Tobacco Documents Online

-- - - 22 Ob.Gyn. News August 15-31, 198 ~ 1Says Passive Smoking, Lung Ca Link Still Unproved BALTIMORE - Current evidence does not support a significantly increased risk of lung cancer attributable to pas- sive smoking, Dr. Irving I. Kessler said at a lung cancer update sponsored by the University of Maryland School of Medicine and the American Cancer So- ciety, Maryland division. 'lhe consensus from several studies is that a person heavily exposed to the cigarette smoking of others gets ap- proximately 0.3 cigarette equivalents per day, compared with the actual num- ber of cigarettes smoked by active smokers. Therefore, the passive smoker is exposed to a small percentage of the toxic substances in tobacco smoke, compared with active smokers, said Dr. Dr. Kessler Kessler, professor and chairman of the department of epidemiology and pre-e ventive medicine at the university. Information from several epidemio- logic studies ies suggests that active smok- ers have an eight times greater risk of developing lung cancer than do passive smokers. It must be kept in mind, however, that reliable studies of the possible ad-e vers_e health effects of passive smoking are extraordinarily difficult to do, and those studies that are done may have inherent weaknesses, he said. Epidemiologic studies of passive Randomized controlled trials of pas- sive smoking are practically impossible to do, largely because of the difficulties in quantifying the degree to which a passive smoker is exposed to the harm- ful constituents of cigarette smoke. The constituents of sidestream smoke, which emanates from the burning end of a cigarette, differ widely from that of mainstream smoke, which is inhaled directly by the active smoker. The amount of smoke inhaled varies from person to person, and sidestream smoke is rapidly diluted by such factors as ventilation and room size, he noted during his presentation. Various chemicals often are mea- sured as indexes of exposure to harm- ful substances. Carbon monoxide, nic- otine, ammonia, and nitrosamines are chemicals found in sidestream smoke, but the exact degree of exposure to those constituents is difficult to mea- sure, Dr. Kessler said. Carbon monoxide can be assessed in terms of plasma levels of carboxy- hemoglobin, but carboxyhemoglobin is not specific for tobacco smoke; a num- ber of additional environmental factors may be involved. Nicotine, on the other hand, is specific for tobacco smoke, but its very short half-life makes it difficult to measure, he pointed out. Problems with methodology in many of the published studies on passive smoking and lung cancer limit the con- clusions that can be drawn from them. These include small sample size, inad- equate histopathologic differentiation of the type of cancer involved, and ques- tionable control selection, Dr. Kessler said. ~01 Asyinptomatic Autoimmune Thyroiditis in Depressed WASHINGTON - Depressed women who respond to antidepressants when thyroid medication is added to their treatment regimen may have asymp- tomatic autoimmune thyroiditis, Dr. Victor I. Reus said at the annual con- vention of the Society of Biological Psychiatry. Of 152 consecutive women inpatients with depression, 22% had elevations of either antimicrosomal or antithyroglob- ulin antibodies, an indication of auto-e immune thyroiditis. "These patients may be the subset of depressives who respond to thyroid sup- plementation," said Dr. Reus, director of the behavioral neuroscience service at the University of California, San Francisco, School of Medicine. Dr. Reus is conducting a study to determine the efficacy of antidepres- sants combined with supplemental thy- roid in depressed women with autoim- mune thyroiditis. It is estimated that asymptomatic thy- roiditis occurs in 8% of all women under age 45 and in 12% of those who are older. Antibody screening may be the best way to identify the illness because asymptomatic autoimmune thy- roiditis can only rarely be diagnosed by palpation of the thyroid, Dr. Reus com- mented. Patients with the illness have no dis- tinguishing behavioral characteristics, as compared with other depressives, even though they demonstrate severe pathologic behavior. Fatigue, anxiety, panic, suicidal tendencies, multiple al- lergies, premenstrual syndrome, head- aches, and sleep, libido, and eating disturbances were common in the wom- en who had autoimmune thyroiditis. These women showed some cogni- tive deficiencies; complaints about los- ing their train of thought were the most noticeable. They also had selective memory deficits, but they had no defi- ciency in reaction time or abstract thinking, the investigator said. «,...,...•..o.-:.-..~..r.......~.4..,..~....w~.-~.wrrw~.....ra ... „~ .,....,~e..Y The thyroid-stimulating-hotmone re- sponse to thyrotropin-releasing hor- mone was significantly higher among the 15 autoimmune thyroiditis patients tested than in matched antibody-nega-e tive depressives, suggesting a subclini- cal hypothyroidism. There is evidence that lithium may trigger autoimmune thyroiditis. De- Dr. Dr. Reus pressed patients who have received lith- ium and are not responding to antide- pressants, therefore, should be routinely screened for antithyroid antibodies. Other antidepressant nonresponders also may benefit from antibody screen-. 7 L 0L L VJ4Qz