use of probit at the cigarette ports will be measured using a analysis. The cover slips (22 mm; Fisher soap bubble flow meter, before each 60-minute Products, Raleigh, NC) used to collect the exposure. aerosol will be weighed using Cahn C-31 Each 30-port smoke generator requires microbalances (Cahn, Cerritos, CA). 10-15 minutes to reach equilibration. During DRAFT: DO NOT QUOTE. Page 4 Source: https://www.industrydocuments.ucsf.edu/docs/ffbb0103