Science
Air transport worries threaten technetium-99m Nuclear medicine meeting airs concern over recent actions to bar certain radiopharmaceuticals from passenger flights Continued use of technetium-99m, a radiopharmaceutical employed in the diagnosis of many diseases in more than 5 million patients every year, may be in serious jeopardy, according to many of the scientists and physicians who attended the 21st Annual Meeting of the Society of Nuclear Medicine in San Diego. Their concern was heightened by recent activities of airline pilots and flight attendants who are becoming increasingly reluctant to carry radioactive materials on commercial passenger jets, as has now become standard practice. The fears of those attending the SNM meeting weren't relieved by the announcement in mid-conference that Trans World Airlines was declaring an embargo on the shipment of hazardous materials—including radiopharmaceuticals—as of midnight, Friday, June 14. TWA apparently moved in response to strike threats from pilots and flight attendants who believe that the radiopharmaceuticals might be a threat to their lives or the lives of their passengers. Before the SNM meeting ended, TWA clarified its position, stating that its ban didn't apply to technetium-99m for the time being. But that did not put an end to the growing controversy, which was aired in detail at an SNM symposium on air transportation of radioactive materials for medical use. Central to the issue are portable molybdenum-99 generators that produce technetium-99m through radioactive decay while en route from manufacturer to physician. Technetium-99m, described as the "heart, soul, and core of the radioactive diagnosis business" by one physician at the SNM meeting, acts as an imaging agent to diagnose or trace the progress of brain tumors, strokes, liver disease, clots, and bone tumors. Physicians argue that passenger jets are the only way that the molybdenum generators can be shipped over the weekend so that they will arrive on Monday morning when hospitals most urgently need them. They point out that air cargo lines do not maintain de-
pendable schedules in the same period and guarantee no backup measures if the radiopharmaceutical is delayed somewhere along the way. In the generators, the molybdenum99, with a half-life of 2.8 days, is carried in solid form on an ion exchange resin and decays continuously to technetium-99m, which has a half-life of six hours. When a generator arrives, a physician-user may remove the technetium-99m from the column as needed by washing the resin with physiologic saline solution. In 1973 more than 100,000 molybdenum generators were shipped by commercial passenger jets. "Because the molybdenum-99 generators, ranging from 50 to 500 millicuries in initial activity, decay to one fourth that amount in five days, they must be shipped over the weekend to the hospitals and clinics that use them," says Dr. Jack K. Goodrich, chairman of SNM's transportation committee. "If they do not arrive on time, a patient may have to extend his stay in the hospital or be treated by diagnostic techniques that have much higher risks. These include delicate cardiac catheterizations, carotid arteriograms, pneumoencephalograms, and the like." Echoing Dr. Goodrich's sentiments, Dr. James J. Smith, chief of the Veterans Administration's Nuclear Medicine Service, remarks, "We just don't have the right to say that the patient shall not have these treatments." Spokesman for the air crews' position was Capt. Rod Gilstrap, chairman of the aeromedical committee of the Air Line Pilots Association, who says, "We have no doubt that every physician has a proper and humanitarian use for the radioactive materials that he uses in his practice. However, in our business, safety comes before all other considerations. If this conflicts with other organizational methods, we are sorry, but our responsibilities require that we have not only a safe operation, but the safest operation." Flight crews first became wary over the potential hazards involved in transporting radioactive materials when in 1971 a leaking canister of liquid molybdenum-99 contaminated passenger-carrying aircraft, baggage, and freight loading ramps in several major cities. In that case, SNM spokesmen point out, the molybdenum-99 was in bulk liquid form and not in the solid form used in the technetium generators. Again, last April, improper packing of 32 curies of an indium-192
source, not used as a radiopharmaceutical, caused radiation exposure to cargo handlers, passengers, and crew. In neither case, however, was there any evidence that anyone was adversely affected by the leaks. Spokesmen for SNM also point out that there is no conclusive evidence that stewardesses who work on flights carrying radioactive materials have experienced a higher than normal incidence of miscarriages, as some have claimed. Along those lines, the Atomic Energy Commission announced on June 14 that 100 flight attendants will start wearing detector badges on flights carrying radioactive cargo to determine just how much radiation passengers and crew receive. Surveys already carried out by AEC in 1973 and reported to the SNM meeting by Dr. Lester Rodgers, director of AEC's division of regulatory standards, indicate the hazard is slight. "The maximum individual dose to passengers that commute frequently or to stewardesses resulting from the transport of radioactive materials aboard passenger aircraft," he says, "is unlikely to be more than 150 millirems per year, and the average radiation dose to those receiving the highest exposure to be about 50 millirems per year. The estimated maximum dose to a pilot is unlikely to be more than about 10 millirems per year and most passengers receive only a small fraction of 1 millirem per year. "These exposvres may be compared to the federal radiation protection guide of 500 millirems per year to an individual member of the public or an annual average dose to the population of 170 millirems per year from all sources of radiation other than medical exposures or exposure from natural background radiation." What troubles most SNM members is that the pilots and flight attendants, in their concern for safety, have lumped the molybdenum-99 generators in the same hazard category as explosives, tear gas grenades, butane lighters, and obviously dangerous chemicals. All of these are occasionally found on the cargo manifests of passenger airlines. Under present law, a pilot can refuse to carry any radioactive packages if he considers them unsafe. In addition, as a radiopharmaceutical travels from manufacturer to physician, its path and progress are regulated by a bevy of agencies, including AEC, the Department of Transportation, the Federal July 1, 1974 C&EN
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Highway Administration, and the Federal Aviation Administration, as well as many local highway, bridge, and tunnel authorities. And, following hearings recently carried out in Congress under the chairmanships of Sen. Warren Magnuson (D.-Wash.) and Rep. Harley Staggers (D.-Tex.), SNM is bracing for still more controls. Any new regulations could only mean increased costs and delays for an already highly regulated industry, according to Dr. J. Calvin Brantley of the Atomic Industrial Forum. "Although this complex and regulated system has operated with an amazing lack of problems for the past 10 years," he says, "various consumer groups, airline personnel, and federal agencies have proposed more reduction in radiation levels by addition of still more weight (through shielding) to already heavy packages, more controls over package preparation and shipment, and removal of packages from passenger-carrying aircraft. "A very recent study shows that under the most restrictive of these regulations, the cost of transportation will add 40 cents to each dollar spent by hospitals for radiopharmaceuticals. The reliability of delivery would simultaneously drop to some as yet unknown figure. But judging from past experience, a 5% reduction means another 30,000 delayed radiodiagnoses and added costs to the patients."
Display method a hit at scientific meeting "County Fair" may replace "Show and Tell" as the primary means of communication at scientific meetings, if the reactions to the "poster sessions" at the recent Biochemistry/Biophysics meeting in Minneapolis are an indication of things to come. For a conventional meeting session, the usual procedure is to hire a hall, furnish it with projectors and projectionist, and give each speaker in turn
some time to show his slides and tell about his work. At the Minneapolis meeting each speaker had 15 minutes; thus' a three-hour session allowed time for a dozen presentations. There were many such sessions. With about 22% of the more than 2300 contributed papers, however, the meeting organizers took a different tack: They put them in poster sessions. For a poster session, a hall still had to be hired. But that hall was assigned to as many as 60 scientists. Each scientist was allocated display space on which to post his charts, graphs, photos, and data. Each scientist had— simultaneously with the other 59—an hour and 15 minutes to discuss his work with anyone who wanted to discuss it. The meeting program indicated the station at which each paper's author could be found. The people attending the session, guided by their programs and books of abstracts, wandered about at will, spending as much or as little time as desired at each station. There was plenty of time to ask questions, plenty of time to copy data, if one cared to. The quality of the presentations varied, just as it did in the ordinary sessions. Some stations drew crowds, some were deserted. But if a particular scientist's work aroused no interest at all and he had to stand forlorn in front of his poster for the whole hour and 15 minutes, that was his tough luck; in a conventional slide session he would have been boring a lot of people who were waiting to hear someone else. Dr. Robert A. Harte, executive officer of the American Society of Biological Chemists, which, with the Biophysical Society of America, cosponsored the Minneapolis meeting, tells C&EN that poster sessions aren't new. Several scientific meetings held in Europe in the past few years have used them for at least part of the presentations. But as far as he knows, the Biochemistry/ Biophysics meeting was the first big scientific meeting in the U.S. to em-
Scientist displays illustrations, discusses work at poster station
Poster sessions draw scientists to discussions at individual stations ploy the poster sessions technique to any great extent. All the contributors to the Minneapolis meeting were asked whether they were willing to take part in the poster session experiment. "We thought it was better to ask than to tell, the first time around," Dr. Harte comments. Finally, 522 papers, divided into 38 topic areas, were scheduled into five half-day poster sessions. "We learned a lot," the ASBC executive says, adding that the participants were "uniformly pleased." The general opinion was that the poster sessions were more difficult but also more gratifying. According to Dr. Harte, the end of a session found the participants "limp and exhausted —but enthusiastic." With poster sessions, the equivalent of 120 papers can be presented in the time and space that, with traditional sessions, would suffice for only 12. Also, there is no requirement for audiovisual devices or their operators—significant items in most meeting budgets. It is necessary, of course, to rent the boards and stands used for the displays. But overall, Dr. Harte says, "the financial advantage is substantial." Poster sessions will play an even larger role in many future scientific meetings, even if they don't entirely do away with the more traditional form. For example, at next year's International Congress of Biophysics, to be held in Copenhagen, only speakers at invited symposia will make their presentations at formal sessions. All the contributed papers will be discussed at informal poster sessions. Poster sessions also will be a major component of the program at the 1975 meeting of the Federation of American Societies for Experimental Biology in Atlantic City. However, the American Chemical Society's department of meetings and expositions says it has no plans for poster sessions at future ACS meetings.
