The New England journal of medicine
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Comparative Study
Pulmonary hazards of smoking marijuana as compared with tobacco.
To compare the pulmonary hazards of smoking marijuana and tobacco, we quantified the relative burden to the lung of insoluble particulates (tar) and carbon monoxide from the smoke of similar quantities of marijuana and tobacco. The 15 subjects, all men, had smoked both marijuana and tobacco habitually for at least five years. We measured each subject's blood carboxyhemoglobin level before and after smoking and the amount of tar inhaled and deposited in the respiratory tract from the smoke of single filter-tipped tobacco cigarettes (900 to 1200 mg) and marijuana cigarettes (741 to 985 mg) containing 0.004 percent or 1.24 percent delta 9-tetrahydrocanabinol. ⋯ Significant differences were also noted in the dynamics of smoking marijuana and tobacco, among them an approximately two-thirds larger puff volume, a one-third greater depth of inhalation, and a fourfold longer breath-holding time with marijuana than with tobacco (P less than 0.01). Smoking dynamics and the delivery of tar during marijuana smoking were only slightly influenced by the percentage of tetrahydrocanabinol. We conclude that smoking marijuana, regardless of tetrahydrocannabinol content, results in a substantially greater respiratory burden of carbon monoxide and tar than smoking a similar quantity of tobacco.
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We estimated the risk of second cancers among 1507 patients with Hodgkin's disease treated at Stanford University Medical Center since 1968. Eight-three second cancers occurred more than one year after diagnosis, as compared with 15.9 expected on the basis of rates in the general population (relative risk, 5.2; 95 percent confidence interval, 4.2 to 6.5). The mean (+/- SE) 15-year actuarial risk of all second cancers was 17.6 +/- 3.1 percent, of which 13.2 +/- 3.1 percent was due to solid tumors. ⋯ The risk of solid tumors did not vary significantly according to treatment category, with the array of neoplasms resembling that previously observed in populations exposed to radiation and in immunosuppressed groups. The risk of leukemia, although elevated after radiation therapy alone (relative risk, 11; 95 percent confidence interval, 1.2 to 38), was much higher after either adjuvant chemotherapy (relative risk, 117; 95 percent confidence interval, 69 to 185) or chemotherapy alone (relative risk, 130; 95 percent confidence interval, 26 to 380). These data suggest that the risk of solid tumors after therapy for Hodgkin's disease continues to increase with time.