Six

INHALATION OF TOXIC SUBSTANCES

Development of Bronchodilator Drugs

As mentioned on p.239, Warner-Lambert Research Institute reported that in 1973, for bronchodilator drug screening, approximately 1800 guinea pigs were subjected to the distress of an aerosol of histamine. Their report to the USDA adds: "If the animals are not protected by a bronchodilator they develop intense bronchospasm and will ultimately expire of asphyxia. These studies must be done in the unanesthetized state in order to determine the endpoint." This experiment is apparently routine at Warner-Lambert since it occurred again in their report for 1976 under the Animal Welfare Act (cf. p.241). In the latter year no less than 3,328 guinea pigs were reported as suffering "pain or distress" in similar tests "for screening and development of new drugs." (USDA/APHIS,1973 & 1976,Warner-Lambert Res.Inst.).


Alternatives: Organ Cultures

Since the drugs concerned have a rapid and direct action on the respiratory system, the situation seems one in which organ culture could replace or at least reduce the use of animals. Organ cultures of rings of rat trachea (windpipe) have been maintained for four to six weeks, and chick, hamster and even human lung tissue has been cultured.

Two experiments using trachea cultures from guinea pigs may be cited. One compared the contrasting effect of spasm-producing histamine and the bronchodilator isoproterenol in live animals and in tissue culture. (Douglas, J., 1977).

The second experiment, from the Harvard School of Public Health, compared the effects of histamine and another spasmogenic agent, acetylcholine, on trachea and lung cultures. The different pharmacological response to these two drugs observed in the cultures was consistent with what had been noted previously in animals. (Drazen, J., 1978).

Furthermore, since it is necessary to know the effects of the drugs on systems of the body other than the lungs, organ cultures can be made, for example, of heart muscle, (Laity, J., 1971), or even of the human vein (Gailer, K., 1971).


Alternative: Human Volunteers

Once the basic safety of drugs has been established, an early use of human volunteers is valuable both in drug development and in clinical testing. It has the great advantage of sidestepping the confusion that often occurs with drug testing in species other than man.

G. Marlin and P. Turner at St. Bartholomew's Hospital, London, investigated the effects of a new drug, rimiterol hydrobromide, potentially useful in the treatment of severe asthma, on seven human subjects who were sufferers from various allergies and hay fever, or were smokers, and who developed bronchial constriction on histamine inhalation. The tests were similar to the Warner-Lambert experiments on rats and showed the protection afforded by rimiterol (and two other comparable drugs) against histamine-induced bronchoconstriction. (Marlin, G., 1975).


Asbestos

Asbestos fibers have been found to produce lung cancer, both in workers exposed to the dust and experimentally in rats, either by inhalation or by inoculation of the fibers into the lungs.


Alternatives

Since these experimental methods are time-consuming (results cannot be expected in less than three years from the initiation of the investigation), Rajan and co-workers obtained human pleura from a lung operation and exposed it to asbestos. Several of the organ cultures lived for up to 8 days, and the asbestos caused marked overgrowth of mesothelial cells, some of which began to invade the underlying tissue (in cancer-like fashion). The researchers comment: "Organ culture systems should be useful in investigating the effect of various fibres, chemicals and perhaps carcinogens in a relatively short period." (Raian, T., 1972).

Andrew Sincock, associated with the same lung research unit in a mining district of South Wales as the above investigators, and his co-worker M. Seabright, carried the work further by exposing cultures of Chinese hamster cells to asbestos fibres. They found that

"Multiple abnormalities at both the chromatid and chromosomal levels were produced in Chinese hamster cells .... It is envisaged that primary cells will be cloned for specific chromosomal abnormalities and then introduced into laboratory animals to ascertain whether or not they induce tumors in vivo." (Sincock, A.,1975).

Although these investigators plan to study the cancer potential of these abnormal cells by injecting them into animals, P. Noguchi and associates at the Bureau of Biologics, U.S. Food and Drug Administration, have shown that chick embryonic skin in organ culture can serve as well as the living mouse does for the identification of cancer cells. The work of two of these associates, J.C. Petricciani and R. O'Donnell, was partly supported by the Lord Dowding Fund (London). (Noguchi, P.,1978).

Tobacco and Smoking

Dog-smoking experiments received much publicity a decade ago when Drs. Auerbach and E. Hammond, who forced 86 beagles to inhale the combustion products of 415,000 cigarettes, sometimes for as long as 2 1/2 years, announced that 12 of the dogs had developed lung cancer. (Altman, L.,1970, p.1).

Human smokers in never-ending supply demonstrate the same results, but, for the animals, there is no let-up. The grotesque experiments keep pace with the relentless promotional advertising of the cigarette manufacturers, now chiefly aimed at the young. The Louisville Courier-Journal, June 18, 1978, (Russell,J.,1978) describes a study under Dr. Lester Bryant at the University of Kentucky Tobacco and Health Research Institute which uses two dozen or so stump-tailed monkeys. Strapped into chair, the monkey wears a mask which covers the nostrils while a bit holds the mouth partly open. A machine delivers smoke at 40-to 50-second intervals and the animal must inhale the smoke if it is to breathe at all. Some of these former inhabitants of the jungles of Vietnam and Thailand are forced to smoke from one to three packs of cigarettes a day.

Alternatives

An alternative series of experiments, not inflicted on animals and more pertinent to humans, have been described by C. Leuchtenberger and associates. They exposed human lung cultures to marijuana and tobacco smoke in a smoking machine and demonstrated abnormal cell growth and chromosome disturbances, precursors of cancer. (Leuchtenberger, C.,1973),

Another link between smoking and cancer has been demonstrated in humans - without resorting to animal experiments - by E. Yamasaki and B. Ames. They concentrated the urine of 21 nonsmokers, and that of 7 smokers who inhaled and smoked ordinary (non low-tar) cigarettes. They subjected the concentrates to a resin adsorption technique, then to an assay by the Salmonella bacteria test for the presence of mutagens (pre-cancer substances). They found the following: none of the nonsmokers had mutagens in their urine; all of the smokers did have them. Four more smokers were tested: two of these who did not inhale had no mutagens in the urine, and of the other two, who inhaled but smoked low-tar cigarettes, one had no mutagens in the urine but the other did. (Yamasaki, E., 1977).

For the record, it should be noted that although smoking relatively low-tar and nicotine cigarettes as against ordinary ones results in slightly lower death rates, those rates are still far higher than the mortality of people who never smoked regularly. (Am.Cancer Soc., 1979).

Chromates

Hexavalent chromium compounds, particularly chromates, are occupational hazards to those employed in the chromeplating and chromate-producing industries. They have been implicated, through the inhalation of the dust and vapor, in diseases of the respiratory tract, including bronchopneumonia, chronic bronchitis and tracheitis, and are thought to be responsible for the high prevalence of bronchiogenic cancer among chromium workers. (NAS Com.on Medical .... 1974, p.42).


Alternatives in vitro

Although studies of chromate toxicity have been made in the whole animal, an increasing number are being done by means of organ culture, since thin slices of trachea will remain alive in suitable media - in vitro - for as long as six weeks. M. Mass and B. Lane at the State University of New York (Stony Brook), removed tracheas from rats in a non-recovery operation and studied the effect of chromates both on the freshly excised tissue and on tracheal rings grown in culture for up to two weeks. They tested different concentrations of the metal, and observed through the microscope that cells were dying at concentrations of chromate in the 10 - 100 microgram/milliliter range, far below the concentration which stopped the ciliary motion of mucus. They concluded from this and other evidence that the chromates did not act primarily as "ciliostats" but that the chemical injury might be occurring at the cell membrane. (Mass, M., 1976).


Radionuclides

The proliferation of nuclear power systems has sparked numerous experiments subjecting animals such as beagle dogs and hamsters to the inhalation of radionuclides. For a discussion of these experiments, see p.138, Chap.VIII, "Radiation."


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